Acoustic And Non-Acoustic Performance Coal Bottom Ash Concrete [1st ed.] 9789811574627, 9789811574634

Citation preview

SPRINGER BRIEFS IN APPLIED SCIENCES AND TECHNOLOGY

Shahiron Shahidan Nurul Izzati Raihan Ramzi Hannan

Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete

SpringerBriefs in Applied Sciences and Technology

SpringerBriefs present concise summaries of cutting-edge research and practical applications across a wide spectrum of fields. Featuring compact volumes of 50 to 125 pages, the series covers a range of content from professional to academic. Typical publications can be: • A timely report of state-of-the art methods • An introduction to or a manual for the application of mathematical or computer techniques • A bridge between new research results, as published in journal articles • A snapshot of a hot or emerging topic • An in-depth case study • A presentation of core concepts that students must understand in order to make independent contributions SpringerBriefs are characterized by fast, global electronic dissemination, standard publishing contracts, standardized manuscript preparation and formatting guidelines, and expedited production schedules. On the one hand, SpringerBriefs in Applied Sciences and Technology are devoted to the publication of fundamentals and applications within the different classical engineering disciplines as well as in interdisciplinary fields that recently emerged between these areas. On the other hand, as the boundary separating fundamental research and applied technology is more and more dissolving, this series is particularly open to trans-disciplinary topics between fundamental science and engineering. Indexed by EI-Compendex, SCOPUS and Springerlink.

More information about this series at http://www.springer.com/series/8884

Shahiron Shahidan Nurul Izzati Raihan Ramzi Hannan •

Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete

With Contributions by Noorwirdawati Ali, Norazura Muhamad Bunnori, Sharifah Salwa Mohd Zuki

123

Shahiron Shahidan Faculty of Civil Engineering and Built Environment Universiti Tun Hussein Onn Malaysia Johor, Malaysia

Nurul Izzati Raihan Ramzi Hannan Faculty of Civil Engineering and Built Environment Universiti Tun Hussein Onn Malaysia Johor, Malaysia

ISSN 2191-530X ISSN 2191-5318 (electronic) SpringerBriefs in Applied Sciences and Technology ISBN 978-981-15-7462-7 ISBN 978-981-15-7463-4 (eBook) https://doi.org/10.1007/978-981-15-7463-4 © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 This work is subject to copyright. All rights are solely and exclusively licensed by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Singapore Pte Ltd. The registered company address is: 152 Beach Road, #21-01/04 Gateway East, Singapore 189721, Singapore

Foreword

In developing a great contribution to the local community in producing an environmentally friendly and sustainable product, coal bottom ash (CBA) has been used extensively in concrete production to reduce negative environmental impacts that are caused by the excessive production of CBA. However, many of the researchers, contractors and employees of the Public Work Department are still not emphasized the beneficial usage of CBA in concrete production especially when it comes to the application of CBA in the assessment of acoustic performance of concrete. This book provides useful information on the acoustic performance on CBA concrete involving fundamental concepts of noise emission, principle of noise control, source location, analysis methods as well as the application of acoustic performance of concrete. Consequently, this book will encourage both contractor and the Public Work Department to utilize the CBA in concrete production and deepen their understanding on the assessment of acoustic performance of concrete. Nurul Izzati Raihan Ramzi Hannan Faculty of Civil Engineering and Built Environment Universiti Tun Hussein Onn Malaysia Johor, Malaysia

v

Preface

The development of new technology and rapid development in many countries have led to various types of pollution, especially acoustic pollution in urban areas. Furthermore, the huge production of coal bottom ash (CBA) is treated as waste and often placed into impoundment ponds, silos or landfills, which has contributed to environmental issues. The usage of CBA in concrete production in reducing railway noise pollution reduces the environmental pollution. This research presents the acoustic and non-acoustic performance for a new concrete product that consists mainly of CBA. Grade 30 MPa concrete was cast with varying replacement percentages (0–100%) of CBA as fine aggregate replacement in concrete mixture. The specimens were cured for periods of 7, 28 and 90 days. The non-acoustic performance of CBA concrete demonstrated similar or even better performance than normal concrete by conducting compressive strength, splitting tensile strength, water absorption, water permeability and ultrasonic pulse velocity. The increase in CBA percentage in the concrete mixture has affected the compressive strength and splitting tensile strength of the sample which were lower than that of control concrete. CBA concrete can be recommended as good concrete due to its absorption properties. Based on the sound test conducted according to ISO 11654: 1997, it was found that CBA concrete can be classified as Class D (absorption). Class D materials are able to absorb more than 30% of sound by conducting impedance tube and reverberation time. In addition, the noise reduction coefficient (NRC) performance for CBA concrete addresses more than 35% of the absorbed railway sound. CBA concrete showed an improvement in acoustic properties

vii

viii

Preface

compared to normal concrete as it is able to reduce up to 3.74 dB of the existing railway noise level, while normal concrete can only reduce up to 1.94 dB of the existing noise level. Shahiron Shahidan Nurul Izzati Raihan Ramzi Hannan Faculty of Civil Engineering and Built Environment Universiti Tun Hussein Onn Malaysia Johor, Malaysia

Acknowledgements

I am deeply grateful to thank Jamilus Research Center, Faculty of Civil Engineering and Built Environment, Universiti Tun Hussein Onn Malaysia (UTHM), for enabling me to publish this book. I would like to express my gratitude to the many people who saw me through this book and those who provided support, talked things over, read, wrote, offered comments, allowed me to quote their remarks and assisted in the editing, proofreading and design this book. Last but not least, I beg for forgiveness from all people who have been with me during the editing process of this book.

ix

Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1 2

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

3 3 5 5 7 9 10 13

3 Environmental Noise . . . . . . . . . . . . . . . . . . 3.1 Environmental Noise . . . . . . . . . . . . . . 3.2 Acoustic Qualities and Noise Control . . 3.2.1 Noise Barrier as Sound Absorber References . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

15 15 17 18 23

2 Coal Bottom Ash (CBA) . . . . . . . . . . . . . . 2.1 Coal Bottom Ash . . . . . . . . . . . . . . . . 2.2 Properties of Coal Bottom Ash (CBA) . 2.2.1 Fineness Modulus . . . . . . . . . . 2.2.2 Specific Gravity . . . . . . . . . . . . 2.2.3 Bulk Density . . . . . . . . . . . . . . 2.2.4 Chemical Composition . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . .

4 Acoustic Performance Testing of CBA Concrete . . . . . . . . . 4.1 Impedance Tube . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 Sound Absorption Coefficients (SAC) and Noise Reduction Coefficients (NRC) . . . . . . . . . . . . . . 4.2 Reverberation Time . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

....... .......

25 25

....... ....... .......

27 28 32

5 Acoustic Performance of CBA Concrete . . . . . . . . . 5.1 Sound Absorption Coefficient of CBA Concrete . 5.2 Noise Reduction Coefficient (NRC) . . . . . . . . . . 5.3 Reverberation Time (Rating Class) . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . .

33 33 36 40 45

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

xi

xii

6 Mechanical Properties of CBA Concrete . . 6.1 Coal Bottom Ash Concrete Specimens . 6.2 Compressive Strength . . . . . . . . . . . . . 6.3 Tensile Splitting Strength . . . . . . . . . . 6.4 Water Absorptions . . . . . . . . . . . . . . . 6.5 Ultrasonic Pulse Velocity . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . .

Contents

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

. . . . . . .

7 General Conclusion and Recommendation on CBA and Noise . 7.1 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1.1 Acoustic Performance of Coal Bottom Ash Concrete . 7.1.2 Non-acoustic Performance of Coal Bottom Ash Concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Recommendation for Future Work . . . . . . . . . . . . . . . . . . . .

. . . . . . .

47 47 48 52 56 59 62

.... .... ....

65 65 65

.... ....

66 68

. . . . . . .

. . . . . . .

. . . . . . .

Symbols and Abbreviations

dB dBA Am Pm kPa Pa a api aw as m mm kg S W MW GW % Hz ACAA ASTM BS CBA CBAC CO2 DOE EHS EN EQA ERL

Decibel A weighted decibels Ante meridiem (Before noon) Post meridiem (After noon) Kilo Pascal Pascal Sound absorption coefficient Arithmetic mean value of sound absorption coefficient Weighted absorption coefficient Sabine’s absorption coefficient Metre Millimetre Kilogram Second Watt Megawatt Gigawatt Per cent Hertz American Coal Ash Association American Society for Testing and Materials British Standard Coal bottom ash Coal bottom ash concrete Carbon dioxide Department of Environment Environmentally hazardous substance European Norm Environment Quality Act Express Rail Line

xiii

xiv

ETS FBA FGD IPP ISO KTMB MPa MRT MSW NRC NRDs PCC RHA RT SAC SCC SEM SF SLM SPAD SW TNB UPV WBA XRF

Symbols and Abbreviations

Electric Train Service Fine bottom ash Fuel gas desulphurization Independent power producers International Standards Organization Keretapi Tanah Melayu Berhad Mega Pascal Mass rapid transit Municipal solid waste Noise reduction coefficient Noise reduction device Portland cement concrete Rice husk ash Reverberation time Sound absorption coefficient Self-compacting concrete Scanning electron microscopy Silica fume Sound level meter Suruhanjaya Pengangkutan Awam Darat Schedule waste Tenaga Nasional Berhad Ultrasonic pulse velocity Washed bottom ash X-Ray fluorescent

Chapter 1

Introduction

Acoustic quality of closed spaces is an increasing concern all around the world, since noise pollution is one of the main nowadays pollutants especially in urban areas. Noise is one of the most negative impacts of transport affecting the quality of the environment. It affects a large number of people as it often causes annoyance and irritation which affect various human activities. Noise pollution had been treated as a public health concern by World Health Organization. Environmental noise pollution Caused by transportation noise in the cities has caused 1 million years of human healthy life are lost yearly. Furthermore, the environmental pollution also caused by the huge production of coal bottom ash (CBA) is treated as waste and often placed into impoundment ponds, silos or landfills, which has contributed to environmental issues. Usages of CBA in concrete production in reducing railway noise pollution reduce the environmental pollution. The demand for usage of trains among the public faces several challenging issues such as noise and vibration issues in residential areas as reported. Noise from railway services has affected human daily activities such as difficulty sleeping. Besides that, babies and the elderly were especially disturbed by the noise generated by trains. This also be supported by Fawwaz [1] where found the residents included babies and the elders that lived nearby train station faced the problem which is difficulties to sleep early due to the noise from train service which is close to their neighbourhood. Considering the increase in noise emissions from railway services in residential areas, environmentally friendly materials are needed. Therefore, based on the issue highlighted, this study has selected CBA as absorptive material in reducing noise pollution. CBA is considered as a waste product which pollutes the environment. However, this issue can be solved through noise reduction devices. One of the effective ways to reduce noise is by using noise barriers. Usually, noise barriers are made of wood, plastic, concrete, metal, and other materials which can be expensive. Based on the review, concrete barriers are commonly used for noise barriers which require high maintenance cost. Thus, the usage of CBA as sound absorptive material © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_1

1

2

1 Introduction

in concrete production is more economical. Coal bottom ash has a porous texture which makes it suitable for sound absorption. Porous materials qualify as good absorber in reducing noise level. Good absorber material could affect the higher sound absorption coefficients (SAC).

Reference 1. A. Fawwaz, B. Ahmad, N. Pollution, C. Study, T. Melati, Noise pollution, case study: Taman Melati (2013)

Chapter 2

Coal Bottom Ash (CBA)

Coal bottom ash (CBA) is waste product that has been produced during the coal combustion for current generation. It is porous particle, angular and irregular in shape. Besides that, some of the particles were spherical and semi-spherical. There were also agglomerate particles and some CBA particles with interlocking characteristics compared than fine aggregate which is round, smooth and uniform in size. CBA has the potential to be used in concrete production. This is due to the material properties such fineness modulus, specific gravity and bulk density of coal bottom ash which is comparable to that of fine aggregate. The usage of coal bottom ash in the construction industry has been increasing along with increasing waste production by power plant stations due to the increasing demand for electricity. This research also conducted several test to obtain the material properties of CBA. The workability of CBA concrete mixtures decreased with the increasing amount of CBA used. This is due to the fineness modulus of CBA which is lower than fine aggregate. This usually results in higher water absorption.

2.1 Coal Bottom Ash Coal is formed from organic rock which is content with heavy carbon resources and known as the main source used for the generation of electricity worldwide. It is mainly used to generate steam for industrial operations and electricity generation. Besides, coal is an advantageous fuel source option for energy suppliers due to its low price and it being most abundantly available. Major power producer countries such as the USA and China use coal as the main source of fuel [1]. Increasing demand for electricity every year, several coal-fired thermal power plants have been set up in large numbers in the country to meet consumer demand [2]. The demand for coal for electricity generation increased sharply from an estimated 6.03 million tonnes in 2000 to between 19 and 20 million tonnes per annum by 2010 © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_2

3

4

2 Coal Bottom Ash (CBA)

[3]. It is also expected to increase by more than 30 million tonnes per annum by 2020. This, in turn, produces large volumes of coal ash [4]. Coal ash is coal combustion waste which is derived from inorganic mineral constituents in coal and unburned organic material. It is a hazardous waste where the toxic remains of coal burning in power plants are full of chemicals that cause cancer, developmental disorders and reproductive problems [5]. There were several types of waste material produced during coal combustion which can be categorised as coal ash. Fly ash, coal bottom ash (CBA), boiler slag and flue gas desulphurisation (FGD) sludge are wastes produced during the combustion process in coal-fired power plants. According to the American Coal Ash Association (ACAA), 80% from the collected coal ash in the furnace is fly ash which is collected at electrostatic precipitators. Meanwhile, another 20% of coal ash contains bottom ash and boiler slag [6]. Figure 2.1 shows the production of coal ash at coal-fired thermal power plants. Coal bottom ash consists of coarse ash particles that are too heavy and large to be carried up in the flue gas into smoke stacks during the combustion process. It settles down at the base of the furnace and is collected from the bottom of the furnace [8]. Bottom ash is removed by means of high pressure water jets and is later transported by sluiceways either to a dumping pond or to a decant basin for dewatering, crushing and stockpiling for removal or use. However, it is not a wellknown product choice like fly ash because bottom ash is still treated as a waste and often placed in impoundment ponds, silos or landfills. Sometimes, it is used in asphalt mixes. Due to pyrite contamination however, it is undesirable for building main roads. Usually, coal ash was disposed into ash ponds especially CBA, which is simply disposed of on land where it is continually being disposed due to the increased volume

Fig. 2.1 Production of coal ash at coal-fired thermal power plant [7]

2.1 Coal Bottom Ash

5

production of coal ash during electricity generation. Ash pond is impoundments used to store or dispose the ash during the coal combustion process, where coal ash is sluiced in the form of slurry that contains 80% of water to ash ponds. According to Chindaprasirt [9], it is reported that CBA is the most types of ash which are disposed into landfills. The huge amount disposal of CBA has contributed to environmental pollution such as the pollution of Emory and Clinch Rivers in Kingston, Tennessee. The disposal of CBA have its disadvantages to the environment, when the pond site is not lined with concrete will cause the heavy metals tends to leach into natural ground water and contamination to the environmental [10]. According to Gottlieb [11], the water in the ponds contained heavy metals such as arsenic and elevated levels of other toxic metals such as lead, thallium, barium, cadmium, chromium, mercury and nickel. It is also had been classified as hazardous waste due to its toxicity. This issues related to industrial waste product management. Therefore, in this studies are focusing on ways to reduce negative environmental impact and save cost by reusing coal bottom ash for other purposes. Although large quantities of fly ash have already been utilised in the construction industry as a partial cement replacement and/or mineral additive in cement production, the usage of coal bottom ash is limited due to its relatively high unburned carbon content and different mechanical properties compared to fly ash.

2.2 Properties of Coal Bottom Ash (CBA) The properties of CBA as fine aggregate replacement in the concrete mixture were determined through several tests which are particle size distribution, specific gravity test, bulk density test, SEM and XRF test.

2.2.1 Fineness Modulus The fineness modulus of aggregates can be obtained from the sum of total cumulative weight percentage at each specified series of sieves that are divided by 100 as shown in Eq. 5.1. The fineness modulus values of fine aggregate and CBA were 3.0 and 2.79, respectively. The CBA particles used in this study were categorised as medium fine aggregate as the grain size varies between 0.6 and 0.2 mm [12]. The CBA used in this study has a fineness modulus between 2.3 to 3.0 as outlined in BS 882:1992 [13]. According to Ajagbe et al. [14], specimens with fineness modulus in the specified range of 2.3–3.0 will pose workability problems. Meanwhile in Table 2.1, a comparison of fineness modulus values of CBA based on previous research report is shown. The fineness modulus of CBA obtained from this study complied with BS EN 12620:2013 [15]. It is important to determine the fineness modulus to find out whether or not CBA can be used as fine aggregate replacement in the concrete mixture. If the fineness modulus of CBA is more than 3.0,

6

2 Coal Bottom Ash (CBA)

Table 2.1 Fineness modulus of CBA reported by previous researchers Specimen

Fine aggregate

CBA

Author

[15]

[17]

[18]

[19]

[20]

[21]

[22]

This study

Fineness modulus

2.3–3.0

2.80

3.65

2.36

2.51

1.37

1.45

2.79

it is considered unsuitable for use as fine aggregate replacement. Based on the ASTM C-33-93 standard, materials which fail to meet the fineness modulus requirements can be accepted on condition that concrete made using similar fine aggregates from the source demonstrates an acceptable performance [16]. Meanwhile, Table 2.2 presents the percentage difference of fineness modulus of CBA between the one obtained from the present study and those reported by previous researchers. The results indicate that the fineness modulus of CBA in this research (3.0) was 7.53% lower than that of fine aggregate as specified in BS EN 12620. It also shows that the fineness modulus of CBA collected from Tanjung Bin plant 2.79 was lower compared to the fineness modulus obtained by Ghafoori and Bucholc [17] and Syahrul et al. [18], which is 0.36% and 30.82%, respectively. Nevertheless, the percentage difference of fineness modulus of CBA in this study was 15.41%, 10.04%, 50.90% and 48.17% higher than the fineness modulus values obtained by Kim and Lee [19], Naganathan et al. [20], Singh and Siddique [21] and Ghosh et al. [22], respectively. The difference percentage in the fineness modulus of CBA is due to difference in power plant stations. Previous studies had utilised CBA from other power plants such as TNB electric power plant station in Perak [18], Kapar thermal power station, Selangor [20], and a thermal power plant located in Kolkata [22]. Therefore, CBA is an acceptable fine aggregate replacement material since its fineness modulus is lower than that of fine aggregate and meets the standard requirements. Besides, from the observations conducted in this study, CBA can be described as a dark grey fine aggregate-like material that has a grain size similar to coarse or fine grains. In addition, the higher the value of fine modulus of CBA has showed the coarser the CBA particles. Due to the higher fine modulus of CBA can affect concrete properties including workability and finishability. The lower fineness modulus of aggregate results in more paste and making the concrete easier to finish. Table 2.2 Percentage difference for fineness modulus of CBA between obtained from the present study and those reported in standard and previous researchers

Researcher

Fineness modulus

This study

Percentage change (%)

[15]

3.0

2.79

[17]

2.8

[18]

3.65

30.82

[19]

2.36

−15.41

[20]

2.51

−10.04

[21]

1.37

−50.90

[22]

1.45

−48.17

7.53 0.36

2.2 Properties of Coal Bottom Ash (CBA)

7

2.2.2 Specific Gravity Specific gravity test is the ratio of the density of aggregate particles to the density of water. Material density is measured by weight and volume, while the specific gravity of CBA is measured using a pycnometer as shown in Fig. 2.2a, b. In this study, the specific gravity of fine aggregate and CBA was determined based on BS EN 12620:2013. As expected, the density values of CBA were lower than the density of fine aggregate. The specific gravity of fine aggregate is 2.81, while the specific gravity of CBA is 2.21. According to Lee et al. [23], the porous structure and popcorn-like particles of CBA result in a lower specific gravity. This also causes it to be easily degraded under loading or compaction. In addition, Abubakar et al. [24] also concluded that the porous structure of CBA leads to a specific gravity value as low as or even lower than 3.00, which is the specific gravity of fine aggregate as specified in BS EN 12620:2013. The specific gravity of CBA usually ranges from 1.39 to 2.98, but the recorded values of the specific gravity of CBA from previous research were as low as 1.99 or as high as 2.39, as presented in Table 2.3. The specific gravity of CBA differs from one power plant station to another power plant station. Thus, it can be concluded that the specific gravity of CBA collected from Tanjung Bin power plant station is lower than the values obtained from previous studies. The difference in the specific gravity values of CBA is dependent on coal type, origin of coal sources and the handling process which includes the disposal and

Fig. 2.2 Specific gravity testing; a fine aggregate and b CBA

Table 2.3 Comparison between specific gravity values of CBA obtained from the present study and the one reported in previous researcher Specimen

Fine aggregate CBA

Author

BS EN 12620

Specific Gravity 2.70

[24]

[25]

[20]

[26]

[28]

This study (Tanjung Bin, Malaysia

1.39–2.98 1.99 2.98 2.06 2.39 2.21

8

2 Coal Bottom Ash (CBA)

storage method of coal ash at every power plant station. In Tanjung Bin power plant, the main sources of coal come from countries such as Indonesia, China and Sarawak. Meanwhile, Table 2.4 presents the percentage difference of specific gravity values of CBA obtained from the present study and those from previous studies. The results indicate that the specific gravity of CBA in this research was 22.17% lower than the specific gravity of fine aggregate as specified in BS EN 12620:2013 where the specific gravity of fine aggregate stipulates as 2.70. Meanwhile, the specific gravity value of CBA collected from Tanjung Bin plant was 34.84 and 5.84% lower compared to the values obtained by Naganathan et al. [20] and Marto and Makhtar [27], respectively. This proves that CBA collected from different locations has different specific gravity values. The percentage difference of specific gravity of CBA in this study was 6.79% and 9.95% higher than the values obtained by Khalid et al. [26], and Muhardi et al. [25], respectively. Marto and Makhtar [27] and Muhardi [25] used the same CBA from Tanjung Bin power plant station, and no significant difference was observed for the specific gravity of CBA. The specific gravity is different depending on whether it is taken near or far away from the slurry disposal point. According to Tong et al. [28], difference in disposal location could influence the physical properties of CBA. The specific gravity of CBA varies depending on the distance where the material is collected from the slurry disposal point. Since the specific gravity of CBA in this study ranges between 1.30 and 2.98 and is lower than the specific gravity of fine aggregate, it is suitable to be used in the concrete mixture. However, several factors can affect the specific gravity value of CBA. The low specific gravity is due to lower iron oxide (Fe2 O3 ) content in chemical compositions. This can be proven by comparing the iron oxide content of CBA of previous studies, as shown in Table 2.6 that been presented next subsection. Besides that, the lower specific gravity of CBA is also due to its vesicular texture as shown in Fig. 2.3. It can be concluded that specific gravity is an important material property because some of the deleterious particles are lighter than good aggregate. Besides that, the specific gravity of materials helps in the identification of material change or possible contamination [29]. In Portland cement concrete, the specific gravity of materials is usually used for the determination of percentage of voids and solid volume of aggregate in computations of yields. In addition, it is also required for the concrete mixture design. Table 2.4 Percentage difference specific gravity values of CBA obtained from the present study and those reported by previous researchers

Author

Specific gravity

This study

Percentage change (%)

BS EN 12620:2013

2.70

2.21

22.17

[20]

2.98

34.84

[25]

1.99

−9.95

[26]

2.06

−6.79

[27]

2.39

5.84

2.2 Properties of Coal Bottom Ash (CBA)

9

Vesicular texture

Fig. 2.3 Vesicular texture of coal bottom ash

2.2.3 Bulk Density One of the factors that affect concrete density is the density of materials used in the concrete mixture. Concrete density varies according to the amount and density of materials used. Therefore, the material density of fine aggregate and CBA used in this study was tested according to BS 812:1967. From the test, the density of fine aggregate in this study was found to be 1223.78 kg/m3 , whereas the density of CBA was 641.03 kg/m3 , as presented in Table 2.5. The lower density of CBA is due to the presence of porous particles. According to Lee et al. [31], the bulk density values for fine CBA, medium CBA and coarse size CBA are 1286 kg/m3 , 988 kg/m3 and 1040 kg/m3 , respectively. It can be observed that the bulk density of CBA varies depending on the size of CBA. In this study, the CBA used in the concrete mixture passes through a 5 mm sieve and is retained on a 75 µm sieve. Thus, it can be categorised as medium size CBA. The difference between the density obtained in this research and that obtained by Lee et al. [31] is 35%. However, based on the previous studies the bulk density of bottom ash usually ranges between 560 and 1286 kg/m3 , which is the bulk density of CBA in this study obtained was 641.03 kg/m3 . However, the density of CBA also varies depending on the location of the power plant. According to Naganathan et al. [20], the bulk density of CBA obtained from

10 Table 2.5 Density of CBA and fine aggregate obtained from the present study and those reported by previous researches

2 Coal Bottom Ash (CBA) Specimen

Researcher

Density (kg/m3 )

CBA

[30]

560

[31]

Fine: 1286 Medium: 988 Coarse: 1040

[20]

Kapar CBA: 890

[17]

Loose: 928 Compacted:1000

[32]

Bituminous:1038 Sub-bituminous: 767.28

This study

Sub-bituminous and loose density: 641.03

Fine aggregate

Loose: 1223.78

Kapar Thermal Power Plant Station, Malaysia, is 890 kg/m3 . Meanwhile, Wearing et al. (2004) found that the bulk density of CBA from Tarong power plant station is 560 kg/m3 . The difference in findings could be due to the different physical properties of coal such as the degree of pulverisation, firing temperature and type of furnace used in power plant stations. In addition, the sources of coal used to generate electricity can also cause the bulk density of CBA to vary. As stated in ASTM D 4254, the bulk density of CBA is different for bituminous coal and sub-bituminous coal. Tanjung Bin power plant uses sub-bituminous coal as the main source for electricity generation. Therefore, the particle density of CBA in Tanjung Bin power plant has a percentage difference of 16% from density of CBA (sub-bituminous coal) as specified in ASTM D 4254. Based on the density of CBA, it can be deduced that CBA also has the potential to be used as lightweight aggregate in concrete mixtures due to its particle density which is less than 1120 kg/m3 . The lower density and specific gravity of CBA indicate the presence of porous particles and a higher water absorption capacity.

2.2.4 Chemical Composition The X-ray fluorescence (XRF) test was used to determine the chemical composition of fine aggregate and CBA collected from Tanjung Bin power plant. In addition, fine aggregate in the form of natural fine aggregate was used. The results of the chemical composition of fine aggregate and CBA are shown in Table 2.6. Table 2.6 shows the comparison between the chemical composition of fine aggregates and CBA based on findings from previous studies. According to Muhardi et al. [25], Naganathan et al. [20], Khalid et al. [26], and Marto and Makhtar [27], the major components of CBA for three thermal power plants were silica, aluminium and iron oxide. The findings in this study were similar as

6.44 12.40

6.83

26.45

51.00

26.10

30.30

This study (Fine aggregate)

46.60

[27]

37.10

17.00

43.56

46.60

[26]

20.75

23.00

This study (CBA)

9.78

[20]

Fe2 O3

SiO2 + Al2 O3 + Fe2 O3 ≥70 (Class F)

42.70

[25]

Al2 O3

ASTM C618 requirement

SiO2

Chemical content (%)

0.32

12.14

8.31

0.68

11.10

9.80

CaO

0.48

9.3 0.40

1.27

–

1.84

3.31

–

1.64

TiO2

>10 class C

1.34

0.50

–

0.96

K2 O

–

1.37

–

1.26

–

3.20

1.54

MgO

–

1.26

Max 5.0

0.62

–

1.04

P2 O5

–

0.67

0.62

–

0.29

Na2 O

Table 2.6 Chemical composition of fine aggregate and CBA obtained from different power plant stations

–

0.61

Max 1.5

0.30

0.09

1.22

SO3

–

0.90

–

1.11

–

0.13

–

–

0.19

BaO

Max 5.0

–

–

1.80

–

ZnO

–

0.22

–

0.19

–

–

–

SrO

–

–

0.17

–

0.64

–

–

–

–

–

LOI (%)

2.2 Properties of Coal Bottom Ash (CBA) 11

12

2 Coal Bottom Ash (CBA)

the chemical analysis conducted shows that CBA contains silicon dioxide (43.56%), aluminium oxide (26.45%), iron oxide (12.14%) and calcium oxide (9.30%), with small amounts of magnesium oxide (1.26%), sodium oxide (0.61%), potassium oxide (1.27%), etc. CBA is classified as Class F ash because the sum of SiO2 + Al2 O3 + Fe2 O3 exceeded 70%, as shown in Table 2.6. The chemical composition of CBA can be attributed to the use of sub-bituminous coal or lignite which contains a significant amount of calcium and other alkaline elements such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). Alkaline earth metals have only two electrons in their outermost electron layer. These elements have been categorised as alkaline because of the basic nature of the compounds they form with oxygen. CBA also has cementitious properties in addition to pozzolanic properties. It requires a cementing agent such as Portland cement, quicklime or hydrated lime that reacts with water. However, according to ASTM C618, CBA derived from bituminous coal or anthracite coal often has low calcium content and high iron content. Besides that, the sum of SiO2 + Al2 O3 + Fe2 O3 for this type of ash exceeds 90%. According to Siddique and Cachim (2018), this type of coal ash has pozzolanic properties only when it comes in contact with water. The percentage value of iron oxide for CBA is related to the variation in specific gravity values. According to Abubakar and Baharudin [24], low iron oxide content in CBA resulted in a lower specific gravity. Previous research indicated that the presence of iron oxide affects the specific gravity of CBA as presented in Table 2.3 from previous subsection and Table 2.6. Besides that, the chemical analysis also showed that the values of magnesium oxide (MgO), sodium oxide (Na2 O) and sulphur trioxide (SO3 ) were lower than the values stated in ASTM C618. The minimum content of SO3 and MgO according to ASTM C618 should be less than 5.0%, while Na2 O should not exceed 1.5%. Meanwhile, the chemical composition of fine aggregate used in this study consists of silicon dioxide (51.00%), aluminium oxide (6.83%), iron oxide (0.32%), calcium oxide (0.48%), with small amounts of potassium oxide (0.40%), etc. The results show that fine aggregate contains a higher content of silica dioxide compared to CBA. The difference in chemical composition between fine aggregate and CBA is the absence of magnesium oxide (MgO) and sodium oxide (Na2 O) in fine aggregate. Although both materials have almost the same chemical composition, the percentage outcome differs. Besides that, the loss of ignition (LOI) of CBA cannot be traced during the test. However, previous research reported that the LOI of CBA is 0.64% (Khalid et al. 2013). CBA with higher LOI is not suitable to be used in mortar or concrete. According to British Standards, the LOI of CBA should not exceed 7% in order for it to be used in cement mortar or concrete. Bruce and Mathew (2013) stated that the mass percentage values for each element may vary between 2 to 5% from plant to plant. Other factors that also influence the variation in the chemical composition of CBA include coal source and coal ash quality.

References

13

References 1. M. Samsudin, W. Rahman, Power Generation Sources in Malaysia: Status and Prospects for Sustainable Development Akademia Baru Power Generation Sources in Malaysia: Status and Prospects for Sustainable Development (2016) 2. M. Singh, R. Siddique, Effect of coal bottom ash as partial replacement of sand on properties of concrete. J. Cleaner Prod. 112, 620–630 (2013) 3. A.R. Mohamed, L.K. Teong, Energy policy for sustainable development in Malaysia, in The Joint International Conference on “Sustainable Energy and Environment (SEE),” 028(December 2004) (2010), pp. 940–944 4. J.E. Oh, J. Moon, M. Mancio, S.M. Clark, P.J.M. Monteiro, Utilization of Yatagan power plant fly ash in production of building bricks, in IOP Conference Series: Earth and Environmental Science (2010) 5. A. Kockwood, L. Evans, Ash in lungs. How breathing coal ash is Hazardous to your health. Earth Justice, 150–190 (2012) 6. M. Singh, R. Siddique, Effect of coal bottom ash as partial replacement of sand on workability and strength properties of concrete. J. Cleaner Prod. 112, 620–630 (2016) 7. B.W. Ramme, E. We, M.P. Tharaniyil, Coal Combustion Product Utilization Handbook 3rd edn. (We Energies, 2013) 8. H. Kurama, M. Kaya, Usage of coal combustion bottom ash in concrete mixture. Constr. Build. Mater. 22(9), 1922–1928 (2008) 9. P.C. Chindaprasirt, W.C. Jaturapitakkul, U. Rattanasak, Comparative study on the characteristics of fly ash and bottom ash geopolymers. Waste Manage. 29(2), 539–543 (2009) 10. A.U. Abubakar, K.S. Baharudin, Potential use of Malaysian thermal power plants. Int. J. Sustain. Constr. Eng. Technol. 3(2), 25–37 (2012) 11. B. Gottlieb, S. Gilbert, L. Gollin Evans, Coal ash: the toxic threat to our health and environment (2010) 12. M.P. Koirala, E.B.R. Joshi, Construction sand, quality and supply management in infrastructure project. Int. J. Adv. Eng. Sci. Res. 4, 2349–4824 (2017) 13. British Standard 882, British Standard for Testing Concrete: Specification for Aggregates from Natural Sources for Concrete (British Standard Institution, 1992) 14. W.O. Ajagbe, M.A. Tijani, I.S. Arohunfegbe, M.T. Akinleye, Assessment of fine aggregates from different sources in Ibadan and environs for concrete production. Niger. J. Technol. Dev. 15, 7–13 (2018) 15. British Standard EN 12620-2, British Standard for Aggregate Concrete (British Standard Institution, 2013) 16. ASTM C 33, Standard Specification for Concrete Aggregates (United States, American Society of Testing Material) 17. N. Ghafoori, J. Bucholc, Properties of high calcium dry bottom ash concrete. ACI Mater. J. 94(2), 90–101 (1997) 18. M. Syahrul, M. Sani, F. Muftah, Z. Muda, The properties of special concrete using washed bottom ash ( WBA ) as partial sand replacement. Int. J. Sustain. Constr. Eng. Technol. 1(2), 65–76 (2010) 19. H.K. Kim, H.K. Lee, Use of power plant bottom ash as fine and coarse aggregates in highstrength concrete. Constr. Build. Mater. 25(2), 1115–1122 (2011) 20. S. Naganathan, N. Subramaniam, K.N. Mustapha, Bin. , Development of brick using thermal power plant bottom ash and fly ash. Asian J. Civil Eng. 13(2), 275–287 (2012) 21. M. Singh, R. Siddique, Compressive strength, drying shrinkage and chemical resistance of concrete incorporating coal bottom ash as partial or total replacement of sand. J. Cleaner Prod. 112, 620–630 (2014) 22. A. Ghosh, A. Ghosh, S. Neogi, Reuse of fly ash and bottom ash in mortars with improved thermal conductivity performance for buildings. Heliyon 4(11), e00934 (2018) 23. H.K. Lee, H.K. Kim, E.A. Hwang, Utilization of power plant bottom ash as aggregates in fiber-reinforced cellular concrete. Waste Manage. 30(2), 274–284 (2010)

14

2 Coal Bottom Ash (CBA)

24. A.U. Abubakar, K.S. Baharudin, Properties of concrete using Tanjung Bin power plant coal bottom ash and fly ash. Int. J. Sustain. Constr. Eng. Technol. 3(2), 56–69 (2012b) 25. Muhardi, A. Marto, K.A. Kassim, A.M. Makhtar, L. Foo wei, Y. Shin lim, Engineering characteristics of, 1117–1129 (2010) 26. N. Khalid, N. Sidek, M.F. Arshad, The California Bearing Ratio (CBR) value of road sub-base aggregate mixed with bottom ash. Malays. J. Civil Eng. 121(1), 112–121 (2013) 27. A. Marto, M. Ahmad Mahir, Geotechnical Properties of Tanjung Bin Coal Ash Mixtures for Backfill Materials in Embankment Construction (January 2011) (2015) 28. Y.G. Tong, H. Abu Bakar, K.A. Mohd. Sari, U. Ewon, M.N. Labeni, N.F.A. Fauzan, Effect of urban noise to the acoustical performance of the secondary school’s learning spaces—a case study, in Batu Pahat IOP Conference Series: Materials Science and Engineering vol. 271 (2017), p. 012029 29. B. Arumugam, Effect of specific gravity on aggregate varies the weight of concrete cube. SSRG Int. J. Civil Eng. (SSRG-IJCE), 1(August), 1–9 (2014) 30. C. Wearing, J.D. Nairn, C. Birch, An assessment of Tarong bottom ssh for use on agricultural soils Dev. Chem. Eng. Miner. Process. 12(5–6), 531 543 (2004) 31. H.K. Lee, H.K. Kim, E.A. Hwang, Utilization of power plant bottom ash as aggregates in fiber-reinforced cellular concrete. Waste Manag.30(2), 274–284 (2010) 32. ASTM D 4254, Standard specification test methods for minimum index density and unit weight of soils and calculation of relative density, United States, American Society of Testing Material

Chapter 3

Environmental Noise

Due to the rapid development in urban areas, environmental pollution such as noise pollution is getting worse due to increasing traffic congestion. Noise created by transportation can influence human health by causing loss of hearing, insomnia, headache and other diseases when they are exposed to noise pollution for a long time. Based on previous research, noise created by railways is getting increasing attention among researchers. Nowadays, the railway system is one of the main modes of public transportation which is popular among the public due to its efficiency. However, the rapid development of rail transportation has also caused discomfort such as noise pollution to residents living in the city, especially those who live close to railway stations. However, this issue can be solved through noise reduction devices. One of the effective ways to reduce noise is by using noise barriers.

3.1 Environmental Noise Nowadays, noise pollution is one of the most negative impacts that affect the quality of the environment. Even though the aspects noise less considered when designing and during the construction building. Sound can be defined as atmospheric or airborne vibration perceptible to the ear, while noise is an energy that is transmitted by pressure waves and air. Noise is one of the most negative impacts of transport affecting the quality of the environment. It has been defined as any unwanted sound created by human activities that is considered harmful or detrimental to human health which causes annoyance and imitation that affect quality of life and human activities [1]. Environmental noise refers to noise that affects humans, and it mostly refers to outdoor sound. According to Sakar [2], there are several types of environmental noise such as transportation noise, noise at the workplace and firing of crackers. However, exposure from transportation sector can interfere and it is also considered as an important environmental public health issue [3]. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_3

15

16

3 Environmental Noise

Table 3.1 Comparative sound level [5] Common sounds

Sound level (dB) Subjective evaluation

Air raid siren at 50 ft. (threshold of pain)

120–130

Intolerable

Maximum level in audience at rock concerts

100–120

Extremely noisy

On platform by passing train

90–100

Very noisy

Typical airliner 3 miles from take-off (directly under 80–90 flight pain) On sidewalk by passing bus

70–80

On sidewalk by passing typical automobile

60–70

Busy office

50–60

Typical suburban area background

40–50

Library, bedroom at night, isolated broadcast study

30–40

Leaves rustling

20–30

Just audible

10–20

Threshold of hearing

0

Loud

Moderate to quiet Quiet to very quiet Almost silent

Traffic noise, railway noise and aircraft noise are categorised as transportation noise. Due to increasing demand, transportation is now a common cause of noise pollution. People who are continuously exposed to 85–90 dB can experience progressive hearing loss [4]. Noise can also be hazardous depending on the duration where humans are exposed to loud noise [5]. Table 3.1 presents a list of common sounds and their respective sound levels. Based on Table 3.1, noise caused by road traffic, rail traffic and aircraft noise was identified as one of the most urgent areas that needs to be addressed as the sound level is between 70 and 100 dB which is classified as loud to extremely noisy [6]. In recent years, a lot of researches have been conducted to identify the source of noise pollution. Transportation noise has been shown to be a predominant source of noise pollution. Table 3.2 shows previous research studies on the types of transportation noise. Table 3.2 summarises the outcomes from previous research on transportation noise. The majority of the findings point to the fact that transportation noise is the main source of noise pollution. It is also the major contributor to the level of annoyance experienced by the community living close to the noise sources. According to Foraster et al. [12], people who have been exposed to transportation noise may have higher risks of obesity which could further lead to cardiometabolic diseases and so on. High noise exposure areas could affect the health of residents by causing headaches, hypertension, and loss of sleep/insomnia and hearing problems [9].

3.2 Acoustic Qualities and Noise Control

17

Table 3.2 Previous study on the transportation noise No

Author

Types of noise

Outcome

1

[7]

Aircraft noise

The aircraft noise affected the communities living close to airport boundaries

2

[8]

Railway noise

Even though urban rail provides convenience to many people, it still causes noise pollution

3

[9]

Aircraft noise

Residents from the noise exposure area experience a high level of noise stress, hypertension, headache, general disturbance, loss of sleep/insomnia and hearing problems than residents from the control area

4

[10]

Road traffic

20.5% of women and 17.9% of men (364 adults in total) were highly annoyed by road traffic noise

5

[11]

Transportation noise (road traffic, railway and aircraft noise)

Noise levels corresponding to annoyance by indoor noise in Korea were 45 dB (road traffic noise), 51 dB (railway noise) and 53 dB (aircraft noise)

6

[12]

Road traffic

Long-term exposure to road traffic noise may increase the risk of obesity and constitute a pathway towards cardiometabolic diseases

7

[13]

Railway noise

The L eq of the four different Keretapi Tanah Melayu (KTM) stations is between 60 and 70 dB, and the noise gradually reduces away from the sources

3.2 Acoustic Qualities and Noise Control Acoustic Quality is defined as the degree of sounds which allow the ear to distinguish the sound that have pitch and loudness based on individual requirements. Term of acoustic quality is refer to the set of characteristic that related to sound pressure level, duration of the sounds and as well related to the surrounding environment that closely related to reverberation time. Reverberation time is allowed to qualify the space regarding its potentialities for the desired use. Besides, acoustic quality is a perceptual reaction to the sound of a product that reflects the listeners reaction to how acceptable the sound; the more acceptable, the greater the sound quality. Therefore, noise controls are often closely related with the concept of acoustic quality. In order to obtain the acoustic quality to protect the health and quality of life of the residents living close to railroads, noise reduction devices such as noise barriers can be used. Noise barriers mainly obstruct sound waves from travelling from railroads

18

3 Environmental Noise

Table 3.3 Active and passive ways for reducing noise Method of reducing noise Description

Sources

Active

Noise reduced by modifications of noise sources

• Modification to railway vehicles and tracks

Passive

Noise reduced by the absorption • Noise tunnels of noise using exterior structures • Barriers • Absorptive skirt on railway vehicles • Noise windows

to its surroundings. Besides, it is also useful for reducing rolling noise, horn noise and so on. Based on, Maffei [14] also stated that noise barriers are the main solution for noise mitigation. They often provide good insulation. Meanwhile, Clairbois and Garai [15] found that noise barriers and all related devices that act on airborne sound propagation (road/rail covers, claddings and added devices) are collectively called noise-reducing devices (NRDs). Active and passive ways can be used in order to reduce the noise level of rail transports due to different buildings and technical noise arrangements [16]. Table 3.3 shows active and passive ways for reducing noise emitted into the environment. There are many ways to mitigate noise pollution produced by railway transportation. However, Pultznerová and Ižvolt [17] concluded that it is not possible to apply both passive and active noise arrangement for the reduction of noise emission produced by rail transport. Thus, passive noise arrangement is effective for reducing noise without modification to the train vehicle (noise source).

3.2.1 Noise Barrier as Sound Absorber Noise barriers are also known as sound wall, sound berms, sound barriers or acoustical barriers which can be formed from earth mounds or “berms” along the road, from high, vertical walls or from a combination of earth berms and walls [18]. Besides that, noise barriers are solid obstructions built between the railway tracks and residential areas. This approach is the most common approach for reducing noise impact which has been proven to be one of the best ways to reduce the noise levels produced during railway operation [19]. However, several criteria of noise barriers need to be fulfilled in order to provide effective noise reduction. According to Bjeli [20], the designs of noise barriers can be divided into two groups, namely acoustic properties and non-acoustical properties of noise barriers. Material selection, location, dimension and shape of noise barriers are the main requirements that need to be considered in order to obtain the acoustic properties. Non-acoustical aspects also include engineering and environmental requirements, as well as safety and maintenance of noise barriers. Both

3.2 Acoustic Qualities and Noise Control

19

Fig. 3.1 Alteration of noise paths using noise barriers (edited from [20])

acoustic and non-acoustic properties and barrier material are very important factors [20]. An effective noise barrier should be high enough and long enough to break the line of sight between the sound source and the receiver as shown in Fig. 3.1. Figure 3.1 shows a simplified sketch that explains the mechanism of noise produced by the mode of transportation when a noise barrier is placed between the source of noise and the receiver. From Fig. 3.1, it can be observed that noise is transmitted from the source directly to the receiver when there is no barrier between the noise source and the receiver. However, when the noise barrier is placed between the noise source and the receiver, the noise path is redirected to path A. The transmitted noise A is originally destined to follow path A, but it is instead diffracted downwards towards the receiver. The straight line noise path from the source to the top of the barrier, originally destined in the direction of A without the barrier, is now diffracted downward towards the receiver as shown in Fig. 3.2. This phenomenon is called the “loss” of acoustical energy. The noise barrier placed between the noise source and the receiver interrupts the original straight line path. A portion of the original noise energy is reflected or scattered back towards the source depending on noise barrier material and surface treatment of the noise barrier wall. Some of the noise portions are absorbed by the noise barrier material, transmitted through the noise barrier or diffracted at the top edge of the noise barrier. However, the transmitted noise reaches the receiver with a “loss” of acoustical energy because a certain portion is redirected and converted into heat. Thus, the noise level is reduced significantly. Another requirement that needs to be considered in order to produce an effective noise barrier is barrier material. According to Bjeli [20], the two main types of barrier materials are reflective barriers and absorptive barriers. There are several types of material that are commonly used in the production of noise barriers such as concrete, wood, metals (steel and aluminium), transparent material and earth berms. However, most of the existing noise barriers in the industry are expensive, require high

20

3 Environmental Noise

Fig. 3.2 Reflection, absorption and transmission of sound [22]

maintenance cost, have a high rate of expansion in hot weather and can sometimes affect the privacy of residential areas. Therefore, material selection for noise barriers is usually dictated by aesthetics, durability, cost and maintenance. Besides that, a good sound-absorbing material must have the ability to absorb as much sound waves as possible with minimal reflection [20]. Sound incident on a material is reflected, absorbed and transmitted, as indicated in Fig. 3.2. The sound absorption coefficient of noise barriers depends on the material used. According to Barron [21], absorption of sound energy occurs due to the reflection of all surfaces even though some materials are highly absorbent. The sound absorption coefficient (SAC) is defined as the ratio of absorbed energy to incident energy noting the amount of sound being absorbed by a material [20]. The coefficient can be viewed as a percentage of sound being absorbed where 1.00 refers to complete absorption (100%), whereas 0.01 (1%) refers to minimal absorption [23]. However, several factors such as type of material, thickness, density and porosity of materials affect the quality of sound absorptive material. Material type is a major factor that influences the sound absorption coefficient of a material. According to Sikora and Turkiewicz [24], several types of materials can be used as sound-absorbing materials including porous, fibrous, honeycomb and granular materials. Numerous researchers have discovered the use of various types of materials for noise barrier production as presented in Table 3.4. However, porous material is an effective material which can be used as a sound absorber. This is because energy can be dissipated in porous material which causes air to lose momentum. Changes in direction and vicious drag are also involved in the movement of air particles in pores [25]. Figure 3.3 shows the movement of air particles through a narrow constriction. When a sound wave enters porous material, the local flow

3.2 Acoustic Qualities and Noise Control

21

Table 3.4 Previous studies on the types of material used as sound absorptive material No Author Materials

Type of materials Outcome

1

[24]

Polypropylene Foamed polystyrene Gravelite Rubber Mineral wool High silica sand

Granular

2

[27]

Kenaf (Hibiscus cannabinus) Fibrous

Higher kenaf fibre has resulted lower SAC

3

[28]

Sugarcane waste

Good acoustic performance was found at 1.2–4.5 kHz with an average absorption coefficient of 0.65

4

[29]

Coconut husk Banana pseudo stem Sugar cane husk

Noise reduction coefficients (0.80 and 0.92 dB), (0.75 and 0.78 dB) and (0.50 and 0.35 dB) each at 800 and 440 Hz, were found from coconut husk, sugarcane husk and banana pseudo stems, respectively

5

[30]

Corn husk

Acoustic absorption was not affected by the increase of layers, while the acoustic absorption peak gradually moves to lower frequency

6

[31]

Recycled polyurethane foam

7

[32]

Steel slag

Porous

The shape of sound absorption characteristics depends on the structure of granular material, irrespective of its type. Granular polypropylene, gravelite and foamed polystyrene may be regarded as narrow-band sound-absorbing materials due to their frequency band (below one octave), in which the greatest sound absorption is observed

These recycled materials have good sound-absorbing properties and could be used as practical substitutions for existing materials in current and future applications Porosity of the specimens can reach above 50%; the compressive strength and average sound absorption coefficient (SAC) values of sintered specimens were above 3.0 MPa and 0.47, respectively (continued)

22

3 Environmental Noise

Table 3.4 (continued) No Author Materials 8

[33]

Recycled sugarcane waste

Type of materials Outcome Material studied had good absorbing properties. There was also good agreement between the measured values of the absorption coefficient

Fig. 3.3 Viscous drag mechanism of absorption in porous material

velocity increases, the direction of flow changes and friction converts sound energy into heat. This scattering is essential to the performance of acoustic absorbers fashioned from materials such as glass fibres, polymers and metal foams. In order to achieve a large number of interactions, the pressure wave must penetrate deeply enough into the material so as to not immediately be reflected to the surrounding air. According to Kuczmarski and Johnston [26], as pore size decreases, less energy is transferred into the solid structure and more is reflected from the surface, making the material less useful as an acoustic absorber. Even though many technologies can be implemented in the railway industry in order to reduce existing noise levels, different technologies result in different impacts and result in response to different environments and systems. Noise barriers should be properly designed according to acoustic and non-acoustic aspects in order to perform more efficiently. Acoustical designs include barrier material, barrier locations and dimensions and shapes. Besides that, good sound-absorbing material could have ability to absorb as much as and transmit more sound waves and reflects as minimal as could it be. The higher noise reduction coefficient of the material that been used to qualify as a good absorber. In this case, the porous material is considered as a good sound absorptive material due to the presence of voids which plays an important role as they act as the medium of sound wave dissipation.

References

23

References 1. E. Murphy, E.A. King, H.J. Rice, Estimating human exposure to transport noise in central Dublin, Ireland. Environ. Int. 35(2), 298–302 (2009) 2. S. Sakar, Assessment of noise level in suburban railways of West Bengal (2013) 3. C. Clark, S.A. Stansfeld, The effect of transportation noise on health and cognitive development: a review of recent evidence (2007) 4. S.C. Kou, C.S. Poon, M. Etxeberria, Influence of recycled aggregates on long term mechanical properties and pore size distribution of concrete. Cem. Concr. Compos. 33(2), 286–291 (2011) 5. F. Florentina, Road traffic noise: a study of Skåne region, Sweden (2008) 6. J. Xie, Road traffic noise mapping in Guangzhou using GIS and GPS. Appl. Acoust. 87, 94–102 (2015) 7. N. Gualandi, L. Mantecchini, Aircraft noise pollution: a model of interaction between airports and local communities. Int. J. Mech. Syst. Sci. Eng. 2 (2008) 8. M.I. Mohd Masirin, N.F. Johari, N.H. Nordin, A.H. Abdullah, M.I. Azis, A field study on urban rail transits in city of Kuala Lumpur: passenger views on train noise and vibration. Appl. Mech. Mater. 773–774, 839–844 (2015) 9. K.A. Alkaabi, Studying the effects of aircraft noise around Abu Dhabi international airport, UAE on the surrounding residential and work places. Civ. Eng. Urban Plann. 4(2) (2017) 10. C. Sieber, M.S. Ragettli, M. Brink, T. Olaniyan, R. Baatjies, A. Saucy et al., Comparison of sensitivity and annoyance to road traffic and community noise between a South African and a Swiss population. Environ. Pollut. 241, 1056–1062 (2018) 11. H.K. Park, Indoor noise annoyance due to transportation noise. J. Asian Archit. Build. Eng. 7581, 149–155 (2018) 12. M. Foraster, I.C. Eze, D. Vienneau, E. Schaffner, A. Jeong, H. Héritier et al., Long-term exposure to transportation noise and its association with adiposity markers and development of obesity. Environ. Int. 121, 879–889 (2018) 13. F. Selamat, F.L. Abdul Rahim, Developing noise maps to monitor railway train noise at four different Keretapi Tanah Melayu (KTM) station. Int. J. Autom. Mech. Eng. 15(2), 5377–5388 (2018) 14. L. Maffei, Influence of the design of railway noise barriers on soundscape perception (2012) 15. J. Clairbois, M. Garai, The European standards for roads and railways noise barriers: state of the art 2015, pp. 45–50 (2015) 16. DuPont, Acoustic: different kinds of materials for traffic noise barriers. Urban Acoust. (2009) 17. A. Pultznerová, L. Ižvolt, Structural modifications, elements and equipment for railway noise reduction. Procedia Eng. 91(TFoCE), 274–279 (2014) 18. L.A. Al-Rahman, R.I. Raja, R.A. Rahman, Attenuation of noise by using absorption materials and barriers: a review. Int. J. Eng. Technol. 2(7), 1207–1217 (2012) 19. S. Amares, E. Sujatmika, T.W. Hong, R. Durairaj, H.S.H.B. Hamid, A review: characteristics of noise absorption material. J. Phys. Conf. (2017) 20. M. Bjeli, M. Vuki, A. Petrovi, M. Pljaki, Analysis of materials used for production of noise protection barriers, in 23rd National Conference and 4th International Conference Noise and Vibration, vol. 10, pp. 101–103 (2012) 21. M. Barron, Auditorium Acoustics and Architectural Design, 2nd edn. (2009) 22. R.W. Floyd, The absorption of sound by materials: a method of measurement with results for some materials (2007) 23. T.G. Hawkins, Studies and research regarding sound reduction materials (2014) 24. J. Sikora, J. Turkiewicz, Sound absorption coefficients of granular materials. Mech. Control 29(3), 149–157 (2010) 25. S. Vasudev, S. Atri, Sound and solid surface. Appl. Acoust. 72(4), 221–225 (2014) 26. M.A. Kuczmarski, J.C. Johnston, Acoustic Absorption in Porous Materials, pp. 1–20 (2011) 27. M.J. Saad, I. Kamal, Kenaf core particleboard and its sound absorbing properties. J. Sci. Technol. 23–34 (2010)

24

3 Environmental Noise

28. A. Putra, Y. Abdullah, H. Efendy, W.M. Farid, R. Ayob, M.S. Py, Utilizing sugarcane wasted fibers as a sustainable acoustic absorber, in Malaysian Technical Universities Conference on Engineering and Technology 2012, MUCET 2012. Part 2 Mechanical and Manufacturing Engineering, vol. 53, pp. 632–638 (2013) 29. R.D.T. Mercado, R.M. Ureta, R.J.D. Templo, The potential of selected agricultural wastes fibers as acoustic absorber and thermal insulator based on their surface morphology via scanning electron microscopy. World News Nat. Sci. 20, 129–147 (2018) 30. X. Tang, X. Zhang, H. Zhang, X. Zhuang, X. Yan, Corn husk for noise reduction: robust acoustic absorption and reduced thickness. Appl. Accoust. 134, 60–68 (2018) 31. R. Rey, J. Alba, J.P. Arenas, V. Sanchis, Sound absorbing materials made of recycled polyurethane foam (2011) 32. P. Sun, Z. Guo, Sintering preparation of porous sound-absorbing materials from steel slag. Trans. Nonferrous Met. Soc. China 25, 2230–2240 (2015) 33. C. Othmani, M. Taktak, A. Zain, T. Hantati, N. Dauchez, T. Elnady, Acoustic characterization of a porous absorber based on recycled sugarcane wastes. Appl. Accoust. 120, 90–97 (2017)

Chapter 4

Acoustic Performance Testing of CBA Concrete

The acoustic performances of CBA concrete have been determined by evaluating the sound absorption coefficient by using impedance tube (small scale) and in reverberation room (large scale). Impedance tube test is used for determination of the sound absorption coefficient concrete specimen. Meanwhile, reverberation time refers to the time needed for a steady-state sound pressure level in an enclosed space.

4.1 Impedance Tube Impedance tube test is used for determination of the sound absorption coefficient concrete specimen. According to BS 10534-1:2001 [1], the sound absorption coefficient of CBA concrete can be obtained by using normal sound incidence. The evaluation of the standing wave pattern of plane waves in a tube can determine normal sound incidence. Meanwhile, the impedance tube testing can also be used to determine the acoustical surface impedance or surface admittance of sound-absorbing materials. Impedance tube testing is a very efficient tool for determining the sound absorption coefficient, the sound reflection factor and the impedance ratio of specimens under laboratory conditions. This apparatus works with a software named PULSE Acoustic Material Testing [2]. In this test, small specimens of the absorber material (concrete specimens) are needed. Therefore, cylindrical concrete specimens with two different of diameter, namely 100 mm (for low frequency) and 29 mm (for high frequency), with a constant thickness of 100 mm were tested.

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_4

25

26

4 Acoustic Performance Testing of CBA Concrete

The range for low frequency is between 250 and 1500 Hz, whereas the range for high frequency is between 1500 and 6000 Hz. The sound absorption coefficient is an important parameter. It is the ratio of sound power entering the surface of a concrete specimen without returning to the incident sound power for a plane wave at normal incidence. This test was conducted at an acoustic laboratory using the impedance tube and the AFD1001 software. Figure 4.1 shows the setup for the impedance tube test. The procedure for software analysis is fully described as follows: 1. The data collected is processed by a software called AFD100. The software is set up and ready to run the data analysis. 2. The distance between the microphone and the distance between specimens is inserted.

Fig. 4.1 a Impedance tube machine and b calibration process of microphone and c impedance tube test in progress

4.1 Impedance Tube

27

3. The calibration process with normal position is conducted at this stage. 4. The microphone is located at the top part of the impedance tube. 5. The impedance tube is calibrated, and the microphone is switched to the opposite direction. 6. The position of the microphones is switched between each other. 7. The measurement of low frequency and high frequency begins, and the results are recorded.

4.1.1 Sound Absorption Coefficients (SAC) and Noise Reduction Coefficients (NRC) The sound absorption coefficient (SAC) for every material varies with frequency. It is a common practice to list the coefficient of a material at frequencies of 125, 250, 500, 1000, 2000 and 4000 Hz. The SAC is denoted by a symbol, α. The higher the coefficient number, the better the absorption. The noise reduction coefficient (NRC) was commonly employed to compare the acoustic behaviour of various materials. NRC value is calculated by averaging the measured sound absorption coefficients at various frequencies [3]. It is calculated at frequencies of 250, 500, 1000 and 2000 Hz, and the NRC value is rounded off to the nearest multiple of 0.05 [4]. It provides a simple quantification of sound absorption which is used as an index of the sound-absorbing efficiency of materials. According to Mahzan et al. [5], NRC is normally used as a simplified descriptor for convenience because it consists of a single number. The NRC has no physical meaning and is a useful means of comparing similar materials [6]. According to Mahzan et al. [5], NRC is normally used as a simplified descriptor for convenience, which it is more convenient to be used because NRC value is a single number than using several of data depending on the frequency. The NRC has no physical meaning, and it is a useful means of comparing similar materials [6]. The coefficient range was in between zero to one which is zero means total reflection and one indicates total absorption. In this study, the NRC was determining as shown in Eq. (4.1). NRC = where α Absorption coefficient.

α250 + α500 + α1000 + α2000 4

(4.1)

28

4 Acoustic Performance Testing of CBA Concrete

4.2 Reverberation Time Reverberation time refers to the time needed for a steady-state sound pressure level in an enclosed space to decay by 60 dB. It is important for building designers to obtain the reverberation time of a space suitable for its intended purpose. The volume and the types of absorbent or reflective surfaces within a space can influence the reverberation time. Hard surfaces such as concrete have long reverberation times that could result in an unpleasant or “echo” acoustic environment. Thus, it is vital to obtain the optimum amount of acoustic material for an area. Acoustic materials and areas are important factors that can affect background noise. The quantity of acoustic absorbent material used can also affect reflected sound. Reverberation test results can be used for comparison purposes and design calculation related to room acoustics as well as noise control. The following equation can be used to calculate the absorption coefficient within a reverberant room: RT60 =

0.161V A

(4.2)

where RT: Reverberation time in s (reverb time) V: Volume of the room (m3 ) A: Equivalent absorption surface or area (m2 ) = Sa S: Total surface area of the room a: Average absorption coefficient of the room = s1 a1 +s2 a2s+···+sn an s: Absorbing surface area (m2 ) a: Absorption coefficient. In this research, the reverberation room test was carried out in a mini chamber at the Faculty of Architecture, Planning and Surveying, Universiti Technologi MARA (UiTM), Shah Alam. This chamber design was based on BS EN ISO 140-1:1998 [7] is used for the measurement of small scale specimen size ±1 m2 . The quadrangular chamber has a total surface area of ±30 m2 and a total volume of 11.8 m3 . The arrangement for test specimens in the mini chamber during the test is shown in Fig. 4.2. The test panels measuring 0.30 m × 0.22 m × 0.1 m of each design mixture were placed at the centre of the test chamber. Figure 4.3 shows how all the perimeter surface area except the top surface of the panels was sealed completely with reflective material.

4.2 Reverberation Time

Fig. 4.2 Specimens arrangement in the mini chamber

Fig. 4.3 All the perimeter surface area of specimen was sealed with reflective material

29

30

4 Acoustic Performance Testing of CBA Concrete

The measurement of reverberation time was done in second (s), starting from the measurement of an empty chamber followed by an occupied chamber containing CBA concrete acoustic panels. The measurement of reverberation time should be done with different microphone positions which are at least 1.5 m apart, 2 m from any sound sources and 1 m from any room surface and the test specimens as stated in BS EN ISO 354:2003 [8]. Figure 4.4 shows the schematic drawing and microphone positions inside the chamber, while Fig. 4.5 show the process of the reverberation time test. The sound in the reverberation room was generated by a sound source with an omnidirectional radiation pattern. A random pink noise was used with a full blast sound power of 93.9 dB (which is obtained from the highest noise level that has been recorded during noise monitoring at railway station) inside the closed chamber.

Fig. 4.4 Schematic drawing and microphone positions

4.2 Reverberation Time

31

Microphone position

Noise sources

Specimen

(a)

(b) Fig. 4.5 a CBA concrete specimen inside the mini chamber, b signal analyser

32

4 Acoustic Performance Testing of CBA Concrete

References 1. British Standard EN ISO 10534-1, British Standard for Acoustic: Determination of Sound Absorption Coefficient and Impedance in Impedances Tubes. Method Using Standing Wave Ratio (British Standard Institution, 2001) 2. Brüel & Kjær, Product Data—PULSE Acoustic Material Testing in a Tube Type 7758 (2007) 3. K.A. Jayaraman, Acoustical absorptive properties of nonwovens, MSc Thesis, North Carolina State University, Raleigh, NC, 2005 4. I.N. Nasidi, L.H. Ismail, E.M. Samsudin, M. Firdaus, A. Khodir, The effect of different fibre length and different urea formaldehyde (UF) content on sound absorption performance of empty fruit bunch (EFB). MATEC Web Conf. 150(January) (2018) 5. S. Mahzan, A.M.A. Zaidi, M.N. Yahya, M. Ismail, Investigation on sound absorption of rice-husk reinforced composite, in Proceedings of MUCEET2009 (2009), pp. 19–22 6. E.D.H.F. Liu, B.G. Liptak, D.H.F. Liu, H. Roberts, C. Howard, Noise Pollution (Boca Raton, CRC Press, 1999) 7. British Standard EN ISO 140, British Standard for Acoustics Measurement of Sound Insulation in Buildings and of Building Elements. Requirements for Laboratory Test Facilities with Suppressed Flanking Transmission (British Standard Institution, 1998) 8. British Standard EN ISO 354, British Standard for Acoustic Measurement of Sound Absorption in a Reverberation Room (British Standard Institution, 2003)

Chapter 5

Acoustic Performance of CBA Concrete

In this chapter, all data obtained on the acoustic properties of CBA concrete was analysed and discussed. The acoustic properties of CBA concrete can be determined through the impedance tube test and the reverberation time test. From the tests conducted, the sound absorption coefficient, noise reduction coefficient and reverberation time of CBA concrete were determined. The sound absorption coefficient of CBA concrete was measured from low and high frequency. Tables and graphs are used to present the data and the effect of incorporating CBA as fine aggregate replacement towards acoustic properties was assessed. Based on the acoustic tests conducted, the sound absorption coefficient of CBA concrete is higher than that of normal concrete. From the impedance tube test, the highest noise reduction coefficient recorded was 0.35 when 100% of CBA was used to replace fine aggregate. Meanwhile, normal concrete has a noise reduction coefficient of 0.20. It was observed that the sound absorption coefficient increases when the percentage replacement of fine aggregate in the concrete mixture increases.

5.1 Sound Absorption Coefficient of CBA Concrete The impedance tube test was carried in order to determine the acoustic properties of CBA concrete, namely sound absorption and reflection coefficients. The apparatus consisted of two arrays of tubes measuring 100 and 28 mm in diameter for acoustic measurement in the low frequency range (150–1500 Hz) and high frequency range (2000–6000 Hz), respectively, as presented in Tables 5.1 and 5.2. Table 5.1 presents the sound absorption coefficient for the low frequency range, meanwhile Table 5.2 presents the sound absorption coefficient for the high frequency range taken on concrete specimens that containing all percentage replacements of CBA in the concrete mixture. According to Brüel & Kjaer [1], the wideband acoustic plane wave source measurement chamber held a couple of microphone receptacles © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_5

33

34

5 Acoustic Performance of CBA Concrete

Table 5.1 Sound absorption coefficient for CBA concrete at low frequency range Frequency (Hz)

250

500

750

1000

1250

1500

CBAC0

CBA replacement (%) 0

0.07

0.11

0.16

0.16

0.11

0.17

CBAC10

10

0.10

0.09

0.12

0.12

0.09

0.23

CBAC20

20

0.09

0.11

0.17

0.17

0.16

0.22

CBAC30

30

0.08

0.09

0.13

0.13

0.1

0.24

CBAC40

40

0.10

0.10

0.19

0.19

0.15

0.22

CBAC50

50

0.11

0.11

0.22

0.22

0.13

0.23

CBAC60

60

0.10

0.12

0.23

0.23

0.13

0.24

CBAC70

70

0.12

0.13

0.24

0.24

0.11

0.25

CBAC80

80

0.10

0.13

0.23

0.23

0.12

0.26

CBAC90

90

0.09

0.15

0.26

0.18

0.11

0.27

CBAC100

100

0.11

0.20

0.18

0.29

0.09

0.28

Table 5.2 Sound absorption coefficient for CBA concrete at high frequency range Frequency CBA 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 (Hz) replacement (%) CBAC0

0

0.17

0.37

0.23

0.18

0.13

0.20

0.10

0.35

0.26

0.16

CBAC10

10

0.23

0.61

0.24

0.26

0.22

0.24

0.17

0.30

0.41

0.38

CBAC20

20

0.22

0.61

0.23

0.24

0.22

0.26

0.18

0.34

0.43

0.36

CBAC30

30

0.24

0.65

0.29

0.26

0.23

0.29

0.19

0.34

0.46

0.39

CBAC40

40

0.22

0.66

0.31

0.26

0.26

0.29

0.20

0.43

0.43

0.39

CBAC50

50

0.23

0.71

0.32

0.27

0.25

0.30

0.21

0.42

0.47

0.40

CBAC60

60

0.24

0.72

0.33

0.26

0.25

0.30

0.22

0.42

0.48

0.42

CBAC70

70

0.25

0.71

0.35

0.26

0.26

0.31

0.23

0.44

0.46

0.43

CBAC80

80

0.26

0.72

0.37

0.31

0.27

0.34

0.24

0.44

0.5

0.45

CBAC90

90

0.27

0.73

0.39

0.34

0.28

0.36

0.26

0.45

0.53

0.44

CBAC100 100

0.28

0.79

0.44

0.36

0.29

0.37

0.27

0.46

0.54

0.45

and an adjustable specimen holder. The results were analysed using the AFD-1001 Acoustic Tube Transfer Function software in the ratio of the amplitude of the reflected wave to the incident wave. During the impedance tube test, the sound is generated by a loud speaker at one end of the tube and the concrete specimen is placed at the other end of tube; thus, the sound absorption ability is measured in the plane wave. A sound wave passes through the material where a portion of the sound wave hits the reflective wall and changes direction. The sound abortion coefficient is the absorbed friction on the concrete specimens.

5.1 Sound Absorption Coefficient of CBA Concrete

35

However, absorption of sound is increased not only due to the friction of sound on the concrete specimen but also because the reflected and direct waves occur. The absorption coefficient as a function of frequency is dependent upon the mass and stiffness of the panel and is therefore determined by the specific design configuration. In general, the absorption coefficients for a basic panel are greater at low frequencies than at high frequencies [2]. Meanwhile, Table 5.2 shows the sound absorption coefficient value for CBA concrete at different percentage replacements of CBA as fine aggregate in the concrete mixture at high-frequency regions. The sound absorption coefficient of CBA was found to increase as the tested frequency increases. At 250 Hz, the sound absorption coefficient of CBA concrete lies between 0.07 and 0.12. According to Irwin and Graf [2], typical values of sound absorption coefficient, α, for 125 Hz are between 0.2 and 0.5. Based on the results, all the specimens started to show increment in the sound absorption coefficient after reaching 750 Hz and achieved their maximum sound absorption coefficient values at high-frequency regions. The sound absorption coefficient value of CBAC100 concrete was 0.79 at 2000 Hz as presented in Fig. 5.1. However, all the specimens were found to decrease in absorption after reaching 2000 Hz. The sound absorption coefficient in the high frequency range is higher than that in the low-frequency region. Conversely, the high-frequency region does not affect normal human hearing very much [3]. Usually, humans are more sensitive to sounds of lower frequency and at a high frequency range between CBAC0 CBAC40 CBAC80

Sound Absorption Coefficient(SAC)

1.00

CBAC10 CBAC50 CBAC90

Low Frequency

0.90

CBAC20 CBAC60 CBAC100

CBAC30 CBAC70

High Frequency

0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 0

1000

2000

3000

4000

5000

6000

Frequency (Hz) Fig. 5.1 Sound absorption coefficient concrete specimens containing different percentage of CBA (low and high frequency)

36

5 Acoustic Performance of CBA Concrete

3000 and 5000 Hz. Mahzan et al. [4] also stated that the low-frequency incident wave is much more effective in causing the panel to flex than a high-frequency one. Based on the results, the sound absorption coefficient of CBA concrete showed a similar and uniform pattern where the sound absorption coefficient was not significantly influenced by the percentage replacement of CBA as fine aggregate in the concrete mixture. However, the sound absorption coefficient of normal concrete (CBAC0) is lower compared to CBA concrete. It can be seen that the sound absorption coefficient of CBA concrete increases from 64.86 to 97.3% at 2000 Hz. Besides that, the sound absorption coefficient of CBA concrete increases with the increased volume of CBA in the concrete mixture. This can be seen at 3000 Hz where the sound absorption coefficient for CBAC10 is 0.26 lower than CBAC100 which is 0.36. However, the sound absorption coefficients of CBA concrete were higher than those of normal concrete (CBAC0) which is 0.18. The higher sound absorption coefficient shows CBA is good absorber for sound. This is due to the open void ratio that appears in CBAC100 due to the higher percentage replacement of CBA in the concrete mixture. As CBA is a porous material, more void spaces between particles in the mixture are present.

5.2 Noise Reduction Coefficient (NRC) The noise reduction coefficient (NRC) of CBA concrete was calculated for all concrete specimens as shown in Table 5.3. NRC is another term that has been used to describe the absorption properties of materials. NRC can be determined based on the average value of sound absorption coefficients obtained from the impedance tube testing at certain frequencies of 250, 500, 1000 and 2000 Hz. The average values obtained from the NRC were rounded off to the nearest multiple of 0.05. According Table 5.3 NRC performance of CBA concrete Specimen/frequency (Hz)

250

500

1000

2000

Average

NRC

CBAC0

0.068

0.106

CBAC10

0.102

0.090

0.163

0.370

0.177

0.20

0.118

0.608

0.230

0.20

CBAC20

0.093

CBAC30

0.075

0.105

0.131

0.610

0.235

0.20

0.092

0.174

0.650

0.248

CBAC40

0.25

0.095

0.096

0.194

0.660

0.261

0.30

CBAC50

0.106

0.109

0.221

0.710

0.287

0.30

CBAC60

0.099

0.118

0.234

0.720

0.293

0.30

CBAC70

0.117

0.134

0.241

0.710

0.300

0.30

CBAC80

0.103

0.125

0.233

0.720

0.295

0.30

CBAC90

0.094

0.146

0.180

0.730

0.288

0.30

CBAC100

0.108

0.197

0.286

0.792

0.346

0.35

5.2 Noise Reduction Coefficient (NRC)

37

Table 5.4 Density, strength and NRC values for CBA concrete Concrete specimen

CBA replacement (%)

Density (kg/m3 )

Strength (MPa)

NRC

CBAC0

0

2360

43.5

0.20

CBAC10

10

2326

39.5

0.20

CBAC20

20

2343

42.5

0.20

CBAC30

30

2356

46.9

0.25

CBAC40

40

2340

47.3

0.30

CBAC50

50

2323

47.5

0.30

CBAC60

60

2316

49.3

0.30

CBAC70

70

2330

46.2

0.30

CBAC80

80

2320

43.9

0.30

CBAC90

90

2296

41.1

0.30

CBAC100

100

2270

38.5

0.35

to Mahzan et al. [4], NRC is more convenient for use because it is a single number. The NRC value is a number between 0 and 1, where “0” indicates 100% reflection of sound, while “1” represents absolute absorption. The determination of NRC values is important in acoustic studies since it usually represents the sound absorption capability of acoustic materials [5]. Table 5.3 summarises the NRC values of all concrete specimens. The highest NRC value of 0.35 was obtained from the concrete specimen containing 100% of CBA as fine aggregate replacement. This means that CBA concrete has the ability to absorb sound more than 35%. Besides that, the NRC value of CBA concrete increases with the increasing percentage replacement of CBA in the concrete mixture. However, the NRC value of normal concrete (CBAC0) was 0.20, which is lower than that of CBA concrete. In addition, Table 5.4 shows that the density of CBA concrete decreases with the increasing amount of CBA in the mixture and also results in higher NRC values. It can be seen that CBAC0 with a density of 2360 kg/m3 has an NRC value of 0.20, whereas CBAC100 with a density of 2270 kg/m3 has an NRC value of 0.35. Generally, density can affect the NRC value of a specimen. According to Nasidi et al. [5] a denser structure results in better NRC values in the mid to high frequency range but the NRC values tend to decrease at low frequency [5]. It is good for high NRC values for any material in acoustic performance. However, Lim et al. [6] stated that the sound absorption coefficient improves as the specimen becomes denser. This is unlike the effect of thickness of the material where the absorption coefficient improves at lower frequencies. However, certain materials with increasing bulk density experience greater energy loss caused by the complexity of the sound path (tortuosity) in the absorber, especially porous materials. Figure 5.2 shows the relationship between NRC values and the density of CBA concrete containing 10–100% of CBA as fine aggregate replacement in concrete mixture. CBA concrete of lower density affects the sound absorption coefficient

38

5 Acoustic Performance of CBA Concrete NRC

Density

0.35 2300

NRC

0.30 0.25

2200

0.20 0.15 0.10

2100

Harden Density (kg/m3)

2400

0.40

0.05 0.00

2000

Concrete specimen Fig. 5.2 Relationship between NRC value and hardened density of CBA concrete

of concrete. Based on the results, the density of CBA concrete decreases with the increasing volume of CBA in the mixture and also results in high NRC values. The optimum percentage was obtained at 90% of CBA replacement which resulted in an NRC value of 0.30. Meanwhile, Fig. 5.3 show the relationships between NRC values and the compressive strength of CBA concrete. The sound absorption coefficient obtained in this study is considered the highest compared to other materials often used as noise barriers in the construction industry such as rough concrete, smooth unpainted concrete and plaster on solid walls as presented in Table 5.5. In order to determine the acoustic and non-acoustic performance of CBA concrete, Fig. 5.3 shows the relationship between NRC values and compressive strength of CBA concrete containing 1–100% of CBA as fine aggregate replacement in concrete mixture. CBA concrete of lower strength affects sound absorption coefficient of concrete. Based on the results, the strength of CBA concrete decreases with the increasing volume of CBA in the mixture and also results in high NRC values. The optimum percentage was obtained at 75% of CBA replacement which resulted in an NRC value of 0.30. The sound absorption coefficient obtained in this study is considered the highest compared to other materials often used as noise barriers in the construction industry such as rough concrete, smooth unpainted concrete and plaster on solid walls. Table 5.5 shows the comparison between the sound absorption coefficient of CBA concrete and other materials.

5.2 Noise Reduction Coefficient (NRC)

39

50 0.3

NRC

40 30

0.2 NRC

Compressive strength 20

0.1

Compressive strength (MPa)

60

0.4

10 0

0

concrete specimen Fig. 5.3 Relationship between NRC value and compressive strength of CBA concrete Table 5.5 Sound absorption coefficient comparison between CBA concrete mixtures with nonCBA concrete mixture Material

Frequency (Hz) 125

250

500

1000

2000

4000

Rough concrete

0.02

0.03

0.03

0.03

0.04

0.07

Smooth unpainted concrete

0.01

0.01

0.02

0.02

0.02

0.05

Smooth concrete (painted or glazed)

0.01

0.01

0.01

0.02

0.02

0.02

Porous concrete block (no surface finish)

0.05

0.05

0.05

0.08

0.14

0.20

Clinker concrete (no surface finish)

0.10

0.20

0.40

0.60

0.50

0.60

Concrete (unpainted, rough finish)

0.01

0.02

0.04

0.06

0.08

0.10

Concrete (sealed or painted)

0.01

0.01

0.02

0.02

0.02

0.02

CBA concrete (90% replacement of fine aggregate)

−

0.09

0.15

0.18

0.73

0.36

40

5 Acoustic Performance of CBA Concrete

5.3 Reverberation Time (Rating Class) One of the most common measurements in acoustic measurement is the reverberation room method. It is often used to measure the sound absorption qualities of building materials. It is stated in BS EN ISO 354:2003 that when there is a sound source in an enclosed space, the extent to which the reverberant sounds builds up and its decline when the source ceases are determined by the sound-absorbing characteristic of boundary surfaces, air and objects contained in that particular space [7]. The reverberation room test was carried out in an RT (reverberation time) mini chamber built according to BS EN ISO 140-1:1998 [8]. The chamber consists of two interconnected chambers as depicted in Fig. 5.4. CBA concrete panels were laid in an orderly manner on the floor at the centre of the chamber. The perimeter surface of the specimen area was completely sealed with aluminium foil, while the top surface of the CBA concrete panels was exposed in order for them to receive the sound incidence. The reverberation time of the room was measured in second (s), beginning with the measurement of an empty chamber. This was followed by an occupied chamber that contains CBA concrete acoustic panels with varying percentages of CBA. A random pink noise was applied in the closed chamber. A shorter reverberation time occurs when absorbent materials are present in the chamber because sound energy dissipates when the sound wave hits an absorptive surface. Since most of chamber surfaces were built using reflective material, higher RT values were recorded when the sound signal stopped. Samsudin et al. [9] discovered that a shorter reverberation time is caused by more sound being absorbed and distance [9]. Different panel designs did not have a large impact on reverberation time as the total surface area of the panels is similar. The longest reverberation time in the empty chamber recorded was 2.01 s at a frequency of 1600 Hz in this study. Typically, the measurement of reverberation time in the occupied chamber was less than 1.5 s between frequencies of 250–500 Hz. Fig. 5.4 RT mini chamber

5.3 Reverberation Time (Rating Class) Empty Room CBAC30 CBAC70

41

CBAC0 CBAC40 CBAC80

CBAC10 CBAC50 CBAC90

CBAC20 CBAC60 CBAC100

2.20 2.00 1.80

Time (s)

1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 5000

4000

3150

2500

2000

1600

1250

1000

800

630

500

400

315

250

200

160

125

100

0.00

Frequency (Hz) Fig. 5.5 Reverberation time for an empty chamber and chamber occupied with CBAC acoustic panels

The results of reverberation time of the empty chamber and the occupied chamber are shown in Fig. 5.5. Figure 5.5 shows that all panel designs had curved lines placed very close to each other which indicate that the performances of all panels with different percentages of CBA were very similar. The reverberation time for the empty chamber was longer compared to the chamber containing CBA concrete panels. Pedrero [10] mentioned that when the reverberation time is too long, the sound produced will persist for a long duration [10]. In contrast, when the reverberation time is short, the sound ceases and becomes inaudible within a short period of time. For rooms or auditoriums, the optimum reverberation time requires a short reverberation time of less than 1.5 s. Meanwhile, bigger room such as concert halls usually need a longer reverberation time of 2.0 or more seconds [11]. Furthermore, a mediumsized, general-purpose auditorium for both speech and music would require an ideal reverberation time of 2 s [12]. Generally, reverberation time depends on room size and its intended use. In the study of Dragonetti et al. [13], plenty of factors affecting sound quality depend on how sound waves bounce around the room. More walls indicate a greater chance of a longer reverberation period. In addition, inserting or removing sound-absorbing material in a room can also control the reverberation period. In this study, the reverberation time of empty chamber is longer than that of an occupied chamber. Azalan et al. [14] suggested that material selection is important

42

5 Acoustic Performance of CBA Concrete

for determining room acoustic characteristics. Since CBA concrete is porous, it has proven to be an absorptive material at high frequency. This is affirmed by a study by Everest [15] where porous materials were found to have a high sound absorption rate [15]. This is because when sound energy hits a porous surface, it will be converted into heat energy due to the vibration caused by the tiny particles of porous materials. Moreover, Emedya et al. [16] explained that reverberation time is strongly affected by absorption coefficients and room volume as shown in the Sabine formula. The Sabine’s absorption coefficient (α s ) connects the ratios of room volume to the total absorbing surface area in a room. A reduction in reverberation time inside the occupied chamber from 2.0 s in an empty chamber to less than 1.5 s in an occupied chamber proves that the test specimens have successfully absorbed sound during the test. Sabine’s absorption performance of CBA acoustic panels in the reverberation chamber is shown in Fig. 5.6. At a frequency of below 200 Hz, the sound absorption coefficients of all specimens are slightly unstable. According to BS EN ISO 11654:1997, results below 250 Hz in the sound absorber rating are not taken into consideration [17]. The rating of sound absorption for building materials refers to the α s value at mid-band frequencies of 250, 500, 1000, 2000 and 4000 Hz. On the other hand, sound absorption materials can be categorised as Class A, B, C, D, E or not classified according to the single number weighted sound absorption coefficient (α w ) value. CBAC0 CBAC40 CBAC80

Sound absorption coefficients (αS)

1.00

CBAC10 CBAC50 CBAC90

CBAC20 CBAC60 CBAC100

CBAC30 CBAC70

0.80

0.60

0.40

0.20

0.00 100

1000

10000

Frequency (Hz) Fig. 5.6 Sound absorption performance of CBAC acoustic panels in the reverberation chamber

5.3 Reverberation Time (Rating Class)

43

In Fig. 5.6, CBAC100 exhibits the higher absorption coefficient value compared to other specimens, followed by CBAC90. This indicates that CBAC90 and CBAC100 are the highest ranking absorbers according to the standard. Table 5.6 summarises the results for all the tested panels, while Fig. 5.7 shows the rating curves for CBA concrete panels according to BS EN ISO 11654:1997. CBAC80, CBAC90 and CBAC100 possess the highest absorption coefficients. In general, high absorption Table 5.6 Sound absorption coefficient for CBAC acoustic panels Specimen/frequency (Hz)

250

500

1000

2000

CBAC0

0.20

0.30

0.30

0.30

4000 0.20

CBAC10

0.10

0.20

0.20

0.20

0.10

CBAC20

0.10

0.20

0.20

0.20

0.10

CBAC30

0.10

0.25

0.25

0.25

0.10

CBAC40

0.10

0.30

0.30

0.30

0.10

CBAC50

0.10

0.30

0.30

0.30

0.10

CBAC60

0.10

0.30

0.30

0.30

0.10

CBAC70

0.15

0.30

0.30

0.30

0.15

CBAC80

0.20

0.30

0.30

0.30

0.20

CBAC90

0.20

0.30

0.30

0.30

0.20

CBAC100

0.20

0.30

0.30

0.30

0.20

Practical sound absorpton coefficient (αp)

1.00

0.80

CBAC20 CBAC60 CBAC100

CBAC10 CBAC50 CBAC90

CBAC0 CBAC40 CBAC80

0.90

CBAC30 CBAC70

0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 250

500

1000

Frequency (Hz) Fig. 5.7 Rating curves for CBAC acoustic panels

2000

4000

44

5 Acoustic Performance of CBA Concrete

Table 5.7 Rating of sound absorption for CBAC acoustic panels according to ISO 11654:1997 2000

4000

α pi

0.30

0.30

0.20

0.30

0.35

D

0.20

0.20

0.10

0.20

0.25

E

0.20

0.20

0.20

0.10

0.20

0.25

E

0.25

0.25

0.25

0.10

0.20

0.25

E

0.10

0.30

0.30

0.30

0.10

0.20

0.25

E

0.10

0.30

0.30

0.30

0.10

0.20

0.25

E

CBAC60

0.10

0.30

0.30

0.30

0.10

0.20

0.25

E

CBAC70

0.15

0.30

0.30

0.30

0.15

0.20

0.25

E

CBAC80

0.20

0.30

0.30

0.30

0.20

0.30

0.35

D

CBAC90

0.20

0.30

0.30

0.30

0.20

0.30

0.35

D

CBAC100

0.20

0.30

0.30

0.30

0.20

0.30

0.35

D

Specimen/frequency (Hz)

250

500

1000

CBAC0

0.20

0.30

CBAC10

0.10

0.20

CBAC20

0.10

CBAC30

0.10

CBAC40 CBAC50

α w (with shape indicator)

Rating absorption class

coefficients were recorded between 500 until 2000 Hz, whereas low absorption coefficients were recorded at 4000 Hz. The sound absorption coefficients of all specimens are slightly unstable at below 200 Hz frequency, since in BS EN ISO 11654:1997 did not count the result for below than 250 Hz in the sound absorber rating [17]; therefore, the results could be ignored. Rating of sound absorption for building material is done referring to α s value at mid-band frequencies of 250, 500, 1000, 2000 and 4000 Hz. According to BS EN ISO 11654:1997, the α pi value is the arithmetic mean value of the sound absorption coefficient at mid-band frequencies of 250, 500, 1000, 2000 and 4000 Hz [17]. As summarised in Table 5.7, the α pi values for CBAC100 were 0.20, 0.30, 0.30, 0.30 and 0.20 at 250 Hz, 500 Hz, 1000 Hz, 2000 Hz and 4000 Hz, respectively. The weight of sound absorption coefficients for this panel was 0.30, which is the highest among others. Figure 5.7 shows that CBAC100 has the highest absorption coefficient of 0.30. CBAC0 is categorised as a Class D absorber as shown in Table 5.7. On the other hand, other CBA concrete panels are usually categorised as Class E absorbers except for CBAC80, CBAC90 and CBAC100 which are categorised as Class D absorbers similar to normal concrete. According to BS EN ISO 11654:1997, a Class D absorber refers to a material that absorbs more than 30% of sound, while a Class E absorber is able to absorb between 15 and 25% of sound [17]. Therefore, CBAC80, CBAC90 and CBAC100 panels could qualify as good absorbers. Normal concrete (CBAC0) was also qualify as good absorber due to the class D.

References

45

References 1. Brüel & Kjær, Product Data—PULSE Acoustic Material Testing in a Tube Type 7758 (2007) 2. J.D. Irwin, E.R. Graf, Industrial Noise and Vibration Control (Prentice-Hall, Alabama, 1979), pp. 237–240 3. E.M. Samsudin, L.H. Ismail, A.A. Kadir, S.S.S. Mokdar, Comparison on acoustic performance between dust and coir form empty fruit bunches (EFB) as sound absorption material. J. Teknol. 5, 191–196 (2016) 4. S. Mahzan, A.M.A. Zaidi, M.N. Yahya, M. Ismail, Investigation on sound absorption of ricehusk reinforced composite, in Proceedings of MUCEET2009 (2009), pp. 19–22 5. I.N. Nasidi, L.H. Ismail, E.M. Samsudin, M. Firdaus, A. Khodir, The effect of different fibre length and different urea formaldehyde (UF) content on sound absorption performance of empty fruit bunch (EFB), in MATEC Web of Conferences, vol. 150, Jan 2018 6. Z.Y. Lim, A. Putra, M.J.M. Nor, M.Y. Yaakob, Sound absorption performance of natural kenaf fibres. Appl. Acoust. 130(Sept 2017), 107–114 (2018) 7. British Standard EN ISO 354, British Standard for Acoustic Measurement of Sound Absorption in a Reverberation Room (British Standard Institution, 2003) 8. British Standard EN ISO 140, British Standard for Acoustics Measurement of Sound Insulation in Buildings and of Building Elements. Requirements for Laboratory Test Facilities with Suppressed Flanking Transmission (British Standard, 1998) 9. E.M. Samsudin, L.H. Ismail, A.A. Kadir, I. Norfaslia, Thickness, density and porosity relationship towards sound thickness, density and porosity relationship towards sound absorption performance of mixed palm oil fiber, in 24th International Congress on Sound and Vibration, 0–8 July 2017 10. A. Pedrero, The reverberation time of furnished rooms in dwellings. Appl. Acoust. 66, 945–956 (2005) 11. J. Chandra, P. Putra, I. Rahmaniar, Evaluation of Reverberation Time of Class Room (2018), p. 020042. 12. N.W. Adelman-Larsen, E.R. Thompson, A.C. Gade, Suitable Reverberation Times for Halls for Rock and Pop Music (2010) 13. R. Dragonetti, C. Lanniello, R.A. Romano, Reverberation time measurement by the product of two room impulse responses. Appl. Acoust. 70(1), 231–243 (2009) 14. A. Azalan, M.I. Ghazali, N. Jafferi, An Investigation on Factors that Cause Error in Reverberation Time Measurement (ISO 3382) in UTHM Lecturer Room, vol. 1 (ISO 3382, 2011), pp. 4–9 15. F.A Everest , K.C. Pohlmann, Master Handbook of Acoustics, 5th edn (Mc Graw Hill, 2009), pp. 164–165, 193–197 16. E.M. Samsudin, L.H. Ismail, A.A. Kadir, I.N. Nasidi, N. Sahidah, Rating of Sound Absorption for EFBMF Acoustic Panels according to ISO Rating of Sound Absorption for EFBMF Acoustic Panels According to ISO 11654: 1997, 0–6 Dec 2017 17. British Standard EN ISO 11654, British Standard for Acoustic Measurement Sound Absorbers for Use in Buildings: Rating of Sound Absorption (British Standard Institution, 1997)

Chapter 6

Mechanical Properties of CBA Concrete

This chapter describes the procedures of the tests carried out for determine the non-acoustic performance of CBA concrete as sound-absorbing material. Besides that, material collection, material preparation and followed by tests to evaluate the mechanical properties of hardened CBA concrete including compressive strength, water absorption, splitting tensile strength and ultrasonic pulse velocity. All the tests and standards used in this study are presented and discussed in this chapter.

6.1 Coal Bottom Ash Concrete Specimens In this research, CBA sample from Tanjung Bin Power Plant Station was used as fine aggregate replacement in the mixture as shown in Fig. 6.1. Upon delivery, CBA was stored in a tank before it was dried in an oven for 24 h at 105 °C. This process is done to ensure that the CBA is free from any moisture that could affect the watercement ratio during the concrete mixing process shown in Fig. 6.2. Besides that, this process was also done to ensure that no impurities were trapped in the material. It also facilitates the sieving process to obtain smaller CBA particles. After this initial process, a sieve analysis test was conducted to make sure that the particle size of CBA used in this study is suitable according to BS1377: Part 2: 1990 [1]. The CBA particles used in this study were passed through a 4.75 mm sieve and retained on a 75-µm sieve. In this research, concrete is made up of three main ingredients which are water, Portland cement, coarse aggregate and fine aggregate. Two types of concrete, namely conventional concrete (control) and CBA concrete, with different percentages of CBA as fine aggregate replacement were cast in order to determine the best material proportion that is able to absorb sound efficiently. The percentages of CBA used were 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100% by volume. Next, the concrete specimens underwent a curing process for 7, 28 and 90 days. The curing process is © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_6

47

48

6 Mechanical Properties of CBA Concrete

Fig. 6.1 Coal bottom ash (CBA) obtained from Tanjung Bin Power Plant

the process of limiting early loss of water from concrete. The best form of curing is to keep a component immersed under water for at least 7 days. The longer the curing period, the better the quality of concrete. Figure 6.3 shows the curing process for concrete specimens.

6.2 Compressive Strength The main purpose of this test is to determine the maximum load that can be sustained by the concrete until it fails. It is an important test for determining the properties of hardened CBA concrete. The compressive strength test was conducted according to BS EN 12,390: Part 3:2009 [2], and Fig. 6.4 shows the machine used for the test. The test was carried out on concrete specimens measuring 100 mm × 100 mm × 100 mm. From the testing, compressive strength results for 7, 28 and 90 days are presented in Table 6.1. The use of CBA as fine aggregate replacement in the concrete mixture has resulted in lower compressive strength after a curing period of 7, 28 and 90 days compared to that of control concrete. It is evident from the results that the compressive strength of CBA concrete continuously increases with curing age. All concrete specimens containing CBA in this study achieved the minimum strength requirement of 30 MPa. Meanwhile, the strength of control concrete strength at 28 days is 43 MPa.

6.2 Compressive Strength

(a) Collection of CBA

(d) Untreated CBA

49

(b) Upon delivery raw CBA

(c) Drying process of CBA

Fig. 6.2 Material preparation for CBA before it is used in concrete mixture Fig. 6.3 The curing process of concrete specimens

50

6 Mechanical Properties of CBA Concrete

Fig. 6.4 Compressive strength testing

Table 6.1 Compressive strength of CBAC at 7, 28 and 90 days Concrete specimen

CBA replacement (%)

Compressive strength (MPa) 7 Days

28 Days

90 Days

CBAC0

0

36.0

43.5

51.9

CBAC10

10

33.4

39.5

43.8

CBAC20

20

34.8

42.5

47.6

CBAC30

30

35.4

46.9

51.5

CBAC40

40

36.4

47.3

53.1

CBAC50

50

37.7

47.5

54.4

CBAC60

60

39.7

47.3

55.6

CBAC70

70

35.5

46.2

52.7

CBAC80

80

34.2

43.9

51.2

CBAC90

90

33.3

41.1

50.7

CBAC100

100

32.8

38.5

49.3

From Table 6.1, it can generally be seen that the compressive strength of CBA concrete decreases when the percentage of CBA increases in the mixture. At 7 days of curing age, the compressive strength of control concrete was 36 MPa. Meanwhile, the highest compressive strength recorded was 39.7 MPa (60%), followed by 36.4 MPa (40%) which is higher than the compressive strength of control concrete (36 MPa). The lowest compressive strength of 32.8 MPa was recorded by the specimen containing 100% of CBA as fine aggregate replacement. It can be seen that the

6.2 Compressive Strength

51

Compressive Strength (MPa)

60

Target Strength: 43 MPa

50 40

Design Strength: 30 MPa

30 20 10 0 7

28

90

Days CBAC0 CBAC60

CBAC10 CBAC70

CBAC20 CBAC80

CBAC30 CBAC90

CBAC40 CBAC100

CBAC50

Fig. 6.5 Compressive strength versus curing days

highest percentage of CBA resulted in the lowest compressive strength. However, the compressive strength of CBA concrete increases with curing age as presented in Fig. 6.5. From Fig. 6.5, it can be seen that the compressive strength of CBA concrete increases with curing age. There were increments in compressive strength at day 7 and day 28. At 28 days of curing age, the highest compressive strength of CBA concrete recorded was 47.5 MPa (CBAC50), followed by 47.3 MPa (CBAC60 an CBAC40), 46.9 MPa (CBAC30) and 46.2 MPa (CBAC70) which is higher than that of control concrete CBAC0 (43.5 MPa). The lowest compressive strength of CBA concrete recorded was 36.5 MPa (CBAC100) at 28 days. A study conducted by Kadam and Patil [3], on the effect of CBA as fine aggregate replacement on the properties of concrete with different w/c ratios concluded that concrete mixture containing up to 30% of CBA resulted in increased compressive strength for curing periods ranging between 7 and 90 days. At 90 days curing age, the compressive strength for CBA concrete showed similar patterns as those cured for 7 and 28 days, respectively. It can be seen that the highest compressive strength recorded was 55.6 MPa (CBAC60), followed by 54.4 MPa (CBAC50), 53.1 MPa (CBAC40) and 52.7 MPa (CBAC70), which is higher than the compressive strength of control concrete CBAC0 (51.9 MPa). The lowest compressive strength recorded was 49.3 MPa (CBAC100) at 90 days. The increment of compressive strength of CBA concrete at 90 days went from 10.14 to 26.17% corresponding to 28 days of CBA concrete strength. The initial reaction of cement with CBA produces early strength concrete with a lower compressive strength at 7 days compared to specimens cured for 28 and 90 days. According to Ghafoori and Bucholc [4], the compressive strength of CBA concrete was lower than that of control concrete at 3 and 7 days. The results are in agreement with the findings of this study. Besides that, with the addition of CBA

52

6 Mechanical Properties of CBA Concrete

in concrete, the connectivity between the capillaries in the paste improves during the early curing stage [5], which influenced the strength development of concrete specimens. Low compressive strength may be due to an internal curing effect caused by bottom ash as reported by [6]. Due to the use of porous aggregates, moisture transfers from the aggregate to the cement paste via porous networks and stimulates a hydration reaction at a later age. Thus, this affects the strength of concrete specimens, which is resulted in the low compressive strength at early age. In addition, due to the high porous surface of CBA, the additional amount of water needed in the concrete mixture results in lower compressive strength. According to Abubakar and Baharudin [7], the compressive strength of concrete increases at all ages when natural fine aggregate and coarse aggregates are replaced with CBA, but the strength decreases with increasing percentage replacement of CBA in the mixture. This is due to the volume of all voids in the mixture as CBA is known to be a very porous material. The compressive strength of CBA concrete did not linearly increase with the percentage replacement of CBA. However, the increasing percentage of CBA in the concrete mixture has led to an increase in concrete porosity which is advantageous for sound absorption structures.

6.3 Tensile Splitting Strength According to BS EN 12390: Part 6: 2009 [8], tensile splitting strength can be determined using cylindrical concrete specimens such as moulded cylinders and drilled cores. This test is conducted to produce strength similar to that of the specimen’s compressive strength. Split tensile tests can be done using cube or cylindrical specimens [9]. However, in the present study concrete specimens measuring 150 mm in diameter and 300 mm in height were prepared in order to identify the tensile splitting strength of concrete as shown in Fig. 6.6. The splitting tensile strength of CBA concrete mixtures is shown in Table 6.2 and Fig. 6.7. The test results indicate that the inclusion of CBA in concrete improved the splitting tensile strength of CBA concrete at all curing ages. The usage of CBA in the concrete mixture as fine aggregate replacement affects the splitting tensile strength and compressive strength differently. The splitting tensile strength of CBA concrete is more dependent on the quality of the paste compared to compressive strength. The properties of fine aggregates also affect the quality of the paste and interfacial transition in the concrete mixture which in turn affect the ratio of tensile strength and compressive strength. The pozzolanic property of CBA improves the quality of the paste, thereby resulting in an increase in the splitting tensile strength of CBA concrete. It can be observed that the splitting tensile strength of CBA concrete decreases when the percentage of CBA increases in the mixture. At 7 days of curing age, the tensile strength of control concrete was 3.36 MPa. Meanwhile, the highest tensile strength recorded was 3.58 MPa (CBAC60) which is higher than that of control

6.3 Tensile Splitting Strength

53

Load

Steel loading pieces

Fig. 6.6 Tensile splitting strength test setup Table 6.2 Splitting tensile strength of CBAC at 7, 28 and 90 days Concrete specimen

CBA replacement (%)

Splitting tensile strength (MPa) 7 Days

28 Days

90 Days

CBAC0

0

3.36

3.56

3.71

CBAC10

10

2.98

3.04

3.21

CBAC20

20

3.00

3.15

3.27

CBAC30

30

3.24

3.55

3.74

CBAC40

40

3.40

3.59

3.81

CBAC50

50

3.50

3.74

3.93

CBAC60

60

3.58

3.66

4.05

CBAC70

70

3.21

3.58

3.89

CBAC80

80

3.00

3.38

3.80

CBAC90

90

2.85

3.16

3.58

CBAC100

100

2.70

2.96

3.09

54

6 Mechanical Properties of CBA Concrete 5.00 Minimum tensile strength 8 % of target strength

Splitting tensile strength (MPa)

4.00

3.00

Minimum

2.00

tensile strength 8 % of design strength

1.00

0.00 7

28

90

Days CBAC0 CBAC60

CBAC10 CBAC70

CBAC20 CBAC80

CBAC30 CBAC90

CBAC40 CBAC100

CBAC50

Fig. 6.7 Splitting tensile strength versus percentage replacement at all curing age

concrete (3.36 MPa), while the lowest tensile strength recorded was 2.70 MPa (CBAC100). It can be seen that the highest percentage of CBA resulted in the lowest tensile strength. Meanwhile, the highest tensile strength of CBA concrete at 28 days of curing age was 3.74 MPa (CBAC50), followed by 3.66 MPa (CBAC60), 3.59 MPa (CBAC40), and 3.58 MPa (CBAC70). These values were all higher than the tensile strength of control concrete (3.56 MPa). The lowest tensile strength of CBA concrete recorded was 2.96 MPa (CBAC100) at 28 days as shown in Fig. 6.7. From Fig. 6.7, it can be seen that the tensile strength of CBA concrete increases with increasing curing age. At 90 days, the tensile strength for CBA concrete shows a similar pattern as the tensile strength achieved at 7 and 28 days. The highest tensile strength recorded was 4.05 MPa (CBAC60), followed by 3.93 MPa (CBAC50), 3.89 MPa (CBAC70), 3.81 MPa (CBAC40), 3.80 MPa (CBAC80) and 3.74 MPa (CBAC30). These values were all higher than the tensile strength of control concrete (3.71 MPa). The lowest tensile strength of CBA concrete recorded was 3.09 MPa (100%) at 90 days curing age. Based on the results, it is evident that the tensile strength of CBA concrete increases along with curing age. However, the tensile strength of CBA concrete decreases with the increasing percentage of CBA as fine aggregate replacement. A study that has been conducted by Sandhya and Reshma (2013) on factors affecting split tensile strength also showed a similar pattern [10]. The percentage replacement of CBA is one of the factors that influence the reduction of tensile strength in CBA concrete. The increasing amount of CBA in the mixture leads to the development of porosity and pore distribution. Kasemchaisiri and Tangtermsirikul [11] also reported that the total porosity of concrete increases

6.3 Tensile Splitting Strength

55

with increasing CBA content in concrete mixtures. According to Singh and Siddique [12], these pores prevent the excellent bonding of cement paste with the aggregate. Therefore, the transition zone between the aggregate and cement paste becomes weak and porous which ultimately results in the reduction in strength of CBA concrete. Besides that, Silva et al. [13] also found another factor that influences the tensile strength of recycled aggregates. They mentioned that the types of aggregates used in the concrete mixture have little influence on direct strength and tensile strength. The influence of aggregate shape is less apparent in the split tensile strength test compared to the flexural strength test because of a stress gradient that delays the progress of cracking leading to ultimate failure. The splitting tensile strength of CBA concrete at 28 days of curing age ranges between 2.96 and 3.74 MPa in this study. Based on previous research by Singh and Siddique [14], the range of splitting tensile strength of CBA concrete was 3.10– 3.36 MPa when 15–45% of CBA was added to the concrete mixture. Meanwhile, Sandhya and Resham [10] observed that the splitting tensile strength of concrete mix with varying percentages of CBA as fine aggregate replacement decreases with increasing percentages of CBA. However, the strength of CBA concrete increases along with the curing period. However, the ASTM standard describes that the splitting tensile strength of concrete should range between 7 to 8% of compressive strength. Meanwhile, BS EN 12390–6:2009 [8] reported that the standard value of splitting tensile strength for concrete ranges between 8 to 12% of compressive strength. The percentage difference of tensile strength with the compressive strength of CBA concrete is presented in Table 6.3. At 28 days of curing age, the splitting tensile strength of CBA concrete is 7.41–7.87% of its compressive strength. For normal concrete (CBAC0), the splitting Table 6.3 Percentage difference of splitting tensile strength with compressive strength of coal bottom ash concrete Concrete specimen

CBA replacement (%)

Percentage difference with compressive strength (%) 7 Days

28 Days

90 Days

CBAC0

0

9.33

8.18

7.15

CBAC10

10

8.92

7.69

7.34

CBAC20

20

8.62

7.41

6.87

CBAC30

30

9.15

7.57

7.26

CBAC40

40

9.35

7.58

7.17

CBAC50

50

9.28

7.87

7.22

CBAC60

60

9.02

7.74

7.28

CBAC70

70

9.04

7.75

7.38

CBAC80

80

8.78

7.69

7.42

CBAC90

90

8.55

7.69

7.06

CBAC100

100

8.22

7.68

6.27

56

6 Mechanical Properties of CBA Concrete

tensile strength was 8.18% of its compressive strength. Besides that, the minimum requirement for the splitting tensile strength of CBA concrete is between 2.40 and 3.44 MPa since the design grade for concrete strength at 28 days of curing age is 30 MPa and the target compressive strength of CBA concrete is 43 MPa. Since the range of splitting tensile strength obtained in this study was 2.96–3.74 MPa at 28 days of curing age, it can be concluded that all the experimental values achieved the recommended standards and were similar to the results obtained in previous studies.

6.4 Water Absorptions The weight of water absorbed by the concrete specimens can be measured according to BS 1881—122: 2011 [15]. The water absorption tests were carried out when the age of concrete is between 28 and 32 days. Thus, the drying of the specimens were begun when they are aged between 24 to 28 days. In this study, three cubes were prepared from fresh concrete, and after 24 h, the concrete specimens were remoulded. Next, the concrete specimens were stored in a curing tank until they are required for the test. Figure 6.8 shows the processes during the water absorption test. The water absorption of concrete specimens can be determined through Eq. 6.1. Water Absorption =

Ww − Wd . Wd

(6.1)

Water absorption of CBA concrete was determined according to the procedures outlined in BS EN 1881-122: 2011 [15]. The results of water absorption in CBA concrete are shown in Table 6.4 and Fig. 5.8. At 7 days of curing age, the water absorption of CBA concrete increases with the increase in CBA content in concrete. The water absorption of CBA concrete was higher than that of control concrete (CBAC0). Based on Table 6.4, the water absorption of CBA concrete at 7 days of curing age is higher than the values recorded at 28 and 90 days. The water absorption of CBA concrete tends to decrease with increasing curing age. This is probably due to pore refinement of bottom ash which has effect on the microstructure of concrete. CBA concrete becomes more porous due to the addition of bottom ash. However, at 28 days of curing age, the water absorption of CBA concrete containing more than 10% of CBA was the highest. It can be observed that the influence of CBA on water absorption is much higher than fine aggregate as the water absorption of CBA concrete increases with CBA content in the concrete mixture as shown in Fig 6.9. The addition of CBA to the concrete mixture improves the connectivity between capillaries in the cement paste [16]. Besides, the porous structure due to the higher content of CBA enables water to easily diffuse through the porous structure of the concrete [17] (Fig. 6.9). However, the water absorption of CBA concrete containing 100% of CBA as fine aggregate replacement in the concrete mixture reduced from 5.57% at 7 days to 5.16% at 90 days of curing age. The reduction in water absorption in CBA concrete with the

6.4 Water Absorptions

57

(a) Specimens were oven dried

(b) Specimens were immersed in water for 72 hours

(c) Specimens were immediately weighed Fig. 6.8 Processes involved in the water absorption test Table 6.4 Water absorption of coal bottom ash concrete (CBAC) Concrete specimen CBA replacement (%) Water absorption( (%) at curing age (Days) 7

28

90

CBAC0

0

4.68

4.52 4.17

CBAC10

10

4.71

4.64 4.30

CBAC20

20

4.74

4.70 4.42

CBAC30

30

4.80

4.77 4.38

CBAC40

40

4.76

4.72 4.44

CBAC50

50

4.9

4.83 4.6

CBAC60

60

5.07

4.85 4.71

CBAC70

70

5.18

5.08 4.77

CBAC80

80

5.21

5.14 4.97

CBAC90

90

5.45

5.39 5.09

CBAC100

100

5.57

5.43 5.16

58

6 Mechanical Properties of CBA Concrete 6

Water absoprtion (%)

5

4

3

2

1

0 7

28

90

Days CBAC0

CBAC20

CBAC10

CBAC30

CBAC40

CBAC60

CBAC70

CBAC80

CBAC90

CBAC100

CBAC50

Fig. 6.9 Water absorption CBA concrete versus percentage of CBA

progress of curing age is significant. The pozzolanic activity of CBA is believed to be responsible for the reduction of water absorption in the concrete mixture due to the high amount of silica and aluminium content present in CBA particles. In addition, the water absorption of CBA concrete increases almost linearly with the increase in CBA content in concrete at all curing ages. The increase in water absorption of CBA concrete affects the strength of concrete. The reduction in the compressive strength of CBA concrete is caused by the higher water demand created by the porous surface of CBA as shown in Fig. 6.10. Figure 6.10 demonstrates the relationship between water absorption and compressive strength of CBA concrete containing 10–100% of CBA as fine aggregate replacement at 28 days of curing age. The influence of CBA content on water absorption values resulted in the reduction in compressive strength of CBA concrete. This is due to the porosity of CBA concrete which increases with the volume of CBA in the concrete mixture. The replacement of fine aggregate with CBA has caused the presence of more voids in the concrete mixture. According to Demir [18], higher rates of water absorption are often due to the presence of open porosity in the mixture. Besides that, the porosity of CBA concrete also influences the resulting concrete density. Besides that, Del Valle et al. [19] found that the reduction in the mechanical properties of concrete is caused by the porosity of CBA. The porosity of CBA also influences concrete density. The strength is decreased as the proportion of bottom ash increased corresponding to the decrease in apparent density [20]. Moreover, Neville [9] noted that the waster absorption of concrete cannot be used as a measure of

6.4 Water Absorptions water absorption

compressive strength

60

5

50

4

40

3

30

2

20

1

10

0

0

Compressive strength (MPa)

water absorption (%)

6

59

Concrete specimen Fig. 6.10 Relationship between water absorption and compressive strength of CBA concrete at 28 days of curing age

concrete quality. He recommended that good quality concrete should have a water absorption value of less than 10% by mass. Based on the data obtained in this research, the water absorption of CBA concrete at all curing ages (7, 28 and 90 days) was less than 10%, which is similar to the findings by [21]. The results also point to the fact that the optimum percentage of CBA as fine aggregate replacement lies between 40% between water absorption and compressive strength of CBA concrete specimen as presented in Fig. 6.10.

6.5 Ultrasonic Pulse Velocity According to BS 1881-203:1986 [22], the measurement of the velocity of ultrasonic pulses that pass through concrete may be used for certain applications such as determining the uniformity of concrete in or between members, detecting the presence of voids and other defects, measuring the changes occurring with time in the properties of concrete, correlating pulse velocity and strength as a measure of concrete quality and determining the modulus of elasticity and dynamic Poisson’s ratio of the concrete specimens. In the present study, the pulse velocities of concrete specimens were tested at 7, 28 and 90 days of curing age. The determination of pulse velocity

60

6 Mechanical Properties of CBA Concrete

depends on the transducer arrangement, where the pulse longitudinal vibration is produced when it is held in contact with one surface of the concrete. Next, the pulse vibration is converted into an electrical signal by a second transducer. By knowing the path length L in the concrete and the transit time T of the pulse, the pulse velocity can be determined as follows: v=

L T

(3.6)

where v: Pulse velocity; L: Path length; T: Time taken by the pulse to traverse that length. The UPV method is based on the fact that the pulse velocity of compressional waves in a concrete body related to elastic properties. The pulse velocity depends only on the elastic properties of the material, and this is a very convenient technique for evaluating concrete quality [23]. Transmission time is measured, and pulse velocity is calculated in the ultrasonic test. The ultrasonic test equipment generates a pulse, transmits this to the concrete by a transducer, and then receives the pulse with a transducer and measures the transmission time. Pulse velocity is calculated by dividing the path length by the transmission time. In this study, UPV was conducted at 7, 28 and 90 days of curing age, and Table 6.5 summarises the results of the average pulse velocity test. At 7 days, the pulse velocity values of CBA concrete were found to be lower than that of control concrete (CBAC0). The average pulse velocity values decreased from 4350 to 2970 m/s for normal concrete and CBAC100 when 100% of CBA was used in the concrete mixture at 7 days of curing age. The decrease in pulse velocity values was significant. At Table 6.5 Ultrasonic pulse velocity of CBAC as replacement of fine aggregate in concrete Concrete specimen

CBA replacement (%)

Pulse velocity (m/s) 7 Days

28 Days

90 Days

CBAC0

0

4350

4560

4650

CBAC10

10

4040

4660

4720

CBAC20

20

3960

4490

4690

CBAC30

30

3890

4400

4650

CBAC40

40

3810

4380

4600

CBAC50

50

3740

4390

4560

CBAC60

60

3540

4400

4550

CBAC70

70

3340

4270

4500

CBAC80

80

3000

4180

4580

CBAC90

90

3010

4100

4400

CBAC100

100

2970

4030

4350

6.5 Ultrasonic Pulse Velocity

61

28 days of curing age, the pulse velocity of CBAC10 was 2.19% higher than that of normal concrete. Based on the result, pulse velocity of CBA concrete increases with age of the concrete specimens. However, Singh and Siddique [5] observed that the incorporation of CBA as fine aggregate replacement in concrete did not have a significant effect on the pulse velocity of concrete. This differed from the views of Topcu and Bilir [24], who stated that the pulse velocity of CBA in concrete mortar decreased linearly. According to BS EN 12504-4:2004 [25], one of the factors that influence pulse velocity measurements is moisture content. These effects are important for the production of correlations for the estimation of concrete strength. There can be a significant difference in pulse velocity among properly cured standard cubical specimens. Figure 6.11 shows a significant decrease in average pulse velocity of concrete mixtures with increasing volumes of CBA at all curing ages. At 90 days of curing age, the pulse velocity values for CBAC20, CBAC30, CBAC40 and CBAC100 increased by 4.45, 5.68, 5.02 and 7.94% at 28 days of curing age as compared to an increase of 1.97% for control concrete. The CBAC concrete specimen has gone through further hydration that caused the density of the matrix structure exhibiting higher improvement in quality in reference with control concrete. However, according to Yaprak et al. [26], the type of waste material used has no impact on the ultrasonic pulse velocity. The ultrasonic pulse velocity of concrete increases with curing age. Meanwhile, Kurama et al. [27] found that concrete containing solid material transfers sound more quickly compared to concrete containing porous materials. Since bottom 5000 4500

Pulse velocity (m/s)

4000

Good grade (3500-4500 m/s)

3500 3000 2500 2000 1500 1000 500 0 7

28

90

Days CBAC0 CBAC60

CBAC10 CBAC70

CBAC20 CBAC80

Fig. 6.11 Variation of pulse velocity with curing age

CBAC30 CBAC90

CBAC40 CBAC100

CBAC50

62 Table 6.6 Concrete quality grading as per BS 1881:1983

6 Mechanical Properties of CBA Concrete UPV (m/s)

Concrete quality

Above 4500

Excellent

3500–4500

Good

3000–3500

Medium

Below 3000

Doubtful

ash is known as a type of porous material, the compressive strength and pulse velocity through concrete decreases with increasing CBA content in the mixture. Based on Table 6.6, the quality of concrete based on pulse velocity values is presented in accordance with the BS 1881:1983 standard [28]. By comparing the pulse velocity values that is obtained in this study with the given value, most of the CBA concrete specimens were found to be of good quality. This is because most of the average pulse velocity values of CBA concrete lie between 3500 and 4500 m/s.

References 1. British Standard 1377-2, British Standard for Soils for Civil Engineering Purpose: Classification Tests (British Standard Institution, 1990) 2. British Standard EN 12390-3, British Standard for Testing Hardened Concrete: Compressive Strength of Test Specimens (British Standard Institution, 2009) 3. M.P. Kadam, D. Patil, Effect of coal bottom ash as sand replacement on the properties of concrete with different w/c ratio. Int. J. Adv. Technol. Civil Eng. ISSN (1), 2231–5721 (2013) 4. N. Ghafoori, J. Bucholc, Properties of high calcium dry bottom ash concrete. ACI Mater. J. 94(2), 90–101 (1997) 5. M. Singh, R. Siddique, Effect of coal bottom ash as partial replacement of sand on workability and strength properties of concrete. Journal of Cleaner Production 112, 620–630 (2016) 6. H. Kim, K. Ha, J. Jang, H. Lee, Mechanical and Chemical Characteristics of Bottom Ash Aggregates Cold-bonded with Fly Ash. J. Korean Ceram. Soc. 51(2), 57–63 (2014) 7. A.U. Abubakar, K.S. Baharudin, Potential use of malaysian thermal power plants. Int. J. Sustain. Construct. Eng. Technol. 3(2), 25–37 (2012) 8. British Standard EN 12390-6, British Standard for Testing Hardened Concrete: Tensile Splitting Strength of Test Specimens (British Standard Institution, 2009) 9. A. Neville, Properties of Concrete, 5th edn. (University of Leeds, England, 2011) 10. B. Sandhya, E.K. Reshma, A study on mechanical properties of cement concrete by partial rreplacement of fine aggregate with bottom ash. Int. J. Stud. Res. Technol. Manag. 1, 591–597 (2013) 11. R. Kasemchaisiri, S. Tangtermsirikul, Properties of self-compacting concrete incorporating bottom ash as partial replacement of fine aggregate. Science Asia 3487–3495 (2008) 12. M. Singh, R. Siddique, Effect of coal bottom ash as partial replacement of sand on properties of concrete. J. Clean. Prod. 112, 620–630 (2013) 13. R.V. Silva, J. De Brito, R.K. Dhir, Tensile strength behaviour of recycled aggregate concrete. Constr. Build. Mater. 83, 108–118 (2015) 14. M. Singh, R. Siddique, Strength properties and micro-structural properties of concrete containing coal bottom ash as partial replacement of fine aggregate. Construct. Build. Mater. 50, 246–256 (2014) 15. British Standard 1881-122, British Standard for Testing Concrete: Method for Determination of Water Absorption (British Standard Institution, 2011)

References

63

16. R. Raju, M.M. Paul, K.A. Aboobacker, Strength performance of concrete using bottom ash as fine aggregate. Int. J. Res. Eng. Technol. 2(9), 111–122 (2014) 17. N. Ernida, Z. Abidin, M. Haziman, W. Ibrahim, The effect of bottom ash on fresh characteristic, compressive strength and water absorption of self-compacting concrete, Oct 2014 18. I. Demir, An investigation on the production of construction brick with processed waste tea. Build. Environ. 41, 1274–1278 (2006) 19. A.L. De la Colina Martínez, G. Martínez Barrera, C.E. Barrera Díaz, L.I. Ávila Córdoba, F. Ureña Núñez, D.J. Delgado Hernández, Recycled polycarbonate from electronic waste and its use in concrete: Effect of irradiation. Construct. Build. Mater. 201, 778–785 (2019) 20. J. Xie, Road traffic noise mapping in Guangzhou using GIS and GPS. Appl. Acoust. 87, 94–102 (2015) 21. M. Rafieizonooz, J. Mirza, M. Razman, M. Warid, E. Khankhaje, Investigation of coal bottom ash and fly ash in concrete as replacement for sand and cement. Constr. Build. Mater. 116, 15–24 (2016) 22. British Standard 1881-203, British Standard for Testing Concrete: Recommendations for Measurement of Velocity of Ultrasonic Pulses in Concrete (British Standard Institution, 1986) 23. R.D.T. Mercado, R.M. Ureta, R.J.D. Templo, The potential of selected agricultural wastes fibers as acoustic absorber and thermal insulator based on their surface morphology via scanning electron microscopy. World News Nat. Sci. 20, 129–147 (2018) 24. I.B. Topçu, T. Bilir, Effect of bottom ash as fine aggregate on shrinkage cracking of mortars. ACI Mat. J. (2008) 25. British Standard EN 12504-4, British Standard for Testing Hardened Concrete: Determination of Ultrasonic Pulse Velocity (British Standard Institution, 2009) 26. H. Yaprak, S. Memis, G. Kaplan, Effect of Industrial Wastes as Replacement of Fine Aggregate on Properties of Concrete. J. Sci. Eng. Res. 4(12), 228–235 (2017) 27. H. Kurama, I.B. Topçu, C. Karakurt, Properties of the autoclaved aerated concrete produced from coal bottom ash. J. Mater. Process. Technol. 209(2), 767–773 (2009) 28. British Standard 1881-102, British Standard for Testing Concrete: Method for Determination of Slump (British Standard Institution, 1983)

Chapter 7

General Conclusion and Recommendation on CBA and Noise

This research has towards investigated the effect of CBA as fine aggregate replacement in concrete mixture. The properties of CBA concrete (CBAC) such as strength and durability were studied. The properties of concrete studied include workability, unit density, compressive strength, splitting tensile strength, water absorption, water permeability and pulse velocity. Besides that, the acoustic performance of CBA concrete was also examined. The sound absorption coefficient and noise reduction coefficient were determined based on the impedance tube test and reverberation room test.

7.1 Conclusion Based on the analysis done, the following conclusions can be drawn.

7.1.1 Acoustic Performance of Coal Bottom Ash Concrete Based on the acoustic tests conducted, it can be concluded that the sound absorption coefficient of CBA concrete is higher than that of normal concrete. In the impedance tube test, the highest noise reduction coefficient recorded was 0.35 when 100% of CBA was used to replace fine aggregate in concrete which showed good sound absorption. Meanwhile, normal concrete has a sound absorption coefficient of 0.20. It can be seen that the sound absorption coefficient increases when the percentage replacement of fine aggregate in the concrete mixture increases. Based on the Sound Absorption Coefficient (SAC) values that obtained from this study has reduced the railway noise level by 3.74 dB (0.35 SAC) and 1.94 dB (0.20 SAC).

© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2020 S. Shahidan and N. Izzati Raihan Ramzi Hannan, Acoustic and Non-Acoustic Performance Coal Bottom Ash Concrete, SpringerBriefs in Applied Sciences and Technology, https://doi.org/10.1007/978-981-15-7463-4_7

65

66

7 General Conclusion and Recommendation on CBA and Noise

Besides that, the analysis on the density of CBA concrete was shown to affect NRC values. The density of CBA concrete decreases with the increasing amount of CBA in the mixture, which further leads to increased NRC values. CBAC0 with a density of 2360 kg/m3 has an NRC value of 0.20 which is lower than that is obtained by CBAC100. CBAC100 has a density of 2270 kg/m3 and an NRC value of 0.35. The optimum replacement percentage is 90% of CBA as it results in an NRC value of 0.30. Meanwhile, the compressive strength of CBA concrete decreases with the increasing amount of CBA in the mixture, which further leads to the increased NRC values for determination of acoustic performance of CBA concrete. The optimum replacement percentage is 75% of CBA as it results in an NRC value 0.30. During the reverberation room test, it was found that the reverberation time for an empty chamber was longer that of an occupied chamber containing concrete specimens. Based on the reverberation tests conducted, the rating of sound absorption for CBA concrete as building material was done by referring to the αs value at midband frequencies of 250, 500, 1000, 2000 and 4000 Hz. With the reference to this result, CBAC0 is rated as a Class D absorber. Meanwhile, other CBA concrete panels were categorised as Class E absorbers, except for CBAC80, CBAC90 and CBAC100 which were categorised in the same class as normal concrete. As a conclusion, the suitable range for replacement of CBA in the concrete production is 40–90% of CBA as fine aggregate replacement could be used as good absorber. In this study, it has been proved that the usage of CBA as absorptive material for reduction noise level of railway noise is significant due to the SAC values that are obtained from acoustic performance testing. However, the amount of CBA in the concrete production affected the mechanical properties of CBA concrete which is the greater amount of CBA which has produced low workability of concrete and reduction in strength development of concrete. But the greater amount of CBA in concrete production has showed that CBA is a good absorber material based on acoustic performance testing that has been conducted.

7.1.2 Non-acoustic Performance of Coal Bottom Ash Concrete Based on the tests conducted, the fineness modulus values of fine aggregate and CBA were 3.0 and 2.79, respectively. The fine aggregate used in this study is categorised as medium-sized sand. CBA was found to be a suitable fine aggregate replacement since its fineness modulus is lower than that of fine aggregate and falls within the range specified by the standards. The specific gravity of CBA collected from Tanjung Bin power plant station is lower compared to the specific gravity values obtained by previous studies. Meanwhile, the specific gravity of fine aggregate (2.81) is higher than that of CBA (2.21). This is because the density of CBA is lower than the density of fine aggregate.

7.1 Conclusion

67

The chemical composition of CBA collected from Tanjung Bin power plant consists of silicon dioxide (43.56%), aluminium oxide (26.45%), iron oxide (12.14%), calcium oxide (9.30%), with small amounts of magnesium oxide (1.26%), sodium oxide (0.61%), potassium oxide (1.27%), etc. The CBA used in this study was classified as Class F ash because the sum of SiO2 + Al2 O3 + Fe2 O3 exceeded 70%. Particle morphology of CBA—CBA has a rough surface with an average diameter size greater than 10 μm. Hence, the appearance of the CBA particles is porous, angular and irregular in shape. Some of the particles are spherical and semi-spherical with interlocking characteristics. Besides that, the mechanical properties and durability of CBAC were identified. For example, the hardened density of CBA concrete increases with curing age, but decreases with the increasing volume of CBA in the concrete mixture. The volume proportion of CBA which is greater than fine aggregate has caused more cement paste in the concrete mixture to be absorbed due to the surface and pores that appear in CBA. The compressive strength of CBA concrete decreases when the percentage of CBA increases in the mixture, but the strength increases with curing age. The lowest compressive strength of CBA concrete was obtained after a curing period of 7 days. The splitting tensile strength of CBA concrete decreases when the percentage of CBA increases in the mixture. The splitting tensile strength of CBA concrete lies in the range stated in BS EN 12390-6:2009 and ASTM which is 8–12% and 7–8% of the compressive strength, respectively. The water absorption of CBA concrete tends to decrease with the increasing curing age of concrete. The water absorption of CBA concrete at 7 days of curing age is higher the values recorded at 28 and 90 days. The ultrasonic pulse velocity of CBA concrete was not significantly affected by the inclusion of CBA in the concrete mixture. By comparing the pulse velocity values in BS 1881:1983 and the pulse velocity values obtained in this study, it can be concluded that CBA concrete is of good quality. Meanwhile, in terms of the relationship between water absorption and compressive strength of CBA concrete, the influence of CBA content in the concrete mixture on the water absorption values led to a reduction in the compressive strength of CBA concrete. This is due to the porosity of CBA concrete which increases with the volume of CBA in the concrete mixture. For mechanical properties of CBA concrete, it can be concluded that the optimum percentage of CBA in the concrete mixture as fine aggregate replacement is 40% due to the medium workability, density, compressive strength, splitting tensile strength, water absorption, water permeability and UPV value of CBA concrete which is complied with the specified requirement in the concrete production.

68

7 General Conclusion and Recommendation on CBA and Noise

7.2 Recommendation for Future Work The findings from this study will hopefully serve as additional information for future work. There were several recommendations for further research due to the low density of CBA; it may be used as a lightweight material. The density of materials can influence its sound absorption coefficient. Besides, researchers also can utilize CBA and other combination of materials such as plasticizer or other materials in concrete production to improve its physical strength. Moreover, the durability of CBA concrete in terms of sorptivity, chloride permeability, acid resistance, carbonation, sulphate resistance and abrasion resistance should be examined in a longer study period to achieve concrete maturity. Due to material characterisation of CBA, it has shown that potential uses of CBA as coarse aggregate or cement replacement should be studied for future research. This is because existing studies do not clearly state its potential uses in the construction industry. In addition, a detailed investigation into the design of noise barriers for the reduction of railway noise can be carried out. This investigation will need to consider and emphasise the characteristics of CBA in the concrete mixture.