Preventive Maintenance Technology for Asphalt Pavement [1st ed.] 9789811562051, 9789811562068

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Springer Tracts on Transportation and Traffic

Feng Li Jinyan Feng Youxin Li Siqi Zhou

Preventive Maintenance Technology for Asphalt Pavement

Springer Tracts on Transportation and Traffic Volume 16

Series Editor Roger P. Roess, New York University Tandon School of Engineering, Brooklyn, NY, USA

About this Series The book series “Springer Tracts on Transportation and Traffic” (STTT) publishes current and historical insights and new developments in the fields of Transportation and Traffic research. The intent is to cover all the technical contents, applications, and multidisciplinary aspects of Transportation and Traffic, as well as the methodologies behind them. The objective of the book series is to publish monographs, handbooks, selected contributions from specialized conferences and workshops, and textbooks, rapidly and informally but with a high quality. The STTT book series is intended to cover both the state-of-the-art and recent developments, hence leading to deeper insight and understanding in Transportation and Traffic Engineering. The series provides valuable references for researchers, engineering practitioners, graduate students and communicates new findings to a large interdisciplinary audience. ** Indexing: The books of this series are submitted to SCOPUS and Springerlink **

More information about this series at http://www.springer.com/series/11059

Feng Li Jinyan Feng Youxin Li Siqi Zhou •

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Preventive Maintenance Technology for Asphalt Pavement

123

Feng Li Beihang University Beijing, China

Jinyan Feng Beihang University Beijing, China

Youxin Li Beihang University Beijing, China

Siqi Zhou Beihang University Beijing, China

ISSN 2194-8119 ISSN 2194-8127 (electronic) Springer Tracts on Transportation and Traffic ISBN 978-981-15-6205-1 ISBN 978-981-15-6206-8 (eBook) https://doi.org/10.1007/978-981-15-6206-8 © Springer Nature Singapore Pte Ltd. 2021 This work is subject to copyright. All rights are reserved 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

I am very glad to see the publication of a book on the current situation and development trend of pavement preventive maintenance technology for asphalt pavement in China. Asphalt pavement is the main pavement form of high-grade highway and urban road in China. With the rapid development of road construction in China, the importance of pavement preventive maintenance for asphalt pavement is increasingly prominent. In the past two decades, China has carried out a large number of preventive maintenance technology engineering applications and made significant progress in maintenance decision-making methods and maintenance implementation rules, making outstanding contributions to maintaining and increasing the value of asphalt pavement in China. Up to now, there are no systematic and comprehensive books on asphalt pavement maintenance technology and engineering application in China. Preventive Maintenance Technology for Asphalt Pavement (Li Feng etc. Singapore: Springer press, 2019.12) of the press, filled the theoretical methods and engineering application in the field of blank, to perfect and develop the preventive maintenance theory method, the preventive maintenance technology applied in the area of countries along the way, has important theoretical significance and practical value. Pavement Preventive Maintenance (PPM) refers to the planned and cost-effective measures taken on the pavement or ancillary facilities with sufficient carrying capacity to maintain the pavement system, delay damage, maintain or improve the functional condition of the pavement. Preventive maintenance is a kind of new curing technology concept, road maintenance department at the beginning of the road pavement structure or good pavement disease occurs, namely to maintenance, damages of delay further into a more profound development, to prolong the service life of pavement, improve the quality of the road, the operation way to extend long or overhaul period goal. Professor Li Feng and his team has been committed to the promotion and application in China research and use of asphalt pavement maintenance, as a technical director completed in Beijing and Jilin province asphalt pavement preventive maintenance technology guide written work, as the person in charge completed the formulation of crack treatment material series standards of the v

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Ministry of transport, as the leading researchers concluded the ministry of transport the writing of the technical specification for regeneration of asphalt pavement technology engineering application of preventive maintenance and more provinces and cities and so on. This book systematically summarizes their essential research achievements in the theoretical methods and engineering applications of asphalt pavement preventive maintenance over the past ten years. The book consists of three chapters, including an introduction to preventive maintenance technology, technical guide and implementation rules of preventive maintenance technology. The main technical features of this book are: • Systemic: involved in preventive maintenance technology, including crack filling, fog seal, thin overlay, chip seal, fiber seal, slurry seal, the micro-surfacing, mastic seal, ultra-thin overlay, in-place hot recycling for asphalt pavement, the original pavement disease treatment, etc. Basically, the book covers the typical asphalt pavement preventive maintenance and technology of China and reflects the technical level of China’s asphalt pavement preventive maintenance. • Practicability: This book describes the specific decision-making process of preventive maintenance, the indoor-test requirements of preventive maintenance materials, and the detailed steps of the construction process of preventive maintenance technology, which can be used to guide the engineering application of asphalt pavement maintenance technology in various countries. • Innovation: It reflects the innovative achievements of preventive maintenance technology of asphalt pavement in China in recent years and describes the latest development trend of preventive maintenance technology, which can be used for reference by countries along the Belt and Road Initiative (BRI). The in-depth research on the preventive maintenance technology of asphalt pavement will accelerate the development of pavement maintenance technology and meet the demand for pavement service life and driving quality. This book reflects the critical progress made in the theoretical research and engineering application of the preventive maintenance technology of asphalt pavement in China. It is hoped that more researchers will carry out research in the field of asphalt pavement maintenance technology in the future and strive to promote the further development of the theory and practice of pavement preventive maintenance. December 2019

Prof. Lijun Sun School of Transportation Engineering Tongji University Shanghai, China

Preface

Construction and maintenance are the two main themes of highway development. Highway construction is the premise, while maintenance and management are the guarantees. If we do well in maintenance and management, the service life of the highway will be extended, meanwhile reducing the consumption of resources and energy, which is the most effective way to accumulate wealth. Strengthening maintenance and management, improving the rate of good roads, giving full play to the maximum benefit of highway stock assets, and promoting the optimization of the entire road network structure are essential means to consolidate construction achievements, serve the public, adapt to economic development, and it is also a meaningful way to achieve sustainable development. In the recent 30 years, highway construction has been the primary task of highway development in China [1]. After the large-scale construction, the mileage of China’s highways increased from 888,000 km in 1980 to 4,846,000 km in 2018. Starting from scratch, the mileage of China’s expressways has reached 143,000 km by the end of 2018 [2–3]. Approved by China’s State Council, the National Development and Reform Commission issued the National Highway Network Plan (2013–2030) in May 2013. According to the plan, a national arterial highway network with reasonable layout, perfect functions, wide-coverage, and safety will be built by 2030, so that the capital will radiate to the provincial capitals, inter-provincial will be connected, and the prefecture-city high-speed connections and county to county national highways will be covered. This indicates that China’s road construction will not stop the pace, but also suggests that the road maintenance work will become more and more oppressive and vital [4]. After decades of leapfrog development, China’s highway construction has made remarkable achievements. At the same time, with the extension of highways’ service life, a large number of highways in China have entered the maintenance period. As the primary pavement type in China, asphalt pavement is facing unprecedented maintenance pressure [5]. In recent years, a large number of high-grade highways built in the early stage of our country have entered the maintenance period with problems such as early pavement damage continuing to arise. Highway maintenance has become increasingly prominent due to excessive debt, backward vii

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maintenance technology, and insufficient maintenance funds [6]. The importance of highway maintenance has become increasingly noteworthy. Highway maintenance has begun to receive the same treatment as highway construction. On the basis of extensive investigation and research, this book summarizes the current status of maintenance decision-making and preventive technical points of asphalt pavement in China, analyzes and prospects the development trend of Pavement Preventive Maintenance technology of asphalt pavement in China, and puts forward technical guidelines and implementation rules for Pavement Preventive Maintenance of asphalt pavement for reference by relevant professionals at home and abroad [7]. In particular, it can be used as a reference for road infrastructure maintenance projects of those countries along the Belt and Road Initiative. Beijing, China

Feng Li Jinyan Feng Youxin Li Siqi Zhou

Contents

1 Introduction to the Pavement Preventive Maintenance Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 The Purpose and Significance of Pavement Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Implementation Background of the Pavement Preventive Maintenance Technology . . . . . . . . . . . . . . . . . . . . . . . . 1.3 The Present Situation of the Pavement Preventive Maintenance Technology Abroad . . . . . . . . . . . . . . . . . . 1.3.1 Preventive Maintenance System . . . . . . . . . . . . . 1.3.2 Pavement Condition Evaluation . . . . . . . . . . . . . 1.3.3 Maintenance Section Division . . . . . . . . . . . . . . . 1.3.4 Service Performance Prediction . . . . . . . . . . . . . . 1.3.5 Determination of Maintenance Timing . . . . . . . . . 1.3.6 Maintenance Strategy Formulation . . . . . . . . . . . 1.3.7 Maintenance Effect Evaluation . . . . . . . . . . . . . . 1.4 Present Situation of the Pavement Preventive Maintenance Technology in China . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Pavement Preventive Maintenance Technology and Its Development Trend . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5.1 Crack Treatment . . . . . . . . . . . . . . . . . . . . . . . . 1.5.2 Fog Seal and Sand Fog Seal . . . . . . . . . . . . . . . . 1.5.3 Slurry Seal and Micro-surfacing . . . . . . . . . . . . . 1.5.4 Chip Seal and Fiber Seal . . . . . . . . . . . . . . . . . . 1.5.5 Thin Overlay and Ultra-Thin Overlay . . . . . . . . . 1.5.6 In-Place Hot Recycling for Asphalt Pavement Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5.7 Development Trend of Pavement Preventive Maintenance Technology . . . . . . . . . . . . . . . . . .

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2 Technical Guide for the Pavement Preventive Maintenance . . . 2.1 General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.1.2 Limitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Terms and Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.1 Pavement Preventive Maintenance . . . . . . . . . . . . . 2.2.2 Maintenance Benefit in Cycle . . . . . . . . . . . . . . . . . 2.2.3 Maintenance Cost in Cycle . . . . . . . . . . . . . . . . . . . 2.2.4 Optimal Time of PPM . . . . . . . . . . . . . . . . . . . . . . 2.2.5 Crack Filling and Sealing . . . . . . . . . . . . . . . . . . . . 2.2.6 Crack Seal Band . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.7 Fog Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.8 Sand Fog Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.9 Mastic Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.10 Slurry Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.11 Micro-surfacing . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.12 Chip Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.13 Fiber Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.14 Thin Overlay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.15 Ultra-Thin Overlay . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.16 In-Place Hot Recycling for Asphalt Pavement Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2.17 Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Expectation Level of Pavement Maintenance . . . . . . . . . . . . 2.3.1 Evaluation Index of Pavement Technical Conditions 2.3.2 Evaluation Index of Technical Condition of Urban Road Surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Preventive Maintenance Decision . . . . . . . . . . . . . . . . . . . . 2.4.1 General Provisions . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2 Evaluation Criteria for Road Conditions Suitable for Preventive Maintenance . . . . . . . . . . . . . . . . . . 2.4.3 Appropriate Time of the Pavement Preventive Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.4 Cost-Benefit Analysis of Maintenance Countermeasures . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.5 Selection of Preventive Maintenance Measures . . . . 2.5 Post-evaluation of Preventive Maintenance Effect . . . . . . . . . 2.6 Cost-Benefit Analysis of Life Cycle . . . . . . . . . . . . . . . . . . . 2.6.1 Periodic Maintenance Costs . . . . . . . . . . . . . . . . . . 2.6.2 Benefit Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6.3 Benefit-Cost Ratio . . . . . . . . . . . . . . . . . . . . . . . . .

Contents

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3 Crack Filling and Crack Seal Band . . . . . . . . . . . . . . . . 3.1 Crack Filling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.2 Construction Machinery . . . . . . . . . . . . . . . . 3.1.3 Construction Procedure and Matters Needing Attention . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1.4 Applicable Conditions . . . . . . . . . . . . . . . . . 3.1.5 Test Method . . . . . . . . . . . . . . . . . . . . . . . . 3.1.6 Quality Inspection and Acceptance . . . . . . . . 3.2 Crack Seal Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.1 Material Science . . . . . . . . . . . . . . . . . . . . . 3.2.2 Construction Machinery . . . . . . . . . . . . . . . . 3.2.3 Construction Procedure and Matters Needing Attention . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.4 Applicable Conditions . . . . . . . . . . . . . . . . . 3.2.5 Test Method . . . . . . . . . . . . . . . . . . . . . . . . 3.2.6 Quality Inspection and Acceptance . . . . . . . .

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4 Fog Seal and Mastic Seal . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Fog Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.1 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.2 Construction Machinery . . . . . . . . . . . . . . . . 4.1.3 Construction Procedure and Matters Needing Attention . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1.4 Applicable Conditions . . . . . . . . . . . . . . . . . 4.1.5 Quality Inspection and Acceptance . . . . . . . . 4.2 Mastic Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2.2 Technical Requirements for Mastic Mixture . . 4.2.3 Mastic Slurry Spraying Construction . . . . . . . 4.2.4 Quality Inspection and Acceptance . . . . . . . .

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5 Chip Seal and Fiber Seal . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Chip Seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.2 Classification . . . . . . . . . . . . . . . . . . . . . . . . 5.1.3 Construction . . . . . . . . . . . . . . . . . . . . . . . . 5.1.4 Construction Machinery . . . . . . . . . . . . . . . . 5.1.5 Construction Procedure and Matters Needing Attention . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1.6 Applicable Conditions . . . . . . . . . . . . . . . . . 5.1.7 Quality Inspection and Acceptance . . . . . . . .

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5.2 Fiber Seal . . . . . . . . . . . . . . . . . . . . . . . . 5.2.1 Material . . . . . . . . . . . . . . . . . . . . 5.2.2 Construction . . . . . . . . . . . . . . . . 5.2.3 Quality Inspection and Acceptance

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7 Thin Overlay and Ultra-Thin Overlay . . . . . . 7.1 Thin Overlay . . . . . . . . . . . . . . . . . . . . . . 7.1.1 General Provisions . . . . . . . . . . . . 7.1.2 Applicable Conditions . . . . . . . . . 7.1.3 Quality Inspection and Acceptance 7.2 Ultra-Thin Overlay . . . . . . . . . . . . . . . . . . 7.2.1 General Provisions . . . . . . . . . . . . 7.2.2 Applicable Conditions . . . . . . . . . 7.2.3 Quality Inspection and Acceptance 7.3 Ultra-Thin Overlay (Type I) . . . . . . . . . . . 7.3.1 Material . . . . . . . . . . . . . . . . . . . . 7.3.2 Mixture . . . . . . . . . . . . . . . . . . . . 7.3.3 Construction . . . . . . . . . . . . . . . . 7.4 Ultra-Thin Overlay (Type II) . . . . . . . . . . . 7.4.1 Material . . . . . . . . . . . . . . . . . . . . 7.4.2 Mixture . . . . . . . . . . . . . . . . . . . . 7.4.3 Construction . . . . . . . . . . . . . . . . 7.5 Ultra-Thin Overlay (Type III) . . . . . . . . . . 7.5.1 Material . . . . . . . . . . . . . . . . . . . . 7.5.2 Mixture . . . . . . . . . . . . . . . . . . . . 7.5.3 Construction . . . . . . . . . . . . . . . . 7.5.4 Quality Inspection and Acceptance

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8 In-Place Hot Recycling for Asphalt Pavement 8.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Construction Machinery . . . . . . . . . . . . . . 8.3 Construction Process and Precautions . . . . 8.4 Paved Test Section . . . . . . . . . . . . . . . . . . 8.5 Regeneration . . . . . . . . . . . . . . . . . . . . . . 8.6 Suitable Conditions . . . . . . . . . . . . . . . . . . 8.7 Quality Inspection and Acceptance . . . . . .

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6 Slurry Seal and Micro-surfacing . . . . . 6.1 Material . . . . . . . . . . . . . . . . . . . . 6.2 Mixture Design . . . . . . . . . . . . . . 6.3 Construction . . . . . . . . . . . . . . . . . 6.4 Construction Quality Control . . . . . 6.5 Quality Inspection and Acceptance

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Contents

9 Original Road Surface Disease Treatment 9.1 The Basic Requirements . . . . . . . . . . . 9.2 Material . . . . . . . . . . . . . . . . . . . . . . . 9.3 Test Method . . . . . . . . . . . . . . . . . . . . 9.4 Local Road Damage Treatment Process

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Chapter 1

Introduction to the Pavement Preventive Maintenance Technology

1.1 The Purpose and Significance of Pavement Preventive Maintenance According to the definition of the Highway Standards Committee of American Association of State Highway and Transportation Officials, Pavement Preventive Maintenance refers to the planned adoption of some cost-effective measures for the wellstructured pavement or ancillary facilities without increasing the bearing capacity of pavement structure, in order to achieve the purpose of maintaining pavement system, delaying the damage, maintaining or improving the functional condition of pavement [8]. Pavement Preventive Maintenance is a new concept of maintenance technology, which means the road maintenance department should maintain the pavement when it is in good condition or in the early stage of pavement diseases, so as not to develop further pavement diseases, prolong the service life of the pavement, maintain the intact rate and smoothness of the road, improve the quality of the road, reduce the cost of road life, and extend the repair or overhaul period of the road. Pavement Preventive Maintenance is a new working method and practical technique, emphasizing prevention, which is totally different from the traditional road maintenance principle of “Repair as soon as it broke.” Pavement Preventive Maintenance of roads is conducive to reducing the lifecycle cost of roads. The life-cycle cost of the road should consider not only the initial construction cost and the service life of the pavement structure but also the cost of various maintenance schemes that may be adopted in the scheduled analysis period, including different combinations of various maintenance and reconstruction measures. The performance of a road with qualified quality decreases by 40% within 75% of its service life [9]. This stage is called the preventive maintenance stage. If it is not maintained in time, the performance will continue to decrease by 40% within 12% of its follow service life, resulting in a significant increase in maintenance costs. Through hundreds of thousands of kilometers of different grades of highway tracking research and a large number of maintenance practices, Crafo, an © Springer Nature Singapore Pte Ltd. 2021 F. Li et al., Preventive Maintenance Technology for Asphalt Pavement, Springer Tracts on Transportation and Traffic 16, https://doi.org/10.1007/978-981-15-6206-8_1

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American company, concluded a new pavement solution that was proved to be able to save 3–10 yuan of later corrective maintenance funds for every 1 yuan spent on preventive maintenance. The most important achievement of the SHRP (Strategic Highway Research Program) program in the United States also points out that Pavement Preventive Maintenance can save 45–50% of the maintenance cost by 3–4 times Pavement Preventive Maintenance in the whole pavement life cycle [10]. With the continuous development of the economy, and the continuous improvement of people’s living standards, higher requirements for the travel environment are desired by people. The “reactive maintenance,” which means people are not going to take any measures to prevent the pavement until it is seriously damaged, can no longer meet the needs of current economic development and road traffic. We must change our practical ideas and take precautions. Pavement Preventive Maintenance measures should be taken when it is in good condition or in the early stage of pavement diseases to ensure road’s integrity and traffic safety. Traditional road maintenance and nursing concepts and modes are not in harmony with the current situation of traffic. The road traffic in the more developed areas of China is characterized by large traffic volume and small per capita road area. Maintenance is not considered until the road is damaged. At this time, the road has been structurally damaged and needs to be treated at the base course. The long maintenance time occupies the road and causes traffic congestion. In addition, before maintenance, the speed of vehicles is greatly restricted due to poor road conditions and bumpy traffic, and the original traffic flow provided by the road cannot be fully developed, which is easy to cause congestion. Pavement Preventive Maintenance mostly plays the role of road reinforcement through the way of road’s surface course treatment, which is convenient and fast and has little impact on traffic. Through Pavement Preventive Maintenance, measures are taken to restore road capacity before the quality of road driving decreases significantly, providing road users with the more mobile, less crowded, safer, more comfortable, and durable pavement. More and more road management departments have implemented the reform of management and maintenance separation. When the maintenance units are transformed into enterprises, economic benefits instead of social benefits become their primary goal to maximize profits. Driven by economic interests, maintenance enterprises often take a neglected attitude towards those early road diseases that just appeared so that they are able to reduce maintenance expenditure, but only repair those diseases that have developed into deep-seated and have to be repaired [11]. The benefits of the maintenance funds cost are relatively low, so it will cause the goal that the government invests maintenance funds in keeping pavement in good condition is harder to achieve. Abandoning the traditional concept of “Repair as soon as it is broken”, Pavement Preventive Maintenance technology is carried out to repair the diseases at the early stage of road damage, which not only guarantees the road’s integrity and smoothness, but also extends the service life of the road, and effectively reduces the maintenance and repair cost, and will certainly receive significant social and economic benefits.

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1.2 Implementation Background of the Pavement Preventive Maintenance Technology By the end of 2008, the total mileage of highway in China had reached 603,000 km, achieving 70% of the construction and planning goals, effectively improving the quality of public services, playing an inestimable positive role in the development of national economy, and also marking the arrival of the era of long-term and large-scale highway maintenance. While expressways play an active and effective role, people inevitably find that with the increase of road age and traffic volume, many service functions of expressways are gradually degrading, which makes the desire to maintain the current service level of the expressway have also become a luxury due to the lack of adequate maintenance funds. According to the Canadian government’s projection, the shortage of funds for the maintenance of public infrastructure in Canada will reach $57 billion. In 1997, the US Congress reported that 48.7% of interstate highways and 60% of urban expressways in the United States were in “qualified” to “poor” road conditions [12]. However, even if the level of road condition remained unchanged at that time, the maintenance funds needed far exceeded the actual funds put into use. According to the statistics of the Ministry of Communications, by the end of 2006, the asphalt concrete pavement of high-grade highways in China had reached more than 220,000 km, and the repair and renovation sections accounted for 13% of the total mileage, about 28,000 km each year. Each highway management department is painfully aware that the actual cost of maintenance and repair is often a drop in the bucket compared with the cost of maintenance and repair required. There is a massive contradiction between the limited maintenance funds and the deteriorating road service level. How to effectively solve this contradiction, and how to use insufficient funds to create maximum maintenance benefits, has gradually become the most urgent problem to be solved by highway management departments in the stage of large-scale maintenance of the road network. Pavement Preventive Maintenance technology has shown outstanding advantages in solving this problem. Without improving the pavement structure capacity [13], it delays pavement damage, maintains or improves the existing traffic conditions of the pavement, and postpones expensive overhaul and reconstruction activities by prolonging the service life of the original pavement. The early damage of asphalt pavement of high-grade highway in China is severe. The most effective way to prevent the expansion of early diseases of asphalt pavement is to implement Pavement Preventive Maintenance. However, Pavement Preventive Maintenance of asphalt pavement in China has not received due attention. In terms of technology research, technology reserve, and technology application, it is still in the initial stage, lacking technical means in production practice, so it is imperative and urgent to carry out the Pavement Preventive Maintenance technology research of asphalt pavement for domestic use of asphalt pavement, especially for the use of high-grade highway asphalt pavement.

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1.3 The Present Situation of the Pavement Preventive Maintenance Technology Abroad The Pavement Preventive Maintenance involves a systematic and complex maintenance system [14], covering road surface condition evaluation, maintenance road segmentation, use performance prediction, maintenance measures selection, maintenance timing determination, maintenance effect evaluation, and maintenance strategy formulation, etc.

1.3.1 Preventive Maintenance System The term “preventive maintenance” first appeared in the late 1980s, and it was put forward by two famous scholars—Blum and Phang [15]. The concept of premaintenance opened the prelude for many countries to conduct in-depth research on the pre-maintenance system. As early as the 1960s, the highway network in developed countries has been built and has entered the maintenance period in an all-round way. In the practice of high-class highway maintenance, the basic experience of developed countries is to carry out preventive maintenance [16]. Through Pavement Preventive Maintenance technology, pavement’s service function can be improved, the time of the pavement maintenance can be prolonged, and the road maintenance costs and user costs can be reduced. The advanced international concept of maintenance and nursing is to advocate the choice of appropriate time and means for preventive maintenance. Advanced maintenance organizations often use preventive maintenance means to maintain the pavement to prevent accidents in the future, reduce maintenance costs, and keep the pavement in good service, but generally, they do not do any extensive renovation. Arizona’s highway department [17] conducted a comparative study on the following three maintenance methods: 1. After the asphalt concrete pavement is paved, there is no intermediate maintenance or maintenance. After 20-year-serving, it will be renovated. 2. After ten years of repair maintenance of asphalt concrete pavement, and then make an asphalt concrete overlay. 3. According to the concept and requirements of preventive maintenance, regular preventive maintenance is carried out on the asphalt concrete pavement that has been paved according to the pavement test results. The research results show that: Based on the third option (preventive maintenance), the direct engineering costs of the first option were 63% higher, and those of the second option were 55% higher. In addition, the long-term good service condition of the road brought by preventive maintenance cannot be compared with the other two schemes. In 1999, the US AASHTO Pavement Preventive Maintenance research group LTPP (LEAD STATES TEAM ON PAVEMENT PRESERVATION) conducted a

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survey of Pavement Preventive Maintenance in 40 states and Puerto Rico. The contents of the survey include whether there is a preventive maintenance plan, the time when the preventive maintenance plan is established, the annual preventive maintenance fund, and what preventive maintenance method is adopted and under what circumstances the preventive maintenance is used. The survey results show that: 1. 36 of the 41 states surveyed have established Pavement Preventive Maintenance systems, accounting for 85% of the total number surveyed. Two states are establishing Pavement Preventive Maintenance systems, and 41 states are using different kinds of Pavement Preventive Maintenance methods for pavement maintenance. In 1996, 26% of the 43 states surveyed had sound preventive maintenance systems, 56% had Pavement Preventive Maintenance systems, while 19% did not. 2. Nearly half (17 states) of the states that already have established Pavement Preventive Maintenance systems and put it in use for more than ten years. 3. Preventive maintenance funds in the states of the United States come from the annual construction budget. Although they are not earmarked funds, they are given priority. 4. Twenty-six states have established Pavement Preventive Maintenance technology guidelines for Pavement Preventive Maintenance and are continually being revised and improved; four states are in the process of developing Pavement Preventive Maintenance technology guidelines. 5. More than half of the States (25) use Pavement Preventive Maintenance technology when the pavement condition is good. Although some states also use Pavement Preventive Maintenance technology for poor pavement conditions due to insufficient funds, they still believe that Pavement Preventive Maintenance must be strictly limited to good and fair pavement conditions [18]. From the results of the AASHTO Pavement Preventive Maintenance Research Group [19], we can see that Pavement Preventive Maintenance technology has been widely popularized in various states of the United States, and a set of pavement preventive maintenance methods suitable for different occasions has been formed. In many places, Pavement Preventive Maintenance technology guidelines ideal for local conditions have also been established. According to the survey report of the AASHTO Advisory Committee on March 2006, 91.3% of 34 states and five provinces in the United States and Canada participated in the survey [20], and 69.6% of States and provinces established technical guidelines for Pavement Preventive Maintenance technology. However, the report also points out that most of these states (provinces) are based on the experience of engineers when formulating Pavement Preventive Maintenance technology schemes [21], and there is no quantifiable method to help the highway management departments design the Pavement Preventive Maintenance technology schemes. Therefore, it is necessary to establish a scientific and quantifiable preventive maintenance

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decision-making system on the basis of an in-depth study of relevant theories in decision science, so as to promote the further development and application of preventive maintenance technology. There are two kinds of maintenance timing judgment methods commonly used abroad. One method [22] is to establish the trigger values of some road performance indicators, obtaining the data of road performance indicators by road performance prediction or field testing. When people find that once the road performance indicators reach their trigger values, it is necessary to take preventive maintenance measures at this time. The application of this method is often embodied in the decision tree and decision matrix of pavement preventive maintenance measures selection. Another method is to track and investigate the application effect of pavement preventive maintenance measures, compare the application effect of maintenance measures in a different time, and then determine the most effective application time. According to this experience, in the process of formulating maintenance strategies in the future, people can determine the application time of some maintenance measures in advance. The NCRP P14-14 project funded by the Federal Highway Administration (FHWA) of the United States studied the optimal timing of pavement preventive maintenance implementation and proposed a method to determine the optimal timing of pavement preventive maintenance implementation based on cost-benefit calculation and an assistant analysis tool [23]. However, this method only chooses one preventive maintenance measure, calculates the benefit-cost ratio of the measure when it is applied at different times and does not consider the application of other types of maintenance measures. It is suggested that a variety of preventive maintenance measures should be selected for comparison in specific use.

1.3.2 Pavement Condition Evaluation The evaluation of road surface condition is the qualitative and quantitative evaluation and measurement of the functionality of the active road surface. It is the basis and premise for determining road maintenance needs and formulating the correct maintenance strategy. The research on pavement condition evaluation in the United States started earlier. The pavement performance evaluation model of the world’s first system is the PSI (Present Serviceability Index) pavement performance evaluation model proposed by the United States. The PSI model is based on subjective scoring and field investigation of road surface disease, and the relationship model between the scoring system and the road surface disease is fitted by multiple regression [24]. As one of the important research results of the road test, the PSI evaluation model is the first successful example of the highway management industry to cite expert scores to establish subjective and objective connections and has a profound impact on the development of road management technologies in other countries around the world [25]. Inspired by the PSI model, the MCI (Maintenance Control Index) evaluation model was developed in Japan in 1981 [26], and it differed significantly from the PSI

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index. In the MCI model, the pavement flatness index has a lower weight, while the crack and rutting index have higher weights, which is entirely opposite to the US PSI model. In addition, the MCI model requires that all members of the expert group be road management personnel, and members are more concerned with indicators that directly reflect changes in road conditions. Therefore, unlike the PSI model from the perspective of road users, the MCI model is based on the evaluation model of the road manager. In 2007, Greek scholars investigated the database of pavement crack disease and analyzed it with the evolutionary neural network model [27]. Take full consideration of external factors such as pavement structure, climate factors, and road age, the damage degree of cracks was divided into five grades. The damage condition of the road surface was evaluated. As the research progresses, more detailed and microscopic road surface data and more sensitive performance evaluation indicators and evaluation methods continue to emerge. At the same time, road condition detection vehicle, laser flatness meter, drop hammer deflection tester, anti-slip performance test vehicle and road radar and other fast non-destructive testing techniques and gray theory, BP neural network, fuzzy algorithm, etc. have strong data processing capabilities and The generalization of high-precision mathematical methods facilitates the evaluation of road conditions from a microscopic perspective.

1.3.3 Maintenance Section Division Due to the vast differences in the spatial characteristics and disease characteristics of the road sections, when judging the performance evaluation and maintenance requirements of the road sections, it is necessary to divide the similar parts of the roads to be studied, and to distinguish and grasp the differences by distinguishing the spatial characteristics of different road sections. Essential characteristics such as the type, extent, and severity of the disease on the road section and targeted maintenance of these road sections. The traditional road surface management system considers that the road sections with the same external conditions can form the same road section, and the same road sections have the same maintenance requirements. However, due to the large variability of highway engineering, the disease characteristics of the road sections with the same external conditions are likely to have vast differences. Therefore, the traditional road segmentation method has more considerable limitations. In 1995, Rabi and Haris [28] used nonparametric clustering analysis and dynamic programming to study the division of conservation road segments. However, due to the complexity of this method, it has not been adequately applied. In 2006, Shalaby and Reggie [29] studied that it is unreasonable to use the subjectively set classification criteria for disease severity to evaluate the road surface condition. The method of maximum likelihood classification is proposed to judge the road surface condition of each road section. And according to this, the road sections are classified. Thomas

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[30] believes that the point of change in the flatness measurement column is undeterminable and has no distribution law so that it can be effectively applied to the division of maintenance sections of different features. In 2007, Weed et al. [31] used statistical hypothesis testing to segment road segments. This method is relatively simple and efficient.

1.3.4 Service Performance Prediction The scientific and accurate maintenance of the pavement puts forward the requirements for the attenuation process of the pavement performance and the prediction of the expected service life. The research on pavement performance prediction is carried out. The early prediction model is mainly an equation established by the statistical and processing of past empirical data. This model has significant errors. In 1951, Carey and Rick first proposed the concept of pavement performance prediction in the study of the test section of the pavement preventive maintenance plan developed by AASHTO in the United States [32]. Subsequent scholars proposed a prediction model of road surface life cycle based on the AASHTO prediction model, which was mainly used to predict the fatigue cracks on the asphalt pavement and the effect of the rut on the asphalt pavement. This method was put into practical use in South Dakota, USA. The traditional probability model is based on the Markov process theory. With the deepening of research, the improved Markov model has been widely used. Madanat and Ben-Akiva established a hidden Markov model in 1994 to consider measurement errors in road condition detection. Pablo Luis Durango established an adaptive-controlled Markov model in 2002 to update the model structure based on real-time supplemental road condition detection data to improve prediction accuracy [33]. Yang established the usual Markov chain method in 2005 to overcome the shortcomings of intense subjectivity and significant data demand when developing the transfer matrix. Markov stochastic process theory has made a significant contribution to predicting pavement performance accurately, but because the Markov stochastic process assumes that the “future” and “past” road conditions are independent of each other under known diseases of the current road conditions [34]. And considering that the state transition matrix has stability, this assumption is quite different from the attenuation mode of pavement performance, so the Markov process is not valid at the project level. Modern mathematical methods have also shown excellent application results in pavement performance prediction. The neural network model is used to predict road surface flatness, crack development, and road service capability index PSI [35]. Fuzzy theory is used to predict road performance in combination with subjective road damage weights. Cluster regression analysis is used to predict the development of flexible pavement cracks, and it has been proved that the prediction accuracy at the project level is far superior to the Markov model [36]. The genetic algorithm is used to combine expert experience and pavement performance data, and to update

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the predictive model structure based on real-time road condition detection data. The competitive risk model predicts the service life of the pavement based on the type and severity of different pavement diseases [37].

1.3.5 Determination of Maintenance Timing The road use and economy of preventive maintenance measures depend on the condition of the original road surface when the test is applied. The road surface conditions are different at all stages of the life of the road surface [38]. Only when appropriate maintenance measures are applied at the right time. The best benefits of this measure can be achieved. In the existing research abroad, the selection methods of preventive maintenance time of pavement mainly include the exercise quality index method, the implementation period method based on each measure, the road condition triggering method, the cost-benefit evaluation method, the sorting method, and the life cycle cost evaluation method. The more commonly used methods for judging the timing of maintenance can be roughly classified into two types [39]. One method is to establish a trigger value of some road performance indicators, and obtain data of a road performance index through road performance prediction or field detection, and find that once the road performance index reaches its trigger value, it is considered to be taken at this time [40]. Preventive maintenance measures, the application of this method is often reflected in the decision tree and decision matrix of the choice of preventive maintenance measures. Another method is to track the application effect of preventive maintenance measures, compare the application effect of conservation measures at different times, determine the application time of the most maintenance effect, and then based on this experience, formulate the maintenance strategy in the future. In the process, the application time of a certain conservation measure is predetermined. Both of the above methods are based on subjective experience to determine the timing of conservation, with obvious limitations. Peshkin et al. [41] proposed a method for judging the optimal maintenance timing in 2004 by determining the best cost-benefit ratio of the maintenance measures over the life cycle of the pavement. This method calculates the cost-benefit ratio of maintenance measures at different points in the life cycle of the road and considers that the time to generate the best cost-effective ratio is the most appropriate maintenance opportunity. The main ideas are [42]: 1.

2.

Select road condition indicators: Select one or several road condition indicators as indicators to judge the timing of maintenance. These indicators should be measurable and quantifiable, and the road surface condition and preventive maintenance measures should be clear. Change these three characteristics. Select the trigger value: Select the trigger value of the application timing of the preventive maintenance technology for each road condition indicator, and the trigger value means the upper and lower limits of the application timing of the maintenance.

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Calculate the area of the zero-maintenance attenuation curve: Use the upper and lower limits of the pavement performance degradation curve and the trigger value to calculate the area of the performance attenuation curve between the upper and lower limits of the trigger value when no preventive maintenance measures are taken. 4. Determine the service life of the original road when zero maintenance: When the attenuation curve of an indicator reaches the lower limit of the trigger value as early as possible, it is the expected service life of the original road surface. 5. Determining the service life of the pavement after using preventive maintenance measures: When the performance decay curve of a certain indicator’s preventive maintenance measures reaches the trigger value at the earliest, it is the expected service life of the preventive maintenance measure. 6. Calculate the area of the road surface performance degradation curve after using preventive maintenance measures. 7. Calculate the benefits of each indicator: The area difference of the performance attenuation curve of preventive maintenance measures and zero maintenance measures. 8. Calculating the total benefit: Calculate the total benefit by multiplying the weight of each indicator by the benefit of each indicator, where the weight is based on experience. 9. Calculating the total cost: Including the owner cost and user cost. 10. Calculate the benefit-to-cost ratio. This method of judging the timing of conservation has strong practical value and is suitable for popularization and application. However, in the specific implementation process, there are still some limitations in the implementation. For example, when the weight of the road condition indicator is judged, the subjectivity is strong, and the life cycle cost analysis is not considered when the factor variability is considered. The US Federal Highway Administration (FHWA) funded the NCHRP P14-14 project conducted an analysis of the best timing for preventive maintenance implementation and proposed a cost-benefit calculation method to determine the optimal timing for preventive maintenance implementation and assisted analysis tool [43]. However, this method only selects a preventive maintenance measure, calculates the benefit-cost ratio of the measure when applied at different times, and does not consider the application of other types of conservation measures. It is recommended to select multiple preventive maintenance measures for a specific use.

1.3.6 Maintenance Strategy Formulation Strategy formulation is based on specific information and experience. After a series of processes such as asking questions, setting goals, collecting data, formulating plans, analyzing and evaluating, making choices, and accepting feedback, the most satisfactory solution is finally selected [44]. The decision-making methods in decision

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science can be divided into three categories: qualitative method, quantitative method, and comprehensive method combining qualitative and quantitative. The qualitative approach is a solution process and approach that is selected through experiences, such as subjective empowerment, decision tree, decision matrix, and expert system [45]. Quantitative methods are methods that use specific mathematical optimization models for decision makings, such as linear programming, integer programming, and dynamic programming [46]. Due to the complexity and randomness of decisionmaking problems, it is challenging to solve various types of decision-making problems with qualitative or quantitative methods alone. Therefore, a comprehensive decision-making method combining qualitative and quantitative results is generated, such as the analytic hierarchy process, fuzzy theory, neural network. And genetic algorithms, etc. At this stage, the main features of preventive maintenance technology are that the functions of alternative maintenance technologies are relatively simple, the risk of failure of the application of maintenance technology is significant, and the accumulation of long-term performance data of various maintenance technologies is far from sufficient [47]. These characteristics lead to the failure of the commonly used pavement management system to solve the decision-making problem of preventive maintenance technology effectively. At the same time, it has caused certain obstacles to the application of modern decision-making methods in preventive maintenance technology decision-making. At present, the most commonly used decision-making methods for preventive maintenance techniques are decision trees or decision matrix methods [48]. A decision tree is a graphical approach to the selection of preventive maintenance measures. It provides a simple and concise mapping of various alternative conservation options, possible natural states, and trigger values for multiple countries on a single chart for management review. Decision-making situation, analysis of the decision-making process. Highway management departments in many countries in the United States have established decision trees or decision matrices for the selection of preventive maintenance measures, such as Ontario, Georgia, and California. The use of decision trees or decision matrices is often accompanied by the cost-effectiveness calculation of conservation measures [49]. By calculating the benefit costs of the selected conservation measures, the most cost-effective conservation measures can be selected as the best maintenance plan. The decision tree or decision matrix method can increase the economics of the choice of conservation measures, but there are many factors to consider when establishing a decision tree or decision matrix, and the variability of various factors is large. When a certain factor changes, the decision tree or decision matrix established must be adjusted to adapt to the new conditions. Therefore, this method is poorly portable and is not convenient to be promoted and applied as a unified method [50]. In the field of traditional conservation technology research, some more advanced mathematical methods, such as expert systems, neural networks, etc., are also used to make conservation technology decisions [51]. The expert system is a computer program with intelligent features. It builds a knowledge base composed of a large number of experts and imitates the thinking of human experts to solve problems in

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specific fields. However, the expert system is less efficient in solving complex problems, and it cannot solve the problem of factor variability. The neural network has also been applied in the choice of maintenance measures due to its inherently superior adaptability and learning ability. The establishment of expert systems and neural networks requires a database of conservation technology decisions formed by a large number of experts’ subjective experience [52]. The process of establishment is not only cumbersome but also subjectively influenced by subjective factors. The lack of scientific and quantifiable methods for preventive maintenance technology decisionmaking is a major obstacle encountered in the development of current preventive maintenance technologies. Researching scientific and applicable conservation technology decision-making methods will contribute to the systematic preventive maintenance strategy. Establish and promote the promotion of preventive maintenance techniques [53].

1.3.7 Maintenance Effect Evaluation A comprehensive evaluation of the application effects of conservation measures will help to accumulate maintenance experience and comprehensively understand the characteristics of various means to guide the development of more scientific and rational maintenance plans [54]. Statistical regression analysis or T-test can be used to evaluate the effectiveness of a preventive maintenance measure or to compare the effects of different preventive maintenance measures [55]. This method of evaluation of maintenance effects helps to understand the preventive maintenance measures of road performance. The research on the SPS test section in 2003 found that the flatness, rutting, and fatigue cracks were used as the evaluation indicators [56]. The most effective conservation measures were arranged in the order of thin layer cover, gravel seal, slurry seal, and seal. Among them, the thin layer cover is the only one of the four measures that have a significant effect on the long-term effect of the pavement flatness. The gravel seal and the slurry seal have a certain influence on the long-term effect of the road surface condition, and the seal is on the road surface. The long-term effects of the situation did not show any influence. A study by Prapaitraku [57] in 2008 showed that there was no significant difference between the rheological properties of the top asphalt and the rheological properties of the untreated asphalt at the top of the pavement after two years of use. Another evaluation method is to use the prolonged maintenance time of the original pavement to evaluate the service life, but the uncertainty in the pavement life prediction will adversely affect the application effect of this method. Her evaluation methods include subdividing the maintenance effect into short-term maintenance effects and long-term maintenance effects. After taking the maintenance measures within one or two years, the road performance jump or the pavement performance decay rate is delayed to calculate the short-term maintenance effect, and the calculation is taken at the same time [58]. The difference between the road performance curve and the coordinate axis when the maintenance measures and

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the maintenance measures are not taken, and the benefit-cost ratio of the two methods in the life cycle of the road surface is analyzed to judge the long-term maintenance effect.

1.4 Present Situation of the Pavement Preventive Maintenance Technology in China Pavement maintenance first needs maintenance decision-making to determine whether the pavement needs to be maintained when to carry out maintenance and what technology to use for maintenance. At present, there are two main factors affecting the decision-making of highway pavement maintenance in China: one is a maintenance concept, the other is maintenance funds. For expressways, part of the expressway management departments throughout the country have established a pavement maintenance management system, and the maintenance funds of some expressways in coastal areas are relatively adequate, objectively, it is able to make scientific maintenance decisions. However, the actual situation is not very optimistic. We are still used to passive maintenance methods in highway pavement maintenance work. The main manifestations are that small diseases can not be cured, and small money can not be spared. We are tired of running and fighting fires after the deterioration of pavement diseases. To reverse the current passive situation of Expressway maintenance, we need to completely abandon the old concept of maintenance, promote the implementation of pavement preventive maintenance, and achieve the purpose of prolonging pavement life, improving pavement service function and saving maintenance costs by spending more small money and doing maintenance early. For ordinary highways, due to the lack of maintenance work and the problem of the maintenance funds being occupied has not been fundamentally solved, the problem of insufficient maintenance funds is very prominent. Maintenance decisionmaking mostly aims at ensuring “continuous road” and implements the principle of “bad road first.” This practice of giving priority to the maintenance of bad roads is very unscientific. Because of the priority of bad road maintenance and the high consumption of maintenance funds of unit mileage, we have no funds to maintain the roads in good condition, and the good road will gradually become a bad road, forming a vicious circle. Therefore, for maintenance decision-making, we should vigorously promote the concept of preventive maintenance, to constantly maintain good pavement, so that they are always in a better road condition, rather than constantly to repair poor pavement. For a long time, pavement maintenance in China is passive maintenance, far from preventive maintenance; more precisely, it is passive maintenance. The focus of maintenance work has turned to extinguish “fires” like fire brigades. There are many reasons for this. There are management reasons, technical reasons, financial reasons, and subjective reasons.

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From the maintenance concept, in recent years, China’s road administration departments have gradually realized the importance and urgency of preventive maintenance. We hope that the pavement maintenance work will be changed from “continuous maintenance of bad roads” to “continuous maintenance of good roads,” and a lot of pavement preventive maintenance technology has been used in the pavement maintenance work, having achieved a lot of ideal results. However, from the perspective of maintenance management, there is no long-term mechanism of preventive maintenance in China. From technical standards, according to the definition of maintenance in current norms of our country, the maintenance of asphalt pavement can be divided into minor maintenance, medium maintenance, overhaul, and special projects. The minor repair project includes routine maintenance and minor repair, the former mainly includes road surface cleaning and snow removal, the latter mainly includes repairing road surface diseases such as flooding, congestion, cracks, pits, ruts, pockmark and so on; the middle repair project mainly includes the whole section of the seal, overlay and treatment of serious diseases. Therefore, the current classification of pavement maintenance is based on the size of the project and the type of the project, rather than on the demand of the pavement, let alone the concept of preventive maintenance. In this case, we can only wait until the road breaks down, and a large area of diseases show up before dealing with them. Pavement maintenance often misses the best time. Finally, we have to go directly into the maintenance stage of the “open belly” type. The maintenance method can only be a single maintenance method, such as road surface excavation, milling, and a planer, which has a great impact on traffic. From maintenance funds, the actual cost of pavement maintenance in China and even in the world is far lower than the maintenance cost required. In this situation, pavement maintenance management departments often invest the limited maintenance funds in the worst-performing sections of the road, so we often choose to keep it work rather than keep it work well. Without preventive maintenance, the road condition drops rapidly and joins the ranks of road sections to be repaired, forming a vicious circle. From the perspective of preventive maintenance technology, with the promotion of the Highway Science Research Institute of the Ministry of Communications, Southeast University and local highway management departments, the research on preventive maintenance technology of pavement, such as micro-surfacing, slurry seal, fog seal, ultra-thin overlay and crack pouring, is very active and its application in our country’s high-class highway maintenance practice is more and more extensive. Chang’an University and Tongji University have studied the preventive maintenance timing of asphalt pavement, respectively, and put forward the method to determine the preventive maintenance opportunity of Asphalt Pavement Based on life cycle cost. According to the characteristics of the Highway Preventive Maintenance project, a calculation model of the effect-cost ratio is established to determine the optimal preventive maintenance time, and the cost composition and calculation method in the life cycle are given. Quantitative analysis of the effect is carried out,

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and the method of quantifying the effect is put forward. By calculating the effect-cost ratio, the best scheme is to determine the time of preventive maintenance with the maximum effect-cost ratio. Since the beginning of the twenty-first century, preventive maintenance technology of asphalt pavement has been carried out in various parts of China, and many local pavement maintenance technical guidelines have been compiled. In 2003, the Shanghai Highway Administration Office, in conjunction with Tongji University, conducted a continuous study on preventive maintenance technology, and compiled the Shanghai Highway Industry Regulations “Technical Regulations for Preventive Maintenance of Highway Asphalt Pavement.” In 2004, Guangdong Highway Co., Ltd. and South China University of Science and Technology carried out a set of technical research on preventive maintenance and asset preservation of asphalt pavement, and compiled Guangdong Highway Industry Regulation “Technical Manual for Preventive Maintenance of Guangdong Higher Asphalt Pavement.” In 2006, the Shandong Highway Bureau, organized by the Ministry of Communications, took the lead in summing up some experience and achievements in preventive maintenance in China. The study found that in the selection of preventive maintenance technology and materials, most of the provinces surveyed are based on experience to determine when and what preventive maintenance measures to take, and lack of systematic preventive maintenance decision-making methods and preventive maintenance planning methods. In 2014, the Road Administration Bureau of Beijing Traffic Committee issued the Technical Guidelines for Preventive Maintenance of Asphalt Pavement in Beijing, and in 2016, Jilin Province Transport Department issued the Technical Guidelines for Preventive Maintenance of Asphalt Pavement in Highway. These two technical guidelines were issued in cooperation with the Highway Science Research Institute of the Ministry of Transportation and standardized the preventive maintenance of asphalt pavement in Beijing and Jilin Province, respectively. From the research aspect of the preventive maintenance system, domestic research is carried out later. Still, it has achieved positive results in all aspects and promoted the development of local preventive maintenance system in the direction of scientific and refined. In terms of road surface condition evaluation, the Ministry of Communications promulgated the Interim Measures for the Inspection and Assessment of Highway Maintenance Quality (JTJ803-79) in 1979 according to the actual conditions of road maintenance. The “good road rate” was used as a performance evaluation indicator for individual use. The rate was obtained according to the proportion of the “excellent” and “good” sections of the maintenance mileage; in 1985, the Ministry of Communications promulgated the “Technical Specifications for Highway Maintenance” (JTJ073-85), which was revised in 1996 and 2009; The “Highway Maintenance Quality Inspection and Evaluation Standard” (JTJ075-94) was promulgated in the year; in 2002, the “Highway Maintenance Quality Inspection Method (Trial)” was promulgated; in 2007, the “Highway Technical Status Assessment Standard” (JTGH20-2007) was published. The road surface is evaluated by the comprehensive evaluation standard PQI. Under the guidance of these norms and standards, some modern mathematical methods, such as BP neural networks and fuzzy algorithms,

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are gradually introduced into China. He et al. discussed the performance evaluation system of asphalt pavement based on fuzzy neural network and considered that this method is not affected by subjective factors. Xin et al. proceeded from the investigation of the content and process of highway asphalt road condition survey, evaluated each individual index of pavement performance, used the weighted geometric mean to calculate the comprehensive evaluation index of pavement performance, and increased the anti-sliding production as an indicator to form a A new method for evaluating the performance of pavement use. Wang et al. assessed the disease conditions of asphalt pavement cracking, rutting and repairing damage area, and used crack rate, rut depth, and repair damaged area as evaluation indicators of pavement disease conditions, and established the deflection value of the road segment. For the evaluation criteria of the signs, the appropriate range of various flatness evaluation indicators is derived. At the same time, an evaluation criterion based on the longitudinal friction coefficient PFC (Profile Friction Coefficient) was established, and the structural depth TD (Texture Depth) and the surface stone polishing value PSV (Polished Stone Value) reflecting the surface structure of the road surface were evaluated as anti-sliding evaluation. The indicators and corresponding evaluation criteria are proposed. Liu used the principal component analysis method to comprehensively evaluate the performance of asphalt pavement, and determined the comprehensive evaluation system of production. In order to grasp the decay law of emulsified asphalt cold reclaimed pavement technology, Xu et al. analyzed the pavement damage index PCI (Pavement Condition Index), road ride quality RQI (Riding Quality Index), and pavement rut depth index RDI (Rutting Depth Index) varies with traffic load and time. Zheng used the fuzzy evaluation method to evaluate the pavement performance comprehensively, and used the geometric weighting method to calculate the PQI value of the comprehensive evaluation index, and used the analytic hierarchy process to determine the weight value of each sub-indicator. In terms of the division of maintenance road sections, the traditional road segmentation method of the domestic road surface management system is divided into equallength segments by the mileage pile as the boundary of the road section. The advantage of this method is that the concept is simple and easy to operate, but it does not meet the actual road surface conditions and cannot meet the needs of scientific prevention and maintenance. Nowadays, more and more road segmentation studies tend to be variable-length segments. On the basis of analyzing the shortcomings of the road segmentation technology in the current pavement management system, Wang Jia introduced a clustering method of sequence samples and merged the minimum primary unit sections with similar performance attributes without changing the order of the highway mileage stations. A unit road section, in order to reduce the workload while ensuring the accuracy of the road section segmentation. Zeng et al. proposed three different clustering methods and analyzed the applicable conditions of each clustering method. The system clustering method is suitable for distinguishing small samples of corrective maintenance road sections and preventive maintenance road

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sections. The dynamic clustering rule is applicable. In the division of preventive maintenance road sections, the orderly clustering method facilitates continuous operation, which can reduce construction costs and improve construction quality, so it is more in line with the needs of road managers and maintenance construction units. In terms of performance prediction, in 2000, Xi’an Highway Research Institute conducted long-term observations on the performance of pavement performance on the test sections of the West Third Line and the West Line, to determine the decay law of pavement performance. The Highway Science Research Institute of the Ministry of Communications analyzed the effects of loads, climatic conditions, pavement materials, and structures on the long-term performance of pavements based on long-term observations of pavement use. Wang et al. proposed an improved grey prediction model based on factors such as flatness, deflection, and friction coefficient. When using the model prediction equation to predict the performance of individual indicators, the time response is the gray prediction model expression. After testing and correcting the model indicators and parameters, it can be used for empirical prediction, and the model can be applied to three different stages: short, medium, and long. In view of the damage rate of road performance, Jiang established a cluster analysis model based on traffic volume, ambient temperature, and humidity. Yu et al. applied the artificial neural network to the pavement performance prediction model. This method can incorporate external variability factors such as the environment that are difficult to consider into the model, and can continuously correct itself, with high fault tolerance, and can easily carry out the selected performance indicators. Effective forecasting. In the study of the preventive maintenance evaluation index system, Zhang et al. proposed the road driving quality, pavement structure strength, road surface condition index, and anti-sliding performance index as indicators for preventive maintenance. They adopted the gray Markov model to test the data. Insufficient road surface prediction, and through the quantitative standard maintenance effect, the cost-benefit method based on the prevention and maintenance timing judgment method is given. Cui and other considerations of the actual situation in different regions, taking the asphalt pavement in Yunnan as an example, through the investigation and analysis of the construction data, traffic flow conditions, road performance test data and maintenance conditions of the local road sections, combined with the operational research planning method to correct the HDM-4 The model is used to verify the accuracy of the model through regression analysis, and the equation for the performance prediction of asphalt road in Yunnan is constructed. Zhang et al. corrected the decay equation proposed by Sun, and analyzed the variation of asphalt pavement performance after implementing the measures of microsurfacing under different materials by regression fitting analysis, and analyzed the economy and quality under various treatment schemes by the equivalent annual cost method. Benefit. Xu et al. used the cold reclaimed pavement as the analysis object and studied according to the standard decay equation of asphalt pavement. It was pointed out that when the road traffic volume increased continuously, the index PCI value of pavement damage and the road surface flatness index RQI value showed the first fast. The slow change rule, and when the PSSI (Pavement Structure Strength Index) value is lower than 85, the PCI value decreases significantly. Zhang et al. analyzed

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the road surface inspection data of some expressways in Beijing, and divided the road surface into three situations: no maintenance, minor repair, and overhaul, and established different damage index prediction models. Some scholars have suggested using the residual curve to predict whether maintenance is needed. The main idea is to determine the proportion of new road sections or rebuilt sections that need to be maintained each season through the records of the existing road construction, operation, maintenance, and reconstruction of the management department. Use this to make predictions. Although there are many types of research on pavement performance prediction models, they are basically single prediction models. On the one hand, the models are usually based on database creation, which has higher requirements on data and does not have generalization. On the other hand, the creation of models does not combine the performance decay rules of pavement use. The prediction accuracy needs to be improved. In terms of the timing of conservation, most domestic research scholars use the cost-benefit assessment method to determine the optimal preventive maintenance time. Wei et al. processed the performance data of asphalt pavement in Tianjin and used the cost-benefit ratio calculation model to determine the optimal preventive maintenance time. The method was mainly through the selection of pavement performance evaluation indicators and the determination of the controllable benefit baseline. Calculate the corresponding cost by combining the decay curve of the pavement performance evaluation index with the benefits area enclosed by the minimum controllable benefit baseline under the conditions that the pavement does not take any preventive maintenance measures and the corresponding preventive maintenance measures are taken. Benefit ratio. Wang et al. used the different pavement preventive maintenance measures to compare the performance degradation of pavement performance indicators before and after construction, and established the optimal maintenance timing prediction model based on the cost-benefit analysis method, and proposed four decision indicators and 5 Decision-making principles. In terms of maintenance strategy formulation, Ling, etc., based on the relatively mature research methods and achievements from abroad, according to the principle of pre-nurturing countermeasures selection, it is believed that the maintenance countermeasures should include the formulation of pre-maintenance measures, cost-benefit analysis of pre-nurturing measures, and project-level pre-nurturing. There are three aspects to the selection of measures. This study considers technical, economic, and engineering factors to determine the method of selecting preventive conservation measures, which is scientific and rational. Li et al. applied the fuzzy optimization theory to establish and solve the preventive maintenance optimization model of asphalt pavement based on the current fuzzy optimization theory. The optimal countermeasures were determined according to the calculation of the model, which effectively reduced the uncertainty of subjective factors. Improve the efficiency of strategy development. Yu et al. took the highway maintenance strategy problem in the provincial level as the research object, established the main framework of the decision-making optimization research of the highway maintenance management system and the road maintenance fund allocation optimization model, discussed the algorithm of the model, and combined The status quo of highway maintenance in

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Sichuan Province, a case study of maintenance management decision-making. Yu and others adopted the basic principles of goal planning to establish a networklevel decision model. Based on the practical problems existing in the maintenance management of highway asphalt pavement, Zhang and others carried out research on the investigation, performance evaluation, performance prediction, and maintenance decision of high-grade highway asphalt pavement, and proposed a comprehensive evaluation model of asphalt pavement based on weighted geometric mean. At the same time, according to the road maintenance decision tree, a set of highway asphalt pavement maintenance measures was established, and the pavement was divided into 60 states, and feasible maintenance measures corresponding to various states were formulated. Regarding the evaluation of maintenance effect, Ren et al. proposed the recommendations for the selection of benefit indicators and the baseline reference values for the pre-conservation analysis of asphalt concrete pavements in China, as well as the recommended values for the control indicators and control standards for the pre-conservation time range. He proposed the calculation method of preconservation benefit standardization and benefits index and analyzed the reasonable pre-conservation cost analysis index, which provided a reference for the costbenefit analysis of asphalt pavement preventive maintenance. Wang et al. based on the predictive maintenance model of asphalt concrete pavement performance, the pre-preventive performance prediction model was established based on the asphalt concrete pavement behavior equation. At the same time, the area enclosed by the pavement performance decay curve was used to approximate the preventive maintenance. Benefits, the cost-benefit ratio is the best choice for preventive maintenance measures and timing. Li and others believe that compared with the growth model, linear model, logarithmic model, an exponential model, the cubic model has higher regression accuracy and can capture the road performance degradation curve. Therefore, it is recommended to use the cubic model to simulate the development of road rutting.

1.5 Pavement Preventive Maintenance Technology and Its Development Trend Pavement Preventive Maintenance is to prevent the further expansion of minor pavement diseases, to slow down the worsening of pavement performance, and prolong the service life of the pavement. It is usually used for the pavement with no damage or only signs of minor diseases and distress. At present, the common preventive maintenance technologies in our country mainly include crack treatment, fog seal, slurry seal, micro-surfacing, chip seal, ultra-thin overlay, thin overlay, etc. Different from traditional milling and planer overlaying technology, preventive maintenance technology usually has a layer thickness of no more than 3 cm after construction, so it is also called “0–3 technology”, as shown in Table 1.1.

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Table 1.1 Layer thickness of traditional maintenance technology and preventive maintenance technology Types of maintenance technology

Thickness (cm)

Technical name of maintenance

Traditional maintenance technology

4

Milling-planing and repaving asphalt course (AC-13, SMA-13 etc.)

Preventive maintenance technology

3

Thin overlay (SMA-10, OGFC-10 etc.)

2

Ultra-thin overlay

1

Slurry seal, micro-surfacing, chip seal

0

Crack treatment, fog seal

1.5.1 Crack Treatment 1. Crack Seal A technology of sealing asphalt pavement cracks with special materials (sealant) and special equipment (slotting machine, road crack-seal machine). The main function of the Crack Seal is to seal the cracks and prevent water from infiltrating into the pavement structure. The construction procedures of crack treatment are usually carried out in four steps: grooving and enlarging, clearing cracks, filling cracks and maintenance, as shown in Fig. 1.1. Figure 1.2 shows the pavement effect after crack treatment. The first step is slotting and enlarging (if necessary). According to the crack marking, adjust the width and depth of the slotting machine, and cut the uniform U-shaped groove in the centerline of the crack. The ratio of groove depth to width should not exceed 2:1. The groove should be at least 1 cm wide and 1.2 cm deep. The second step is to clear the cracks. Clean up loose particles, dust, and debris in the cracks to ensure the strong bond between the filling material and the crack wall. Clean up the residue in the cracks to ensure the strong bond between the sealants and the crack wall. Generally, the method of compressed air is used to clean up cracks. The third step is filling. The special road crack-seal machine is used for this operation. In order to prevent the wheel from sticking to the sealants, sometimes after filling the sealants, sand will be also sprayed on it. The fourth step is maintenance. After filling the cracks, according to the temperature, traffic will be opened after cooling the pavement for 10–20 min. 2. Crack Seal Band In recent years, crack treatment has been paid more and more attention, and “Filling every crack” has become the maintenance strategy of asphalt pavement in most provinces of China. Crack treatment technology has developed from traditional modified asphalt and modified emulsified asphalt filling to slotting filling with special sealant at the present stage. Maintenance materials, equipment, and technology have made great progress. With the increasing traffic volume, the traffic pressure caused by maintenance operations is also increasing. Therefore, a fast non-destructive repair

1.5 Pavement Preventive Maintenance Technology and Its Development …

a. Slotting and Expanding

c. Crack Seal Fig. 1.1 Construction steps of the crack treatment

Fig. 1.2 Pavement after the crack treatment

b. Cracking Cleaning

d. Maintenance

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technology (Crack Seal Band technology) for cracks is being gradually promoted and applied in China. Traditional slotting and jointing technology need slotting, clearing, jointing, maintenance and other processes, which is time-consuming and laborconsuming. Crack Seal Band technology does not need slotting, and the construction efficiency can be increased by 2–4 times by using sealant directly to the crack position of pavement. It has little impact on the traffic environment and can avoid the occurrence of secondary diseases. It has good application prospects (Figs. 1.3 and 1.4). Fig. 1.3 Crack seal band construction

Fig. 1.4 Pavement after crack seal band construction

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1.5.2 Fog Seal and Sand Fog Seal 1. Fog Seal A preventive maintenance technology of asphalt pavement is introduced, which uses special fog seal material to spray on the surface of asphalt pavement to seal some micro-cracks and voids of asphalt pavement, so as to waterproof, prevent further aging of pavement and improve the appearance of pavement. The Fog Seal is usually constructed by asphalt spreader (Fig. 1.5). After construction, the pavement is black (Fig. 1.6). Fog seal can reduce the pavement seepage coefficient to some extent, but it is harmful to the anti-skid performance of the pavement. After construction, the seepage coefficient and anti-skid performance should be tested (Figs. 1.7 and 1.8). Fig. 1.5 Fog seal construction

Fig. 1.6 Pavement after fog seal construction

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Fig. 1.7 Detection of percolation coefficient

Fig. 1.8 Anti-skid performance testing

2. Sand Fog Seal In the early stage, emulsified asphalt was the main function of Fog Seal, which was to seal fine pore and improve the water sealing effect of pavement. With the development of fog seal technology, Reductant Seal (regenerant seal) and Sand Fog Seal have appeared one after another. The performance of old asphalt can be partly restored by using asphalt reductant in reducing agent seal (regenerative agent seal), which plays the role of asphalt reduction. The sand-containing fog seal material is mixed with clay and other fillers in the original fog seal material, which improves the skid resistance and wears resistance of the Fog Seal (Fig. 1.9). Fog Seal technology is developing from the original single water sealing function to the multi-functional direction of restoring asphalt performance and improving pavement skid resistance.

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Fig. 1.9 Sand fog seal

1.5.3 Slurry Seal and Micro-surfacing 1. Slurry Seal Slurry seal paver is used to mix emulsified asphalt, coarse and fine aggregates, fillers, water, and additives in accordance with the design ratio and then form a thin layer of slurry mixtures on the original pavement. It has the characteristics of fast construction, low cost, wide use, and energy consumption. During the Eighth Five-Year Plan period, the “Emulsified Asphalt Slurry Seal Complete Technology” was listed as a key new technology promotion project in China. At present, Slurry Seal is widely used in highway construction and maintenance engineering. The main functions of Slurry Seal are to seal the infiltration of surface water, to provide anti-skid surface, to slightly improve the smoothness of the road surface, and to improve the appearance of the road surface. The effect of the slurry seal construction site and pavement after construction are shown in Figs. 1.10 and 1.11. Fig. 1.10 Slurry seal construction

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Fig. 1.11 Pavement after slurry seal construction

2. Micro-surfacing Modified emulsified asphalt, coarse and fine aggregates, fillers, water, and additives are mixed into slurry mixture by micro-surfacing paver to pave the original pavement according to the design ratio, and the thin layer technology with high skid resistance and durability of traffic is quickly opened. Micro-surfacing can effectively prevent surface water seepage, improve the anti-wear and anti-skid performance of pavement, and complete the repair of rutting at the same time. After Micro-surfacing construction, traffic can be opened within 1–2 h, which can minimize the impact of construction on traffic. The effect of Micro-surfacing construction site and pavement after construction is shown in Figs. 1.12 and 1.13. Micro-surfacing can be used for pavement rutting repair, bridge deck, and tunnel construction, as shown in Figs. 1.14, 1.15 and 1.16. Micro-surfacing is a technical upgrade version of the Slurry Seal. The two technologies are similar, but the equipment and material requirements of Micro-surfacing Fig. 1.12 Micro-surfacing construction

1.5 Pavement Preventive Maintenance Technology and Its Development … Fig. 1.13 Pavement (expressway) after micro-surfacing

Fig. 1.14 Rutting filling

Fig. 1.15 Bridge deck construction

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Fig. 1.16 Tunnel construction

are higher than Slurry Seal, and its performance is also better than the Slurry Seal. Entering the United States in the 1980s, it has now become one of the main road maintenance methods in many countries, such as the United States, Canada, Europe and so on. Since 2000, Micro-surfacing Technology has been studied and popularized in China. It has been widely used in highway pavement maintenance projects. The amount of Micro-surfacing used in China is about 30 million m2 every year. The main problem of Micro-surfacing technology is that the noise is large, which affects the driving comfort. For this reason, the application of low noise microsurfacing technology has been developed in China in recent years. In 2013, Beijing Road Administration adopted low-noise micro-surfacing technology to carry out preventive maintenance of six roads with a total area of 366,000 m2 . After the opening of the vehicle, the field noise test was carried out. The test results show that for the outside noise, the noise after the micro-surfacing of the pavement is less than that before the pavement. From the driving feeling and the field observation, the driving noise is still greater than that of other sections, but it is acceptable.

1.5.4 Chip Seal and Fiber Seal 1. Chip Seal Chip Seal is a kind of technology that uses a layer-by-layer method to construct, directly spraying asphalt binder and crushed stone with single particle size, and then forming a thin layer after rolling. The asphalt in the chip seal is covered by continuous film on the surface of the underlying layer, so it can effectively prevent the surface from seepage underwater and reduce the damage of pavement water. It has good following deformation ability and can adapt to relatively poor underlying stratum conditions. The stone in the gravel seal is directly exposed on the road surface, so it has excellent skid resistance and abrasion resistance.

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The construction of Chip Seal can be divided into synchronous gravel seal and step gravel seal (Figs. 1.17 and 1.18). In traditional Chip Seal construction, asphalt spraying and stone distribution are carried out by different equipment. In recent years, synchronous gravel sealing equipment has been widely used, which integrates asphalt spraying and stone spreading into construction equipment. It shortens the distribution interval between asphalt and stone to the greatest extent and greatly improves construction efficiency. After the gravel is spread, it needs to be rolled by a pneumatic roller (Fig. 1.19) to form a dense and rough gravel surface (Fig. 1.20). In addition, Chip Seal can also be used for interlayer bonding of asphalt pavement or waterproof bonding layer of bridge deck (Fig. 1.21). Unlike Chip Seal used for road surface as abrasion layer, the area of gravel on waterproof bonding layer surface accounts for about 2/3 and that of asphalt bonding material for about 1/3 (Fig. 1.22), which is beneficial to interlayer bonding between overlay and waterproof bonding layer. Fig. 1.17 Synchronous construction of chip seal

Fig. 1.18 Sub-step chip seal construction

30 Fig. 1.19 Rolling after spreading gravel

Fig. 1.20 Pavement after chip seal construction

Fig. 1.21 Chip seal for waterproof bonding layer

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Fig. 1.22 Surface appearance of waterproof bonding layer after construction

The chip seal is a layer-by-layer construction method with low price, simple construction equipment, simple construction technology, and fast construction speed. Because of its high-cost performance, gravel seal technology has been widely used in Europe and the United States. For example, in Australia, about 250,000 km of highway use chip seal as wear layer, accounting for nearly one-third of the total mileage of highway. The construction area of gravel seal in France is about 350 million m2 every year. The gravel seal technology is also very suitable for China’s national conditions. Besides expressways, gravel seal technology is suitable for preventive maintenance, construction, and reconstruction of other highways. 2. Fiber Seal Fiber Seal refers to a new type of pavement rapid maintenance technology, which uses synchronous Fiber Seal construction equipment, sprays two layers of asphalt binder and one layer of glass fiber at the same time, then spreads gravel on it, and forms a new wear layer (Fig. 1.23) or stress absorption intermediate layer (SAMI) (Fig. 1.24) after rolling.

Fig. 1.23 Application of fiber chip seal in asphalt surface abrasion layer

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Fig. 1.24 Fiber chip seal for stress absorbing layer

In the construction of fiber seal, glass fibers, which have been broken and cut by special technology, distribute randomly and evenly in the upper and lower layers of uniformly sprayed asphalt binder, overlap each other, and form network winding structure with asphalt mixture, which effectively improves the comprehensive mechanical properties of the seal, such as tensile, shear, compressive and impact strength. It is similar to adding a protective mat with high elasticity and strength between the new road base and the surface layer or on the basis of the original road surface. It is especially suitable for the construction of old asphalt pavement (or new roadbed), interlayer stress absorption intermediate layer and old asphalt pavement wear-resistant layer. It plays an effective protective role in the construction and maintenance of new and old asphalt pavement and can prolong its maintenance cycle and service life. The construction of fiber seal is shown in Fig. 1.25, and the pavement effect after spreading asphalt binder and fiber is shown in Fig. 1.26. Compared with the gravel seal, the fiber seal has a better ability to prevent reflective cracks due to the addition of glass fibers. It is widely used in stress absorption layer Fig. 1.25 Construction of fiber seal

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Fig. 1.26 Pavement after spreading asphalt binder and fiber

between layers, wear-resistant layer of new/old asphalt pavement, lower seal layer of highways of all grades, old cement pavement modification and waterproof layer of bridges, etc.

1.5.5 Thin Overlay and Ultra-Thin Overlay 1. Thin Overlay The Thin Overlay is a kind of overlay with thinner thickness than the traditional one (usually more than 40 mm in thickness). Tts, cracks, ruts, etc. to a certain extent, and prolong the hot-mix asphalt concrete overlay with compacted thickness of 30 mm (+5 mm) is usually called thin overlay. The main functions of the thin overlay are to improve the smoothness, restore the surface roughness, control the original surface damage of the pavement (such as service life of the pavement). 2. Ultra-Thin Overlay The ultra-thin overlay is a technical upgrade version of thin overlay. The ultra-thin overlay can greatly reduce the cost of pavement maintenance under the premise of achieving the same performance of pavement, so it has gradually replaced the technology of thin cover. Ultra-thin overlays commonly used in China can be divided into three categories: 1. Ultra-thin overlays with modified emulsified asphalt and graded asphalt (represented by Shell Novachip); 2. Ultra-thin overlays with warm mixing technology and dense-graded asphalt; 3. Ultra-thin overlay with rubber asphalt. Figure 1.27 shows the construction site of an ultra-thin overlay. The traditional overlay is over 4 cm thick. The thin overlay and the ultra-thin overlay are thinner than the traditional overlay. Thin and ultra-thin overlays are not usually used as pavement structural layer, but as wearing layer. When the surface function meets the requirements, the thinner the thickness, the better the economy.

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1 Introduction to the Pavement Preventive Maintenance Technology

Fig. 1.27 Ultra-thin overlay construction

Fig. 1.28 Pavement after ultra-thin overlay construction

With the progress of technology, some new materials, equipment, and technology have been applied to mask engineering, which has promoted the development of the mask technology to a thinner and thinner direction. At present, the thinnest thickness of ultra-thin overlay can be achieved at about 12 mm. Figure 1.28 shows the pavement effect after an Ultra-thin overlay construction. It can be seen that the thickness of the Ultra-thin overlay is only half the height of RMB coin.

1.5.6 In-Place Hot Recycling for Asphalt Pavement Surface It refers to the technology of regenerating old asphalt pavement in the range of 20–30 mm by using special in situ thermal regeneration equipment, heating and loosening asphalt pavement, mixing a certain amount of new asphalt, new aggregate, new asphalt mixture or regenerative agent in situ, and through hot mixing, paving,

1.5 Pavement Preventive Maintenance Technology and Its Development …

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Fig. 1.29 Construction of in-place hot recycling for asphalt pavement surface

rolling and other processes (Fig. 1.29). It is suitable for preventive maintenance of Expressway Asphalt Pavement and disease treatment of original pavement in front of cover. Since the late 1990s, China has introduced nearly 10 sets of In-place Hot Recycling paving machine units from Japan, Germany, Canada, Finland, and other countries. Beijing-Tianjin-Tang Expressway, Beijing-Shijiazhuang Expressway, Chengdu-Chongqing Expressway, Beijing-Fuzhou Expressway, and ShanghaiNanjing Expressway have all implemented In-place Hot Recycling with unequal area. At present, the cumulative implementation area of In-place Hot Recycling in China is more than 10 million m2 . The main functions of In-place Hot Recycling are repairing surface diseases, restoring pavement smoothness and realizing In-place Hot Recycling of old asphalt layer materials.

1.5.7 Development Trend of Pavement Preventive Maintenance Technology In recent years, the concept of Pavement Preventive Maintenance has become increasingly popular, and the application of preventive maintenance technology has become increasingly common. Meanwhile, preventive maintenance technology innovation and technology introduction is being carried out in various places in order to reduce engineering costs, reduce the impact of construction on traffic, and improve road use effect. According to the need of preventive maintenance of highway asphalt pavement in China, the development trend of preventive maintenance technology in recent years can be summarized as follows: 1. 2. 3. 4. 5.

Crack treatment is developing towards fast and non-destructive Fog Seal is advancing towards Multi-function Micro-Surfacing is advancing towards low noise Chip Seal is advancing towards Fiber Seal Ultra-thin Overlay is advancing towards Super-thin Overlay.

Chapter 2

Technical Guide for the Pavement Preventive Maintenance

2.1 General Provisions 2.1.1 Purpose In order to standardize and guide the preventive maintenance of asphalt pavement, improve the maintenance technology of asphalt pavement, maintain and improve the performance of pavement, prolong the overhaul period of pavement, and reduce the maintenance cost of the whole life cycle of pavement, this guide is formulated.

2.1.2 Limitation This guideline is suitable for preventive maintenance of asphalt pavement of expressway, First, Second and Third-Class Highway. Other roads can use this guide for reference.

2.2 Terms and Symbols 2.2.1 Pavement Preventive Maintenance Pavement Preventive Maintenance is a pavement maintenance measure that does not disturb the pavement structure and does not change the strength of the pavement structure on the pavement without damage or only signs of minor diseases and diseases, which is for the sake of improving the whole maintenance benefit in

© Springer Nature Singapore Pte Ltd. 2021 F. Li et al., Preventive Maintenance Technology for Asphalt Pavement, Springer Tracts on Transportation and Traffic 16, https://doi.org/10.1007/978-981-15-6206-8_2

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cycle of pavement, preventing the occurrence of pavement diseases or the further expansion of minor diseases, delaying the attenuation of pavement performance, and maintaining and improving pavement performance.

2.2.2 Maintenance Benefit in Cycle According to the pavement preventive maintenance mode, Maintenance Benefit in Cycle is the economic and social benefits generated by the pavement preventive maintenance during the period between new construction and overhaul or two overhauls of pavement.

2.2.3 Maintenance Cost in Cycle According to the preventive maintenance mode, Maintenance Cost in Cycle is the maintenance costs that occur during the period between new construction and overhaul or two overhauls of the pavement.

2.2.4 Optimal Time of PPM During the period from new construction to overhaul or two overhauls, the Optimal Time of PPM is the preventive maintenance implementation time point with the maximum benefit-cost ratio can be obtained.

2.2.5 Crack Filling and Sealing Crack Filling and Sealing is a technique of filling cracks in asphalt pavement with special sealant.

2.2.6 Crack Seal Band Crack Seal Band is a technology of using a joint band to stick cracks in asphalt pavement.

2.2 Terms and Symbols

39

2.2.7 Fog Seal Fog Seal is a kind of pavement preventive maintenance technology, which sprays special fog seal material on the surface of asphalt pavement, closes some microcracks and voids of asphalt pavement, plays a waterproof role, prevents further aging of pavement, and improves the appearance of pavement.

2.2.8 Sand Fog Seal Sand Fog Seal refers to the original fog seal material mixed with adding clay, clay and other fillers, which improves the anti-slip performance and wear resistance of the fog seal.

2.2.9 Mastic Seal It is a pavement preventive maintenance technology which uses special modified emulsified asphalt and fine aggregate to evenly spray or scrape to the surface of asphalt pavement, seal the micro cracks and pores of asphalt pavement, stabilize the loose aggregate on the surface of old pavement, improve the waterproof performance of old pavement and slow down the aging rate of pavement.

2.2.10 Slurry Seal Slurry Seal is a thin layer technology that uses special mechanical equipment to spread emulsified asphalt, coarse and fine aggregates, fillers, water, and additives into slurry mixture on the original pavement according to the design ratio.

2.2.11 Micro-surfacing Micro-surfacing is a thin layer technology with high skid resistance and durability, which uses special mechanical equipment to spread polymer modified emulsified asphalt, coarse and fine aggregates, fillers, water and additives into slurry mixture according to the design ratio on the original pavement, and quickly restores the traffic.

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2 Technical Guide for the Pavement Preventive Maintenance

2.2.12 Chip Seal Chip Seal is a technology that uses aggregates of near single particle size and asphalt binder that meets the requirements in accordance with the laying method.

2.2.13 Fiber Seal Fiber Seal is a technology that uses Construction Equipment for Synchronized Fiber Seal, spraying two layers of asphalt binder and one layer of glass fiber at the same time, then spreading gravel on it, and forming a new wearing surface or stress absorbing membrane interlayer (SAMI) after rolling.

2.2.14 Thin Overlay Thin Overlay is an asphalt overlay technology with a thickness of 30 mm (+5 mm) on the original asphalt pavement.

2.2.15 Ultra-Thin Overlay Ultra-thin Overlay is an asphalt overlay technology with a thickness of 20 mm (+5 mm) on the original asphalt pavement.

2.2.16 In-Place Hot Recycling for Asphalt Pavement Surface In-place Hot Recycling for Asphalt Pavement Surface is a technology of regenerating old asphalt pavement in the range of 20–30 mm by using special in situ thermal regeneration equipment, heating and loosening asphalt pavement, mixing a certain amount of new asphalt, new aggregates, new asphalt mixture or regeneration agent in situ, and through hot mixing, paving, rolling and other processes.

2.2.17 Symbols Symbols used in this guide and their meanings are listed in Table 2.1.

2.3 Expectation Level of Pavement Maintenance

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Table 2.1 Symbols and their meanings Number

Symbols

Meanings

2.2.1

PPM

Pavement preventive maintenance

2.2.2

AADT

Annual average daily traffic

2.2.3

PQI

Pavement quality index

2.2.4

PCI

Pavement condition index

2.2.5

RQI

Road quality index

2.2.6

RDI

Rutting depth index

2.2.7

SRI

Sliding resistance index

2.2.8

PSSI

Pavement structural strength index

2.2.9

IRI

International roughness index

2.2.10

PBI

Preventive benefit index

2.2.11

EUAC

Equivalent uniform annual cost

2.2.12

BCR

Benefit-cost ratio

2.2.13

EAC

Equivalent annual cost

2.3 Expectation Level of Pavement Maintenance 2.3.1 Evaluation Index of Pavement Technical Conditions The evaluation of asphalt pavement technical condition is expressed by Pavement Quality Index (PQI) and Pavement Condition Index (PCI), Road Quality Index (RQI), Rutting Depth Index (RDI), Skid Resistance Index (SRI) and Pavement Structural Strength Index (PSSI). The range of PQI and corresponding sub-index is 1–100. Asphalt pavement technology is divided into five grades: Excellent, Good, Medium, Secondary and Inferiority. The grade of technical condition of asphalt pavement is determined according to the standard specified in Table 2.2. The performance index (PQI) of asphalt pavement is calculated by Formula (2.1). PQI = wPCI PCI + wRQI RQI + wRDI RDI + wSRI SRI

(2.1)

Formula: wPCI —The weight of PCI in PQI is calculated in Table 2.3. wRQI —The weight of RQI in PQI is calculated in Table 2.3. wRDI —The weight of RDI in PQI is calculated in Table 2.3. wSRI —The weight of SRI in PQI is calculated in Table 2.3. Table 2.2 Standard for evaluating the technical condition of asphalt pavement Rating level

Excellent Good

PQI and sub-indicators at all levels ≥90

Medium

Secondary Inferiority

≥80,