Reviews on Advanced Materials Science 2021; 60: 438–449 Review Article Hua-Ping Wang*, Yan-Xin Guo, Meng-Yi Wu, Kang Xiang, and Shi-Rong Sun Review on structural damage rehabilitation and performance assessment of asphalt pavements https://doi.org/10.1515/rams-2021-0030 them, the proportion of asphalt pavement is about 90%. received January 29, 2021; accepted April 10, 2021 The actual service life of asphalt pavements built by the Abstract: Asphalt pavements have been extensively used current design standards is generally short, far below the [ ] in highway system. However, a great number of asphalt design life of 15 years 1,2 . Current studies show that – pavements suffer from early distresses after servicing 60% of asphalt highways after serving for 10 12 years – - for about 2–3 years, which leads to frequent rehabilita- and 17% of that after serving for 6 8 years require exten - tion and increased maintenance cost. To understand sive repairs. The frequent maintenance of asphalt pave the damage propagation principle and the correlated ment significantly reduces the traffic capacity of the rehabilitation measure, the progress of pavement distress highway and the transportation efficiency of the road rehabilitation, structural performance, and damage assess- network, and also brings about a significant increase ment of asphalt pavements has been explored in the per- in maintenance and repair costs during the operation spectives of materials and structures. The current advance period. Therefore, to improve the level of preventive on the parameters for describing the cracking and rutting maintenance, it is necessary to develop the monitoring - of asphalt pavements has been introduced. The develop- technology for exploring the service performance, struc ment tendency for the damage self-healing and rehabilita- tural degradation, and damage failure mechanism of tion, and structural assessment has also been discussed. asphalt pavement based on the effective response data [ – ] The study can provide a scientific guidance for under- in field 3 5 . It can be adopted to determine the repair standing the generally used structural damage rehabilita- design scheme and rehabilitation effect evaluation of tion measure and performance assessment methods of asphalt pavement structural damage. The formulation - asphalt pavements. of maintenance strategies for asphalt pavement struc tures is of great scientific importance and engineering Keywords: asphalt pavement, distress, structural degra- meaning for the whole life cycle management of pave- dation, rehabilitation measure, performance assessment ment structures and the durable study of asphalt pave- ment structures. Because of the rapid growth of highway mileage and traffic volume, the demand for high-grade highway main- 1 Introduction tenance becomes increasingly diversified. The develop- ment trend of highways is that the construction and Until 2019, the total mileage of highways in China has maintenance have equal weight. Therefore, to scientifi- reached 150,000 km, ranking first in the world. Among cally maintain and effectively extend the service life of pavements, pavement functional rehabilitation technology will develop from the perspectives of material performance enhancement, structural composition optimization, and * Corresponding author: Hua-Ping Wang, School of Civil repair-effect information [6,7]. To better understand the Engineering and Mechanics, Lanzhou University, Lanzhou, 730000, - China; Key Laboratory of Mechanics on Western Disaster and current domestic and international research and engi Environment, Lanzhou University, Lanzhou, China; Key Lab of neering application of structural damage repair of asphalt Structures Dynamic Behavior and Control (Harbin Institute of pavements, this paper will take asphalt pavements as an Technology), Ministry of Education, Harbin, 150090, China, example and review the main research progress in the - e mail: [email protected], [email protected] academic and engineering fields at home and abroad. - Yan Xin Guo: Key Laboratory of Mechanics on Western Disaster and - Environment, Lanzhou University, Lanzhou, China The major contents summarize the rehabilitation mea Meng-Yi Wu, Kang Xiang, Shi-Rong Sun: School of Civil Engineering sure of material and structural performance, and the and Mechanics, Lanzhou University, Lanzhou, 730000, China method to assess the pavement service performance Open Access. © 2021 Hua-Ping Wang et al., published by De Gruyter. This work is licensed under the Creative Commons Attribution 4.0 International License. Structural damage rehabilitation/performance assessment of asphalt pavements 439 and damage. It intends to provide scientific basis and course, as shown in Figure 2. Water penetration or poor technical guarantee for the whole life cycle maintenance subsurface can also lead to the occurrence of fatigue management of pavement structures. cracks, which appear in spiderweb. Reflective cracks The main objective of the study is to explore the develop from the underlying cracks [2]. Block cracks occurrence mechanism of various distresses (i.e., cracks, appear as randomly distributed linear cracks. Transverse rutting, and depression) in asphalt pavements and the cracking is often because of seasonal temperature change- critical mechanical parameters to control the damage. induced shrinkage or reflective cracks. Slippage cracks are The rehabilitation measures of the damaged asphalt generally caused by the weak bonding action or a lack of pavements are summarized from the perspectives of adhesion between layers. They are in half-crescent shape materials and structures. The major assessment methods and clearly show the top surface separating from the on structural performance of asphalt pavements are dis- under-surface [8]. As the distress is caused by a problem cussed. Suggestions on the development tendency on under the road surface, the area surrounding the crack health monitoring and inverse design of asphalt pave- need to be removed and re-laid.Thisrepairrequiresa ments are also provided. partial or full depth patch. 2 Distresses of asphalt pavements 2.2 Rutting Asphalt pavement is the most common type in highway Rutting is caused by vehicles traveling down the pave- transportation system. Besides the advanced functions, ments over a long period, resulting in clear areas of wear asphalt pavements have downsides, which is the sheer that tires most commonly travel. Heavily rutted pavement variety of distresses existing over the lifetime. The major may point to poor compaction of multilayers during the distresses that deteriorate the performance of asphalt construction, settlement of the subgrade, or a poorly ( - pavements include the cracks fatigue crack, top down designed asphalt concrete (AC)[5]. crack, reflective crack, and block crack), rutting, pot- It generally contains the structural rutting and fluid holes, upheaval, corrugation, and shoving. rutting, as shown in Figure 3. When the traffic load- induced action is beyond the strength of each layer, permanent deformation occurs in asphalt course and sub- 2.1 Cracks layers in the multilayered pavement, denoted as struc- tural rutting [2]. Strength is the critical factor. When the Asphalt pavement can suffer from fatigue crack, reflec- shear stress induced by the repeated traffic loads under tive crack, low-temperature-induced shrinkage cracks, high temperature exceeds the shear strength of AC, fluid transversal cracks, and so on as shown in Figure 1. deformation accumulates around the vehicle wheels and Fatigue cracking can be mainly because of the repeated induces the transversal cross section in W-shape, as heavy traffic loads improperly distributed on the asphalt shown in Figure 3(b), denoted as fluid rutting. A physical Figure 1: Various kinds of cracks developed in asphalt pavements. (a) Fatigue cracks; (b) reflective crack; (c) low temperature induced shrinkage cracks. 440 Hua-Ping Wang et al. Figure 2: Surface shape of cracks in asphalt pavements. (a) Fatigue cracks; (b) block cracks; (c) linear cracks. photo of rutting is displayed in Figure 3(c). As rutting can course is compromised, a depression occurs in the pave- be characterized by the deformation, the rutting distress ment, known as a pothole. The major reasons for the can be decreased or solved by increasing both the com- occurrence of potholes can be attributed to weak pave- pressive and shear strengths of ACs. ment surface, base, or subgrade, thin surface, and poor drainage [6,7]. Potholes can affect the moving stability and cause damage on the traffic vehicles. Asphalt patch 2.3 Potholes is the most common routine maintenance for repairing a pothole. Recurring potholes induced by the repeated Pothole is usually an alligator crack or collection of alli- traffic loads often start along the bonding surface between gator cracks that have been left untreated until pieces of the repairing material and the original asphalt pavement. AC become completely dislodged and leave the road sur- Therefore, it is important to enhance the bonding strength face, revealing the concrete underlayer, as shown in between the old asphalt course and the newly patched Figure 4. When the area beneath the asphalt surface ACs, so as to prevent the pothole distresses. Figure 3: Characteristics of rutting in asphalt pavements. (a) Structural rutting in bottom base and subgrade; (b) fluid rutting; (c) photo of rutting in asphalt pavement. Structural damage rehabilitation/performance assessment of asphalt