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Preparation and Road Performance of Cold Patching Materials Modified by Polyurethane Prepolymer
YANG Wei, ZHAI Xueguo, GUO Weixiong, and CHI Haozhan

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.025

Traditional cold asphalt mixtures present challenges such as inapplicability in humid environments and poor durability when used for repairing potholes in asphalt pavements. To address these issues, with polyurethane prepolymer (PUA), 70# base asphalt, and additives as raw materials, a cold patch asphalt base liquid with optimal comprehensive performance was developed using the simplex design and the ideal point method. Cold patching asphalt mixtures were also prepared, with pavement performance systematically evaluated. It indicates that the PUA content has the greatest influence on the low-temperature performance and tensile strength of the cold patching asphalt liquid. The effects of components on workability and volatility follow the order: diluent > asphalt > PUA. The prepared liquid also exhibits excellent storage stability and adhesion. Furthermore, the PUA-modified cold patch materials demonstrate good strength, high-temperature stability, low-temperature crack resistance, moisture resistance, and fatigue resistance. These findings facilitate the application of polyurethane prepolymer-modified cold patch asphalt in rapid repair projects for asphalt pavement distress.

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A Review of Pavement Condition Evaluation Index Systems in China and Abroad
CHEN Leilei, YANG-LI Wenyun, LI Wei, Muhammad Thlha, and QIAN Zhendong

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.007

With the increasingly complex operating conditions of roads, it has become a consensus among countries to improve the accuracy and systematicness of maintenance decisions. Since the pavement condition evaluation index system is the core tool supporting the judgment of schemes, its construction method and applicable ability directly affect the maintenance efficiency and resource allocation level. Based on the construction logic of the index model, the scoring mechanism of grade division, and the conditions of road grade adaptation, the characteristics of the evaluation index systems in typical countries in China and abroad were compared and sorted out. The internal causes affecting the characteristics of the index system were discussed from in-depth perspectives such as management concepts and institutional arrangements. Research findings show that some systems abroad emphasize hierarchical structural response or public experience, while in China, unified deployment and hierarchical downward management are emphasized. In China's case, the system has a certain foundation in terms of universality and standardization, but there are obvious shortcomings in threshold adjustment, scene adaptation, and system integration. Therefore, suggestions are proposed including setting dynamic thresholds in combination with maintenance goals, enhancing the adaptability to various types of road operating environments, and promoting the effective integration of evaluation results with the actual management process, which provides ideological support for the structural optimization and institutional coordination of the evaluation system.

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Review of design for combined base asphalt pavements with asphalt treated base and cement stabilized subbase
LI Xuelian, CHEN Peng, and CHA Xudong

Date posted: 11-24-2023
DOI: https://doi.org/10.14048/j.issn.1671-2579.2023.05.001

At present, there are great differences in the material composition, structure form, damage type, disease cause, design index, and design method of asphalt pavement with asphalt-treated base and cement-stabilized base in various countries. In view of this, this paper summarized the material type and structure form selected in China and abroad and analyzed the damage type and disease cause of this kind of asphalt pavement structure. This paper discussed the differences in the design methods of combined base asphalt pavement in different countries and summarized the disease control types and design indexes in different countries. On this basis, the reasonable material, structure combination, and design indexes of combined base asphalt pavements were recommended, which provided a reference for the design and application of this kind of asphalt pavement.

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Pavement Performance Prediction Based on Integrated Particle Swarm Optimization-Gray Back Propagation Neural Network Model
LI Xuelian, HUANG Yan, and LI Xiong

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.005

The existing performance prediction model of asphalt pavements is limited by low accuracy and a lack of historical measured data. To address this issue and maximally optimize the pavement maintenance decision, a pavement performance prediction model integrating particle swarm optimization (PSO), gray model (GM), and back propagation neural network (BPNN) was proposed based on network management. Meanwhile, the model was compared with the GM (1, 1) model, support vector regression (SVR) model, BPNN model, and PSO-BPNN model. Then, the prediction accuracy of the models was evaluated by the mean absolute error (EMAE), the root mean square error (ERMSE), and the mean absolute percentage error (EMAPE). The fitting results of the PSO-gray BPNN model were assessed by the R-squared (R2). The results indicate that by optimizing the BPNN model with the PSO algorithm and the GM model, the accuracy of the PSO-gray BPNN model is significantly improved. Based on the performance data of 14 expressways in Hubei Province, a high correlation between the predicted values of the model and the measured data is found. For the IPCI index, the value of EMAE, ERMSE, and EMAPE is reduced to 1.721 8, 2.296 8, and 1.897 1, respectively. The value of R2 could be up to 0.919. Compared to the other four models, the PSO-gray BPNN model has the smallest values of prediction error for IPCI, IRQI, IRDI, and ISRI, fully showing the superiority of the model. With higher prediction accuracy, the proposed PSO-gray BPNN model has prediction results more consistent with the actual situation, providing an accurate and reliable technical support for the prediction of pavement performance at the network level.

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Mesoscopic Simulation Stu dy on Fatigue Performance of Asphalt Mixture Based on Discrete Element Method
MAO Quan, ZHENG Junqiu, MA Hui, and WANG Min

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.002

Asphalt pavement is prone to fatigue cracking during long-term service, which can lead to secondary diseases and weaken the structural durability. For in-depth revelation of the fatigue damage behavior of asphalt mixtures, in this paper, a semi-circular bending (SCB) mesoscopic model was established based on the discrete element method. The fatigue fracture behavior of three typical asphalt mixtures in Jiangsu Province's expressways, including SMA-13, SUP-20, and SUP-25, was simulated under different stress ratio conditions. The fatigue damage mechanism and evolution law of asphalt mixtures were analyzed from the aspects of fatigue life, crack propagation, and residual strength. The results show that all three mixtures exhibit typical three-stage fatigue damage characteristics, and the increase of stress ratio will significantly shorten the fatigue life and accelerate the crack development. SMA-13 shows excellent fatigue resistance due to its dense skeleton and modified asphalt mortar, followed by SUP-20, while SUP-25 performs the worst due to insufficient skeleton constraint and low mortar toughness. Meanwhile, the crack propagation paths and residual strength attenuation laws of different mixtures are significantly different, further revealing the key role of skeleton structure and asphalt mortar performance in the fatigue damage mechanism.

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Review of Snow and Ice Melting Techniques for Road and Bridge in Cold Regions
TANG Liyun, SHAO Haitao, TANG Huaming, QIU Peiyong, DU Xiaoqi, ZHANG Lei, and PENG Hui

Date posted: 10-28-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2024.05.003

Snow and ice melting of road and bridge surfaces is crucial for traffic safety，but current research on snow and ice melting techniques mainly focuses on engineering effects and technical evaluation，without the analysis and elaboration from the perspective of their mechanisms.To this end，based on the different mechanisms，this study divided snow and ice melting techniques into three types and summarized them：passive deicing，active deicing，and energy utilization deicing.This study systematically evaluated the advantages and disadvantages of traditional deicing methods such as deicing agents and mechanical deicing，analyzed two active deicing techniques，namely inhibitive freezing pavement and phase change material pavement，discussed the environmental-friendly method for road deicing by using phase change materials，and introduced the mechanisms of different energy utilization deicing techniques.This study analyzed the existing road deicing techniques，their actual application effects，and existing problems，to provide foundational support for the research of snow and ice melting on roads and bridges in cold regions.

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Research on Enhancement of Toughness Performance in Polyurethane-Modified Epoxy Asphalt
LIANG Bo, LIAO Xintao, LIAO Wei, JIANG Hui, and QIN Ruiming

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.011

To solve low toughness and high brittleness of epoxy asphalt under low-temperature conditions, in this study, polyether-type polyurethane (JMPU) and polyester-type polyurethane (JZPU) were employed to prepare modified epoxy asphalt. Firstly, the Brookfield viscosity test, infrared spectroscopy test, and fluorescence microscopy were utilized to characterize the curing process. The curing time and curing temperature of JMPU and JZPU modified epoxy asphalt were 3 h/140°C and 4 h/150°C, respectively. With styrene-butadiene-styrene block copolymer (SBS), a common modifier, as the control, the performance changes of epoxy asphalt before and after modification with different toughening agents were evaluated through mechanical tensile test, rheological property test, multiple stress creep recovery (MSCR) test, and storage stability test. The research findings indicate that the polyurethane system can effectively enhance the elongation at break, low-temperature performance, and storage stability of epoxy asphalt by forming an interpenetrating network structure (IPNs) with epoxy asphalt, while maintaining excellent high-temperature performance. The elongation at break of JMPU-modified epoxy asphalt and its low-temperature creep stiffness at ‒12°C can reach 233% and 169 MPa, respectively. Results of an aging test on the toughened and modified epoxy asphalt show that the incorporation of JMPU and JZPU effectively mitigates the adverse effects of aging on epoxy asphalt performance, evidenced by lower creep stiffness aging index and rutting factor aging index, as well as higher creep rate aging index. Therefore, the addition of the PU system as a toughening agent improves the toughness of epoxy asphalt and enhances its compatibility and anti-aging performance.

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Research on Fatigue Damage and Crack Propagation of Pre-Cut Seam Asphalt Mixture Composite Beams
HUANG Dengke and LIU Hongfu

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.013

This study investigated the influence of reflective cracking on the fatigue performance of asphalt pavements subjected to milling and resurfacing under varying service conditions. The fatigue life of composite beams was evaluated via four-point bending fatigue tests, considering the effects of different stress ratios, soaking durations, air void contents, and types of tack coat. Meanwhile, the digital image correlation (DIC) technique was employed to analyze the crack propagation behavior of composite beams. To accurately characterize the failure of composite beam specimens, the dynamic modulus was employed to define damage variables, enabling the calculation of critical fatigue damage for the composite beams. A nonlinear fatigue damage model, accounting for critical damage under multi-factor influences, was subsequently proposed. In addition, a modified Logistic function model was developed to analyze crack propagation behavior and fatigue life of composite beams under diverse stress ratios, air void conditions, and tack coat configurations. The results indicate that at different stress levels, the modulus of composite beams decreases with crack propagation, and the decay rate is proportional to the crack growth rate. At the same stress level, the modulus decay curves and crack propagation curves intersect as the life ratio increases. This intersection marks the transition from a stable state to an unstable state, beyond which cracks propagate rapidly and the modulus declines sharply until specimen failure. The modulus ratios corresponding to these intersection points are consistently within the range of 0.5‒0.6. Based on these findings, it is recommended that milled and resurfaced asphalt pavements be maintained promptly before their modulus decreases by 50%. This research provides a decision-making basis for the maintenance and management of asphalt pavements.

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An Overview on the "ReusePotential" for Managing Shield Tunnel Spoilsas Resource
ZHANG Junhui, LI Hai, YANG Hao, WANG Hualei, and HAN Shanpeng

Date posted: 1-18-2024
DOI: https://doi.org/10.14048/j.issn.1671-2579.2022.06.001

In response to the challenges posed by massive shield muck production and inadequate disposal solutions, scholars have systematically reviewed the research on shield muck recycling technologies. Based on the challenges faced by the treatment of shield muck in China, this paper formed a systematic understanding of the classification of shield muck, the progress of resource recycling technologies, and typical applications, introduced the pretreatment methods of shield musk in China and abroad, and summarized the application scenarios and resource recycling technologies of shield musk in detail. Then, the paper analyzed the problems of shield musk recycling technologies, such as expensive curing agents, serious pollution, lack of pollutant analysis of roadbed backfill materials, low strength of recycled brick, and unconspicuous market benefit. The standardized technical process of “pre-classification treatment of shield musk, feasibility evaluation of recycling, resource recycling scenario, and performance and benefit evaluation” for shield musk recycling was constructed. The research directions of the development of shield musk curing agents and the migration of pollutants were emphasized. Finally, the development trend of shield musk recycling technologies was prospected.

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Mechanical and Durability Properties of Flowable Solidified Soil Based on Waste Slurry from Pile Foundations
LI Hongzhen, WU Shuxin, CHE N Chen, YIN Shurui, WANG Luwen, ZHU Kongyou, and FENG Zhuangzhuang

Date posted: 10-27-2025
DOI: https://doi.org/10.14048/j.issn.1671-2579.2025.05.004

To address the challenge of pile foundation waste slurry disposal, this study proposes a resource utilization approach based on alkali activation technology, enabling rapid solidification of the waste slurry into a flowable solidified soil suitable for engineering backfill. An orthogonal experimental design was employed to determine the optimal mix ratio of the solidifying agent, identified as cement:slag:fly ash = 0.5:0.35:0.15, with NaOH accounting for 6% of the total mass. Based on this, the mechanical and durability properties of the solidified soil were systematically investigated. Results indicate that within a certain range, both unconfined compressive strength and splitting tensile strength increase linearly with higher solidifying agent content and longer curing age, and a fitting relationship between the two was established. An increase in construction delay time weakens the mechanical performance, highlighting the need for appropriate time control during construction. In terms of durability, resistance to wet-dry cycles improves with greater solidifying agent content, though a saturation effect is observed. The water stability coefficient shows different growth trends with changes in solidifying agent content and immersion age. Freeze-thaw cycles significantly degrade the strength, and increasing the solidifying agent content does not effectively improve frost resistance. The findings provide theoretical and technical support for the engineering application of premixed flowable solidified soil.