To enhance the application value of CT technology in road engineering and offer significant technical support for digital characterization and visual examination of the microstructure of asphalt mixtures, the operational principles of X-ray CT and its applications related to the development of digital models for asphalt mixtures were introduced. The factors influencing the quality of CT images of asphalt mixtures have been systematically summarized, and the impact of various scanning process parameters on image quality was analyzed. The characteristics and application scope of CT image quality enhancement and threshold segmentation techniques were elucidated. The primary applications of X-ray CT in the context of digital models of asphalt mixtures were discussed, including phase analysis (encompassing air voids, aggregates, and additives), damage assessment (addressing freeze-thaw damage, mechanical damage, and crack healing), dimensional measurement (such as asphalt mortar thickness and pavement surface texture depth), and virtual experimentation (including finite element and discrete element methods). Additionally, the current state of research and the challenges associated with the use of X-ray CT in the analysis of the microstructure of asphalt mixtures were examined. This study serves as a valuable reference for future investigations into the application of X-ray CT in the digital characterization and analysis of asphalt mixtures.

To address pavement defects such as cracking and loosening caused by increased highway traffic volume and heavy-duty vehicles, and to enhance structural load-bearing capacity and service life, a novel high-permeability, strong-bonding polymer grouting material has been developed for pavement rehabilitation. This study investigated the deflection characteristics and mechanical behavior of pavement structures before and after permeable polymer grouting repairs through full-scale model testing. A pavement model was developed to simulate pavement response under dynamic loading. Research findings indicate that permeable polymer grouting effectively improves the condition of damaged road surfaces. Surface layer index SCI, base layer index BDI, and subgrade index D8 all showed significant reductions. This confirms that polymers not only effectively consolidate fragmented base layers but also enhance the overall stiffness of the surface layer and subgrade through permeation and diffusion. The numerical simulation results closely align with the measured data trends, validating the reliability of the established model in predicting repair effectiveness. These findings provide a theoretical basis and practical reference for the engineering application of polymer grouting repair technology and the prevention and control of structural defects.

To eliminate the gradation variability of reclaimed asphalt pavement (RAP) materials and improve the road performance of cold-recycled mixtures, this study analyses the gradation variability of recycled materials and conducts gradation design using the actual particle sizes of extracted aged materials. An optimisation method for the mix proportion of cold-recycled mixtures is proposed by combining the uniform method for design and the Bailey method for verification. A comparative study on the road performance of cold-recycled mixtures with two different gradations was then carried out. Based on low-temperature beam bending and semi-circular bending (SCB) tests, the low-temperature performance of the recycled mixtures was comprehensively evaluated from the perspectives of conventional analysis and energy analysis. Moreover, the correlation between fracture energy, strain energy density and the low-temperature indices specified in the current technical code was analysed to determine the low-temperature performance evaluation index for cold-recycled mixtures in severely cold regions. The results show that gradation design using only the sieving data of milled RAP materials will lead to an overall finer gradation of the recycled mixtures. For the optimised gradation verified by the uniform design and Bailey verification, the dynamic stability of the mixtures is increased by 9%~15% and the water stability is improved by 3%~6% under different cement contents. In addition, the flexural tensile strength and flexural tensile strain of the mixtures are increased by 3% and approximately 6%, respectively after gradation optimisation, indicating an improvement in low-temperature performance, with the optimal effect achieved at a cement content of 1.5%. Through the correlation analysis of fracture energy, strain energy density and flexural tensile strain, fracture energy is proposed as the low-temperature performance evaluation index for cold-recycled mixtures, and the recommended value of this index is determined to be 1000 J/m2 for severely cold regions in winter. The research results provide a theoretical basis for the gradation design and performance evaluation of recycled mixtures applied in severely cold regions.

To address the challenge that traditional detection methods struggle to reveal full-time-domain cumulative damage induced by temperature stress in asphalt pavements, this study analyzes the spatiotemporal evolution patterns of the asphalt pavement temperature field based on sensor monitoring data. According to these patterns, a dual-sine temperature field prediction model capable of reflecting asymmetric heating and cooling processes was established. Utilizing this model in conjunction with Miner’s linear cumulative damage theory, a complete quantitative analysis methodology translating the temperature field into a stress field and subsequently into a damage field was constructed. The results demonstrate that the dual-sine model achieves a goodness-of-fit (R2) exceeding 0.91, showcasing its unique advantage in characterizing the asymmetric daily temperature cycles in pavements. Full-time-domain damage analysis reveals that temperature-induced fatigue damage decreases significantly with depth, with annual damage degrees of 1.32 × 10−2 and 6.78 × 10−3 at depths of 0.02 m and 0.1 m, respectively. The critical source of temperature fatigue damage is identified as daily temperature differentials exceeding 18°C. Although this temperature range constitutes only about 6% of the annual duration, its damage contribution rate reaches as high as 99%. This study provides a novel, transferable method for quantifying environmental fatigue damage in asphalt pavements without requiring in-situ stress sensors, and it identifies the large-ΔT periods (spring/autumn) as the key maintenance window—a scientifically and practically significant insight for pavement design and preservation.

Damage to semi-rigid base asphalt pavements, caused by factors such as poor construction quality and repeated vehicle loads (e.g., base layer cracking, fragmentation, and subgrade weakening), can induce various distresses that further develop into structural failures, severely compromising driving safety. Non-destructive testing and accurate evaluation of the current structural performance of pavements are crucial for the proper diagnosis and repair of highway distresses. Given the limitations of existing evaluation indices for semi-rigid base asphalt pavement structures, this study first employs three-dimensional finite element simulations to construct pavement structural models and analyze the effects of structural damage at different locations on deflection basin indices, specifically D0-D300, D300-D600, and D1800. Subsequently, an evaluation index, (D300-D900)/(D600-D900), is proposed to assess the interlayer bonding condition between the base and surface layers of semi-rigid base pavements. Field tests were conducted to validate the method, and core sampling results indicate that when D0-D300 is set to 100 and D300-D600 to 40, the proposed deflection basin index-based evaluation method achieves an accuracy exceeding 85% in assessing surface and base layer damage in semi-rigid base asphalt pavements.

Waste tire rubber particles have potential to improve the road durability and reduce road noise. However, the current research on the influencing factors and noise reduction mechanisms of rubber asphalt mixtures' noise reduction performance is not very in-depth, which hinders the balanced design of low-noise road performance and noise reduction function. This research aims to investigate the effects of dry-process rubber particle addition on the road performance and noise reduction capabilities of asphalt mixtures, clarifying the road performance enhancement and noise reduction mechanism of dry-process rubber asphalt mixtures. This study initially evaluated the high- and low-temperature performance, water stability, and fatigue performance of Stone Matrix Asphalt (SMA) mixtures with varying rubber particle contents (0 %, 1 %, 1.5 %, and 2 %) prepared using the dry -process, and clarified the modification mechanism of dry-process rubber particles from a microscopic perspective. Furthermore, explored the trend of damping characteristics of asphalt mixtures with rubber particle content through dynamic modulus tests. The dry-process rubberised asphalt mixtures sound absorption and noise reduction performance were analyzed through tire/road noise test and absorption coefficient detection. The results show that the road performance of asphalt mixture first improves and then decreases with the increase of rubber particles content. The optimal road performance of asphalt mixture is achieved when the rubber content is 1.5 %. The formed semi continuous phase network structure between rubber particles and asphalt can enhance the structural strength of asphalt mixtures, thereby improving its road performance. Rubber particles enhance the sound absorption and damping capabilities of asphalt mixtures, improving their noise-reduction performance. The 1.5 %RSMA (SMA mixture with 1.5 wt% rubber particles by aggregate) can reduce noise to 3 dB(A) compared to the 0 %RSMA mixture, and road noise levels are correlated with vehicle speed and rainwater blockage.

To improve the working performance of fog seal material and leverage its quality enhancement role in maintaining pavement, the new fog seal materials with significant permeability and bonding properties were prepared by adding penetrant. The change rules in the permeability of fog seal materials at different working conditions were studied. The macroscopic and microscopic combined method for evaluating the permeability of fog seal materials was proposed, and the correlation between permeability and asphalt mixture porosity was determined. The results showed that the fog seal materials with 4 % II penetrant have best permeability. The recommended spraying volume of fog seal is 0.6 kg/m 2 , and the construction temperature is 25 degrees C. The fog seal has a penetration depth of 8.4 -34.4 mm at a porosity of 4 %-10 %. The proposed penetration depth evaluation method combining indoor testing and CT scanning can accurately evaluate the penetration performance of fog seal materials.

The fatigue property of the recycled mixture affects the structural design of recycled pavement. In order to explore the effect of different reclaimed asphalt pavement (RAP) content on the fatigue properties of recycled mixtures, the fatigue properties of recycled mixtures were analyzed through an indoor fatigue test and finite element numerical simulation. Based on the phenomenological method and the dissipated energy theory, the fatigue properties of recycled mixtures with different RAP contents were analyzed and the fatigue damage of the mixtures were also studies under various strain levels. Based on the finite element numerical model of fatigue damage, the stress distribution and internal damage field distribution of trabecular specimens under different temperatures, strain levels and RAP contents were analyzed. The results showed that the anti-fatigue level of the mixture decreased as the RAP content was increased. The relative change rate of dissipated energy for different types of mixtures showed a two-stage change rule with the change of load times, that is, the value is large and decreasing, and the value is small and stable. The correlation between the plateau value (PV) and the fatigue life was established under the double logarithm coordinates, which could better analyze the influence law of the RAP content on the fatigue performance of the recycled mixture. Under different temperatures, strain levels, and RAP contents, the stress at the bottom of trabecular specimen and the overall damage field were mainly generated at the upper part under compressive stress and the bottom under tensile stress, and the damage field distribution area accounted for a small part of the whole specimen. According to the test results and fatigue damage distribution, it is recommended that the content of recycled aggregate in recycled asphalt mixtures be less than 30% to ensure good performance. The research results have important practical significance for the improvement of fatigue performance and engineering application of recycled mixtures.

为科学准确地分析高速公路沥青路面使用性能的影响因素,保证高速公路的高效营运和科学养护.本文依托实际工况,详细分析了实际交通量、路面结构与材料、路面养护历史、温湿度状况及线形指标等因素对高等级公路路面性能的影响,然后基于层次分析法(AHP),将路面使用性能影响因素作为目标层建立层次结构,进行各影响因素的敏感性分析,最终得到高等级公路路面性能的影响因素敏感性排序,对高速公路科学养护决策具有重要指导意义.

The new generation of pavement technology with the goal of longevity is an important supporting technology that can promote the achievement of sustainable development of high-speed roadways. To further investigate the evolution trend of long-life pavement performance, this paper paved experimental sections to explore the correlations between pavement structure combinations and pavement performances. This paper presented four experimental sections with different pavement structures, asphalt concrete layer thicknesses, and pavement materials. Then, this paper analyzed the effects of the seasonal factors, pavement structure, and lanes on the deflection value and rut depth from three dimensions by the Pearson correlation coefficient (PCC). Finally, this paper used the analysis of variance (ANOVA) to analyze the relationships between the layer thickness of various materials in the pavement structure and the pavement performances, including the deflection value, international roughness index (IRI), texture depth (TD), British Pendulum Number (BPN), sideway force coefficient (SFC), rut depth, and disease area. The results showed that the seasonal factors significantly affected the deflection values of pavement structures with PCCs of 0.61, 0.72, 0.53, and 0.78. The high temperatures increased the average deflection values by 22.85%, 72.88%, 77.61%, and 88.13%, respectively. Under the influence of high temperature in summer and traffic loads, the increased ranges of average rut depth were −0.2%, 4.89%, 9.56%, and 7.31%, respectively. The results of ANOVA showed that the pavement structure type and thickness of each structural layer significantly affected the deflection value, and there also was a strong correlation between the pavement structure type, thickness, BPN, and SFC with p-values less than 0.05. Increasing the thickness of the asphalt surface was beneficial for reducing the area of defects, while laying the semi-rigid base layer was beneficial for maintaining the deflection value and rut depth at a lower level.

为研究旧路不同层位沥青的老化规律,得到不同层位铣刨料混合使用时旧沥青的整体老化程度,进而确定再生混合料的应用层位,文章基于三大指标、四组分试验及红外光谱测试,分析了旧路面层不同层位的旧沥青分层老化规律,以此为基础确定了基于分层老化的旧沥青整体老化程度评价方法,并提出沥青老化程度分级标准,根据老化程度分级细化了再生混合料的应用层位推荐.研究成果为铣刨料的精准化利用提供了基础.

为准确分析旧路路面状况,合理优选改扩建加铺方案,依托内蒙古省际大通道工程,全面评价了旧路路面破坏状况,创新性地以行驶质量中的平稳颠簸情况来反映公路基层破坏状况,提出了以弯沉为主、旧路路面破坏状况和行驶质量指数为辅的旧路改扩建加铺标准并联合采用3D-Radar和钻芯取样的方法进行了验证与评价.该研究成果可为旧路综合评价和改扩建加铺提供理论依据.

近年来,由水稳基层膨胀引起的沥青路面隆起现象在我国新疆、内蒙古等地频繁出现,沥青路面隆起高度可达3～5 cm,严重影响了道路寿命和行车安全,且维修难度大.因此,对比论证了在保证路面不发生膨胀隆起破坏时原材料、水稳基层混合料和环境中的硫酸盐含量阈值范围,得到了荒漠区高速公路路基土硫酸盐含量侵蚀等级划分标准,并根据实际工程经验、试验结果和理论研究,从材料、道路结构和施工工艺3个方面提出了基于设防分级的抗膨胀技术措施.该研究成果可为国内类似地区水稳基层膨胀的预防设计和处治提供参考.

The interlayer bonding of an asphalt pavement significantly influences the mechanical properties and long-term durability of the pavement structure. In order to develop a rapid and comprehensive evaluation method for assessing the interlayer condition of asphalt pavements using 3D GPR, we propose the stacking peak ratio (SPR) method. This method involves stacking the ratio between the amplitude peak of the interlayer and that of surface reflection to evaluate the interlayer state. Comparative analysis with direct shear tests and field measurements leads us to draw several conclusions: the optimal test parameters for the SPR method are a stacking peak ratio at 35 ns with a residence time of 1 us; the SPR method is compatible with various bonding materials and pollution layers, demonstrating its ability to effectively assess the bonding state of asphalt pavements; field tests further validate that the SPR approach can identify insufficient layer bonding and predict potential flaws in advance. Through our test findings and data analysis, it is evident that this SPR approach provides theoretical support and technological assistance for promptly evaluating the bonding status in asphalt pavements.

In order to solve the problems of difficult compaction and poor durability of ultrathin overlays, the performance of easy-compaction and high-durability (ECHD) modified asphalt and mixtures were studied. Taking matrix asphalt and SBS modified asphalt as the control group, the high- and low-temperature rheological properties of the asphalt were analysed by MSCR and BBR. The asphalt samples were observed and analysed by fluorescence microscope and infrared spectrometer, and the road performance, compaction performance and surface functional durability of the asphalt mixture were tested. The results show that the ECHD asphalt has the best high- and low-temperature properties. The modifier particles are uniformly dispersed in the asphalt, which can form a dense network structure and a stable system. The ECHD asphalt mixture has good low temperature and water stability, and the high-temperature stability is slightly lower than that of the SBS-modified asphalt mixture, but meets the requirements of the specification. It has the smallest compaction energy index CEI, and the largest compaction rate K. Before and after wearing 30,000 times, the asphalt mixture has the best wear resistance and surface texture, and the surface functional durability is the best. This paper provides a reference for material selection of ultrathin overlays.

ABSTRACT The arch expansion of cement stabilised base materials has become increasingly serious due to the current design guideline, typical climate and geological environment in the west of China. This research systematically investigated the influence of different factors on temperature expansion and also salt expansion of the cement stabilised base course through laboratory-scale slab tests and microscopic tests. Optimised gradation type of aggregate and other design indexes were proposed. The radial basis function network (RBFN) was used to establish a predication model of the amount of arch expansion. The micro-mechanism of arch expansion was further detailed by scanning images. The test results showed that the temperature expansion occurred most significantly during 20°C to 40°C and the optimised gradation could alleviate the arch expansion effectively. In the range of 20°C to 30°C, the arch expansion of cement stabilised materials was dominated by temperature expansion, and the expansion was mainly salt expansion between −10°C and 0°C. It is suggested that reasonable prevention measures should be taken considering different environmental factors by the inhibition weight 1/d i , and thus the most effective preventing methods of arch expansion would be taken.

为了探究大温差荒漠区路面拱胀与路基内部可溶性盐分毛细迁移作用之间的关系,从而进一步确定路面拱胀病害成因,首先对新疆南部地区拱胀病害典型路段进行了实地调查,通过现场开挖探坑、填料取样试验检测病害路段基层及路基内部盐的种类与含量.然后结合室内模拟试验,深入研究温度梯度和盐分梯度作用下路基填料内部水-盐迁移规律及含水量、颗粒级配、压实度等关键因素对水-盐迁移的影响,得到了各关键因素作用下水-盐迁移特点,并据此提出了阻隔路基内部水-盐迁移的方法.结果表明:拱胀病害产生原因与路基硫酸盐含量过高及道路结构层内部水-盐迁移有关;温度梯度变化对水分盐分重分布影响显著,在土基内部形成明显的"水盐补给过渡区",而盐分梯度对水盐迁移的影响仅有温度梯度的17.3％;初始含水量及土质类别对表层最终含盐量及含水量的迁移影响显著;初始含水量越大盐分迁移越明显,在表层集聚的含盐量越高;土体颗粒越细,水-盐迁移速度越快,盐分表聚现象越明显;压实度每增加1％,含水率减少0.2％左右,含盐量降低约0.06％;可选取风积沙阻隔路基内部水-盐迁移,厚度宜为40～50 cm,位置在路堤顶面以下30～50 cm.

Snowfall in northern China often occurs, and melting snow salt, which was mainly composed of sodium chloride, was widely applied to remove snow. And at the same time, it had a serious corrosion effect on the asphalt pavement. In this paper, melting snow salt was used to prepare different concentrations of solution. And different types of asphalt mixtures, such as Stone Matrix Asphalt (SMA-13), Asphalt Concrete (AC-13) and Open-graded Friction Courses (OGFC-13) were tested in different corrosion conditions——different concentration of melting salt solution and different drying-watering cycle times. The dynamic stability (DS), residual marshall stability (MS′), freeze-thaw splitting strength ratio (TSR), and maximum flexural-tensile strain (εB) were tested after corrosion, and the change rules were analysed also. The residual pavement performance percentage of asphalt mixtures was predicted at last. The results indicated that as the concentration of melting salt solution and the drying-watering cycle times increased, the performances of asphalt mixtures were all became worse and worse, the corrosion effect of melting snow salt on asphalt mixture was serious, especially on OGFC.

目前采用土工格栅处治桥涵台背路基的差异沉降效果良好,为了提高土工格栅在路基处治中的利用率,本工作创新性地将行车舒适性指标引入涵洞台背路基差异沉降控制.基于人-车-路耦合系统模型,分析了不同车型和不同车辆速度对人体最大竖向加速度的影响,通过多次回归计算得到不同车速下人体竖向加速度与差异沉降值的相关关系,提出折线型路基模式下基于行车舒适性的差异沉降控制标准;通过建立涵洞台背路基数值计算模型,计算分析了不同土工格栅铺设方式、密度、位置、长度和格栅模量下涵洞路基顶面的差异沉降分布规律,提出了基于行车舒适性的土工格栅处治涵洞路基差异沉降布设方案,并通过现场试验验证了方案的有效性.研究结果表明:格栅长度是影响涵洞台背路基处治效果的主要因素,所提出的基于舒适性的涵洞台背路基土工格栅铺设方案,可以显著提高格栅的利用率,有效控制路基差异沉降.研究成果可以为山区涵洞台背路基土工格栅铺设提供理论价值与借鉴意义.