Porous asphalt (PA) pavement is subjected to the coupling effects of vehicle load, high temperature and moisture saturation during rainy summer days. The harsh traffic and environmental conditions pose a great challenge to the longevity of PA pavement, which still lacks quantitative evidence. This study aims to characterize the internal structure change of PA mixtures under the actual coupling conditions through a modified dynamic creep test, in which the temperature of rainfall is realized through constant temperature water tank during repeated loading process. The microstructure changes of PA mixtures were characterized using image processing and analysis methods. The test results show that the influence of water saturation on permanent deformation is obvious in the compaction stage. At this stage, the creep rate of the saturated specimen is the highest, followed by the scoured specimen and dry specimen. The greater the degree of water saturation, the earlier the void area stops decreasing. The presence of moisture aggravates the occurrence of failure, and leads to an increase in the number of small voids. In addition, it is also found that the increase of water saturation will expand the influence range of load compaction, resulting in the difference in void area between upper and lower parts of PA-13 decrease. The difference in the number of small voids between upper and lower parts of PA-13 is also reduced. The greater the degree of water saturation, the more obvious the decrease of contact length at the initial stage of loading, which could be attributed to the increase of water saturation that promotes the filling failure at the initial stage of loading and leads to rheological failure and overpressure failure in advance. Moreover, the division of the change process of void area, quantity, and contact length are consistent with the permanent deformation. The findings of this study reveal important information about the damage evolution of PA pavement rutting resistance under different saturation states.

公路沿线设施的尺寸特征是公路资产管理的关键指标,为准确提取公路沿线设施的尺寸,以三维激光点云与全景相机装置为核心,集成研发公路沿线设施巡检装备,开展检测速度对尺寸特征提取的对比分析实验.研究结果表明,检测速度对尺寸提取的平均测量误差和最大测量误差影响较大,呈正相关的关系.

为研究水温耦合作用对沥青表面能及其与集料黏附性能的影响,采用静滴法测定3种测试液体与玄武岩以及高温水浴、冻融循环2种水温耦合条件作用前后SBS(苯乙烯-丁二烯-苯乙烯嵌段共聚物)改性沥青和高黏沥青(HVA)的接触角,基于表面自由能理论,分析水温耦合前后不同沥青的表面能、黏聚功及其与集料的黏附功,同时通过大空隙沥青混合料浸水飞散试验验证不同沥青与集料的黏结性能.结果表明,水温耦合作用降低了沥青的表面能、黏聚功和沥青-集料界面的黏附功;相较于冻融循环,高温水浴的影响更大.高黏沥青抵抗水温耦合作用的性能要优于SBS改性沥青.大空隙沥青混合料肯塔堡飞散损失表征的不同沥青与集料的黏结性能试验结果与表面自由能计算结果一致,沥青的表面能可以很好地解释沥青混合料的抗松散能力.水温耦合作用下,沥青-集料界面的黏附功受沥青性质的影响显著,使用高黏沥青可显著提升黏附功,在水稳定性要求苛刻的地区推荐采用高黏沥青作为沥青混合料的胶结料.

为研究养护工况下沥青玛蹄脂碎石混合料(SMA)的压实特性及其与高温性能相关性,考虑不同成型温度和存储时间工况对SMA-13改性沥青混合料进行旋转压实成型;采用密实度斜率K和能量指数CEI指标分析旋转压实成型过程中的密实曲线,评价各种工况下成型试件的压实特性.对成型试件进行60℃的贯入强度试验,通过贯入强度值评价其高温性能,对不同压实度条件下试件的高温性能进行了对比研究,并分析了Sasobit添加剂对其性能的影响.结果表明:降低成型温度、延长存储时间导致SMA-13沥青混合料更难压实.压实度较低时,改善压实度可显著提升沥青混合料高温性能,综合考虑压实效率和高温性能,SMA-13改性沥青混合料成型温度宜达到160℃,存储时间不宜超过4 h.Sasobit添加剂可以改善SMA-13沥青混合料的压实特性和高温性能.

Fiberglass prepared from broken waste glass can be used in epoxy asphalt mixtures for performance enhancement and a toughening effect. There is no systematic study on the influence mechanism of the size and the amount of glass fiber on the properties of epoxy asphalt mixtures. The effects of fiberglass on the properties of epoxy asphalt concrete were evaluated using a tensile test, three-point bending test, four-point bending fatigue test and an SEM scanning test. The results verify that the tensile strength of epoxy asphalt mastic with a 6 mm length and 2% content increased the most. Compared with the nondoped glass fiber, it increased by 69.2%. Under the influence of the internal composition of the asphalt mixture, the optimal ratio scheme is different from that of epoxy asphalt mastic. A microscopic analysis showed that uniformly dispersed fiberglass in the epoxy asphalt mixture forms a spatial network structure, leading to reinforcement and the restraint of microcrack expansion. The addition of fiberglass with a length of 9 mm and at a concentration of 5% to the epoxy asphalt mixture resulted in the maximum road performance. The Marshall stability increased by 43.5%, and the flexural and tensile strength increased by 33.7%. The fiberglass length is the most important factor limiting the strength and toughening effects of epoxy asphalt mixtures.

A modified wheel tracking test was produced to investigate the high-temperature failure of porous asphalt mixture under wheel loading. The sectional images of specimens, which were cured in different conditions, were acquired and analyzed by 2D image analysis after different loading times. Air voids with reference to size were divided into small void, medium void and large void. Air void indices in the sectional images, such as void number, total void area (TVA) as well as long and short axis ratio (L/S), were obtained. Based on the multi-factor analysis of variance method, the sensitivity of air void indices to curing conditions and loading times was evaluated, and a linear regression model was produced to investigate the relationship between air void indices and the average rutting depth. The results show that the air void indices including small void number (SVN), small void area (SVA), TVA and L/S were significantly affected by the loading time. The linear regression shows that the product of SVN, TVA and L/S could successfully evaluate the high-temperature failure of porous asphalt mixture during the wheel loading.