改性多孔沥青混合料水稳定性与损伤规律

为了提高季冻区多孔沥青路面的使用质量、减轻路面冻融损伤，采用玻璃纤维、硅藻土与沥青路面旧料以改善多孔沥青混合料性能。分析不同材料掺量的多孔沥青混合料在冻融循环下的抗压强度、空隙率及应变变化，并考虑不同材料与不同材料掺量对多孔沥青混合料水稳定性的影响；基于损伤力学理论以抗压强度为指标表示强度率，研究改性多孔沥青混合料的冻融损伤演化规律；基于CT无损检测与数字图像处理技术，分析玻璃纤维多孔沥青混合料冻融前后空隙数量与空隙面积的变化规律。结果表明：混合料抗压强度随冻融循环次数的增加而降低，而空隙率与应变呈上升趋势；具有玻璃纤维掺量0.7%、沥青路面旧料掺量15%、硅藻土掺量25%和掺量15%沥青路面旧料及20%硅藻土的4种多孔沥青混合料水稳定性能最好，其中玻璃纤维的改性效果最佳；掺入玻璃纤维、15%掺量硅藻土与15%掺量沥青路面旧料能减轻多孔沥青混合料的冻融损伤，但硅藻土再生多孔沥青混合料损伤程度均较大，损伤前期强度较高，更适用于短时冻土区；与硅藻土再生多孔沥青混合料相比，玻璃纤维多孔沥青混合料、再生多孔沥青混合料与硅藻土多孔沥青混合料经历了长时间的快速损伤期、短时间的损伤稳定期与损伤发展期；玻璃纤维掺量较低的试样空隙数量增加，平均单个空隙面积减小，而掺量较高的试样表现相反。

Moisture Stability and Damage Law of Modified Porous Asphalt Mixture

In order to improve the quality of the porous asphalt pavement in seasonal freezing areas and reduce the freeze-thaw damage of the pavement, glass fiber, diatomite and old asphalt pavement materials are used to improve the performance of the porous asphalt mixture. The changes in compressive strength, porosity, and strain of porous asphalt mixtures with different material contents after freeze-thaw cycles are analyzed by considering the influence of different materials and different material contents on the water stability of porous asphalt mixtures. Based on the theory of damage mechanics, the compressive strength is used as an index to represent damage variables, and the evolution of freeze-thaw damage of modified porous asphalt mixtures is also studied. Based on the CT non-destructive testing and digital image processing technology, the changes in the number of air voids and air void area of the glass fiber porous asphalt mixture before and after freezing-thawing are analyzed. The test results show that the compressive strength of the mixture decreases with the increase of the number of freeze-thaw cycles, and the void ratio and strain show an increasing trend. Four porous asphalt mixtures with 0.7% glass fiber content, 15% old asphalt pavement material content, 25% diatomite content and 15% old asphalt pavement material and 20% diatomite content present the best water stability. The modification effect of glass fiber is the best. Mixing glass fiber, 15% diatomite and 15% old asphalt pavement material may reduce the freeze-thaw damage of porous asphalt mixtures. However the recycled porous asphalt mixtures containing diatomite have more serious damage and have higher strength in the early stage of damage, which are more suitable for short-term frozen soil areas. Compared with recycled porous asphalt mixtures containing diatomite, the porous asphalt mixture containing glass fiber, recycled porous asphalt mixture and porous asphalt mixture containing diatomite have a long rapid damage period, a short damage stability period and a damage evolving period. The number of air voids in the sample increases and the average single air void area decreases with a lower glass fiber content, while the sample with a higher glass fiber content has the opposite.