寒区大空隙沥青混合料性能衍化效应研究

Performance Evolution Effect of Large-Void Asphalt Mixture in Cold Regions

为明确大空隙沥青混合料在寒区服役环境下的损伤规律,研究采用宏观损伤试验和细观定量分析技术〔无损CT扫描和Image-Pro Plus(IPP)图像处理技术〕相结合的方法,对寒区冲刷、堵塞和冻融作用下OGFC-13和OGFC-16的性能和细观空隙结构特性进行了分析。结果表明:在动态水压冲刷作用下,空隙率为25%的试件强度降幅明显,最大降幅达到30%以上;在极端堵塞试验中,堵塞物最大堵塞深度达到20 mm左右,堵塞后的渗透系数均小于0.06 cm/s;冻融作用下,混合料的损伤度随循环次数而升高,而OGFC-13损伤度低于OGFC-16,且在23%的孔隙率下损伤度最低;细观空隙结构定量分析显示,混合料空隙率在冻融和冲刷作用下会略微升高,在堵塞状态下会大幅降低;孔隙数量变化趋势与孔隙率相反,孔隙特征表现为其等效直径均以1.18~4.75 mm为主,约占空隙数量的50%。本项研究得出了寒区大空隙沥青混合料宏观性能和细观空隙结构衍化规律,可为寒冷地区大空隙混合料设计提供技术支撑。

To clarify the damage patterns of large-void asphalt mixtures in cold regions,macroscopic damage tests were combined with microscopic quantitative analysis techniques(non-destructive CT scanning and Image Pro Plus(IPP)image processing technology)to analyze the performance and microscopic void structural characteristics of OGFC-13 and OGFC-16 under the effects of erosion,blockage,and freeze-thaw in cold regions.The results show that under the action of dynamic water erosion,the strength of the specimen with a porosity of 25%decreases significantly,with a maximum range of over 30%.In the extreme blockage test,the maximum blockage depth of the blockage reaches about 20mm,and the permeability coefficient after blockage is all less than 0.06cm/s.Under freeze-thaw action,the damage degree of the mixture increases with the number of cycles,while the damage degree of OGFC-13 is lower than that of OGFC-16 and shows the lowest at a porosity of 23%.Quantitative analysis of microscopic pore structure shows that the void fraction of the mixture can slightly increase under the action of freeze-thaw and erosion,but will significantly decrease under the effect of blockage.The change trend of pore quantity is opposite to that of porosity,and the pore characteristics are characterized by its equivalent diameter mainly ranging from 1.18 to 4.75 mm,accounting for about 50%of the void quantity.The macroscopic performance and microscopic evolution patterns of void structure of large-void asphalt mixtures in cold regions are obtained,which can provide technical support for the design of large-void mixtures in cold regions.