冻融循环作用下盐浓度对温拌胶粉改性沥青混合料开裂特性影响

Effect of Salt Concentration on CR-WMA Cracking Characteristics under Freeze-Thaw Cycles

为科学分析冻融循环作用下除冰盐侵蚀对温拌胶粉改性沥青混合料(CR-WMA)和热拌胶粉改性沥青混合料(CR-HMA)路面开裂特性的影响,运用数字图像(DIC)技术对三点弯曲重复加载试验下两种半圆试件产生的水平应变进行分析,定量描述沥青混合料的损伤开裂特性。采用半圆弯拉试验(SCB)分析两种试件的蠕变应变能(D_(CSE)),并与基于DIC技术下的损伤开裂指标进行相关性分析。试验结果表明:水平应变场中数值较大的点与试件损伤开裂的演化有密切关系;CR-WMA和CR-HMA的抗损伤开裂性能随着盐浓度的增加先降低后升高,且在盐浓度为8%时最差;无论是水冻还是盐冻条件下,CR-WMA的损伤累积密度D_(E)值和D_(CSE)值较CR-HMA高,说明CR-WMA抗开裂性能及抗盐侵蚀能力均优于CR-HMA;发现D_(E)和D_(CSE)具有较好的相关性,验证了DIC技术评价沥青混合料损伤开裂特性的合理性。

In order to scientifically analyze the effect of deicing salt erosion on the cracking characteristics of warm rubber powder modified asphalt mixture(CR-WMA)and hot rubber powder modified asphalt mixture(CR-HMA)under the action of freeze-thaw cycles,application of digital image(DIC)technique for three-point bending test repeated loading levels of the two semi-circular pieces under the test strain generated analysis were used for quantitative description damage cracking of asphalt mixture.The semicircular bending tensile test(SCB)was used to analyze the creep strain energy(D_(CSE))of the two specimens,and the correlation analysis with the damage and cracking index based on DIC technology was carried out.The test results show that the point with a larger value in the horizontal strain field is closely related to the evolution of damage and cracking of the specimen.The damage and cracking resistance of CR-WMA and CR-HMA first decreases and then increases with the increase of salt concentration at worst concentration of 8%.Whether it is frozen or salt water freezing conditions,D_(E) value and the value CR-WMA D_(CSE) relatively high CR-HMA,described CR-WMA cracking resistance and were superior erosion salt CR-HMA:it is found that D_(E) and D_(CSE) have a good correlation,which verifies the rationality of the DIC technology to evaluate the cracking characteristics of asphalt mixtures.