基于DIC技术的老化作用下温拌胶粉改性沥青胶浆低温抗裂性能研究

沥青胶浆对沥青混合料性能具有重要影响。为研究热氧老化作用对温拌胶粉改性沥青胶浆（WCRM）低温抗裂性能的影响，以热拌胶粉改性沥青胶浆（HCRM）作为对比试件，采用数字图像相关（DIC）技术对单边切口弯曲梁试验（SENB）中2种试件的开裂全过程进行图像采集，利用Vic-3D软件计算加载过程中试件的水平应变，从宏细观相结合的角度定量分析沥青胶浆的抗裂性能。对比分析沥青胶浆的荷载-位移（L-D）曲线和水平应变-时间（E_xx-t）曲线，通过在细观尺度下胶粉改性沥青胶浆裂纹萌生和发展的规律来解释沥青胶浆宏观力学行为。通过弯曲梁流变试验（BBR）分析老化前后WCRM和HCRM的低温流变性能，并对沥青胶浆低温性能评价指标进行相关性分析。结果表明：随热氧老化程度的加深，HCRM和WCRM的水平应变密度D_E值（细观层面）和临界断裂韧度J_IC值（宏观层面）均减小，证明热氧老化会降低2种胶粉改性沥青胶浆的抗裂性能；相同条件下，WCRM的D_E值和J_IC值均大于HCRM，即与HCRM相比，WCRM具有更好的抗开裂和抗老化性能；在沥青胶浆开裂过程中，微裂纹形成时的荷载、峰值荷载及最大水平应变对应荷载并非同一荷载值；老化后，2种胶粉改性沥青胶浆的低温流变性能降低，同一条件下，WCRM具有更加优异的低温流变性能；沥青胶浆低温流变参数（S/m）与宏细观开裂指标（J_IC，D_E）均具有较好的相关性，即将DIC技术应用到SENB试验来分析老化作用及温拌剂对胶粉改性沥青胶浆宏细观开裂特性的影响具有较好的可靠性。

Low-temperature Crack Resistance of Warm-mixed Crumb Rubber Asphalt Mortar Under Aging Effect Based on DIC Technology

Asphalt mortar has an important effect on the performance of asphalt mixtures. To study the effect of thermo-oxidative aging on the low-temperature crack resistance of warm-mixed crumb rubber asphalt mortar (WCRM), hot-mixed crumb rubber asphalt mortar (HCRM) was used as a comparative test sample. Image acquisition of the entire cracking process of the two specimens in the single-edge notch bending (SENB) test was conducted using digital image correlation (DIC) technology. The VIC-3D software was used to calculate the horizontal strain field of the test piece during the loading process; the crack resistance of the asphalt mortar was quantitatively analyzed from macro level and meso level. The load-displacement (L-D) curve and horizontal strain-time (E_xx-t) curve of asphalt mortar were compared and analyzed, and the macro-mechanical behavior of asphalt mortar was explained using the law of crack initiation and development of crumb rubber asphalt mortar on meso-scale. The low-temperature rheological properties of WCRM and HCRM before and after aging were analyzed using the bending beam rheological test (BBR). Moreover, the correlation analysis of the low-temperature performance evaluation indicators of asphalt mortar was performed. The results show that after thermal oxygen aging, the value of horizontal strain density, D_E (meso level), and the value of critical fracture toughness, J_IC (macro level) of HCRM and WCRM decrease, which proves that the thermo-oxidative aging reduces the crack resistance of two crumb rubber asphalt mortars. Under the same conditions, the value of D_E and J_IC of WCRM were found to be greater than HCRM, which implies that WCRM has better anti-cracking and anti-aging properties than HCRM. During the cracking process of asphalt mortar, the load at the time of microcrack formation, the peak load, and the load corresponding to the maximum horizontal strain do not have the same value of load. After aging, the low-temperature rheological properties of the two crumb rubber asphalt mortars are reduced. Under the same conditions, WCRM shows better low-temperature rheological properties. The low-temperature rheological parameters (S/m) and the macro-and meso-cracking indicators (J_IC and D_E) of asphalt mortar have a good correlation. Therefore, applying the DIC technique for the SENB test to analyze the effects of aging and warm mixes on the macro-and meso-cracking resistance of crumb rubber asphalt mortar shows good reliability.