盐冻融和重复荷载作用下沥青混凝土开裂的细观分析

选用普通沥青混凝土、玄武岩纤维沥青混凝土、SBS改性沥青混凝土、玄武岩纤维+SBS改性沥青混凝土为研究样本,采用数字图像相关(DIC)技术,从细观角度对重复荷载作用下4种沥青混凝土小梁试件进行全局位移、应变测量,并对其裂缝发展进行时间及空间上的分析;以融雪剂(盐溶液)冻融循环作用下裂纹稳定发展阶段的应变集中速率为指标,采用正交试验极差分析和方差分析,研究玄武岩纤维、冻融循环次数、盐溶液(NaCl、CH3 COOK、CaCl2)对沥青混凝土小梁试件应变集中速率的影响.结果 表明:玄武岩纤维沥青混凝土的寿命与应变集中程度有很大关联;SBS改性剂与玄武岩纤维的加强方式有互补性;在相同盐冻融循环条件下,玄武岩纤维的加入可以减小沥青混凝土的应变集中速率;盐溶液对沥青混凝土应变集中速率的影响大小依次为CaCl2、NaCl、CH3 COOK;盐冻融的主要作用方式依旧是冰冻结晶刺入.

Mesoscopic Analysis on Cracking of Asphalt Concreteunder Repeated Load and Salt Freeze Thaw Action

Choose matrix asphalt concrete, basalt fiber asphalt concrete, SBS modified asphalt concrete, basalt fiber+SBS modified asphalt concrete as research samples. Using digital image correlation(DIC) technology to measure the global displacement and strain of four types of asphalt concrete beam specimens under repeated loads from microscope view, and the crack development was analyzed in time and space. With the strain concentration rate in the stable development stage of the crack under the action of the freeze thaw cycle of the snow melting agent(salt solution) for index, the orthogonal test range analysis and the variance analysis are used as the methods to study the strain concentration rate effects of basalt fiber, freeze thaw times, salt solutions (NaCl, CH3COOK, CaCl2) on asphalt concrete beams specimen. The results show that the life of basalt fiber asphalt concrete is closely related to the degree of strain concentration; the reinforce methods of SBS and basalt fiber are complementary; under the same salt freeze thaw cycle conditions, the addition of basalt fiber can reduce the strain concentration rate of asphalt concrete; the effect of salt solutions on the strain concentration rate of asphalt concrete is in order of CaCl2, NaCl, CH3COOK; the main action mode of salt freeze thaw is still the penetration of ice crystals.