干湿循环作用下水泥乳化沥青砂浆质量变化与体积稳定性

Mass Change and Volume Stability of Cement Emulsified Asphalt Mortar in Wetting-drying Cycles

为了了解服役过程中环境湿度变化对水泥乳化沥青（CA）砂浆体积稳定性及质量变化的影响,测试了CA砂浆干湿循环作用下质量与体积随时间的变化,并借助扫描电子显微镜、X射线衍射、热重分析及核磁共振等测试手段,以揭示其变化机理。结果表明：长期处于干燥或水中的CA砂浆,早期体积收缩或膨胀较大,200 d后趋于稳定。干湿循环下,质量与体积变化可分3个阶段,300 d后趋向稳定;浸水状态或干燥状态下的体积,均先随循环次数的增加而收缩,140 d后,再随循环次数的增加而增大,280 d后,变形规律与干燥环境的相对湿度相关。未水化水泥的持续水化、氢氧化钙溶析以及碳化等因素的综合作用是CA砂浆在干湿循环过程中质量与体积呈3阶段变化的原因。

In order to investigate the influence of environmental moisture conditions on cement emulsified asphalt（CA） mortar, the changes of mass and volume of CA mortar with time were examined, and the corresponding mechanisms were analyzed by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis and nuclear magnetic resonance, respectively. The results show that CA mortar shrinks or expands largely in early stage and then tends to be stable after 200 d under air dry or water immersion conditions for a long term. The changes of mass and volume of CA mortar are divided into 3 stages and tend to be stable after 300 d in wetting-drying cycles, i.e., its volume in wetting or drying cycles decreases firstly with cycles, and then expands with cycles after 140 d. After 280 d, the rules of deformation are related to the relative humidity of the drying cycles. The mass or volume changes having 3 stages in wetting-drying cycles are due to the continuous hydration of unhydrated cement, portlandite leaching, carbonation and other factors.