基于不同砂浆类型的围护结构冻融模拟性能研究

为了提升冻融环境下围护墙体的服役性能，以砂浆类型为变量研究冻融条件下围护结构砂浆层的抗冻融性能。分别设计水泥砂浆、聚丙烯纤维砂浆和聚合物砂浆围护结构试件并进行100次冻融循环试验，采用智能弦式应变传感器监测应变变化；并采用顺序耦合热应力分析法建立数值模型模拟冻融循环作用下的温度场和由此产生的应变，进行结果验证。结果表明：经过100次的冻融循环试验，水泥砂浆围护结构的最大应变值超过3.0×10^-4，并产生裂缝；相对于水泥砂浆，聚丙烯纤维砂浆和聚合物砂浆围护结构在冻融循环作用下，峰值应变大幅降低，最大应变值范围在3.0×10^-5~4.0×10^-5，且砂浆层均未开裂，数值模拟结果与试验结果基本一致。研究揭示了不同砂浆类型围护结构在冻融循环过程中病害形成机制，通过在砂浆中掺入聚合物和纤维增强其抗冻融性能，使围护结构在冻融条件下保持良好的服役性能，对提高围护结构耐久性具有重要的工程应用价值和理论意义。

Research on freeze-thaw simulation performance of enclosure structures based on different types of mortar

In order to improve the service performance of the enclosure wall under freeze-thaw environment, the freeze-thaw resistance of the mortar layer of the enclosure structure under freeze-thaw conditions was investigated with the mortar type as the variable. Cement mortar, polypropylene fiber mortar and polymer mortar enclosure specimens were designed for the freeze-thaw cycling test studies, and 100 freeze-thaw cycling test studies were conducted. The strain changes were monitored by intelligent string strain sensors and the results were verified by using a numerical model, which used sequential coupled thermal stress analysis to simulate the temperature field and the resultant strain under the action of freeze-thaw cycling. The results show that after 100 freeze-thaw cycle tests, the maximum strain value of cement mortar in the enclosure structure is more than 30×10^-4, and cracks are generated. Compared to cement mortar, polypropylene fiber mortar and polymer mortar enclosure structure under the action of freeze-thaw cycle, the peak strain is greatly reduced, the maximum strain value is in the range of 30×10^-5~40×10^-5, none of the mortar layer is cracked, and the numerical simulation result is basically the same as the experimental result. The study reveals the disease formation mechanism of different mortar types of enclosure structures during freeze-thaw cycles, and proposes the enhancement of freeze-thaw resistance by mixing polymers and fibers in mortar, so as to maintains good service performance of the enclosure structure under freeze-thaw conditions. It has important engineering application value and theoretical significance for improving the durability of enclosure structures.