硅灰-橡胶水泥砂浆的蠕变性能及微观机制

Creep Properties and Microscopic Mechanism of Silica Fume-Rubber Cement Mortar

摘要:

为探究硅灰掺量及橡胶粒径对水泥砂浆蠕变性能的影响，设计16组试件进行正交试验，分别对不同硅灰掺量、不同橡胶粒径水泥砂浆的无侧限抗压强度、蠕变特性及微观特征进行分析.结果表明：橡胶颗粒会减小砂浆的无侧限抗压强度，增大其蠕变变形，但在硅灰加入后橡胶砂浆（为掺橡胶颗粒的水泥砂浆的简称，下同）的强度回升，蠕变变形减少；橡胶砂浆与普通砂浆都经历了三级加载，且橡胶砂浆的蠕变历时更长，硅灰的加入使试件发生破坏的载荷等级明显提高；基于减速蠕变阶段和等速蠕变阶段的试验数据对Burgers模型的参数进行辨识，发现二者的吻合情况较好；微观结构与细观模型很好地阐明了橡胶、硅灰对砂浆蠕变性能的协同作用机理.

Abstract:

In order to investigate the effects of silica fume dosing and rubber particle size on the creep properties of cement mortar， orthogonal tests were carried out using 16 groups of specimens designed to analyse the unconfined compressive strength， creep properties and microscopic characteristics of cement mortar with different silica fume dosing and different rubber particle sizes， respectively. The results show that the rubber particles would reduce the unconfined compressive strength and increase the creep deformation of the mortar， and the strength of the mortar recovers and the creep deformation decreases after the addition of silica fume. Both rubber mortar and ordinary mortar experienced three levels of loading， and the creep of rubber mortar lasted longer， while the addition of silica fume significantly increased the load level at which the specimen suffered damage. The parameters of the Burgers model are identified based on the test data of the decelerated creep stage and the isokinetic creep stage， and it is found that they are in good agreement.The microstructure and fine-scale modelling show well the synergistic mechanism of rubber and silica fume on the creep performance of mortar.