干、湿养护下橡胶细集料水泥砂浆压缩破裂及能量演化特性

Compressive Rupture and Energy Evolution Characteristics of Rubber Fine Aggregate Cement Mortar Under Dry and Wet Curing Conditions

开展相对湿度为95%和50%养护条件下橡胶水泥砂浆试件的单轴压缩试验,对试件压缩变形过程的破裂机理及能量转化进行了分析,建立了橡胶水泥砂浆的单轴受压理想细观模型。结果表明,与普通水泥砂浆相比,橡胶水泥砂浆单轴压缩破坏模式有很大差异,表现为裂而不散的延性破坏模式,而非普通水泥砂浆的锥形脆性破坏模式。试件破裂能量演化过程包括压密、弹性变形、破裂发展、峰后软化四个阶段,并伴随着能量输入、能量积聚、能量耗散、能量释放四个过程。降低养护湿度和增加橡胶掺量均会使试件吸收能量的速率降低,在破坏阶段试件仍然可以继续积聚弹性能,且随橡胶掺量的增加其积聚弹性能的能力越强。养护湿度对普通水泥砂浆的储能极限影响较大,对橡胶水泥砂浆的储能极限影响较小,橡胶水泥砂浆|Uc95-Uc50|的最大值也仅为普通水泥砂浆|Uc95-Uc50|的1/10左右。

The uniaxial compression test of rubber cement mortar specimens under curing conditions of 95%and 50%relative humidity was carried out.The fracture mechanism and energy conversion of the specimens during compression deformation were analyzed.The ideal mesoscopic model of uniaxial compression of rubber cement mortar was established.The results showed that the uniaxial compression failure mode of rubber cement mortar is quite different from that of normal cement mortar.It is a ductile failure mode that does not scatter even if it is cracked,rather than the cone-shaped brittle failure mode of normal cement mortar.The evolution process of the fracture energy of the specimen includes four stages of compaction,elastic deformation,rupture development and post-peak softening,accompanied by energy input,energy accumulation,energy dissipation and energy release.Both the decrease of curing humidity and the increase of rubber content will reduce the rate of energy absorption,but the specimen can still continue to accumulate elastic energy in the failure stage,and with the increase of rubber content,the ability of specimens to accumulate elastic energy is stronger.Curing humidity has great influence on the energy storage limit of normal cement mortar,but has little influence on the energy storage limit of rubber cement mortar,the maximum value of the rubber cement mortar|Uc95-Uc50| is only about 1/10 of the ordinary cement mortar |Uc95-Uc50|.