高温后再生混凝土受压强度退化及微观结构性能分析

Compressive strength degradation and micro-structure characteristics of recycled concrete after high temperature

为研究高温作用后再生混凝土受压强度退化机理及高温作用对再生混凝土微观结构的影响,配制C30全天然骨料混凝土和全再生骨料混凝土,观测了受0、300、400、500℃高温后两种混凝土的表观物理现象并测试其抗压强度,选取典型样本,利用超景深三维显微系统观察四种温度作用后两种混凝土的微观结构形貌,对比分析其骨料和砂浆的界面特征,从微观角度解释界面特征对其宏观受压破坏现象产生的影响。结果表明:当受热温度小于400℃时,再生混凝土强度损失率大于天然混凝土,天然混凝土抗压强度及温度稳定性较好;但当受热温度大于400℃时,再生混凝土强度损失率较小,高温稳定性较好;高温前后再生混凝土薄弱面破坏先后顺序相同。

In order to study the mechanism of compressive strength degradation and micro - structure characteristics of recycled con-crete（RC） after high temperature, the apparent physical phenomena and the compressive strength of C30 natural concrete （NC）and RC under 0,300,400,500℃ has been tested.The typical samples have been chosen to observed the micro -structure characteristics by using super depth of 3D microscopic system.Comparative analysis the interface characteristics of aggregate and mortar of this two kinds of concrete after high temperature effected. The macroscopic compressive damage phenomenon has been explained from the angle of the micro interface characteristics.Results show that strength loss rate of RC is greater than NC when the heating temperature is less than 400℃. NC has better compressive strength and temperature stability. But when the temperature is higher than 400℃, the strength loss rate of RC is smaller and the high temperature stability is better. Another result is that the weak surface of RC has the same destruction order before and after high temperature.