【摘要】 通过抗压强度、X射线衍射和扫描电镜观测试验,研究了高温影响矿渣混凝土抗压强度与微观结构的规律和机理。结果表明,20℃升温至400℃时,矿渣混凝土抗压强度缓慢降低,超过400℃时,矿渣混凝土抗压强度随着温度的升高急剧减小;高温后矿渣混凝土抗压强度残余率高于普通混凝土,掺入适量矿渣微粉有利于改善高温环境下混凝土的力学性能。200℃时矿渣水泥浆体中的钙矾石全部分解;600℃时矿渣水泥浆体中大部分Ca（OH）₂已经分解;超过600℃时,矿渣水泥浆体中水化硅酸钙和CaCO₃开始分解,800℃时CaCO₃衍射峰消失。低于400℃时,矿渣水泥浆体由层状的Ca（OH）₂和网络状的水化硅酸钙胶体等构成,微观形态致密;高于400℃时,随着温度升高,矿渣水泥浆体的微观形貌逐渐变为疏松多孔的蜂窝状。高温导致矿渣水泥水化产物分解、浆体与骨料界面开裂是高温下矿渣混凝土力学性能劣化的主要因素。更多还原

【Abstract】 The effect of high temperature on the compressive strength and microstructure of slag-concrete is studied by means of compressive strength,X-ray diffraction and SEM observation. The results show that the compressive strength of slag concrete decreases slowly when the temperature rises to 400℃ from 20℃. When the temperature exceeds 400℃,the compressive strength of slag concrete decreases sharply with the increase of temperature. The residual strength of slag concrete after high temperature is higher than that. Ordinary concrete mixed with an appropriate amount of slag powder is beneficial to improve the mechanical properties of concrete under high temperature environment. At 200℃,the ettringite in the slag cement slurry is completely decomposed; at 600℃,most of the Ca（OH）₂ in the slag cement slurry has been decomposed; when it exceeds 600℃,the hydrated calcium silicate and CaCO₃ in the slag cement slurry begin to decompose, and the CaCO₃ diffraction peak disappeared at 800℃. Below 400℃,the slag cement paste is composed of layered Ca（OH）₂ and networked calcium silicate colloid,and the microscopic shape is dense; when it is higher than 400℃,the slag cement increases with temperature. The microscopic morphology of the slurry gradually changes from a dense layered,networked shape to a loose porous honeycomb. The high temperature causes the decomposition of the slag cement hydration product and the cracking of the slurry and aggregate interface is the main factor for the deterioration of the mechanical properties of the slag concrete at high temperature.更多还原