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以橡胶颗粒部分取代细集料砂子配制高强混凝土,研究橡胶颗粒不同取代率(体积分数)对高强混凝土工作性、高温后质量和强度的损失,并用电镜表征高温前后硬化水泥基体的微观结构。研究结果表明:常温下橡胶集料高强混凝土的表观密度随着橡胶颗粒掺量的递增而下降。抗压强度随橡胶颗粒掺量的递增表现为先减后增,当掺量为6%时强度最低。硬化水泥基体微观结构致密,水泥水化产物结晶发达,600℃高温作用后,混凝土表观密度、抗压和劈拉强度明显下降,但适当掺入橡胶颗粒可以明显提高混凝土强度剩余百分率。高温后硬化水泥基体微观结构疏松、孔隙增大,粗集料以及水泥基体均产生裂纹,水泥水化产物结晶消失。
The microstructures of the hardened cement matrix before and after high temperature were characterized by electron microscopy. The high-strength concrete was prepared by partially replacing the fine aggregate sand with rubber particles. The effects of different substitution rate (volume fraction) of rubber particles on the workability and the post-high temperature quality and strength were studied. The results show that the apparent density of high-strength concrete with rubber aggregates decreases with the increase of rubber particle content at room temperature. Compressive strength with the increase of rubber particles for the first increase and then increase, when the amount of 6%, the lowest strength. The microstructure of the hardened cement matrix is dense and the hydration products of the cement are well developed. After 600 ℃ high temperature, the apparent density, compressive strength and splitting tensile strength of the concrete decrease obviously. However, when the rubber particles are blended properly, the remaining percentage of the concrete strength can be obviously increased. After high temperature, the microstructure of the hardened cement matrix is loose, the pores increase, the coarse aggregate and the cement matrix are cracked, and the crystallization of cement hydration products disappears.