粗水泥改善碾压混凝土抗裂性试验研究

为改善碾压混凝土(RCC)的抗裂性,结合西部某工程RCC重力坝抗裂问题,从材料角度探讨粗水泥改善RCC抗裂性的可行性。采用同种水泥熟料分别磨制4种细度的PⅠ42.5水泥,按照C18015三级配RCC设计要求,配制4组RCC,研究水泥细度对RCC力学性能、变形性能、热学性能的影响,并采用抗裂指标K研究水泥细度对RCC综合抗裂能力的影响。结果表明,粗水泥配制的RCC性能可达设计指标要求,且与细水泥的发展水平相当;粗水泥可改善RCC抗裂性(尤其是早期);水泥细度与抗裂指标K呈负线性相关,即在满足RCC设计性能要求前提下,水泥越粗,其RCC综合抗裂能力越强;采用粗水泥配制低热高抗裂RCC是一项技术经济良好的有效措施。

Experimental Research on Coarse Cement Improving Crack-resistance of RCC

In a western engineering, the problem how to improve crack-resistance of RCC gravity dam should be solved. From the standpoint of material, the paper explored the feasibility of improving crack-resistance of RCC with the coarse cement. The 4 kinds of fineness P I 42.5 cement were grounded by the same clinker and gypsum. And then 4 groups of RCC were made based on three-gradation RCC design demand of C18015. The influence of cement fineness on the mechanical property, deformation performance and thermal property of RCC was studied. Finally, the crack-resistance index (K) was used to research the impact of cement fineness on the general crack-resistance of RCC. The results show that the RCC made with coarse cement could satisfy the design demand and reach the level of fine cement; crack-resistance of RCC could be improved by coarse cement especially on the early age; crack-resistance index (K) was linearly decreased with the increase of cement fineness. Under the design requirement of RCC, the coarser the cement was, the stronger the general crack-resistance of RCC was. The technology of using coarse cement was an effective and economical measure to make up low heat crack-resistance of RCC.