贝壳混合材对硅酸盐水泥性能的影响

以纯碳酸钙、贝壳和石灰石为混合材,探讨掺量变化对硅酸盐水泥性能的影响.试验表明:硅酸盐水泥掺入质量分数为5%～15%的贝壳混合材后,水泥标准稠度用水量减少.3 d、7 d抗折强度高于普通硅酸盐水泥,28 d抗折强度先增后减.28 d抗压强度损失率为石灰石-硅酸盐水泥>贝壳-硅酸盐水泥>纯碳酸钙-硅酸盐水泥.贝壳混合材最佳掺量为10%,此时减水效果最好.早期强度高,28 d抗压强度损失率最小.贝壳化学组成和微观结构使其具有颗粒形态效应、化学反应活性和微细集料填充效应,可成为石灰石混合材的良好替代品.

Effects of Shell Admixture on Properties of Portland Cement

The effects of mixing amount on the properties of Portland cement are discussed by using pure calcium carbonate, shells and limestone as admixture. When the shell mixing amount is 5% - 15%, the water requirement of normal standard consistency decreases and the setting time is shortened. Furthermore, the 3d and 7d flexural strength is better than that of Portland cement, the 28d flexural strength increases first and then decreases. The loss rates of 28d compressive strength of various cements decreases in the following order： limestone-Portland cement 〉 shell-Portland cement 〉 pure calcium carbonate-Portland cement. The results show that when the shell admixture amount is 10%, the water reducing effect is the best, the initial strength is high, and the loss rate of 28d compres-sive strength is the minimum. The chemical composition and microstructure of shell endow it with advantages such as particle size effect, chemical reactivity and filling effect of fine aggregate, which makes it possible to replace limestone.