混合材对水泥浆体脆性的影响及其机理的研究

Effect of admixture on brittleness of cement paste and its mechanism

研究了不同掺量的矿渣和粉煤灰对水泥脆性的影响及规律,同时就混合材改善水泥脆性的机理进行了分析。结果表明,混合材能够改善水泥的脆性,但只有掺量>15%后效果才比较明显;混合材改善水泥脆性的机理,除了已有共识的二次水化反应消耗浆体中的Ca(OH)2和改善界面过渡带外,还包括以下机理:由于Ca(OH)2浓度的降低,使其不能饱和结晶,而形成薄弱的层状结构;水泥浆体成为相对低钙体系,利于纤维状钙矾石的形成;混合材的使用,降低了水泥的水化速率,减少了因化学收缩、自收缩、温差收缩等原因造成的微裂缝。

Effect of GGBS and fly ash with different proportions in cement on the brittleness of cement paste and its rule were studied.The results showed that admixture could improve the brittleness of cement paste,but the content of GGBS should be more than 15%.The mechanism of improve effect of Admixtures on brittleness of cement paste were studied too.The secondary hydration reaction would consume Ca（OH）2 in paste and improve interface transitional zone.The Ca（OH）2 would not saturation crystal,but form weak layered structure for the decreasing of Ca（OH）2 concentration in paste.The cement would be a relative low calcium system for incorporation of admixture,and could help to promote the formation of fibrous ettringite.The incorporation of admixture could decrease hydration rate and microcrack that caused by chemical shrinkage,autogenous shrinkage,and temperature difference shrinkage.