水化硅酸钙晶种对粉煤灰-水泥砂浆增强作用及机理研究

Enhancement and mechanism of hydrated calcium silicate crystal seed on the strength of fly ash-cement mortars

研究了水化硅酸钙晶种(C-S-H晶种)对粉煤灰-水泥砂浆抗压强度和粉煤灰活性指数的影响,通过粉煤灰在饱和Ca(OH)2溶液中的火山灰反应试验研究了C-S-H晶种对粉煤灰活性的激发作用,并分析其作用机理。结果表明,C-S-H晶种不仅有效提高了粉煤灰-水泥砂浆的早期抗压强度,对28 d抗压强度也有增强效果,掺量为1.5%时,粉煤灰-水泥砂浆的1、7、28 d抗压强度较未掺C-S-H晶种的分别提高了69.7%、24.8%、23.7%。C-S-H晶种对粉煤灰在饱和Ca(OH)2溶液中的火山灰反应有明显的促进作用,7 d龄期时Ca(OH)2含量减少了5.35个百分点,化学结合水含量增加了1.05个百分点,粉煤灰颗粒表面明显解体并覆盖了大量的反应产物。

In this study,the effects of hydrated calcium silicate crystal seed(C-S-H seed)on the compressive strength of fly ash-cement mortars and activity index of fly ash were studied.The activiation effect of C-S-H seed on the reactivity of fly ash was studied by measurement of pozzolanic reactivity of fly ash in saturated Ca(OH)_(2)solution,and its action mechanisms were analyzed.The results show that the C-S-H seed not only effectively improves the early compressive strength of fly ash-cement mortars,but also improves its 28 d compressive strength.When the content of calcium silicate hydrate in fly ash-cement mortar reached 1.5%,the 1 d,7d and 28d compressive strength of fly ash-cement mortars increased by 69.7%,24.8%and 23.7%,respectively.The pozzolanic reaction of fly ash in saturated Ca(OH)_(2)solution can be significantly promoted by the C-S-H seed.At 7 d of reaction,the content of Ca(OH)_(2)decreased by 5.35 percent point,the content of chemically bound water increased by 1.05 percent point,and the surface of fly ash particles was obviously dissolved and covered with large amount of reaction products.