摘要
实验研究了经20℃(标准养护)和60℃养护后,高掺量粉煤灰水泥砂浆的干缩性能。用结合水法、压汞法对水泥水化程度、水泥石孔结构及其分布进行研究。分析了养护温度对不同掺量粉煤灰硅酸盐水泥砂浆干缩性能影响的机理。结果表明:经20℃养护后,高掺量粉煤灰水泥砂浆在各龄期的干缩均小于不掺或低掺量粉煤灰水泥砂浆的干缩。经60℃养护后,高掺量粉煤灰水泥砂浆的干缩大于不掺或低掺量粉煤灰水泥砂浆的干缩。当粉煤灰掺量较低时(0～20%),经高温养护的水泥砂浆的干缩小于低温养护的。粉煤灰掺量较高时,高温养护的水泥砂浆的干缩大于低温养护的。掺粉煤灰水泥砂浆,无论经高、低温养护,各龄期的干缩均比标准养护的小,并且掺粉煤灰水泥砂浆的干缩稳定期较不掺粉煤灰水泥的早。温度对不掺粉煤灰的硅酸盐水泥砂浆干缩的影响主要是影响CSH凝胶的微观结构,而对于粉煤灰水泥则主要是影响水泥石的孔径分布及水化程度。
The drying shrinkage of portland cement mortars with different fly ash dosages after curing at 20°C and 60°C before drying was investigated. The hydration degree of cements, the pore structure and the pore size distribution of hydrated cement mortars were analyzed by chemical binding water and mercury intrusion porosimetry (MIP). Effects of curing temperatures on the drying shrinkage of the portland cement mortars with and without doping of fly ash were discussed. Results show that after curing at 20°C and before drying, drying shrinkage values of cement mortars with higher mass of fly ash are lower than that of the cement mortars without or with lower mass of fly ash. After curing at 60°C and before drying, the drying shrinkage values of the cement mortars with higher mass of the fly ash are greater than that of the cement mortars without or with lower mass of the fly ash. However for the cement mortars with the same fly ash dosage when the curing temperature increases from 20°C to 60°C, the drying shrinkage of the cement mortars are remarkably decreases. When the dosage of the fly ash is lower (0-20%) the drying shrinkage of the cement mortars cured at higher temperature is lower than that of the cement mortars cured at lower temperature, while the fly ash dosage is higher, the result is just reverse. The drying shrinkage values at all stages of cement mortars with fly ash, no matter cured at 20°C or 60°C before drying, are lower and the stabilized period are shorter than that of portland cement mortars cured at 20°C before drying. For the portland cement without the fly ash, curing temperature mainly affects the microstructure of C-S-H gel phase and consequently affects the drying shrinkage. For the Portland cement with the fly ash curing temperature mainly affects hydration rate of system and pore size distribution of the hydrated cement mortars and consequently affects the drying shrinkage.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2005年第1期100-104,共5页
Journal of The Chinese Ceramic Society
基金
国家"973"基金(2001CB610705)资助项目。
