氢氧化钙对硫铝酸盐水泥-粉煤灰复合胶凝材料的水化影响

通过凝结时间、抗压强度和电阻率等分析手段,研究了Ca(OH)2对硫铝酸盐水泥-粉煤灰复合胶凝材料水化过程的影响.结果表明,掺入Ca(OH)2明显缩短了硫铝酸盐水泥-粉煤灰复合胶凝材料的凝结时间;当Ca(OH)2掺量为0.5%时,初凝时间最短,1 d、28 d强度均明显提高;当Ca(OH)2的掺量为2%时,28 d强度相比空白样提高了61.9%;掺入Ca(OH)2后,硫铝酸盐水泥-粉煤灰复合胶凝材料的1 d电阻率减小,随着Ca(OH)2掺量增大,电阻率逐渐减小,电阻率变化率极大值提前,说明Ca(OH)2加快了该复合胶凝材料的早期水化进程.XRD分析表明,掺入Ca(OH)2后,水化1 d时钙矾石的生成量增多,消耗无水硫铝酸钙的量增多;水化28 d时钙矾石的生成量相对变化较小,但强度明显增大,粉煤灰对硫铝酸盐水泥强度的贡献较为明显.

Influence of Calcium Hydroxide on the Hydration of Sulphoaluminate Cement-Fly Ash Composite Cementitious Materials

The influence of different contents of calcium hydroxide on the setting time , compressive strength and electrical resistivity of sulphoaluminate cement-fly ash composite cementitious materials were investigated .The results show that the setting time of cement paste was obviously shorten with the addition of calcium hydroxide .When the dosage of calcium hydroxide is 0 .5%, the setting time is the shortest , both the compressive strength at 1 d and 28 d are greatly enhanced .The compressive strength of cement paste at 28 d is 61.9%higher than the control when the dosage of calcium hydroxide is 2%.The electrical resistivity of cement pastes at 1 d decreases with the increase of calcium hydroxide .The maximum of the rate of electrical resistivity also decreases with the increase of calcium hydroxide , it indicates that calcium hydroxide accelerates the early hydration process of the sulphoaluminate cement paste blended with fly ash .The results from XRD analysis indicate that the amount of ettringite increases at 1 d with the addition of calcium hydroxide .At the age of 28 d, the amount of ettringite shows little change , but the compressive strength increases greatly , illustrates that fly ash contributes more to the development of strength .