水泥-粉煤灰复合胶凝体系的早期水化性能

为了研究粉煤灰掺量和温度对水泥水化的影响，测试了粉煤灰掺量0～60%的水泥-粉煤灰水化体系，在温度20、24和28 ℃下的凝结时间及2d内的电阻率发展及抗压强度，发现凝结时间与电阻率发展速率曲线的第一峰值点对应时间遵循线性关系. 在同一温度下，2d的抗压强度和电阻率值显示出良好的正相关线性关系——温度越高，斜率越小，表明电阻率比强度对温度变化更加敏感. 扫描电镜结果论证了粉煤灰在2d内尚未参与水化反应，主要起填充和稀释作用. 因此，可借助电测法估算和预测变温条件下水泥-粉煤灰水化体系的抗压强度及凝结时间.

Early Hydration Properties of Cement-Fly Ash Cementitious System

To explore the effects of fly ash dosage and temperature on cement hydration， the cementitious hydration system with fly ash dosages of 0-60% was tested. The setting time at 20， 24 and 28 ℃， the electrical resistivity and the compressive strength in 2d were obtained. The results show that the peak time of the electrical resistivity rate curve and the setting time follow the linear relationship. The compressive strength and the resistivity of the pastes in 2d at the same temperature show a good positive linear relationship: the higher temperature， the smaller slope， which demonstrates that the electrical resistivity development is more sensitive to temperature change than the strength. The Scanning Electron Microscopy results reveal that the fly ash does not react in early stage， only acting as fillers to dilute cement. Thus， the setting time and compressive strength of the cementitious hydration system at different temperatures can be estimated and predicted by electrical measurement.