粉煤灰和矿粉低热硅酸盐水泥胶凝材料的水化特征

采用不同掺量粉煤灰和矿粉取代低热硅酸盐水泥,制备水泥砂浆和净浆。测试砂浆抗压强度和抗折强度发展,用XRD分析水泥净浆物相组成,用恒温量热仪测试水泥净浆的放热速率和放热量。结果表明:掺入粉煤灰使低热硅酸盐水泥强度下降,强度发展速度变慢,掺入矿粉对低热硅酸盐水泥强度发展影响较小;与纯水泥体系相比,掺粉煤灰胶材体系的水化物相种类没有变化,水化产物中氢氧化钙含量下降,掺矿粉对氢氧化钙的降低作用更明显,且会促进AFm的形成;粉煤灰和矿粉可降低低热硅酸盐水泥水化放热速率和放热量,粉煤灰对水化进程影响不明显,矿粉对水化进程有促进作用。

Hydration characteristics of low heat portland cement mixtures with fly ash or slag

Low-heat portland cement (PLH) mortars and pastes with different dosage of fly ash and slag were prepared and the compressive strength and flexural strength of the mortars were tested.Phase composition of the pastes was tested by XRD while hydration heat flow was measured by calorimeter.The results show that the application of fly ash causes decreases in mortar strength and strength development rate.The influence of slag on mortar strength is not obvious.The phase composition of fly ash pastes is similar to that of the reference mixture.However,the content of CH is decreased by the use of fly ash.The application of slag can reduce CH content more significant than fly ash and meanwhile promote the formation of AFm.Both the heat flow and hydration heat of the PLH paste are decreased by fly ash and slag.The influence of fly ash on PLH hydration evolution is not significant whereas slag promotes the hydration evolution.