矿物外加剂-中热水泥组合胶凝材料的砂浆基本性能对比

Comparison of the basic properties of mortar of mineral admixture-medium-heat cement combination cementitious materials

为研究不同矿物外加剂与水泥组合胶凝材料的砂浆性能,采用F类II级粉煤灰、天然火山灰、S75级矿渣粉,分别以10%、30%和50%这3种掺量取代中热水泥,形成组合胶凝材料,对其水胶比为0.5的砂浆流动度、凝结时间、抗压强度和胶砂比为1∶3的水化放热量开展试验研究,比较不同组合胶凝材料的砂浆基本性能。结果表明:当取代量为10%~50%时,掺粉煤灰的砂浆流动度增大3.2%~22.5%,初凝时间延迟11.2%~20.4%、终凝时间延迟13.3%~43.5%,7d水化放热量降低7.4%~39.7%;掺天然火山灰的砂浆流动度减小3.2%~21.9%,初凝时间提前8.4%~24.6%、终凝时间提前5.3%~20.0%,7 d水化放热量下降2.9%~25.4%;掺矿渣粉的砂浆流动度减小1.1%~6.4%,初凝时间推迟8.4%~28.8%、终凝时间推迟9.6%~25.1%,7 d水化放热量减少4.8%~30.1%。在掺量为10%时,掺粉煤灰的90 d龄期胶砂抗压强度与纯水泥的接近,掺矿渣粉的28 d和90 d龄期抗压强度较纯水泥分别提高1.6%和2.4%,而在其它掺量及龄期时,3种组合胶凝材料的胶砂抗压强度均表现为下降,并随掺量增加强度递减。研究结论可为混凝土工程胶凝材料体系的选择提供参考。

In order to study the mortar performance of different mineral admixtures and cement composite cementitious materials,F class II fly ash,natural Volcanic ash,and S75 slag powder are used to replace medium heat cement with 10%,30%,and 50%respectively to form composite cementitious materials.Experimental studies are carried out on the fluidity,setting time,compressive strength,and hydration heat release of mortar with a water binder ratio of 0.5,and a cement sand ratio of 1∶3,and the basic properties of mortar with different combinations of cementitious materials are compared.The results show that when the substitution amount is 10%~50%,the fluidity of the mortar mixed with fly ash increases by 3.2%~22.5%,the initial setting time is delayed by 11.2%~20.4%,the final setting time is delayed by 13.3%~43.5%,and the hydration heat release after 7 days is reduced by 7.4%~39.7%;The fluidity of mortar mixed with natural Volcanic ash decreased by 3.2%~21.9%,the initial setting time was 8.4%~24.6%ahead,the final setting time was 5.3%~20.0%ahead,and the hydration heat release in 7 days decreased by 2.9%~25.4%;The fluidity of mortar mixed with slag powder decreased by 1.1%~6.4%,the initial setting time is delayed by 8.4%~28.8%,the final setting time was delayed by 9.6%~25.1%,and the hydration heat release in 7 days was reduced by 4.8%~30.1%.At a dosage of 10%,the compressive strength of the 90 day old mortar mixed with fly ash is close to that of pure cement.The compressive strength of the 28 day and 90 day old mortar mixed with slag powder is increased by 1.6%and 2.4%,respectively,compared to pure cement.However,at other dosages and ages,the compressive strength of the mortar of the three combination cementitious materials shows a decrease,and the strength decreases with the increase of the dosage.The research conclusion can provide reference for the selection of cementitious material systems in concrete engineering.