矿物掺合料对含硼碱式硫酸镁水泥强度的影响

Influence of Mineral Admixtures on Strength of Boron-Containing Basic Magnesium Sulfate Cement

将Mg(OH)_(2)作为煅烧MgO的前驱体,同时以在MgO中掺入H_(3)BO_(3)的方式引入杂质硼,采用水化热、X射线衍射仪(XRD)、扫描电镜(SEM)和压汞仪(MIP)等测试技术,研究矿物掺合料对含H_(3)BO_(3)的碱式硫酸镁水泥(BMSC)凝结硬化过程的影响机理.结果表明:未掺加矿物掺合料时,含H_(3)BO_(3)的BMSC水化放热速率较控制组慢、凝结硬化时间延长,且对BMSC的早期强度影响较大;掺加矿物掺合料后,含H_(3)BO_(3)的BMSC后期强度提高,其中外掺H_(3)BO_(3)的BMSC强度提高更加显著,且进一步延缓了水化放热速率;掺加矿物掺合料后,含H_(3)BO_(3)的BMSC水化结晶相未发生改变,仍为5·1·7相和Mg(OH)_(2),孔隙率较低,原因是矿物掺合料发挥了微集料效应,填充了BMSC内部孔隙,使得内部结构更加致密.

Using Mg(OH)_(2)as the precursor of calcined MgO,the impurity boron was introduced into MgO in the form of H_(3)BO_(3).The heat of hydration,X-ray diffractometer(XRD),scanning electron microscope(SEM)and mercury intrusion porosimeter(MIP)were used to study and analyze the effect of adding mineral admixtures with the presence of H_(3)BO_(3)on the setting and hardening process of basic magnesium sulfate cement(BMSC).The results show that without adding the mineral admixture the early strength is lower,the coagulation hardening time is longer,and hydration heat release rate of BMSC containing H_(3)BO_(3)is lowered.Whereas with the addition of mineral admixture the late strength of BMSC containing H_(3)BO_(3)increases significantly,and the exothermic rate of the BMSC that contained H_(3)BO_(3)is further lowered.After the addition of mineral admixture,the hydrated crystalline phase of BMSC containing H_(3)BO_(3)remains primarily to be the 5·1·7 phase and Mg(OH)_(2),and the porosity is low because of the mineral admixture has a microaggregate effect,filling the internal pores of BMSC and increasing the density of the internal structure.