硅酸盐与磷铝酸盐复合水泥水化动力学的研究

Research on Hydration Kinetics of Composite Cement of Phosphoaluminate and Silicate

研究了石膏掺量为3.5%(以SO3计,质量分数,下同)、磷铝酸盐水泥熟料掺量为10%的硅酸盐与磷铝酸盐复合水泥的力学性能和水化动力学,测定了该复合水泥在不同水化时间下的Ca2+和[SiO4]4-溶出浓度、相应的电导率及pH值.研究结果表明,磷铝酸盐水泥的掺入不仅可以提高硅酸盐水泥的水化硬化速率,而且能使硅酸盐水泥的早期以及后期强度有不同程度的提高.该复合水泥水化硬化浆体的Ca2+和[SiO4]4-的相对溶出浓度、电导率及pH值均较同龄期的硅酸盐水泥低,说明该复合水泥的水化产物较为稳定,不易溶解,而且碱性较低.硅酸盐与磷铝酸盐复合水泥的水化历程与硅酸盐水泥相同,经历5个阶段,即初始期或预诱导期、诱导期、加速反应期、减速反应期和稳定期.加速反应期的水化主要由成核反应控制,而稳定期的水化主要由扩散过程控制.

The compressive strength and hydration kinetics of the composite cement of silicate clinker and phosphoaluminate clinker prepared with the mass fraction of gypsum of 3.5%（calculated based on SO3） and the amount of phosphoaluminate clinker of 10% were studied.The concentrations of soluble Ca^2＋ and [SiO4]^4- ions from the hardened pastes and the relative conductivity rates and pH values at different hydration ages of the composite cement were measured.The results show that the phosphoaluminate clinker might not only accelerate the hydration rate of ordinary Portland cement,but also make the compressive strength of all ages increase for ordinary Portland cement at different extent.The concentrations of soluble Ca^2＋ and [SiO4]^4- ions from the hardened pastes and the relative conductivity rates and pH values at different hydration ages of the composite cement are lower than those of ordinary Portland cement,which indicates that the stable hydration products of composite cement are not easy to dissolve and they all have low alkalinity.The hydration processes of the composite cement and ordinary Portland cement have（identical） five stages,that is,pre-induction,induction,acceleration,deceleration and stabilization.The hydration is controlled by nucleation reaction and diffusion process in acceleration stage and stabilization stage respectively.