Investigation of early hydration of high aluminate cement-based binder at different ambient temperatures

Abstract

The effect of spent FCC catalyst on early hydration (up to 48 h) of high aluminate cement (Al2O3 [70%) at different ambient temperatures (10, 20, and 30 C) was investigated. Cement pastes with constant ratio of water/binder = 0.35 (binder = cement ? addition) and containing 0, 5, 10, and 15% mass of addition as replacement of cement were studied. The hydration kinetics was determined by calorimetric measurements and the structure of hardened binders after 2 days of curing at an appropriate temperature was also investigated using X-ray, SEM, and thermal analysis methods. Due to the fact that hydration of aluminate cements is highly sensitive to temperature conditions as well as certain changes of temperature are inevitable in practice, the evaluation of the impact of the waste catalyst addition in such conditions is justified. On the basis of obtained results, it was stated that the temperature determines the early hydration of high aluminate cement and decides about the influence of waste aluminosilicate. The introduction of the discussed addition has a big impact on the kinetics of cement hydration closely related to the curing temperature. The presence of spent catalyst accelerates the hydration at the temperatures of 20 and 30 C, but at the temperature of 10 C this waste aluminosilicate acts as a retarding agent. The effect of the addition on the microstructure of hardened binders after 48 h of hydration is rather insignificant, especially at 20 C, compared to the influence of the temperature on hydration. At the temperature of 10 C, a formation of low amount of C2AH8 can be observed because of the presence of spent catalyst, while at the temperature of 30 C the introduction of the mineral addition prevents the hydrogarnet formation.