Effect of High-Magnesium Nickel Slag on Hydration Characteristics of Portland Cement

Abstract

This paper aims to study the effect of high-magnesium nickel slag on the hydration characteristics of portland cement paste. High-magnesium nickel slag was used as supplementary cementitious material. The compressive strength and shrinkage of the specimens were tested. The phase evolution and microstructure of the pastes were investigated using Fourier transform infrared spectrometry, isothermal conduction calorimetry, Brunauer–Emmett–Teller, X-ray diffractometry, thermogravimetric analysis, and scanning electron microscopy (SEM). The results show that the cumulative heat release of cement paste hydration decreases as the nickel slag content increases. This indicates that nickel slag has low pozzolanic activity. The maximum heat evolution rate of the exothermic peaks in cement pastes with 10%, 20%, 30%, 40%, and 50% nickel slag are 0.00298, 0.00269, 0.00240, 0.00205, and 0.00178 W/g, respectively. The compressive strength of hardened cement pastes decreases as the nickel slag content increases. The total porosity of the cement pastes increases with nickel slag content. Hardened cement pastes with nickel slag show less mass loss caused by dehydration of C–S–H, C–A–S–H, and C–A–H gel phases than the control sample without nickel slag. The SEM images reveal that the abundant platelike C–S–H can be observed in the cement paste with 30% nickel slag addition.