Long-Term Performance of Sulphoaluminate Cement Blended with Different Contents of Limestone

Abstract

Compared with portland cement, sulphoaluminate cement (SAC) is considered a low carbon emission and low energy consumption cement. To further reduce the cost of SAC and promote extensive engineering application, the hydration and hardened properties of SAC blended with different dosages (0%, 5%, 10%, and 20% by weight) of limestone were investigated over 360 days. Isothermal calorimeter, X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) were used to determine the hydration rate, hydration products, micromorphology, and pore structure of the hardened cement paste. In addition, the mechanical strength and deformation of the mortars were monitored over 360 days. The results show that the addition of limestone has a negative effect on the hydration of SAC due to its large particle size. The compressive strength of the mortars with 0%–20% limestone exhibited a continuous increase within 360 days of curing, even though it decreased gradually as the limestone content increased from 0% to 20% due to the dilution effect. Moreover, all mortars exhibited excellent dimensional stability, and linear deformation over 360 days was less than 30 microstrain.