Effect of carbide slag dosage on hydration behavior and mechanical properties of supersulfated cement
Shuaihu Cui, Kunjie Fan, Yao Yao
Abstract
Supersulfated cement (SSC) is a low-carbon, environmentally friendly cementitious material, but its performance is highly sensitive to the dosage of alkaline activator, making it difficult to balance the development of early and later strength. In this paper, carbide slag, an alkaline industrial solid waste, was used as an activator to systematically study the influence of its dosage on the evolution of SSC compressive strength. The action mechanism of carbide slag in the hydration process of SSC was revealed by a variety of characterization methods such as hydration heat analysis, mineral phase composition, and pore structure. The results show that the introduction of an appropriate dosage of carbide slag can significantly increase the alkalinity of the system, promote the formation of Ettringite and C-(A)-S-H gel, and thus accelerate the early hydration reaction. When the dosage is too high, the excessively generated hydration products will delay the appearance of the exothermic peak in the acceleration period, inhibit the later hydration reaction, and lead to a decrease in the 28-day compressive strength. When the carbide slag dosage is 3 wt%, the sample exhibits the best comprehensive performance, with a 3-day compressive strength of 20.1 MPa and a 28-day strength of 43.7 MPa. X-ray diffraction analysis and pore structure test further confirmed that 3 wt% carbide slag contributed to the continuous generation of hydration products and reduced porosity. The above results showed that carbide slag was an ideal activator with sustainability and activation efficiency in the SSC system.