Effects of Portland cement addition on the early-age properties of solid-waste-based sulphoaluminate cement

This paper investigated the effects of different proportions of Portland cement addition (0-20%) on the setting time and early-age strength of solid-waste-based sulphoaluminate cement. The mechanism of hydration process was analyzed by X-ray diffraction (XRD) technology. It was found that the incorporation of Portland cement could reduce the early-age strength of the composite cement, and shorten the setting time. When the Portland cement reached 20%, the early-age strength of the composite cement was the lowest and the setting time was the shortest. The XRD analysis demonstrated that the addition of Portland cement could accelerate the hydration process of the composite cement, and the more the Portland cement was added, the faster the hydration process of the composite cement was observed. The main reason is that the addition of Portland cement could increase the alkalinity of the composite cement and promote the hydration of anhydrous calcium sulphoaluminate. This study provides an important reference for the production of solid-waste-based composite cement.