Synergistic Activation of Manufactured Sand Powder-Slag-Gypsum Cementitious Composites Using Response Surface Methodology

Abstract

The synergistic effects of alkali and sulfate activators on the flexural and compressive strengths of manufactured cementitious composites comprising slag, fly ash and cement were studied in the present manuscript. The experimental procedure used a central composite design (CCD) for the response surfaces. A regression model was established and tested with the experimental results. The maximum flexural strength, compressive strength, and stone powder content at each age were used as the target values for optimisation. The optimal mixing proportion included 14.45 % manufactured sand powder and 0.91 % gypsum. In addition, the effects of the sulfate activator on the manufactured sand powder-slag-gypsum cementitious composite (MSGCC) hydration were analysed after 1 and 3 days, and the mechanism for the synergistic activation of MSGCC by alkali and sulfate activators was elucidated upon/clarified.