LAUSR

Abstract This paper investigates the combined effects of gap-graded cement blended with supplementary cementitious materials (SCMs) by using response surface methodology (RSM). A three-factor three-level Box–Behnken design (BBD) is used to discuss the following independent variables: fly ash (FA), quartz powder (QP) and silica fume (SF). Linear, quadratic, and interaction relationship between primary properties (initial fluidity, rheological properties, hydration heat, mechanical properties, and volume stability) and complex cementitious materials of gap-graded cement paste has been discussed. Analysis of variance (ANOVA) results indicate that SF has a significant effect on all the primary properties of the blended cement pastes. A high-slump paste with four responses is subjected to simultaneous nonlinear optimization to obtain an optimum content of total cementitious materials. The selected range of SCMs contents is (by mass): FA (0–30%), QP (0–20%), and SF (0–10%). The composite desirability function value is 0.939. Hence, the multi-objective optimization is an effective method for optimizing the fresh and hardened properties of complex cement pastes containing SCMs.