Optimization of Self-Consolidating Pastes Containing Limestone Powder and Chemical Admixtures

This paper describes how the performance of self-consolidating pastes was optimized by studying the effect of three mix composition parameters, limestone powder (LSP) content, dosage of superplasticizer (SP), and that of viscosity-modifying admixture (VMA), in a statistically designed experiment. Four properties of the pastes were measured: fluidity (mini-slump flow), Vicat setting times, volume change in the fresh state, and 28-day compressive strength. The optimization was preceded by the evaluation of the response surfaces of all chosen properties in the specified ranges of the three variables. The response surface results emphasized the primary and secondary effects on the properties of cement paste. The optimization indicated that pastes with properties acceptable for self-consolidating applications could be obtained with a moderate LSP content (for example, 19.5% by mass of total powder) and low dosage of the chemical admixtures (for example, 0.64% of SP and 0.01% of VMA by mass of total powder).