Analysis of hydration and strength optimization of cement-fly ash-limestone ternary blended concrete

Abstract

Limestone powder improves concrete early-age strength while fly ash improves concrete late-age strength due to its pozzolanic reaction. The optimal mixture of cement, fly ash, and limestone is crucial for material design of ternary blended concrete. This research presents a simulation program for evaluating the hydration and strength optimization of ternary blended concrete. The simulation program begins with a kinetic hydration model which simulates the hydration of cement-fly ash-limestone ternary blends. The hydration model considers the mutual effects among reactions of cement, fly ash, and limestone by means of the contents of calcium hydroxide and capillary water. The individual reaction degrees of components of ternary blends are calculated from the hydration model. Furthermore, the compressive strength growth of hydrating ternary blended concrete is calculated by means of gel-space ratio and Powers’ strength theory. Finally, based on parameter studies, the optimal combinations of cement, fly ash, and limestone at different ages are determined. The proposed numerical procedure is valuable for making composite cements as it pertains to compressive strength and environment regulations.