Experimental Research on Magnesium Phosphate Cements Modified by Fly Ash and Metakaolin

Abstract

To increase performance and save costs when utilizing magnesium phosphate cements (MPC) to repair a damaged building structure or a cement pavement, MPC is typically combined with fly ash (FA) and metakaolin (MK). The influence of FA and MK on the workability, rheological characteristics, flexural strength, compressive strength, and drying shrinkage of MPC was investigated in this research. MPC samples with different percentages of FA and MK by weight replacement were prepared. The results indicate that an appropriate dosage of MK and FA could decrease MPC fluidity and delay the setting time. MPC’s yield stress and plastic viscosity were increased when MK was added. FA has a negative influence on flexural and compressive strength as compared to control MPC and the compressive strength of MPC with MK increases and then decreases. The drying shrinkage of MPC containing MK and FA is superior to control mixture. MPC with 10% FA and 10% MK has the best-modified performance in terms of the comprehensive performance of MPC at all test ages.