Positive impact of polymer impregnated on the enhancement of the physico-mechanical characteristics and thermal resistance of high-volume fly-ash blended cement

•Using high-volume fly ash (HVFA) as a supplementary cementitious material.•Polymer impregnation for blended cement OPC-FA pastes.•Impact of polymer impregnation on the mechanical characteristics and fire resistivity of OPC- FA blended cement pastes. To predict the enhanced performance and microstructure design of cement-based composites to achieve sustainability in construction, our study aims to investigate for the first time the positive impact of polymer impregnation on fire resistance and mechanical properties of cement-based composite pastes especially those with high percentages of high-volume fly ash (HVFA) at different water/cement ratios of 0.35, 0.40, and 0.45 and cured up to 90 days. These pastes were dried and impregnated with methyl methacrylate monomer and thermally treated at 70 °C for 3 h using 1% benzoyl peroxide as initiator. The effect of water/cement ratio, curing time, gel space ratio, and bulk density were investigated. Also, XRD, DTG/TGA analysis, and SEM are included. The compressive strength and polymer load were measured after the formation of impregnated- polymer pastes. The results indicated that reducing the w/c ratio leads to the production of hardened cement pastes with dense structures and relatively high compressive strength. For the polymer-impregnated samples, the values of compressive strength were decreased with increasing w/c ratio. The obtained data affirmed that the application of polymer impregnation within a cement matrix can be used to strengthen structures exposed to elevated temperatures. The impregnated cement pastes of ordinary Portland cement (mix OPC1) and blended cement OPC-FA pastes (mix OF1) with water/cement ratios of 0.35 showed higher compressive strength values when thermally treated up to 600 °C after 14 and 28 days of curing.