Effect of multi-minerals on the mechanical behavior and pore structure of fiber reinforced internal-cured green concrete

Abstract

In this study, multi-minerals were incorporated in fiber reinforced internal-cured green concrete (FRICC) to achieve both an improvement in concrete performance and environmental sustainability. The effect of multi-minerals on FRICC with pre-wetted lightweight fine aggregate (LWFA) and basalt-polypropylene (BF-PF) fiber was investigated through examining compressive and flexural strengths, flexural toughness, microstructure, pore structure and CO2 emissions. In comparison to ordinary concrete (mixture PO), FRICC presented good flexural performance but a decreased compressive behavior with an increase of 20.5% in flexural strength and a minor decrease of 1.6% in compressive strength. With the addition of multi-minerals, an enhancement in fiber-strengthening and anti-cracking performance was achieved, presenting a positive effect on concrete's strengths, post-cracking manner and pore structure. The internal curing of pre-wetted LWFA stimulated the pozzolanic reaction of minerals given that a denser microstructure with less porosity and more C–S–H gel effectively bound with aggregates and BF-PF fiber was identified. FRICC with a ternary mix of minerals (10% fly ash, 10% blast furnace slag and 5% metakaolin) exhibited the best mechanical performance and pore structure with an increase of 19.6% and 19.2% in compressive and flexural strength, respectively, and a decrease of 29.3% and 13.6% in porosity and mean pore diameter, respectively. Additionally, a reduction in CO2 emissions of up to 19.7% was achieved through adding multi-minerals. In general, the incorporation of multi-minerals brings positive consequences to both the performance of FRICC and environmental sustainability.