Enhancing concrete resilience and sustainability through fly ash-assisted microbial biomineralization for self-healing: From waste to greening construction materials

Abstract

This study presents a pioneering approach that enables remarkable crack closure up to 0.8 mm through stimulated biomineralization aiming to enhance the self-healing capacity of concrete. The innovative synergy tackles the pressing environmental challenges head-on investigates the intriguing germination process of endospores in a cementitious environment and underscores the function of calcareous fly ash in promoting Microbially Induced Calcium Carbonate Precipitation (MICP) by providing additional Ca2+ ions, that are converted into carbonate phases through bacterial metabolic processes. These phenomena are thoroughly examined using an in-situ model particularly concerning MICP in bio-concrete, and thermodynamic modelling is performed to forecast the influence of fly ash on the quantity of Ca-bearing (carbonation sensitive) phases present in the hydrated phases of fly ash-blended cement system. Incorporating 30 % class C fly ash significantly amplifies the biomineralization activity, with 6.5 % calcium carbonate deposition in bio-concrete leds to significant healing activity. Concurrently, MICP contributes to a significant reduction in pore sizes, thereby enhancing the overall durability of concrete. Beyond structural improvements, this innovative bio-concrete formulation showcases an impressive 39 % reduction in CO2 emissions, aligning with sustainability goals. Additionally, repurposing fly ash, typically consigned to landfills, seamlessly adheres to the tenets of a circular economy, despite incurring a 7 % rise in the initial production cost. That promising advanced methodology can deliver transformative environmental benefits, ushering in a paradigm shift in sustainable construction practices, and finding the synergistic interplay between microbial activity and calcium-dependent fly ash.