Optimizing Biomineralization in Concrete Restoration: Superfine Sand Ratios and their Impact on Mechanical Properties

Abstract

This study explores the application of biomineralization technologies, including Microbially Induced Calcium Carbonate Precipitation (MICP) and Enzyme Induced Carbonate Precipitation (EICP), for the self-healing of concrete. We investigate the synergistic effects of cement, fly ash, and ultrafine sand, focusing on the optimal formulation for enhanced mechanical properties. The restoration process employs the culture of Bacillus subtilis, optimized for bio-mineralization in concrete matrices. Experimental setups were designed to analyze the effect of ultrafine sand ratios on the restoration outcomes. Notably, the optimal ultrafine sand content was identified based on the mechanical strength outcomes and the efficiency of bio-mineral deposition induced by varying urease levels. Results show that higher urease concentrations (5.0unit/mL) significantly expedite the mineralization process, achieving complete deposition within 2 hours. Additionally, the compressive strength was highest in samples with a peat ratio of 0.3 and a 15% superfine sand admixture. Temperature studies indicated that urease activity retains significant functionality even after 6 days at elevated temperatures, crucial for practical applications. This research not only confirms the efficacy of biomineralization in concrete restoration but also optimizes the sand admixture proportions, offering a scalable approach for commercial bio-restoration of concrete structures.