Self-healing of recycled aggregate fungi concrete using Fusarium oxysporum and Trichoderma longibrachiatum

Abstract

This research is aimed to investigate the performance and crack healing phenomenon of recycled aggregate concrete (RAC) by using fungi (Fusarium oxysporum and Trichoderma longibrachiatum) as potential bio-admixtures. The microbial behavior and efficiency of the chosen fungal strains were studied on induction in the RAC by direct intrusion and after being immobilized in recycled coarse aggregate (RCA). The microbial activity in concrete was activated using calcium lactate as nutrition medium. Analysis and comparison of both fungal inoculation approaches with the reference matrix was conducted based on mechanical performance, durability tests, self-healing attributes, and the supporting forensics. Based on the results, F. oxysporum is proven as the potential strain for enhancing RAC performance when immobilized in RCA. The attained increase in compression and tension using F. oxysporum is 11.62 % and 31.18 % respectively at the age of 28 days. Further, the mentioned strain reduced the water absorption by 0.8 % and enhanced the acid resistance of concrete by 4.5 % in terms of measured mass loss. The crack size of 1.34 mm was completely sealed through bio-metabolic activity of F. oxysporum immobilized in RAC and restored 58.75 % of its compressive strength. Fungus hyphae of both the strains were identified in the respective RAC mixes through microscopic examination by Field Emission Scanning Electron Microscopy (FESEM) which proves the compatibility of RCA as the suitable carrier medium for fungi. The crack filler compound was forensically confirmed as bio-calcite through Energy Dispersive X-ray spectroscopy (EDX), Thermogravimetry Analysis (TGA), and X-ray Diffraction (XRD) technique.