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 biometabolic 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 Xray spectroscopy (EDX), Thermogravimetry Analysis (TGA), and X-ray Diffraction (XRD)
technique
