Abstract:
Bacteria-based self-healing concrete can be made more efficient by using immobilization techniques; hence shielding the bacteria from crushing during mixing to remain dormant till the development of concrete cracks for uniform healing of developed cracks. In this study, two intrusion approaches, direct induction and immobilization, are deliberated by using ‘Bacillus Subtilis’ bacteria for self-healing concrete. Furthermore, for immobilization evaluation, two media iron oxide Nano/micro (INMP) and bentonite Nano/Micro particles (BNMP) are selected. Compressive and tensile strengths were computed at 3, 7 and 28 days. Moreover, Scanning Electron microscopy, X-ray Diffraction, X-Ray Fluorescence and Thermogravimetric Analysis are employed for monitoring self-healing efficacy. Results revealed that Immobilization through INMP media is best among all intrusions , as it can heal cracks up to 1.2mm and 85% recovery in compressive strength was observed after crack formation followed by direct intrusion with 65% strength recovery and 0.4mm crack healing. Rather, BNMP immobilization exhibited crack healing up to only 0.15mm width with 45% strength recovery. Thus, it can be concluded that media selection for immobilization is important as BMNP was least effective as compared to other methods.
