MECHANICAL AND PHYSICAL BEHAVIOR OF SELF-HEALING CONCRETE USING BACILLUS MEGATERIUM BACTERIA
Keywords:
Concrete, Bacillus Megaterium, Mechanical and physical behavior, Permeable void, CaCO3Abstract
The Bacillus megaterium bacteria synergy on concrete mechanical and physical properties to enhance durability and strength through self-healing is studied. Two Bacillus megaterium concentration variations, variations of 4% and 8% to water volume, were added to fresh concrete based on the substitution method. NC0 stands for 0% bacteria and functions as a control specimen, while SHC4 and SHC8 represented 4% and 8% bacteria content, respectively. The primary focus was to analyze the compressive strength, density, permeable voids, and water absorption behavior at ages 28 and 56 days. Results indicated that the bacteria significantly improved the mechanical properties of hardened concrete. SHC4 and SHC8 exhibited a compressive strength increase of 8% and 14% at 28 days and 15% and 19% at 56 days compared to NC0. This strength increase resulted from permeable voids and water absorption reduction, as well as an improved aggregate-to-mortar ITZ bond due to the formation of bacteria-produced CaCO3, which filled the voids. Reduction in permeable voids and water absorption were 7% to 17%, while density improvement was up to 10% at 28 days. A higher bacteria content consequently produced a better void-filling mechanism. The SHC8 with 8% Bacillus megaterium was proven more effective than SHC4. The 56-day specimens revealed that a significant concrete performance enhancement resulted from the development of CaCO3 deposits over time. It is interesting for further studies to determine the bacteria effectiveness convergence as a function of hardening time. This research highlights the potential of biological approach methods for developing sustainable and resilient construction materials.