Investigation of the Flexural Behavior of Bacterial Concrete Beams

Abstract Bacterial self-healing concrete is an eco-friendly and superior treatment technique that has efficient bonding capacity and compatibility with concrete compositions. It is capable of filling deep microcracks and healing the crack autonomously by calcium carbonate precipitating phenomenon which results in sustainable construction materials. The purpose of this research is to investigate the use of microorganisms Bacillus Subtilis to improve the mechanical properties and the efficiency of self-healing of reinforced concrete beams for two types of concrete, reactive powder concrete (RPC), and lightweight self-compacting concrete (LWASCC), by two methods of addition (direct addition, and encapsulation). The experimental program consists of casting six simply supported beams tested under monotonic and repeated loading. Incorporate bacteria and the precursor (calcium lactate) in concrete mixtures show an improvement in compressive strength, splitting, and flexural strength by up to 21.74 %, 10.92 %, 21.21 % by encapsulation method, and 17.7 %, 18.0 %, 20.84 % by direct addition. In addition, there is an enhancement in the first crack load and ultimate load. Microscopical image demonstrated that calcium carbonates had been deposited in the crack up to 1.0 mm width by bacterial activity within 32 days.