Feasibility study of novel bacteria-based self-healing concrete

Abstract

Cracking in concrete has resulted in the need for repair as cracking affects the mechanical properties of concrete. Introduction of encapsulated bacteria has proven to be effective in closing these cracks thus reducing the need for repair to concrete structures. This paper presents an experimental study on a novel bacteria-based self-healing system using M-S-H to encapsulate Bacillus cohnii. The mix design for M-S-H was tested before adding the bacteria into the paste. The bacteria survivability was then tested within the M-S-H capsule which suggested little reduction. Various mix designs of Portland Cement (PC) were casted with and without encapsulation of bacteria, and without the capsules and nutrients. The compressive strength of the sample groups were tested and the inclusion of capsules resulted in an increase in compressive strength while the addition of nutrients decreased the compressive strength. Cylindrical samples were casted, and cracks of varying widths were generated and observed on a microscope for healing after every 10 healing cycles. The self-healing abilities of the samples were also tested and proved to be effective with varying crack widths and a maximum average crack closure rate of 86% after 30 healing cycles.