STUDY OF SELF-HEALING PROPERTIES OF CONCRETE CONTAINING BIO-CHAR, BACTERIA AND POLYVINYL ALCOHOL FIBRES

Abstract

Self-healing concrete is able to carry out crack repair without the need for human intervention. Bacteria such as Bacillus Sphaericus can carry out carbonate precipitation to seal the cracks. It has been difficult to find a suitable encapsulation material for the bacteria spores. This study looks at the use of biochar for the immobilisation of Bacillus Sphaericus. Biochar has the ability to sequester carbon and potentially turn cities into carbon sinks. Additives of Bacillus Sphaericus immobilised in biochar, superabsorbent polymer (SAP) and polyvinyl alcohol (PVA) fibres in different compositions were tested in this study. The physical properties of self-healing concrete and its capacity to heal cracks were investigated with different mixes. Concrete was damaged to 60% of its full loading capacity and left to heal before laboratory tests were conducted on damaged and undamaged samples of the same age. During this experiment, the rate of sorptivity, depth of water penetration, compressive strength, and split tensile strength was tested, with data tabulated. The three mixes tested showed an improved healing ability as compared to the control mix. Results also showed that the most promising self-healing concrete includes a combination of Bacillus Sphaericus immobilised in biochar, SAP and PVA fibres. Exact composition of each material within the concrete may be adjusted to obtain the most ideal mix.