Study on Strength and Self-Healing Behaviour of Bio-Concrete

Abstract

Micro cracks are very commonly observed in concrete structures. Due to increased permeability through these micro cracks, durability of concrete structures reduces by the entry of chemical through these micro pores particularly in moist environments. In the field, crack repair is labour intensive. It is more advisable to restrict the early age small cracks the moment they appear instead of repairing after large cracks formed. In order to increase the durability of concrete against these commonly observed pores in concrete structures, autogenous pore refinement method can be adopted so that monitoring of the structure against these micro pores can be avoided. By using the principle of Biomineralization, Bacteria forms the Calcium precipitations which is usually called microbial induced calcite precipitation (MIC) .In the present work, the bacteria which will grow in the high alkaline media is chosen since concrete is highly alkaline material and cultured in the controlled medium to get the desired concentration of cells. In the present work, Un-identified and Bacillus sphericus bacterial broth is used for the study. It is observed that these bacteria when mixed with concrete at the concentration of 10⁶ cells per ml, the compressive strength is increased by 36.36 % and 13.63 % and for 10⁷ concentrations of cells, the un-identified bacteria show the increase of compressive strength as 29.56 %. Modulus of elasticity of concrete is increased by 23.78 % and 31 % for both bacteria at the concentration of 10⁶ cells per ml of water and Split tensile strength is increased by 23.5 % and 28.5 % for concentration 10⁶ and 107 cells of Bacillus sphericus. SEM and EDAX analysis reveals the deposition of calcium carbonate

Keywords: Self-healing, bio mineralization, strength