An Experimental Study on Performance of Bacillus pumilus KC845305 and Bacillus flexus KC845306 in Bacterial Concrete

Abstract

In recent years, concrete has become an important versatile construction material. This paper evaluates the strength obtained by concrete with the influence of bacteria. The bacterial strains were isolated from calcareous sludge and urea ware house. The bacterial strains were identified through 16srRNA gene sequencing as Bacillus pumilus and Bacillus flexus. Using these strains, an experiment on cylinder and prisms cast was performed. Compressive strength, split tensile and flexural tests were conducted at the age of 7, 28 and 56 days with ultrasonic pulse velocity and rebound hammer. The results were compared with Bacillus cohnii MTCC 3616 obtained from microbial type culture collection and gene bank, Chandigarh, India. Based on the experimental results, the improvement in the mechanical strength is due to the deposition of calcite crystals on the bacterial cell surfaces within the pores which enhanced the strength of concrete and reduced porosity and permeability.

Keywords

• biomineralization
• bacterial concrete
• ultra sonic pulse velocity
• scanning electron microscope (sem)
• x-ray diffraction (xrd)