SYNERGISTIC EFFECT OF METAKAOLIN AND BACILLUS SUBTILIS ON STRENGTH AND DURABILITY OF CONCRETE

Paper ID: EIJTEM_2026_13_2_142-152

Author's Name: Venkatesh Kondamuru, Vijaya Sekhar B, Kalyani Gurram, Maheswararao R and Naveen Kumar G

Volume: 13

Issue: 2

Year: 2026

Page No: 142-152

Abstract:

In order to increase the durability of M25 grade concrete, this study examines the effectiveness of bacterial concrete, specifically using Bacillus subtilis and metakaolin as a partial cement alternative. Seven concrete mixes (M0–M6) with varying amounts of Bacillus and metakaolin were developed, along with a control mix. At 7 and 28 days, mechanical characteristics such flexural strength, split tensile strength, compressive strength and durability tests were evaluated. The best mix demonstrated a 28-day compressive strength of 39.2 MPa, split tensile strength of 3.4 MPa, and flexural strength of 5.7 MPa, indicating that bacterial concrete performed better than traditional concrete. Significantly, this mixture reduced water absorption by 30.8%, sorptivity by 25%, acid resistance by 40%, and chloride permeability by 43.75%. These improvements are ascribed to microbial-induced calcite precipitation, which helps close microcracks, and the pozzolanic activity of metakaolin, which refines the concrete's pore structure. All things considered, this study is in favor of using bacterial concrete as a long-lasting and sustainable substitute for traditional concrete, especially in challenging environmental circumstances.

Keywords: Bacterial Concrete, Bacillus subtilis, Metakaolin, MICP, Mechanical Properties.

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