PSI - Issue 70

Vijaya Sundravel K et al. / Procedia Structural Integrity 70 (2025) 485–492

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2. 3. 4. 5. 6. 7. 8. 9.

SHM-B2Z10 SHM-B3Z10 SHM-B1Z20 SHM-B2Z20 SHM-B3Z20 SHM-B1Z30 SHM-B2Z30 SHM-B3Z30

0.5% Bacillus Sps. with 5% Zeolite 0.6% Bacillus Sps. with 5% Zeolite 0.4% Bacillus Sps. with 15% Zeolite 0.5% Bacillus Sps. with 15% Zeolite 0.6% Bacillus Sps. with 15% Zeolite 0.4% Bacillus Sps. with 25% Zeolite 0.5% Bacillus Sps. with 25% Zeolite 0.6% Bacillus Sps. with 25% Zeolite

3.2. Mechanical Properties The mechanical performance of the concrete were evaluated using standardized testing methods as per Indian Standards Reddy and Ravitheja (2019). The structural strength of 15 cm cubic elements was measured in accordance with Indian Standard 1086:1982 Sundravel et al. (2023). Split tension strength tests were conducted on cylindrical specimens with dimensions of 15 cm in diameter and 30 cm in length, while flexural strength was assessed using prism specimens measuring 10 cm×10 cm×50 cm. Also, the flexural behavior of reinforced concrete beams (15 cm × 15 cm × 100 cm) under two-point static loading conditions Jagadeshwaran and Sundravel (2019). To identify the optimal bacterial strain and dosage for enhancing strength, concrete mixes with 0.1%, 0.2%, and 0.3% concentrations of Bacillus species, Pseudomonas, and Escherichia coli were examined at curing durations of 7, 14, 28, 56, and 90 days Chindasiriphan et al. (2020). Based on these evaluations, the most effective bacterial concrete mix was selected and further tested with partial cement replacements of 10%, 20%, and 30% zeolite. The analysis demonstrated that bacterial concrete consistently exhibited higher compressive strength compared to conventional concrete. Among all tested mixes, the combination containing 20% zeolite and 0.5% Bacillus species (SHM-B2Z20) achieved the highest compressive strength. This improvement can be additive to the synergistic affect of MICP and the pozzolanic properties of zeolite, which densify the concrete matrix and enhance its structural integrity. The combined compressive force findings for all tested mixes are illustated in Figure 1.

Fig. 1. Compressive strength of various mix compositions

3.3. Load-Deflection Behavior Beam specimens prepared using bacterial concrete mixes (SHM-CC and SHM-BC-02) along with conventional concrete were evaluated to analyze their load-deflection characteristics. The results indicated that beams made with bacterial concrete demonstrated higher load-bearing capacities and reduced deflection compared to conventional concrete beams. Figures 2 and 3 illustrate the load versus deflection response curves for controlled concrete beams