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<p>The environmental burden associated with cement-intensive concrete production has accelerated the need for innovative, low-carbon material strategies. This study investigates a hybrid chemical–biological approach that integrates silica fume (SF), nano-silica (NS), and Microbially Induced Calcite Precipitation (MICP) using <i>Bacillus subtilis</i> (10⁵ CFU/mL) to enhance the mechanical and durability performance of concrete. Cement was partially replaced with SF (5–20%) and NS (1–3%), selected based on their established pozzolanic reactivity ranges, while MICP was incorporated to promote in-situ CaCO₃ deposition and microcrack healing. A Central Composite Design under Response Surface Methodology (RSM) was employed to evaluate and optimize the combined influence of SF, NS, and curing period on compressive, split tensile, and flexural strengths, as well as durability parameters including water absorption, sorptivity, ultrasonic pulse velocity (UPV), and rapid chloride permeability (RCPT). Results revealed that NS combined with MICP produced superior performance compared to SF-MICP blends, attributed to enhanced nucleation of C-S-H and more efficient microbial calcite precipitation. SEM and XRD analyses confirmed increased matrix densification, reduced pore connectivity, and distinct CaCO₃ crystallinity in bio-pozzolanic mixes. The study demonstrates that coupling pozzolanic refinement with bio-mineralization offers a synergistic route toward durable, eco-efficient concrete, with potential application in precast elements, repair mortars, and self-healing infrastructure systems.</p>

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Effect of Microbially Induced Calcite Precipitation and Pozzolanic Additives on Concrete Performance

  • 期刊论文

  • 发表日期：

    2026年2月3日

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  • Shradha Jena,
  • Bidyadhar Basa,
  • Kishor Chandra Panda

摘要

The environmental burden associated with cement-intensive concrete production has accelerated the need for innovative, low-carbon material strategies. This study investigates a hybrid chemical–biological approach that integrates silica fume (SF), nano-silica (NS), and Microbially Induced Calcite Precipitation (MICP) using Bacillus subtilis (10⁵ CFU/mL) to enhance the mechanical and durability performance of concrete. Cement was partially replaced with SF (5–20%) and NS (1–3%), selected based on their established pozzolanic reactivity ranges, while MICP was incorporated to promote in-situ CaCO₃ deposition and microcrack healing. A Central Composite Design under Response Surface Methodology (RSM) was employed to evaluate and optimize the combined influence of SF, NS, and curing period on compressive, split tensile, and flexural strengths, as well as durability parameters including water absorption, sorptivity, ultrasonic pulse velocity (UPV), and rapid chloride permeability (RCPT). Results revealed that NS combined with MICP produced superior performance compared to SF-MICP blends, attributed to enhanced nucleation of C-S-H and more efficient microbial calcite precipitation. SEM and XRD analyses confirmed increased matrix densification, reduced pore connectivity, and distinct CaCO₃ crystallinity in bio-pozzolanic mixes. The study demonstrates that coupling pozzolanic refinement with bio-mineralization offers a synergistic route toward durable, eco-efficient concrete, with potential application in precast elements, repair mortars, and self-healing infrastructure systems.