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<p>Bacteria-based self-healing concrete holds significant potential for enhancing durability, but its success relies on selecting a strain that withstands alkaline environments and a biocarrier that preserves bacterial viability without compromising strength. Many urease-producing bacteria exhibit varying performance, necessitating a comparative evaluation. Similarly, traditional biocarriers, such as synthetics and lightweight aggregates, often weaken concrete, underscoring the need for supplementary cementitious material (SCM)-based alternatives that improve both bacterial survival and structural integrity. This study systematically screened nine bacterial strains for urease and carbonic anhydrase activities, identifying <i>Paenibacillus sp.</i> (5410) as the most effective candidate. Five SCMs—metakaolin, fly ash, ceramic clay, diatomaceous earth, and shadu—were evaluated as bacterial biocarriers, with metakaolin demonstrating superior waterproofing, structural integrity, and bacterial viability. Metakaolin-coated biocarrier beads were incorporated into mortar at varying dosages (0–10%) to assess their impact on mechanical and durability properties. At an 8% dosage, the biocarrier-enhanced mortar exhibited a 22.9% increase in compressive strength (13.23&#xa0;MPa) and a 19.4% increase in tensile strength (1.42&#xa0;MPa) compared to the control. Durability assessments revealed reduced porosity, lower water absorption, and improved resistance to chloride ion penetration. Self-healing efficacy was confirmed through crack closure observations, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which detected bacterial-induced calcium carbonate precipitation. These findings highlight metakaolin’s effectiveness as a biocarrier and demonstrate that <i>Paenibacillus sp.</i> (5410) enhances mortar durability through microbial-induced self-healing. This study presents a promising approach to developing sustainable and resilient construction materials.</p> Graphical abstract <p></p>

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Comparative evaluation of bacterial strains and novel SCM-based biocarriers for self-healing and strength enhancement in mortar

  • 期刊论文

  • 发表日期：

    2025年8月13日

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  • Deeksha Patil,
  • Anant Mishra,
  • Gaurav Tyagi,
  • Pingili Manvith Reddy,
  • Mukund Lahoti,
  • Anupama Pable,
  • Umesh U. Jadhav,
  • Steven G. Sachs

摘要

Bacteria-based self-healing concrete holds significant potential for enhancing durability, but its success relies on selecting a strain that withstands alkaline environments and a biocarrier that preserves bacterial viability without compromising strength. Many urease-producing bacteria exhibit varying performance, necessitating a comparative evaluation. Similarly, traditional biocarriers, such as synthetics and lightweight aggregates, often weaken concrete, underscoring the need for supplementary cementitious material (SCM)-based alternatives that improve both bacterial survival and structural integrity. This study systematically screened nine bacterial strains for urease and carbonic anhydrase activities, identifying Paenibacillus sp. (5410) as the most effective candidate. Five SCMs—metakaolin, fly ash, ceramic clay, diatomaceous earth, and shadu—were evaluated as bacterial biocarriers, with metakaolin demonstrating superior waterproofing, structural integrity, and bacterial viability. Metakaolin-coated biocarrier beads were incorporated into mortar at varying dosages (0–10%) to assess their impact on mechanical and durability properties. At an 8% dosage, the biocarrier-enhanced mortar exhibited a 22.9% increase in compressive strength (13.23 MPa) and a 19.4% increase in tensile strength (1.42 MPa) compared to the control. Durability assessments revealed reduced porosity, lower water absorption, and improved resistance to chloride ion penetration. Self-healing efficacy was confirmed through crack closure observations, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which detected bacterial-induced calcium carbonate precipitation. These findings highlight metakaolin’s effectiveness as a biocarrier and demonstrate that Paenibacillus sp. (5410) enhances mortar durability through microbial-induced self-healing. This study presents a promising approach to developing sustainable and resilient construction materials.

Graphical abstract