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<p>The construction and mining infrastructure sector is under pressure to reduce carbon emissions. Ordinary Portland cement is responsible for nearly 8% of global CO₂. Low-carbon composites (LCC) are emerging as sustainable alternatives. These materials use industrial by-products such as fly ash, slag, and metakaolin. They reduce clinker content and lower CO₂ emissions by up to 50%. However, LCC is more brittle than conventional concrete. Cracks form more easily, reducing durability. Autogenous healing is limited due to low portlandite content. Repairing cracks with epoxy or polymer coatings is costly and generates additional emissions. Microbial self-healing (SH) offers a promising solution. Bacteria such as <i>Bacillus subtilis</i> and <i>Sporosarcina pasteurii</i> can precipitate calcium carbonate (CaCO₃) in situ. This fills cracks, restores strength, and improves durability. Healing depends on crack width, curing conditions, and microbial carriers. Different LCC systems show varying performance. Metakaolin-based mortars can heal cracks up to 200 μm, while GGBS-based systems typically heal cracks in the range of 100–400 μm. Fly ash and alkali-activated composites also show strong SH potential, with higher crack closure in some cases. Microbial systems can also sequester CO₂ during the healing process, enhancing sustainability. This review evaluates microbial SH mechanisms in LCC, comparing performance, durability, and environmental impact. Key challenges such as microbial survival, nutrient supply, and cost are discussed. Field limitations and future research needs are also highlighted. Microbial SH can significantly extend service life, reduce maintenance, and preserve the environmental benefits of LCCs. It bridges the gap between durability and sustainability in modern construction and mining infrastructure.</p>

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Microbial self-healing in low-carbon cementitious composites: mechanisms, performance, and sustainability

  • 期刊论文

  • 发表日期：

    2026年6月3日

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  • Nejib Ghazouani,
  • Khaled Mohamed Elhadi,
  • Aqeel Ur Rehman

摘要

The construction and mining infrastructure sector is under pressure to reduce carbon emissions. Ordinary Portland cement is responsible for nearly 8% of global CO₂. Low-carbon composites (LCC) are emerging as sustainable alternatives. These materials use industrial by-products such as fly ash, slag, and metakaolin. They reduce clinker content and lower CO₂ emissions by up to 50%. However, LCC is more brittle than conventional concrete. Cracks form more easily, reducing durability. Autogenous healing is limited due to low portlandite content. Repairing cracks with epoxy or polymer coatings is costly and generates additional emissions. Microbial self-healing (SH) offers a promising solution. Bacteria such as Bacillus subtilis and Sporosarcina pasteurii can precipitate calcium carbonate (CaCO₃) in situ. This fills cracks, restores strength, and improves durability. Healing depends on crack width, curing conditions, and microbial carriers. Different LCC systems show varying performance. Metakaolin-based mortars can heal cracks up to 200 μm, while GGBS-based systems typically heal cracks in the range of 100–400 μm. Fly ash and alkali-activated composites also show strong SH potential, with higher crack closure in some cases. Microbial systems can also sequester CO₂ during the healing process, enhancing sustainability. This review evaluates microbial SH mechanisms in LCC, comparing performance, durability, and environmental impact. Key challenges such as microbial survival, nutrient supply, and cost are discussed. Field limitations and future research needs are also highlighted. Microbial SH can significantly extend service life, reduce maintenance, and preserve the environmental benefits of LCCs. It bridges the gap between durability and sustainability in modern construction and mining infrastructure.