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Microbial Self-Healing Concrete: A Sustainable Solution for Crack Repair -…
Microbial Self-Healing Concrete: A Sustainable Solution for Crack Repair
Mechanism of Microbial Self-Healing
Biomineralization process
Bacteria induce CaCO₃ precipitation (MICP)
Ureolysis and nitrate reduction pathways
Crack repair cycle
Dormant bacterial spores
Water ingress activates bacteria
CaCO₃ crystals fill cracks
Return to dormant state after healing
Key outcome
Crack sealing
Improved durability
Maximum healed crack ≈ 970 μm
Bacterial Viability & Implementation
Survival requirements
High pH tolerance (12–13)
Temperature resistance (up to 70°C)
Nutrient and moisture availability
Suitable bacterial species
Sporosarcina pasteurii
Bacillus cereus
B. licheniformis
B. halodurans
B. muralis
B. simplex
Direct implementation
Surface spraying
Crack injection
Direct mixing
Indirect implementation
Porous aggregates
Polymer/mineral capsules
Hydrogels
Trade-off
Direct = simpler, cheaper
Indirect = better protection, higher cost
Performance & Efficiency Factors
Factors affecting healing
Calcium source availability
Crack width
Crack age
Curing conditions
Efficiency evaluation
Crack closure measurements
Optical microscopy
SEM, XRD, EDS, TGA analyses
Durability and strength testing
Mechanical improvements
Compressive strength ↑ up to 42.8%
Splitting tensile strength ↑ up to 32.3%
Flexural strength ↑ up to 48%
Influencing variables
Bacterial strain
Cell concentration
Environmental conditions
Applications, Benefits & Future Challenges
Benefits
Autonomous crack repair
Reduced maintenance costs
Increased service life
Sustainable alternative to traditional repairs
Real-world applications
Drainage pipe roof slabs
Highway retaining walls
Ship locks
Irrigation canals
Countries implementing technology
China
Netherlands
Belgium
United Kingdom
Current challenges
Harsh concrete environment
Long-term bacterial stability
High encapsulation costs
Lack of standardized evaluation methods
Limited field-scale studies
Future directions
Genetically enhanced bacteria
Improved encapsulation systems
Smart sensors and monitoring
Life Cycle Assessment (LCA)
Large-scale outdoor validation studies