Geopolymer Bio-Patch Repair: Microbially-Induced Calcite and Pozzolanic Fly Ash and Rice Husk Ash for Corrosion-Resistant of Reinforced Concrete Repair

Pinta Astuti
Angga Jordi Wisnu Nouvaldi
Aprilia Rahmayanti
Pramudya Surya Shabura
Muhammad Etandra Fara Adzani
Dylan Ataa Tsany
Adhitya Yoga Purnama
Rahmita Sari Rafdinal

Advance Sustainable Science, Engineering and Technology (ASSET)
Vol. 8 No. 1 (2026): November - January

Indonesia’s archipelagic environment subjects concrete structures to severe corrosion and sulfate attacks, necessitating sustainable repair solutions. This study evaluates a geopolymer-based bio-patch repair mortar utilizing fly ash (FA), rice husk ash (RHA), and Bacillus subtilis bacteria to induce Microbially Induced Calcite Precipitation (MICP). While the silica-rich ashes act as pozzolanic materials, the bacteria enhance durability by reducing oxygen levels and lowering corrosion rates. Microscopic analysis confirmed the formation of calcium carbonate ($CaCO_3$) and calcium silicate hydrate (C-S-H), both of which significantly improve mechanical properties. The research identified an optimum mixture of 93% FA, 6% RHA, and 1% bacteria, which achieved a compressive strength of 30 MPa, a density of 2.32 g/cm³, and a low water absorption rate of 3.25%. These results meet standard performance requirements, demonstrating that this eco-friendly geopolymer-MICP system is a viable and innovative contribution to structural repair in aggressive environments.