Strength characteristic and life cycle cost of sustainable bio-patch repair geopolymer mortar using rice husk ash as an alternative silica and alumina source

Abstract

Rapid development in construction has increased cement use, raising CO₂ emissions. Geopolymers offer an eco-friendly alternative, reducing reliance on cement. This study examines rice husk ash (RHA), a pozzolanic material, as a binder. Three alkali activator variations (AA40%, AA45%, AA50%) were tested for mechanical properties, focusing on compressive strength. The mix design was optimized and cured at 70°C and room temperature. The AA40% variation showed the highest compressive strength of 8.14 MPa. RHA-based geopolymer mortar supports UN SDGs 9, 12, and 13, showing a significantly lower 30-year life cycle cost (IDR 4,125,000 vs. IDR 6,225,000 for Portland cement). It reduces agricultural waste, lowers carbon footprints, and offers long-term economic benefits, highlighting its potential as a sustainable building material.