Biomass is gaining in popularity as an energy source. However, the combustion process generates a significant amount of ash, posing an environmental challenge. Previous studies have explored the incorporation of biomass ash into cement concrete to reduce its environmental impact; however, this has resulted in reduced strength performance. Biomass ash has been increasingly used as a component of geopolymer binder materials. This research examined how the treatment processes influence the physical and mechanical properties of geopolymer mortars that include parawood ash and fly ash. The parawood ash was mixed at 0%, 20%, 40%, and 60% by weight of the binder, and the specimens were subjected to heat curing at 80°C for 6, 12, and 24 h and cured at ambient temperature (30 ± 2°C) for 24 h. The compressive strength, bulk density, compressive strength loss after immersion in seawater, microstructure, chemical composition, and mineral composition of the test specimens were evaluated. The results demonstrated significant improvements in compressive strength. The geopolymer specimens with 20% parawood ash, cured at ambient temperature for 24 h, achieved the highest compressive strength of 32.31 MPa at 28 days. However, the specimens subjected to heat curing for 6-24 hours exhibited optimal compressive strengths within the first 24 h. Prolonged heat curing also effectively reduced the bulk density of the geopolymer. In addition to enhancing the compressive strength, the incorporation of parawood ash contributes to the reduction of waste materials.

biomass, geopolymer, fly ash, parawood ash, microstructure