Influence of source materials and the role of oxide composition on the performance of ternary blended sustainable geopolymer mortar

This research article reports the contribution of different oxides present in rice husk ash (RHA), ground granulated blast furnace slag (GGBS) and metakaolin (MK) on the performance of geopolymer mortars. Twenty-six mixes were designed with combined base materials and varied NaOHaq concentration, that was used as one of the activators. RHA, GGBS and MK contents were varied between 15% and 70%, 0% and 75%, and 0% and 40%, respectively. The binder/fine aggregate, water/binder and alkaline activator/binder ratios were kept constant while all the specimens were cured at 65 °C for 24 h. The mixture (ternary) that contained 25% RHA, 25% MK and 50% GGBS (M25R25G50) produced the highest compressive strength of 48 MPa; in addition, it produced better flow rate and lower density than any binary combinations. The findings through microstructural and characterization tools show that regardless of the source, SiO2 and CaO present in the base materials contributed to the strength, while Al2O3 influenced the amorphorsity of the products.