Investigation on Strength Enhancement of U-TPOFA Based Binary Blended Alkali Activated Mortar Through Addition of Fly Ash

Alkaline activated binders (AAB), which are the results of reaction between source aluminosilicates and alkaline activator, are an environmentally friendly binder that exhibits high compressive strength (CS). This study explores the effects of different combinations of ultrafine treated palm oil fuel ash (u-TPOFA) and fly ash (FA) on the compressive strength and structural composition changes of the u-TPOFA-FA alkali-activated binary binder mortar (AABBM). The alkaline activated mortar (AAM) was synthesized using mixtures of u-TPOFA and FA in varying ratio of u-TPOFA:FA of (100:0), (90:10), (80:20), (70:30), (50:50), (25,75) and (0:100), respectively, and the alkaline activating solution consist of a combination of Na2SiO3 and NaOH. The combination and concentration of Na2SiO3 and NaOH were constant for all mixtures. Primarily, it was found that mixture with a combination of u-TPOFA:FA of 25:75 gain the highest compressive strength (CS) of 54.82 MPa at 28 days. Therefore, the replacement of SiO2 from u-TPOFA by Al2O3 provided by FA contributes towards significant CS enhancement due to the formation of more N-A-S-H gel binder. The result observed for the gel binder formation was emphasized with XRD and FTIR analyses.