Investigation of microstructure and mechanical properties of geopolymer mortars containing different percentage of nano aluminum

In this study, the effect of 1% and 2% nano-aluminum on the mechanical strength of alkali activated mortar specimens was investigated. In this context, alkali activated mortar specimens were produced with 50% ground granulated blast furnace slag and 50% F-type (low calcium content) fly ash. Sodium silicate and sodium hydroxide were used as alkaline activators and sodium silicate/hydroxide ratio of 2.5 and sodium hydroxide molarity of 14 M were selected. Compressive strength, flexural strength and ultrasonic sound transmission velocity (UPV) value experiments were performed on the alkali activated mortar specimens at 28th day and the effects of using different ratios of nano-aluminum on these properties were investigated in detail. According to the results obtained, it was observed that the use of nano-aluminum increased the compressive and flexural strengths and increased the compatibility values according to the UPV results. Based on the control sample (27.64 MPa) at 28 days, a 5% increase in compressive strength was observed with the addition of 1% and 2% nano-aluminum, and a 21% increase in flexural strength for 1% nano and a 32% increase with the addition of 2% nano-aluminum. According to UPV results, 7% increase was obtained with 1% nano-Al2O3 addition and 5.5% increase with 2% nano addition. As a result, the addition of nano Al2O3 to alkali activated mortars improved the mechanical properties of the mortars.