Effect of waste concrete powder on slag-based sustainable geopolymer composite mortars

Abstract

In this study, the effect of waste concrete powder (WCP) on slag-based geopolymer composite mortars was investigated. Blast furnace slag (BFS) and WCP were used as binders in geopolymer mortars. WCP was substituted into the geopolymer mortar composites at rates of 10%, 20%, 30%, and 40% by weight of slag. Sodium hydroxide (NaOH) solution was used as the alkali activator in the mixtures and the solution activator concentration was chosen as 16 molars (M). After the prepared mortars were cured at 100°C for 24 hours, they were subjected to flexural strength (ffs), compressive strength (fcs), and ultrasonic pulse velocity (UPV) tests. When the obtained results were examined, it was observed that ffs, fcs, and UPV results decreased with the increase in WCP replacement ratio. These decrements were seen clearly, especially after the 20% replacement ratio. However, despite these decrements, the compressive strengths of all groups were found to be above 50 MPa. In addition, it is thought that environmental pollution can be reduced by using WCP in geopolymer composite mortars.