Development of a self-leveling fly ash-slag geopolymer mortar

Exponential growth in the world population and increase in demand for concrete are pressing researchers and scientists to find sustainable alternative materials for Portland cement and natural aggregates. Self-leveling mortar is extensively used in construction applications, such as floor leveling, repair, resurfacing, or adhesion. Yet, limited research has been carried out on enhancing this material’s sustainability. This paper aims to produce a geopolymer mortar produced with fly-ash (FA), ground granulated blast furnace slag (BFS), and desert dune sand. Geopolymer mortar samples were produced with different binder-to-sand (B:S), FA-to-slag (FA:BFS), and alkali-activator solution-to-binder (AAS/B) ratios. Alkaline solution was blended with sodium silicate and sodium hydroxide with a molarity of 8 M (ratio of 1.5). Fresh and hardened properties of the developed self-leveling mortars were assessed. Experimental results showed that the flow, initial and final setting time, and 7-and 14-day compressive strength were in respective ranges of 17.3-40.3 cm, 21-155 minutes, 42-221 minutes, 6.0-70.3 MPa, and 5.2-78.7 MPa. Furthermore, an increase in FA:BFS, B:S, and AAS/B ratios enhanced flowability and prolonged setting time but reduced compressive strength at both ages. These research findings advocate the use of a self-leveling, cement-free geopolymer mortar to be utilized in various buildings and repair applications.