PERFORMANCE EVALUATION OF GEOPOLYMER CONCRETE WITH VARIED CONCENTRATION OF ALKALINE ACTIVATORS

Cement is the primary ingredient in concrete, a substance that is frequently used in construction. Concrete is typically made using ordinary portland cement (OPC) as the main binder. When limestone is burned during the cement-making process, carbon dioxide (CO2) gas is released into the environment. Finding alternative binders that are stronger, use less energy, deplete fewer natural resources, and have a lower carbon impact than cement is crucial. The greatest substitute among the numerous options is geopolymer binder. A paste that binds the loose coarse and fine aggregates in geopolymer concrete is created when various alkaline solutions, such as KOH and K2SiO3, chemically activate by-product materials rich in silicon and aluminum, such as sawdust ash and rice husk ash. In this work, the physical characteristics of coarse and fine aggregate (specific gravity, sieve analysis, and water absorption) as well as the compressive strength of geopolymer concrete were tested, along with the oxide composition. In this study, an experimental laboratory sample test was conducted. M-15, which has a water-to-binder ratio of 0.55, is utilized in the design of geopolymer concrete mixes. To create a concrete sample, 50*50*50 mm cubes of geopolymer concrete with a water/binder ratio of 0.55, a K2SiO3 to KOH ratio of 2.5, and alkaline activator solutions with different KOH concentrations of 4, 6, 8, and 10M are prepared. They are then left for 3, 7, 14, 21, and 28 days before being oven-cured for 24 hours at 1000C. A total of 120 samples were cast in five distinct geopolymer concrete types. and each source material has 60 samples. Three specimens are made for the compressive strength test for each variable. When compared to SDA at a 28-day rest period, the results showed that the geopolymer concrete made with RHA had a greater aluminum-silicate content, indicating an optimal compressive strength. As the KOH concentration rises, the strength of each specimens increases proportionately. Moreover, the RHA-based geopolymer concrete's compressive strength has improved over that of SDA concrete, and the durability of the tested specimens with a 28-day rest period increased as the KOH concentration increased. However, there was a slight increase in the percentage weight gain in all specimens because of the lower absorption quality on its pores. It was noted that RHA less porosity, resistance to absorption, higher alumina-silicate content, the dosage of KOH concentration, and finer properties of source materials with varied concentrations of alkaline activators at 28 days resulted in a percentage change in strength for specimens soaked in H2SO4 and Na2SO4 solutions. These specimens are suitable as structurally intact and retained substantial load capacity in the construction industry. vi