The Effects of Solid to Liquid Ratio on Fly Ash Based Lightweight Geopolymer

Abstract Geopolymer material was used as the raw material because it promotes the green technology. In this study, lightweight geopolymer was produced using fly ash as raw material with the addition of alkali activation which is mixture of sodium silicate and sodium hydroxide, foaming agent that gives lightweight properties and finally, underwent curing process. The molarity of sodium hydroxide (NaOH) used was fixed at 12 M while the ratio of fly ash to alkali activator (solid to liquid) used were varied in the range of 2.0, 2.5, 3.0 and 3.5, by mass. Besides that, foaming agent (Polyoxyethylene alkyether Sulfate) was added to the geopolymer sample to give the lightweight properties. The samples were cured at 80 °C for 24 hours in the oven for curing process and left at room temperature prior for testing for 14 days. The testing of sample was conducted in this study which includes density test, compression strength test, water absorption test and scanning electron microstructure (SEM) test. The results obtained for optimum solid to liquid ratio is 2.5, by mass with the optimum value of compressive strength density value. The mechanical and physical properties of lightweight geopolymer were based on the ASTM International Standard.