Comparison of Effects of Alkaline Activator Molarity and Cure Temperature for Geopolymer Synthesized from Alternative Laterite Sources

Abstract

Geological source material remains one of the options for developing countries to participate in deployment of geopolymer material technology for environmental friendly infrastructure development. Geological source materials for geopolymer are heterogeneous in nature. This study sort to investigate and provide information for aggregation of repository comparative information on geopolymer specimen properties of alternative source material and their response to effect of alkaline activator molarity and cure temperatures. Pulverized 750°c calcined laterite obtained from two alternate sources were activated with alkaline activator solution of NaOH of 8M, 10M, and 12M with NaSiO3 and sterile water of ratio 7:3:3 were properly mixed at activator to source material ratio of 0.45. 50×50×50 specimen cubes were cast for density, porosity and comprehensive strength test for specimen cure at 27°c (room temperature), and 50°c and 90°c in oven temperature respectively for 28 days and 72 hours. The study shows that in each geopolymer specimen source material, the density of the specimen decreases with increased cure temperature while specimen porosity increases with increased cure temperature. Increased activator molarity increases the density of the specimen while specimen porosity does not follow a definite trend with activator molarity. Ekiti parapo pavilion laterite based geopolymer specimen has minimum density, porosity and comprehensive strength of 2.15 g/cm³, 5.27% and 1.74 N/mm². Geopolymer specimen based on polytechnic gate source material have density, porosity and compressive strength minimum values of 1.86 g/cm³, 11.46% and 0.58 N/mm2.. Their corresponding maximum values are respectively 2.40 g/cm³, 19.24% and 14.92 N/mm2 for pavilion based geopolymer specimens, 2.33 g/cm³, 26.08% and 6.90 N/mm².