Abstract

• Geopolymer is a new family of synthetic aluminosilicate materials formed by alkali activation of solidaluminosilicate raw materials. Rice husk ash (RHA) and kaolinite based geopolymer had been prepared from rice husk ash collected from Taungoo Township, Bago region and kaolinite sample from Kyaut Taga, Kyauk Padaung Township, Mandalay Region. The physicochemical properties (moisture content, weight loss on ignition, pH, specific gravity and pozzolanic reactivity ) of rice husk ash and kaolinite were determined and these samples were characterized by conventional and modern spectroscopic method (XRD, EDXRF, SEM ). Moisture content, weight loss-on-ignition, pH, specific gravity of rice husk ash and kaolinite were found to be 1.9% and 4.6%, 2.6% and 12.3%, 8.8 and 8.3 and 1.87 and 2.82 respectively. The chemical analysis (SiO2, Al2O3, CaO, MgO) was also carried out. It was found that the samples were silica – alumina rich compound. The pozzolanic reactivity of rice husk ash and kaolinite were ranged from 64 % to 94 %. The optimum condition of sodium hydroxide concentration and the ratio of sodium hydroxide and sodium silicate which were used in the preparation of geopolymer have been determined. The physical properties such as apparent porosity, water absorption, apparent density and the mechanical properties such as compressive strength of RHA and kaolinite based geopolymer (GP) were also determined. The apparent porosity and water absorption were ranged from 10.48% to 25.92 % and 5.3% to 16.93 %, respectively. The apparent density values of geopolymer were ranged from 0.52 to 1.89 g/cm3.The blended cements were prepared by various mixing ratios of GP : commercial cement,(1:1, 2:1,1:2). Compressive strengths of the prepared GP and blended cements at different time intervals have been determined. For all types of cements the maximum compressive strengths were achieved at 28 days after mixing. The optimum ratio of alkali solution was found to be 2:3 volume ratio of 8 M NaOH and Na2SiO3.