This research was aimed to a present the physical and thermal properties of geopolymer pastes made of fly ash (FA) and bagasse ash (BA) with rice husk ash (RHA) containing at the doses of 0%, 2%, 4%, 6%, 8% and 10% by weight. The sodium hydroxide concentration of 15 molars, sodium silicate per sodium hydroxide by weight ratio of 2.0, the alkaline liquid per binder at the ratio of 0.60 and curing at ambient temperature were used at the to mix all mixtures to gether for 7 and 28 days. The properties analysis of the geopolymer pastes such as compressive strength, bulk density, water absorption, thermal conductivity, thermal diffusivity and thermal capacity were tested. The results were indicated that geopolymer pastes that containing rice husk ash 2% by weight for 28 days of curing gave the maximum compressive strength of 84.42 kg/cm², low water absorption of 1.16 %, low bulk density of 2,065.71 kg/cm³, lower thermal conductivity of 1.1173 W/m.K, lower thermal diffusion of 6.643 µm²/s and lower thermal capacity of 1.6819 MJ/m³K, respectively. The utilization of waste from agriculture industry via geopolymer pastes for green building materials can be achieved. For this research, physical properties and thermal insulation of geopolymer pastes were siqnificantly improved.