This paper reports the results of an experimental work conducted to investigate the correlation between thermal insulation properties with compressive strength and density of lightweight geopolymer prepared by using fly ash as source material and combination of sodium hydroxide and sodium silicate as alkaline activator. The experiments were conducted by varying the ageing time of 3, 7, 28, 60 and 90 days, respectively. The specimens cured for a period of 90 days have presented the highest compressive strength and lowest density accompanied with satisfied value of thermal conductivity. From the results obtained, it was evident that the thermal conductivity had a high correlation coefficient with compressive strength and density.
