LAUSR

Abstract The composition of the alkali activator was proven to significantly affect the properties of Hongsa fly ash-based geopolymer paste, which, in turn, was found to be beneficial to the product application design. In this research, the composition of the alkali activator was selected by adjusting Na2SiO3/NaOH ratio. The results showed that the compressive strength of the geopolymer paste increased when the ratio of Na2SiO3/NaOH increased and reached its maximum of 26.54 MPa at the ratio of 0.6 before being decreased with further increasing the ratio. The high-temperature resistance of the geopolymers prepared with two conditions, Na2SiO3-free (M-00) and 0.6 Na2SiO3/NaOH ratios (M-06), was assessed. The results showed that the geopolymer M-06 started to deform and crack after heating at ≥ 600°C while the geopolymer M-00 did not show significant deterioration. The geopolymer M-00 could retain its compressive strength much better than the geopolymer M-06, making it suitable as a lightweight high temperature resistant-component in construction. The geopolymer M-06 was marked to provide an excellent low-temperature compressive strength so it can be used as a geocement binding material.