The mechanical properties of fly ash geopolymer in long term performance

This paper gives an insight of using high Si content of fly ash as cement replacement material for geopolymer concrete. The paper reports on experimental work that has been carried out to identify the long term performance of the mechanical properties of fly ash geopolymer (FAG) concrete. The FAG was prepared using a low calcium class F fly ash activated by high concentration alkali solution. The fly ash used had high silicate (Si) content. The properties of FAG were assessed using compressive strength, modulus of elasticity and modulus of rupture indirect tensile strength tests up to the age of 540 days. The results showed that the short term performance of FAG was lower compared to traditional concrete. However, the FAG developed comparable mechanical properties at a later age demonstrating that the properties of FAG were improving with time. The observed results are attributed to the high content of silicate in the fly ash used.