Strength and water penetrability of fly ash geopolymer concrete

Abstract

This paper presents a study on the strength development, water absorption and water permeability of low calcium fly ash geopolymer concrete. Geopolymer mixtures with variations of water/binder ratio, aggregate/binder ratio, aggregate grading, and alkaline/fly ash ratio were investigated. OPC (Ordinary Portland Cement) concrete with the same strength level was used as a control mix. Strength was measured by compressive strength, while water penetrability was evaluated by water absorption and water permeability. In addition, the AVPV (Apparent Volume of Permeable Voids) was measured. The results show that the strength of fly ash geopolymer concrete was increased by reducing the water/binder and aggregate/binder ratios; and the water absorption of low calcium fly ash geopolymer was improved by decreasing the water/binder ratio, increasing the fly ash content, and using a well-graded aggregate. There was no significant change in water permeability coefficient for the geopolymer with different parameters. The test data indicates that a good quality of low calcium fly ash geopolymer concrete can be produced with appropriate parameterisation and mix design.