Abstract:
This paper presents a study on water penetrability properties, namely water absorption,
volume of permeable voids, permeability and sorptivity of low calcium fly ash geopolymer
concrete. In this research, geopolymer concrete is made from fly ash with a combination of
sodium hydroxide and sodium silicate as alkaline activator. Seven mixes were cast in
100x200mm cylinders and cured for 24 hours at 600C in the steam curing chamber. After 28
days, the cylinders were cut into slices for permeability, sorptivity and volume of permeable
voids tests. In addition, a microstructure characteristic of geopolymer concrete was studied
using Scanning Electron Microscopy (SEM). Results indicate that geopolymer concrete has
low water absorption, volume of permeable voids and sorptivity. It is found that the
geopolymer concrete could be classified as a concrete with an average quality according to
water permeability value. Moreover, a low water/binder ratio and a well-graded aggregate
are some important factors to achieve low water penetrability of geopolymer concrete.
