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This paper investigates the effect of corrosion on the bond between reinforcing steel bars and fibre reinforced geopolymer concrete. An accelerated corrosion method was used to corrode the reinforcing steel bars embedded in geopolymer concrete. Three types of steel fibres including straight micro steel fibre, deformed macro steel fibre, and hybrid steel fibre were used in this study. A total of ten geopolymer concrete mixes were used to evaluate the effect of corrosion of steel bar on the bond between steel bar and fibre reinforced geopolymer concrete. The pull-out test specimens were composed of concrete cubes with a side length of 160mm and reinforced with a deformed steel bar of 16 mm diameter located at the centre of the specimens. The test results showed that the addition of steel fibres in geopolymer concrete (fibre reinforced geopolymer concrete) significantly enhanced the bond strength of reinforcing steel bar. The bond strength of reinforcing steel bars embedded in steel fibre reinforced geopolymer concrete specimens reduced due to corrosion of reinforcement. However, the reduction of bond strength in steel fibre reinforced geopolymer concrete specimens was less than the reduction of bond strength in plain geopolymer concrete specimen.

This paper investigates the influence of different types of steel fibers on the engineering properties of ambient cured alkali-activated slag-fly ash concrete. The engineering properties investigated include workability, compressive strength, splitting tensile strength, flexural strength, direct tensile strength, and stress-strain response under axial compression. Three types of steel fibers, i.e., straight micro steel fiber, deformed macro steel fiber and hybrid steel fiber, were added to the alkali-activated slag-fly ash mixes. It was found that the workability of the alkali-activated slag-fly ash concrete mixes decreased with the increase in the volume fraction of steel fibers. It was also found that the compressive strength, splitting tensile strength, flexural strength, and direct tensile strength of alkali-activated slag-fly ash concrete mixes increased with the addition of steel fibers. The stress-strain response of alkali-activated slag-fly ash concrete mixes changed from brittle to ductile by the addition of steel fibers. Significant improvements in the mechanical properties of alkaliactivated slag-fly ash concrete were observed for the addition of 2% by volume of all three types of steel fiber. The addition of hybrid steel fiber (1% straight micro steel fiber plus 1% deformed macro steel fibers) showed the highest improvement in the mechanical properties of ambient cured alkali-activated slag-fly ash concrete.