Engineering Properties of Ambient Cured Alkali-Activated Fly Ash–Slag Concrete Reinforced with Different Types of Steel Fiber

Abstract

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 alkali-activated 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.