Abstract
•Fibers increase ductility, load carrying capacity, flexural and splitting strengths.•Steel fibers have negative effect on workability and porosity of FA-geopolymers.•Steel fibers decrease compressive strength and permeability of slag-geopolymers.•Long fibers exhibit higher strength, toughness and shrinkage than short ones.•Fibers have negative effect on workability and porosity of blended geopolymers.
Recently, the introduction of steel fibers to geopolymers as a reinforcement has developed and increased owing to the rapid development of geopolymers. Despite geopolymers exhibit potential properties such as low energy consumption and carbon footprint, flame resistance, fire resistance, valuable compressive strength and good durability, they suffer from low flexural and tensile strengths. To solve these problems, steel fibers are added to geopolymers to improve their ductility, toughness, flexural and tensile strengths. The present paper targets to summarize the earlier studies carried out on the influence of steel fibers on the fresh and the hardened properties of the geopolymers. This review confirmed that the incorporations of steel fibers into geopolymers have a positive effect on flexural strength, splitting tensile strength, ductility, modulus of rupture, modulus of elasticity, Poisson’s ratio, toughness, chemical resistance, shrinkage, sorptivity, water absorption, permeability, water penetration depth, load carrying capacity, crack propagation and post-cracking. In addition, in most cases compressive strength increased. On the other hand, they have a negative effect on porosity and workability.