Effect of external sulfate attack on the tensile properties of steel-fibre-reinforced sprayed concrete

An investigation into the effects of external sulfate attack (ESA) on the mechanical and microstructural properties of steel fibre-reinforced sprayed concrete (SFRSC) was conducted. Crimped carbon steel fibres, 40 mm long, were used as reinforcement in three different mixtures with specified fibre contents of 30, 60 and 90 kg/m³. Cylindrical specimens, drilled from SFRSC panels, were subjected to sulfate attack for up to 270 days. Double-punch tests were used to determine the matrix crack strength and the post-crack tensile strength of the SFRSC. The effective fibre content of each specimen was determined by inductive tests and subsequently correlated with the mechanical results. Scanning electron microscopy was used to evaluate the phases formed in the concrete pores during the ESA. The results showed that fibre reinforcement may reduce cracking due to ESA.