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

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