Rheological, mechanical properties, and statistical significance analysis of shotcrete with various natural fibers and mixing ratios

The rheological properties of concrete with natural fibers is studied herein. Natural fibers improve the concrete performance, moreover it covers the similarity between natural fibers and cement matrix. Natural fibers may decrease the pumpability of shotcrete as they reduce workability, which is a critical factor for shotcrete application in construction. The rheological analysis was conducted on 28 specimens, both with and without natural fibers, considering three natural fibers—kenaf, flax, and jute—three fiber lengths—5 mm, 10 mm, and 20 mm—and three mixing weights—0.5 kg, 1.0 kg, and 1.5 kg. The rheological properties of the specimens, such as flow resistance and torque viscosity, were measured using an ICAR rheometer, and correlated with pumpability and shootability. To adequately compare the recorded data, the rheological parameters were converted to Bingham model parameters. Furthermore, the compressive strength, flexural strength, and chloride penetration resistance of the specimens were determined to evaluate their durability. Slump and air content decreased based on the fiber weight and types compared with OPC. Moreover, rheological properties and mechanical properties of the fiber incorporated concrete are analyzed here. Finally, the statistical significance of the fibers was determined through an analysis of variance (ANOVA). Based on the results of the tests determined the optimal combination of fiber parameters that provides the best shotcrete performance.