Assessment of mechanical bond and surface chemistry of commercial and alternatives steel fibers embedded in concretes with varying water-to-cement ratios via pullout testing

This research investigates the influence of steel fiber reinforced concrete (SFRC) mechanical properties when residual domestic water is incorporated, as well as the physical and chemical effects of the steel fibers (SF). The study involves chemical and mechanical concrete characterization, including pullout tests. The experimental analysis utilized alternatives steel fibers (annealed and galvanized) and industrial steel fibers (3D). Specimens were prepared by varying the proportion of treated water mixed with regular water at 0%, 25%, 50%, 75%, and 100%, resulting in 75 samples. The results revealed that none of the fibers outperformed the control samples; an increased concentration of treated water corresponded to a decline in mechanical performance. The steel fiber (SF) that exhibited the most significant reduction in mechanical properties was the annealed steel fiber exposed to 100% treated water. This decline was linked to the concentrations of hardness, phosphates, nitrates, nitrites, sulfates, and chlorides found in the surface sediments of the fibers, analyzed using a YSI 9000 probe. The results indicate that the reduction in mechanical performance is multifactorial, influenced by various chemical species. However, mechanical performance decreases as the treated water increases.