Effect of fly ash replacement level on the bond strength of reinforcing steel in concrete beams

This study compares the bond strength of reinforcing steel in high-volume fly ash concrete (HVFAC) mixes. Three mixes with 0% (conventional concrete), 50%, and 70% replacement of Portland cement with a Class C fly ash investigated in this study. Three beams (simply supported four-point loading condition) as well as three pull-out specimens (based on RILEM recommendations) were tested for each mix. Test results evaluated based on different codes as well as a bond database of conventional concrete specimens. These comparisons indicate that with increasing replacement level of fly ash in concrete the bond strength of reinforcing steel in concrete increases. s of this study show that the increase in basic mechanical properties (splitting tensile strength, flexural strength, and fracture energy) for the HVFAC parallels the increase in full-scale bond behavior and can be used as a predictor in mixes containing fly ash.