Bond strength of corroded reinforced recycled aggregate concrete with treated wastewater and fly ash

This study investigates the bond strength of steel-to-concrete of 36 cubical pull-out specimens with a side length of 200 mm. The specimens were produced with treated wastewater (TWW), recycled concrete aggregates (RCA), and fly ash (FA) and subjected to corrosion. Potable water and natural coarse aggregates were entirely replaced by TWW and RCA, respectively, whereas FA partially replaced cement by 20%. Three target corrosion levels (CL) were evaluated (0%, 2%, and 10%). Experimental results revealed that TWW and RCA reduced the bond strength of concrete by 30% and 18%, respectively, whereas 20% FA enhanced the bond strength by 10%. In the view of corrosion effect, it was observed that a slight CL of 3.56% or less can improve the bond strength of concrete. In addition, TWW and RCA concrete specimens with a 10% target CL had a 36% and 46% reduction in bond strength compared to their respective non-corroded specimens, respectively. Nonetheless, corroded specimens with FA recorded a drop of only 3% in the bond strength. Furthermore, the specimens' bond strength was analytically predicted using the available analytical formulations. The models of Seara-Paz et al., Chung et al., and Yalciner et al. provided the most accurate prediction for uncorroded, 2% CL, and 10% CL specimens, respectively.