Effect of Marble Waste Powder and Silica Fume on the Bond Behavior of Corroded Reinforcing Bar Embedded in Concrete

Bond behavior is the mutual effect and the force transmission between concrete and reinforcing bar that directly influence the behavior of reinforced concrete structures. Considering the silica fume (SF) and marble waste powder (MWP) could enhance the concrete matrix and improve its adherence, the bond-slip behavior of corroded reinforcing bar in concrete containing SF and MWP as ordinary portland cement (OPC) is examined in this work. Three of 16 concrete mixes were selected for this investigation: one control mix, a second mix containing 10% SF and 5% MWP as OPC replacements, and the third containing 10% SF and 20% MWP as OPC replacements. The pullout test was applied to the specimens with 0%, 2%, 5%, and 10% corroded reinforcement. According to the results of specimens with uncorroded reinforcement, replacing 10% of cement by SF and 5% or 20% by MWP, the bond strength between concrete and reinforcing bar increased by 27% and 13%, respectively, compared to that of the control specimens. Also, the samples containing SF and MWP showed higher corrosion resistance and their bond strength's loss due to the corrosion of reinforcing bars was less than the control samples. The results also indicate that bond stress at low corrosion (2%) levels is partially increased because of the friction resulting from the accumulation of corrosion products on reinforcement's surface. However, for higher corrosion levels (5% and 10%), the bond strength decreases. By comparing the two diameters of reinforcing bars (12 and 16 mm), it was recognized that the reduction of bond strength due to the corrosion is more severe in the reinforcements with greater diameters.