Bond behavior of steel and GFRP bars in self-compacting concrete

• Investigation of bond behavior of GFRP bars in SCC.
• Comparison of bond behavior of GFRP bars with Steel ones in SCC.
• Variations of bond strength of GFRP bars in vertical and horizontal SCC specimens.
• Comparison of bond behavior of GFRP bars with Steel ones in vertical and horizontal SCC specimens.
• Comparison of available codes and equations regarding to the prediction of bond strength.

The bond behavior of steel and GFRP bars in concrete is one of the most important issues in reinforced concrete structures and depends on several factors, such as the structural characteristics, bar and concrete properties. Self-compacting concrete (SCC) is a highly flowable, non-segregation concrete that spreads into place, fills formwork, and moves between even the most congested reinforcement, all without any mechanical vibration. In order to investigate the effect of bleeding, statistical and dynamical segregation on the bond behavior of steel and GFRP bars in SCC, two types of vertical and horizontal concrete elements with four bars located at different positions were built and the bond behaviors of the above mentioned bars in two types of SCC were investigated and compared with that of normal concrete (NC).The results revealed that regarding the suitable adhesion treatment of steel bars, their bond behavior is higher than that of GFRP bars in SCC. The drop in bond strength of steel bars at the top of vertical elements averages 5.49% less in SCC than in NC and 8.06% in the case of GFRP bars. Also, for both SCC and NC, reducing the water to cement ratio and using high powdery materials decreases the bond strength variations in horizontal and vertical elements. However, the bond strength variations of steel bars are less than that of GFRP bars.