Bond strength of post-installed high strength deformed rebar in concrete

One of the major aspects of retrofitting or strengthening of existing concrete structures is to install rebars using chemical adhesives. In a view to lighten the disturbance of existing structures by reducing the number of holes, high strength rebars (80 grade; nominal yield strength of 550 MPa) are more preferable for repairing and strengthening structural components. Here, a total of 108 specimens were prepared to evaluate the performance of post-installed high strength deformed rebar (PIHSDR) in concrete using pull-out tests. Test parameters included concrete compressive strength (f(c)' ), rebar diameter, embedment length of rebar into concrete and concrete cover to rebar diameter ratio (c/d(b)) to investigate the bond behaviors of PIHSDR at the epoxy-concrete interface. Bond stress-slip relationships for PIHSDR were obtained, investigated, and hence compared with previous research and available codes. It was observed that most of the specimens showed concrete rapture, splitting, or rebar rapture failure and none of them showed pull-out failure which indicates that the epoxy resins are very much effective as bonding chemicals for retrofitting concrete structures in the steel-concrete interface. Besides, regression analyses were performed using the experimental data to obtain a closed-form equation for predicting the bond strength for PIHSDR. The predicted bond strengths were observed close to the actual test data with a high coefficient of determination (R-2 = 0.99) and very low root mean square error (0.078).