EFFECTS OF CRACK WIDTHS AND ENVIRONMENTS ON THE BOND STRENGTH BETWEEN CONCRETE AND STEEL BARS

Durability of reinforced concrete (RC) structures in marine environment was impacted by loading damage, concrete mixture, and working environment, etc..The loading damage is mainly expressed as crack widths on RC structure and the working environment is expressed as chloride erosion by wet-dry circles of seawater. The coupling effect of cracking width and chloride corrosion environment on bond response between steel bars and concrete was experimental investigated, where the impact factors, such as crack widths (0.0-0.24mm), type of steel bars (plain or deformed bar) and exposing environments (chloride or atmosphere) were considered. The experimental results show that the bond strength of specimens with deformed bars was about 2 times of that with plain bar; all crack widths remained almost constant in atmospheric environment. In wet-dry circles of seawater, the width of initial crack increased when initial crack width was larger than 0.08mm.There is no clear effect of tendency of crack width and environment on bond strength in our experiments. The chloride concentration decreases from concrete surface to the cover depth.And at the same depth, the chloride content increased as the width of initial crack increased, especial when width of initial crack was 0.24mm, obvious difference of the chloride content appeared from other small width of initial crack.