Improving the bond strength between steel rebar and concrete by increasing the water/cement ratio

The bond strength between steel rebar and concrete was found to increase monotonically with an increasing water/cement ratio from 0.45 to 0.60, while the contact electrical resistivity between rebar and concrete decreased slightly. Both effects are due to the decrease of the interfacial void content, which results from the increase in the fluidity of the concrete mix. An increase in bond strength was also observed when a water-wetted rebar was in place of a dry rebar, although the increase was less than that obtained by increasing the water/cement ratio.