Bond strength of epoxy-coated bars in underwater concrete

A comprehensive research project was carried out to assess the effect of washout loss on bond between underwater concrete (UWC) and epoxy-coated reinforcing steel. Washout loss of investigated mixtures was evaluated using the CRD C61 test method. The compressive and bond strengths of UWC were determined using the same concrete samples that were used for washout loss measurement.Test results showed that the ultimate bond strengths of epoxy-coated bars embedded in UWC are affected by the level of washout loss. Compared to reference concrete sampled in dry condition, a decrease in bond varying from 15% to 25% was measured for UWC possessing washout loss in the range of 8% ± 3%. The bond stress vs. slip behavior of epoxy-coated bars is remarkably different than the one obtained using reference concrete. Mixtures subjected to some washout exhibited less stiffness together with a decrease in the ultimate bond strength and shifting of the slip towards lower values.

► Effect of washout loss on bond behavior between UWC and epoxy-coated reinforcing steel.
► Estimation of development and splice lengths of bars embedded in underwater structures.
► Correlations between washout loss of UWC and corresponding pullout bond strength.