A UNIFIED FAILURE ENVELOPE FROM THE EVALUATION OF CONCRETE REPAIR BOND TESTS

This Paper compares the core pull-off and slant-shear tests with the p arch test (developed by the Authors and reported in a previous paper) as methods of evaluating the bond of shallow concrete patch repairs. T he effects of repair material properties, surface roughness and soundn ess, moisture condition and artificial partial debonding on bond perfo rmance are described, with reference to both physical tests and materi al modelling. The pull-off and patch tests were found to be sensitive to surface roughness and soundness and to incomplete bonding. In contr ast, the slant-shear test was found to be insensitive to changes in su rface roughness and soundness, and with rough surfaces was also relati vely insensitive to partial debonding. The bond strength values obtain ed from the two tests are not directly comparable because of the diffe rent stress rates along the repair interface. A bond failure envelope is proposed which enables a meaningful comparison of information from different test methods to be made. Bond failure envelopes are presente d for the two plain sand-cement mortars, which emphasize the superior bond performance of the one with the higher water-cement ratio. Bond f ailure envelopes for the two polymer-modified materials could not be e stablished because bond failure did not occur.