Development of patch test to study behaviour of shallow concrete patch repairs

The work reported is concerned with developing an understanding of the behaviour of shallow concrete patch repairs and methods of assessing the bond between cementitious repair materials and a concrete substrate. A new patch repair test specimen is described which may be loaded in a variety of configurations that model typical structural elements containing a patch repair. In particular, the specimen loads the repair material indirectly, as would occur in practice; this is in contrast with other bond tests, such as the slant shear and core pull-off, with which the patch test is compared in a subsequent paper. Two sandkement and two proprietary polymer-modified repair mortars were investigated. Following initial development work on the specimen geometry and failure modes in compression, the effects of surface roughness, moisture condition, repair stifiess and partial debonding were examined. The results conjrmed the sensitivity of the test specimen to changes in bond quality and highlighted the influence of relative material stifiess on patch repair behaviour. There was also good agreement with more complex tests in which the repair was applied to a pre-compressed specimen which was subsequently released to put the repair in tension.