Concrete removal techniques: influence on residual cracking and bond strength

The aim of concrete surface preparation prior to repair is to obtain a surface with properties close to that of the bulk concrete. In this paper, the results of an investigation intended to evaluate the mechanical degradation induced by different surface preparation techniques are presented. Optical microscope observations clearly show that more cracking is induced with jack-hammers than with the other investigated techniques and that the cracking density increases with the hammer weight. While more information is needed to evaluate quantitatively the effects of concrete removal operations, it appears from the reported results that techniques such as sandblasting, scarifying and water jetting are preferable, as they clearly leave much less defects in the substrate.