Shear bond testing of concrete repairs

Good adhesion of a repair material to concrete is of vital importance in th e application and performance of concrete repairs. This paper reviews and c ompares techniques and results of bond strength test methods that induce sh ear, including a tensile slant-shear test. The effect of surface preparatio n (particularly as it affects roughness and soundness) and modulus mismatch between repair and substrate are illustrated by experimental and theoretic al data. While these tests can provide individually useful information on b ond strength and a limited picture of bond characteristics, they can, taken in isolation, result in a misunderstanding of the behaviour of bonded ceme ntitious materials. A more complete appreciation can be obtained by conside ration of a bond failure envelope that encompasses all possible normal/shea r stress states. Such an envelope is presented in the context of Mohr-Coulo mb and Griffith's fracture criteria. (C) 1999 Elsevier Science Ltd. All rig hts reserved.