Influence of elastic modulus on stress redistribution and cracking in repair patches

The paper presents the results of a field investigation of repairs to two highway bridges. The repairs were applied by spraying onto unpropped compression members of the bridges. Two categories of commercial repair materials were used, low stiffness materials relative to the substrate (E-rm < E-sub) and high stiffness materials relative to the substrate (E-rm > E-sub) The repair materials also represented a range of other properties such as strength, density, shrinkage, and creep. The results show that repairs applied with relatively stiff materials, E-rm > E-sub, display efficient structural interaction with the structure. High stiffness repairs are effective in redistributing shrinkage strain to the substrate and attracting external loading in the long term. Low stiffness repair materials (E-rm < E-sub) are much more likely to undergo tensile cracking due to restrained shrinkage. Low stiffness repairs are ineffective in redistributing strain. 2000 (C) Elsevier Science Ltd. All rights reserved.