Failure due to delamination in concrete elements strengthened with cementitious composites

Failure due to delamination of fibre reinforced polymer (FRP) composites has been studied in a number of experimental investigations (see for e.g.[1]), with the aim of understanding its influence on structural behaviour at the ultimate limit state when applied as strengthening of reinforced concrete elements. Some studies have resulted in the first design guidelines for reinforced concrete structures strengthened with externally bonded FRP. American ACI 440-08 [2], European fib-T.G. 9.3 [3] and Italian Recommendations CNR DT-200/04 [4] are examples of such guidelines. On the other hand very few information is available on bond behaviour between concrete and cementitious composite reinforcement particularly in relation to specific design code formulations. In this work an experimental study aimed at giving some insights on failure modes due to delamination in concrete elements strengthened with cementitious composites is presented. According to the results of this study, some elements about the estimation of the maximum bearing capacity of structural elements strengthened by means of composites with cementitious matrix can be obtained.