Detrimental effects of various environmental phenomena such as earthquakes on Reinforced Concrete (RC) structures make repairing, strengthening and rehabilitation necessary to satisfy current code requirements. For achieving compliance and safer structures, many efforts involve attaching composites to damaged or identified damage-prone zones of RC members. In recent years, a type of novel composites, named Fiber Reinforced Cementitious Matrix (FRCM) has been developed which comprises of two internal and external layers of mineral cement based matrix cover, reinforced with one or more layers of fiber. In any newly developed composite, among the first steps for performance evaluation is the investigation into bond characteristics of the various structural elements. In this respect, direct shear tests, owing to their straightforward outputs, are the most aptly utilized kind of tests in order to study behavior of composite bonds. This paper investigates various aspects of FRCM bond performance on concrete blocks in shear tests. A numerical bond - slip relation was developed based on experimental data on FRCM strengthened concrete blocks. The results obtained from the numerical model show good agreement with the experimental results and provide in depth information about stress - slip relation, load responses, width effect as well as slip and strain profiles in FRCM composites.

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