Fatigue performance of NSM CFRP strips embedded in concrete using innovative high-strength self-compacting cementitious adhesive (IHSSC-CA) made with graphene oxide

The efficiency of strengthening reinforced concrete (RC) structures using the near-surface mounted (NSM) fibre reinforced polymer (FRP) technique depends on the bond between the NSM FRP and the concrete substrate. This paper presents the results of an experimental study of NSM carbon FRP strips bonded to concrete substrate with innovative high-strength self-compacting cementitious adhesive (IHSSC-CA) under fatigue loading using single-lap shear tests. Graphene oxide and cementitious materials were used to synthesise the IHSSC-CA. The test variables were: CFRP strip dimensions (1.4 × 10 mm, 1.4 × 20 mm) and CFRP strip surface conditions (smooth, rough). 61 specimens were tested under different fatigue load ranges to develop the load range (LR)-fatigue life (N) relationships. Finally, equations were developed to predict fatigue lives based on the experimental results. It was found that the rough surface CFRP strips 1.4 × 20 mm in dimensions showed the best fatigue life under different fatigue load levels. Moreover, the test results confirm the effectiveness of using IHSSC-CA to bond NSM CFRP strips to the concrete substrate. Furthermore, the proposed equations can predict fatigue life reasonably well and can be used in the design of NSM CFRP-strengthened RC members.