Modified cement-based adhesive for near-surface mounted CFRP strengthening system

The near-surface mounted (NSM) strengthening system has emerged as a promising technology to increase the strength of concrete for flexure, shear and torsion. Strengthening by this technique has been applied to a large number of concrete structures worldwide using epoxy adhesives. Due to the rapid deterioration of the mechanical properties of epoxy-based polymer matrix with elevated temperature, and the hazards from toxic fumes, replacing this polymer with a new cement-based bonding agent is essential to enhance the performance of structures in high-temperature environments and reduce the environmental and health hazards. The application of cement-based adhesive has been studied for externally-bonded techniques using CFRP textile. Although, the good bond properties has been achieved, debonding was the critical failure between fiber and concrete substrate. To exploit the advantages of NSM technique, a new modification of cement-based adhesive has been achieved to meet the requirements of NSM application system. To assess the efficiency of this adhesive, an experimental investigation of pull-out testing using a single-lap shear test set-up was conducted to study the bond characteristics between CFRP textile and concret. Four different mixes were used in this investigation. The test results show the efficiency of the NSM technique using modified cement adhesive and its superior bond properties compared to externally-bonded CFRP.