A Focused Review of Nanomaterial-Enhanced Cement-Based Adhesives for Optimized FRP-to- Concrete Bonding

The ongoing concern about sustainable infrastructure has driven the development of cement-based adhesives (CBAs) for fibre-reinforced polymer (FRP) retrofitting of con-crete structures. Nevertheless, traditional CBAs usually have low bond strength, low crack resistance, and low long-term durability that undermine the performance of FRP-concrete systems. To overcome these shortcomings, this review focuses on the po-tential of nanomaterial-modified CBAs to improve interfacial bonding and mechanical integrity. A systematic literature review assessment was used to analyze recent experimental studies on CBAs with nanosilica, carbon nanotubes, graphene oxide, and other nanomaterials. Their functions in enhancing adhesion, load transfer efficiency, environmental stressor resistance, and the overall structural performance have been emphasized in the review. It also contrasts the performance of neat and nano-modified CBAs in the FRP-based retrofitting systems, highlighting their ad-vantages and shortcomings. Particular emphasis is put on new high-strength self-compacting cementitious adhesives (IHSSC-CAs), which have a high level of me-chanical performance and environmental friendliness in relation to traditional bonding systems. The paper concludes with the identification of research gaps, a discussion of the practical implementation issues, and an explanation of the future perspectives of the next-generation sustainable and resilient concrete retrofitting technologies development.