Influence of Material Stiffness on Bond Behaviour for CFRP and BFRP Strips Glued to Concrete Surface

In the last years, the development of fibre reinforced polymers poses new challenges in the creation of new construction and in retrofitting of old buildings and in some cases also bridges. Advanced solutions for refurbishment and strengthening should be an alternative to demolishing old structures and building new ones. One of the established retrofitting methods is the system with carbon fibre reinforced polymer (CFRP) strips. New and innovative materials like basalt fibre reinforced polymer (BFRP) strips can replace well-known CFRP. So far more extensively analysed are the mechanical properties of composites materials like tensile strength, modulus of elasticity and fracture point. Till yet unexplored field of BFRP strips is the bond stress-slip relationship on the concrete surface. This unexplored field is necessary for the calculation of external reinforcement in concrete elements. The aim of this article is to investigate the force transfer between the concrete member and BFRP strips. The intermediate crack element specimens were carried out. The experimental part serves to determine the bond stress–slip relationship of BFRP glued to concrete. In this paper, the effect of material stiffness on the load-bearing behaviour of reinforced concrete structures strengthened with BFRP strips will be considered.