Shear stress transfer at the SRG-concrete interface: influence of the number of layers

Externally bonded SRG (steel reinforced grout) is a promising technique for strengthening existing RC (reinforced concrete) and masonry structures. SRG is a composite material made of high-strength steel fibers embedded in a geopolymeric (inorganic) matrix. The failure of structural members strengthened with SRG composites typically occurs due to debonding when an interfacial crack develops at the fiber-matrix interface. This paper presents the results of single-lap shear tests performed in order to study the debonding phenomenon of SRG composites bonded to a concrete substrate. Specimens with one and two textile layers were tested to assess the dependency of the debonding mechanism and bond capacity on the number of layers. The results of the single-lap-shear tests were then used to derive a local CML (cohesive material law), which describes the interaction between the concrete substrate and the SRG strips.