Modeling of the interface between the concrete and the fibers grid in concrete slab

Fiber grid reinforcements are widely used in construction, especially in the rehabilitation of structures; short fibers are also used in concrete. However, reinforcing mortars with textiles (fiber gratings) which offers an improved concrete, and a wide variety of new and exciting architectural forms, is still a relatively new application that shows a need for research. Tests on the use of Glass Fiber Grids (GFG) and Polypropylene Grids (PPG) in the concrete matrix which can be an interesting solution to improve the bearing capacity and change the failure mode of slabs subjected to a load of punching have been realized. The results showed a significant increase in the bearing capacity, a better distribution of the cracks, as well as an improvement of the deflexion before failure; compared to unreinforced reference slabs. In order to understand the behaviour of the concrete-GFG interface of the tested slabs, a modeling of this latter was carried out using a constitutive law expressing the shear stress between the two materials as a function of the relative sliding between the surfaces in contact, taking into account the mechanical characteristics of both materials. The analysis of the bond-slip curve obtained has shown that the use of the glass fiber grid inside the concrete matrix allows a better behaviour of the interface between constituent materials with respect to the glued fiber-reinforced polymer (FRP) plates on the surface of the slab.