Investigations on the Bond Strength of Non-metallic, Textile Reinforcements in Concrete Components

Knowledge of the bond behaviour of reinforcing elements in concrete structures is crucial, as it has a particular influence on the load-bearing behaviour of components. Realistic mathematical modelling is therefore important in order to be able to make statements about, for example, deformations, cracking or anchoring. For reinforced concrete, this has been studied and described in detail, so that today’s design can be calculated with the sufficiently accurate, simple assumption of a constant, average bond stress as a function of the concrete tensile strength. For concrete with non-metallic reinforcement, such a formulation has yet to be derived. The large number of different types of reinforcing fibers and their impregnation, together with the desired slender design, result in different bond load mechanisms to be considered. This paper presents investigations on the characterization of the local bond behaviour of non-metallic, textile reinforcing elements. The derivation of a material-specific parameter is investigated by means of tests on the composite material and with digital image correlation (DIC) and distributed fiber optic measurement (dFOS). In the still valid mechanical idealizations of the bond behaviour, their applicability is investigated.