Textile Reinforced Concrete Structures - Bending tests of one-way slabs

Abstract

Textile Reinforced Concrete (TRC) is a promising solution to optimize material use, reduce carbon emissions, and develop new building techniques to reduce the use of finite resources. The possibilities with TRC also include its corrosion-resistance, which prolongs the service life and reduces maintenance needs. In this thesis, experiments on carbon fibre reinforced one-way concrete slabs were carried out, to study the flexural behaviour in four-point bending tests. The aim of this Master’s thesis project was to provide data for further development of modelling methods for TRC and give new insights in the structural behaviour of TRC. Specimens were produced with two manufacturing methods: clamped mesh and wet lay-up. Two different types of carbon fibre meshes, placed in two different orientations, and combined with two types of concrete were studied. Load-and deflection relation, maximum load, crack pattern and crack width were studied. To observe and measure the behaviour, Digital Image Correlation (DIC) was used. Thereby the full strain field, and thus the deformations, crack width and crack propagation were measured in detail. Specimens with type 2 mesh, which was a denser mesh, had a higher load capacity than those with type 1 mesh. The specimens with mesh type 2 also showed a smaller deflection at failure compared to all other specimens, and had a higher stiffness in the cracked stage. Type 1 mesh was tested as both 0° and 45° orientation angle. A brittle failure with rupture of the textile took place in tests with the mesh in 0°, while a slightly more ductile behaviour in form of pull-out of the bundles occurred in tests with the mesh in 45°. The number of cracks in each specimen showed a large variety and better casting quality of the specimen resulted in more cracks. Further, the transverse yarn showed to be a crack initiator for mesh type 1. The utilization factor of the tensile strength of the textile mesh was on average 0.37 for specimens with 0° orientation mesh, while it was only 0.23 for specimens with 45°. The utilization factor is an important design parameter to consider and improve to make TRC-structures more competitive.