Evaluation of Pull-out Behaviour in Textile Reinforced Concrete

Paper in proceeding, 2014

Concrete reinforced with conventional steel is one of the most commonly used building materials, yet it has historically shown disadvantages in terms of durability and vulnerability to corrosion attack. Various remedial methods have been applied to overcome the shortcomings of this building material, such as increasing the concrete cover, which, however, leads to an increased self-weight of the struc-ture. Over the past decade, Textile Reinforced Concrete (TRC), encompassing a combination of fine-grained concrete and non-corrosive multi-axial textile fabrics, has emerged as a promising novel alternative offering corrosion resistance, as well as thinner and light-weight structures such as foot bridges and façade elements. Although TRC has been extensively researched, the formalization of experimental methods and design standards is still in progress. The aim of this paper is to quantify and model the bond behaviour of TRC basalt fibre meshes. The bond between the textile fibre mesh and fine-grained concrete matrix is a critical element influencing the overall performance of this composite material. The yarn structure is rather complex including a multitude of outer and inner filaments; thus inevitably, the constituents of one yarn are unevenly bonded to the concrete matrix. As such, experiments help quantify complex material behaviour which can be further used to develop and calibrate analytical and non-linear finite-element models. The bond behaviour of TRC was characterized through means of direct pull-out tests with unsymmet-rical embedment lengths such that the test specimens were notched at a prescribed breaking point. The test specimens consisted of one-layer of reinforcement mesh, centrally cast, made of basalt fibres. The applied force and average deformation of the test specimen were measured. The evaluation of varying embedment lengths was explored in order to quantify pull-out and textile rupture failure modes. The experimental results were thereafter evaluated using an analytical 1D bond model. Pull-out and rupture failure were observed in the experimental pull-out results. A local bond stress-slip curve was calibrated for the basalt specimens based on the experimental results. Finally, it was observed that the simulation results from the 1D bond model had a reasonable correlation with the experimental results in spite of the complex bond behaviour of TRC.