Efficient Adaptive Test Method for Textile Development Length in TRC

Natural resources can be conserved if we carefully maintain the building stock and indeed extend the useful economic life of buildings. One way to achieve this is to enhance load-bearing structures by repair, restoration, or strengthening. Such upgrading often involves applying a strengthening to existing concrete elements. Over the past decade, textile-reinforced concrete (TRC), encompassing a combination of fine-grained concrete and noncorrosive multiaxial textile fabrics, has emerged as a promising novel alternative for strengthening of conventional steel-reinforced concrete (RC) structures, offering enhanced load-bearing capacity with minimal weight and stiffness change. Although TRC has been extensively researched during the last two decades, the formalization of experimental methods and design standards is still in progress. Attempts to design for good load transfer are often hindered by lack of knowledge regarding bond behaviour. For instance, there are neither standard recommendations nor proofs regarding the required development length of textile fibres in TRC for practical applications up to now. The aim of this work was to provide a test specification, which gives a direct result for the development length (required for the anchorage of a reinforcement, also referred to as “anchorage length”) of textile reinforcements in fine-grained concrete—quickly and easily. The aim of this paper was to present the test specification developed in a way that it is useful for the future work of other researchers as well as for construction engineers. Some selected experimental investigations with different textile reinforcements and different bonding properties were performed with the aim of showing the applicability of the proposed adaptive test specification. The results of these tests indicated that conventional AR glass and carbon fabrics without coating required large anchoring lengths. The tests further showed that an additional application of different kinds of coating to textile fabrics greatly increased the reinforcement’s resistance to pullout. This is of special interest for carbon fibres, which have a substantially higher strength than AR glass fibres and different bond behaviour; that is, carbon fibres have, by nature, larger development lengths