Textile Reinforced Concrete for free-form concrete elements: Influence of the binding type of textile reinforcements on the drapability for manufacturing double-curved concrete elements

Abstract

Textile reinforced concrete (TRC) is a sustainable composite material consisting of a cementitious based matrix in combination with an open meshed technical textile reinforcement made of carbon or glass fibres. In the future, TRC could be increasingly used in the form of double-curved concrete elements with the aim of producing filigree yet load-bearing concrete shell structures. To assess whether a textile is suitable as a reinforcement structure in double-curved textile concrete elements, numerous properties need to be investigated and evaluated. The most important of these include good handling properties, bending stiffness tailored to the application, sufficiently pronounced mesh openings, and defect-free drapability. In the course of this work, biaxially reinforced knitted fabrics with five different stitch types (pillar open, pillar closed, tricot counterlaid, tricot closed and plain) were investigated to evaluate the above properties. The draping tests were conducted on a robot-controlled draping test apparatus and evaluated with the aid of an optical measuring system. In addition, the geometric relationship between surface curvature of the double curved elements and the shear angle of different textiles was used to classify the influence of the stitch type on the drapability. Finally, for a given double curved geometry, based on the results the selection of an appropriate textile reinforcement which fulfil the component requirements is carried out and a double curved TRC demonstrator element is prefabricated.