In-Situ Polymer Coating of Open Grid Warp Knitted Fabrics for Textile Reinforced Concrete Application

This article presents the research work done in the framework of the Collaborative Research Centre — Textile Reinforcement for Structural Strengthening and Retrofitting. Previous results of textile reinforced concrete (TRC) have shown that the mechanical properties of the applied open grid warp knitted fabrics made of alkali-resistant glass filament yarns or carbon filament yarns as reinforcement material have not been utilized to complete satisfaction in the composition with the mineral matrix system. Further we have noticed that the orientation and configuration of the reinforcing fiber material is quite influenced by the handling in the further processing steps, which leads to the need of a sustainable structural stabilization.Different technologies for a subsequent structural stabilization e.g., dip-or spray coating with water-based polymer dispersions, thermal bonding, and laminating have been investigated. The results of these preliminary investigations have been published [2] and in consequence a suitable technology for a structural strengthening process has been selected. The structural strengthening of open grid warp knitted fabrics by means of an in-situ polymer coating process, which is completely integrated, as a modular line concept, into a multi-axial warp knitting machine from Karl Mayer Malimo increases the utilization of mechanical performance in TRC applications. Further the developed structural strengthening process improves the handling properties of the textile fabric. The modular line concept consisting of coating and drying moduless will be described. The influence of process and structure parameters to the mechanical properties of polymer-modified textile fabrics will be explained and sets the basis for the development and manufacturing of textile fabrics with structural properties adjusted to the requirements of the intended application. The effect of polymer-modified fabrics to the load bearing capacity of TRC will be discussed. To demonstrate the application potential of the developed composite material the TRC has been applied to reinforce a hypar shell structure of a campus building at the University of Applied Sciences in Schweinfurt, Germany.