Efficiency Increase of TRC by Using Textile Reinforcements from the Extended Warp Knitting Process

Abstract

In practice, there are different possibilities to strengthen load bearing structures by sensible combinations of different materials. The composite material, textile reinforced concrete (TRC) is an effective and very innovative strengthening method. Due to the increased lateral tensile loading, there exists the danger of an early failure by delamination in end anchorages and overlaps, where loads are transferred to the textile reinforcement. This leads to a reduction in the tensile load bearing capacity of the textile in the entire structural member. The crack formation effects, which depend on loading, are substantially influenced by existing bond between fiber and matrix and by the size of the process-related fiber undulations. An improved textile manufacturing method was developed by the Institute of Textile Machinery and High Performance Material Technology in Dresden, Germany, to increase the efficiency of the textile reinforcement. The so-called needle shift technology in the extended warp knitting process considerably reduces the thread waviness (undulations) compared to the standard textile manufacturing method. The article in hand describes comparative tests of the bond and strength properties using textiles manufactured with the standard and the extended warp knitting process. The new developed textile fabrics did not only increase the tensile strength of the TRC specimens but also significantly reduced cracking. The results show that, with the developments in needle shift, a substantial improvement in TRC is possible.