Mechanical and Fracture Mechanical Properties of Fine Grained Concrete for Textile Reinforced Composites

INTRODUCTION In civil engineering steel reinforced concrete is the most important composite material which is used for structural applications. The combination of a high compressive strength of the concrete and a high tensile strength of the steel reinforcement leads to an appropriate load carrying capacity for many applications in the building industry. A rather new development of a composite material is textile reinforced concrete (TRC), where multi-axial fabrics are used in combination with fine grained concrete. This allows the design of very thin-structured concrete elements with a high strength in compression as well as tension. The use of the technical textiles, mainly made of alkali resistant (AR)-glass and sometimes with other materials like carbon or aramid, which are placed in the main stress direction of the composite, leads to a high effectiveness in comparison to the use of randomly distributed short fibres in the already known glass fibre reinforced concrete (GRC). However, as TRC is an innovative material, detailed information needed for the safe design of TRC load bearing structures is still missing and therefore ambitious investigations in research are carried out. Thus, the collaborative research centre “Textile Reinforced Concrete (TRC) – Technical Basis for the Development of a New Technology” (SFB 532) at RWTH Aachen University [Ban05, Cur03, Heg01, Orl05] sponsored by the “Deutsche Forschungsgemeinschaft (DFG)” has set out to investigate the basic mechanisms regarding durability aspects, bonding characteristics as well as load carrying capacity within guidelines and standards for dimensioning such thinstructured TRC elements. For example U-shaped profiles (Fig. 1.1) are provided of the type that will be produced in a continuous production process within the research project. For this reason, the material properties of the fine grained concrete as a main component of the composite also have to be known as they are implemented in different models supporting analytical and numerical simulations of the TRC structures. These newly developed matrices meet special demands regarding e.g. production processes and chemical stability of the textile reinforcement. As a result they show a finer and more homogeneous structure in comparison with ordinary concrete and hence provide an improved performance with high strengths and enhanced durability characteristics…