The first practical application of the innovative strengthening method using textile reinforced concrete was carried out in October/November 2006 in the retrofit of a reinforced-concrete roof shell structure at the Univer-sity of Applied Sciences in Schweinfurt, Germany. Since textilereinforced concrete had not yet been standardized as a construction material, a single “special-case” technical approval was sought from and granted by the appropriate authorities for this particular application of textile reinforced concrete. This strengthening method entailed the layer-by-layer application of three layers of fine-grained concrete and textile fabric comprising 800 tex carbon rovings onto a rough, sandblasted concrete surface. The resulting strengthening layer has a thickness of only 15 mm (0.6 in.) and extended the roof structure’s service life.

The use of technical textiles to reinforce concrete (i.e., textile reinforced concrete [TRC]) extends into entirely new areas of application. The thick concrete covers, as required for steel reinforced concrete, are no longer needed due to the corrosion resistance of textile materials. Slender structural members with thicknesses as small as 10 mm (appr. 4 in.) are possible. Additional characteristic features of textile reinforcement include two-dimensional planar characteristics, as well as ease of deformability and adaptability to complex and curved geometries. This can be exemplified by a pedestrian bridge built of TRC [1, 2, 3]. Various geometric forms, such as slabs, beams, T-beams, shells, and columns can easily be strengthened using TRC [4, 5]. Dimensioning of elements and structures using TRC requires detailed knowledge of the load-bearing behavior of this composite material. Indeed, such behavior resembles that of steel reinforced concrete; however, this behavior is more heavily influenced by the bond between the textile reinforcement and the fine concrete, as well as the bond between filaments within the textile reinforcement [6]. Minimal thicknesses also make it possible to strengthen existing concrete structures using TRC. Such strengthening increases both the ultimate load bearing capacity, as well as the serviceability, of the structure. Experimental results of strengthened slabs and beams, as well as a design model for flexural strengthening, is presented in this paper.

Nowadays, thin-walled load bearing structures can be realized using textile-reinforced concrete (Brameshuber and RILEM TC 201-TRC, 2006). The required tensile strength is achieved by embedding several layers of textile. By means of the laminating technique the number of textile layers that can be included into the concrete could be increased. To further increase the first crack strength and the ductility and to optimize the crack development, fine-grained concrete mixtures with short fibers can be used. By simultaneously using different types of short fibers, the positive properties of each fiber may be combined. By a schematic stress-strain curve, the demands on short-fiber mixtures are defined. Within the scope of this study, short fibers made of glass, carbon, aramid, and polyvinyl alcohol are investigated in terms of their ability to fit these requirements. Furthermore, examinations to determine the fiber types and fiber volumes are presented. Finally, two hybrid fiber-reinforced concretes are introduced. On the basis of stress-strain curves of textile-reinforced concrete, the advantages of these fiber mixtures are discussed.

Textile-reinforced concrete (TRC) is a composite material made of open-meshed textile structures and a fine-grained concrete. The application of TRC leads to the design of filigree and lightweight concrete structures with high durability and high quality surfaces. In recent years, TRC has become an attractive choice for the production of ventilated façade systems. To attain the goal of a lightweight façade with large spans and without bracing stud-frame-systems, sandwich panels with two thin TRC-facings and a core of rigid polyurethane foam have been developed at RWTH Aachen University. Within a compact section, this slender building envelope provides a capable load-bearing behavior, superior heat insulation and fire resistance as well as a sufficient sound insulation. In the paper, the investigated production methods, the test results of sandwich members loaded by bending and shear forces, tests on sound insulation and fire resistance, as well as the deduced calculation models are presented.

Many regions in Germany show a rising groundwater level. Hence, the load case of buildings concerned changes from non-pressing to pressing water. Residential buildings not designed for the load case of pressing water have to be refitted. Conventional sealing methods are often associated with high complexity and high costs as well as the loss of living space. Furthermore, in many cases, they do not consider the additional static load of pressing water at all. This paper presents a newly developed, subsequently applied sealing against pressing water. It is made of textile-reinforced concrete. Using this composite material, it is possible to produce a sealing system with a wall thickness of about 30 to 35 mm (1.18 to 1.38 in.). During the production of an exhibit wall, it became apparent that the spraying technique is an adequate and practicable method to produce a subsequent sealing of textile reinforced concrete. Initial observations of the wall subjected to hydrostatic pressure reveal the application potential of this construction.