International Concrete Abstracts Portal

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.

The tensile load carrying behavior under cyclic loading of filaments made of alkali-resistant glass, which is the basic component of the textile reinforcement used for textile reinforced concrete, has been analyzed. Therefore, tensile tests under cyclic loading at four different stress levels were carried out. A damage accumulation, which led in some cases to a failure of the specimens during the cyclic loading, could be observed. This motivated to introduce a strength degradation model. A calibration of the model parameters on the experimental data was performed using an optimization method. A statistical analysis was carried out beforehand, to estimate the initial tensile strengths of the specimens, which were needed for the calibration.

At present there is a rising interest of architects and engineers in the application of textile-reinforced concrete (TRC) as a construction material. Filigree, self-supporting and ventilated façade systems are state of the art in the application of TRC. In current investigations, potentials for lightweight structural members are developed. The required models for a secure design of structural members are deduced within the framework of the research activities in the collaborative research center 532 at RWTH Aachen University [1]. The article outlines fundamental research results as well as their realization in first applications.

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.