Although the bond of a multi-filament yarn in a cementitious matrix is controlled by the bond properties between filaments and matrix, more detailed information is needed to evaluate the failure mechanisms of such a complex system under a pull-out load and hence allow an analytical and numerical simulation of this composite. In this study innovative test methods are presented and used to identify the debonding process of a yarn as a result of the pull-out process, and ascertain the contact faces between the individual filaments and the matrix. Additionally, numerical procedures are proposed based on these findings and allow to establish a direct relationship between the load history of a pull-out test, and the failure process of an AR-glass yarn, by means of a mathematical function, defined as the active filaments versus displacement relation NF(O). Together with the load versus displacement relationship P(O) derived also during the pull-out test an analytical characterization and simulation of the bond between an AR-glass multi-filament yarn and a cement based matrix will be possible.

This paper presents the research activities in the field of textile reinforced concrete carried out by the Institute of Textile and Clothing Technology (ITB) of the Technische Universitaet Dresden, Germany. Extensive research has been conducted with the aim to fully use the tensile strength of the applied high-performance fiber material in the reinforcing textile. To achieve this, the textile machinery was adjusted and improved and new testing methods were developed. This research has resulted so far in several innova-tive applications for the repair of buildings as well as the production of precast concrete members. This paper was originally presented in 2005 Spring ACI Convention, New York under the title "State of the art and perspectives of textile reinforcements of con-crete components."

Cement-based materials are brittle in nature, with high compressive strength and low tensile strength and toughness. Therefore, the use of these materials in practice involves their combination with reinforcement. This article demonstrates possible reinforcing strategies by using textile structures with high strength behavior. Different textile structures are shown as they are used in practical applications more and more. A special focus will be put to the production and design possibilities of 3D-textiles. Although there are two definitions for 3D-textiles, the 3D-structures as well as the 3D-geometries here mainly the 3D-structured spacer fabric are described. A double needle bar raschel machine is the most common machine type for this type of 3D-textile production. Those 3D-textiles allow a defined positioning of the reinforcement as well as a providing of reinforcement in the third dimension. Finally a survey of possible applications for 3D-textile reinforced concrete elements are given.

Textile Reinforced Concrete (TRC) is a composite material taking advantage of the non-corrosiveness of fiber materials such as alkali-resistant glass (AR-glass), carbon or aramid in order to design slender and filigree structural elements. Compared to short cut fibers, a textile reinforcement features a higher effectiveness, because the fiber bundles are arranged in the direction of the main tensile stresses. These properties make TRC a promising construction material opening up new fields of application for concrete. In this paper, the results of experimental investigations and numerical simulations on TRC-components are presented. The load bearing behavior and important properties of TRC are described and the differences between the reinforcement materials AR-glass and carbon are elaborated. These differences are not only due to the different mechanical properties of the two materials but particularly the result of their different bond performance. Design models for the tensile strength and the bending capacity of TRC-components are given which have been derived on basis of the investigations.

Concrete specimens with unidirectional embedded AR-glass rovings were stored in a climatic test chamber at 40 °C (104 °F) and 99 % r.h. After this storage, the bending strengths of the specimens were tested. The uncovered fibers were observed with an Environmental Scanning Electron Microscope (ESEM). The specimens made of the low alkaline matrix and AR-glass rovings showed no strength losses. Whereas, the specimens reinforced with E-glass showed dramatic losses of strength and corrosion of glass fibers. Also, the specimens made of the high alkaline matrix and AR-glass reinforcement showed losses of strength. A corrosion of the fibers could not be detected. Causes for the measured losses of load capacity when using AR-glass reinforcement and Portland cement matrix are the weak points inside the interface fiber-matrix, caused by portlandit crystals. Storage tests in simulated pore solution of 80 °C (176 °F) and pH 13 showed clearly, that glass corrosion cannot start before the protective fiber size is at least partially dissolved. In this case, the VET-AR-glass fibers are of advantage. During the alkaline attack on the unprotected AR-glass surface, the content of zirconium dioxide determines the corrosion resistance for the respective glass. In this case, the NEG-AR fibers are of advantage. The investigations show, that durable fiber concretes and textile reinforced concretes with AR-glass respectively can be produced by optimizing the mixtures. In this respect, the climatic test chamber storage proved to be an accelerated aging test.