5 th World Textile Conference AUTEX 2005 27-29 June 2005, Portorož, Slovenia BRAIDED FIBRE REINFORCED COMPOSITE RODS FOR CONCRETE REINFORCEMENT R. Fangueiro 1 , G. Sousa 1 , F. Soutinho 1 , S. Jalali 2 and M. de Araújo 1 1 Department of Textile Engineering, University of Minho 2 Department of Civil Engineering, University of Minho Abstract This paper describes the work that is being done at the University of Minho concerning the development of braided rods for concrete reinforcement. A preliminary research study has been conducted to understand the mechanical behaviour of braided fabrics. Various samples have been produced varying the type of fiber (glass, polyester and aramid), the type of braided fabric (simple, hybrid and core reinforced) and in the latter case, the number of core reinforcing yarns. The tensile properties of these samples have been evaluated and the results presented. The influence of each factor on the tensile properties of braided fabrics has also been analysed and discussed. In order to produce braided reinforced composite rods to use as a concrete reinforcement, a special technique has been developed using a standard vertical braiding machine. The braided reinforced composite materials have been produced in a ribbed structure to improve adhesion between them and the concrete. Special samples have been prepared and tested to evaluate the adherence between both materials involved. The tensile and bending properties of braided reinforced composite rods have been evaluated and the results obtained presented and discussed. Key Words Concrete, braided fabrics, composite, reinforcement 1. INTRODUCTION Concrete structures are subjected to repeated loading and to aggressive environmental agents which may lead to poor mechanical and durability performance of the structures with time. One of the most serious problems affecting concrete is corrosion of the steel reinforcement. As shown in Fig.1 corrosion may occur due to reaction of lime present in hydrated cement with carbon dioxide or to the action of chlorides. In the first case, the lime reaction with the carbon dioxide present in the atmosphere leads to a gradual decrease in concrete alkalinity. When the pH of the concrete cover is lower than 9 the compact oxide layer that protects the steel is destroyed, thus leading to the formation of electrochemical reactions which are responsible for the corrosion of the steel. The chloride ion attack is due mainly to migration of chlorides ions present in the vicinity of the structure. It is accepted that when the chloride ions reach a given critical amount the potential for steel corrosion increases significantly. This fact is particularly hazardous in marine or structures in contact with de-icing salts. Figure 1 – Corrosion of steel armours The braiding technique is probably the most ancient production process for textile structures. Normally used for ropes and cables, braided fabrics are also very interesting for composite reinforcements due to their characteristics: in-plane multiaxial orientation, conformability, excellent damage tolerance and