Geometrical characteristics and efficiency of textile fabrics for reinforcing cement composites

One of the most efficient ways to obtain a high performance cementitious co mposite is by reinforcement with continuous fibers. Production of such comp osites can readily be based on the use of textile fabrics, which are impreg nated with cement paste or mortar. The present paper discusses the bulk pro perties and geometrical characteristics of textile fabrics that should be c onsidered in order to predict the performance of cement composites reinforc ed with fabrics. Geometrical characteristics are the nature of the basic re inforcing unit in the fabric (yam) and the various geometries by which thes e yarns are combined together in the fabric (weft insertion warp knitted, s hort weft warp knitted, and woven fabrics). It was found that the geometry of a given fabric could enhance the bonding and enable one to obtain strain hardening behavior from low modulus yam fabrics. On the other hand, variat ions of the geometry in a fabric could drastically reduce the efficiency, r esulting in a reduced strengthening effect of the yams in the fabric relati ve to single yams not in a fabric form. The improved bonding in low modulus yam was found to be mainly the result of the special shape of the yam indu ced by the fabric. Therefore, in cement composites, the fabrics cannot be v iewed simply as a means for holding together continuous yams so that they c an be readily placed in the matrix. (C) 2000 Elsevier Science Ltd. All righ ts reserved.