Geometrical characteristics and efficiency of textile fabrics for reinforcing cement composites

One of the most efficient ways to obtain a high performance cementitious composite is by reinforcement with continuous fibers. Production of such composites can readily be based on the use of textile fabrics, which are impregnated with cement paste or mortar. The present paper discusses the bulk properties and geometrical characteristics of textile fabrics that should be considered in order to predict the performance of cement composites reinforced with fabrics. Geometrical characteristics are the nature of the basic reinforcing unit in the fabric (yam) and the various geometries by which these yarns are combined together in the fabric (weft insertion warp knitted, short 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, variations of the geometry in a fabric could drastically reduce the efficiency, resulting in a reduced strengthening effect of the yams in the fabric relative 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 induced by the fabric. Therefore, in cement composites, the fabrics cannot be viewed simply as a means for holding together continuous yams so that they can be readily placed in the matrix. (C) 2000 Elsevier Science Ltd. All rights reserved.