Composites under self-compression

Fiber reinforced brittle matrix composites are disclosed with improved mechanical properties. The composites comprise extensible, somewhat elastic fibers and hardened brittle matrix materials. The fibers are positioned to support the composite in a three dimensional manner. Temporary tension forces are applied to some of the fibers before the matrix has completely hardened. The resulting three dimensional array of aligned fibers acts to improve the properties of the composite by providing self-compression. Self-compression is enabled by the alignment and stored elastic energy resulting from the temporary tension and from other deformations acting with the fiber network. The composites have improved response to challenges such as matrix shrinkage during hardening or bending forces and impacts. The invention is particularly useful with brittle, high modulus matrixes, such as cementitious materials and elastic fibers such as polymeric fibers. The composites are useful as structural members and as barriers to protect materials such as steel or fiberglass and articles such as plastic pipes. Selected composites of this invention can exhibit self-healing after having been damaged by destructive deformations.