A method for upgrading existing nylon fibers comprising the steps of (a) impregnating the existing nylon fibers with a chemical for obtaining impregnated nylon fibers; (b) drawing the impregnated nylon fibers for obtaining drawn nylon fibers; and (c) drying the drawn nylon fibers for obtaining upgraded nylon fibers. An upgraded nylon fiber, derived from an existing nylon fiber by the method. A nylon fiber reinforced hardened cementitious composite comprising a hardened cementitious matrix, the cementitious matrix including staples of textile or non-textile (technical) upgraded nylon fibers. In both cases the fibers are preferably upgraded using the method. A method for manufacturing a nylon fiber reinforced hardened cementitious composite. The method comprising the steps of (a) preparing a mix including a cementitious material, staples of upgraded nylon fibers and/or textile nylon fibers and an activating material (e.g., water) for activating said cementitious material to form a hardened cementitious matrix; (b) placing the mix; and (c) allowing the mix to harden.
The present invention discloses novel fibers for use as secondary reinforcement materials in cementitious composites, which fibers are effective in preventing cracking far better than prior art fibers. Also disclosed are methods of producing the fibers and methods for producing cementitious composite containing the fibers.