Polymer Fiber, Its Use And Process For Its Manufacture

A process for improving the fire resistance of concrete, mortar, plaster, cement or refractory material comprising incorporating a polymer fiber as an additive in the concrete, mortar, plaster, cement or refractory material,

• wherein the polymer fiber is obtained by melt-spinning of a polymer and subsequent treatment of the fiber with ionizing radiation, wherein the polymer is a polypropylene homopolymer, a polypropylene copolymer or a mixture thereof, the polymer fiber has a length in the range of 0.1 to 40 mm, a diameter in the range of about 12 μm to about 170 μm and an MFI of more than 500 g/10 min, measured according to DIN EN ISO 1133.