SAT FIBER are polypropylene multifilament fibres of high tenacity, length of 19 mm. and 10 m m, with use recommended in concretes and mortars till 7 cm of thickness, like reinforcement of them, used to eliminate cracking due to shrinkage in plastic state. Fibres are treated to improve wetting and dispersion in the paste of cement and on the other side to increase capacity of contact and adhesion between fibres and concrete in hardened solid state.