Concrete reinforced with irradiated nylon fibers

Polymeric fibers have been used since the 1980s for improvement of the concrete. However, high mechanical performance has been obtained at high cost and using complex technologies. At least two parameters are important here: dimensions and surface characteristics of the fibers. We have modified nylon 6,12 fiber surfaces by 5, 10, 50, and 100 kGy gamma irradiation dosages. Tensile strength of the irradiated fibers was determined and then the fibers mixed at 1.5%, 2.0%, and 2.5% in volume with Portland cement, gravel, sand, and water. The compressive strength of the fiber reinforced concrete (FRC) was evaluated and the results were compared with results for similar materials reported before. The highest values of the compressive strength of FRC are seen for fibers at 50 kGy and 2.0% in volume of fiber; the strength is 122.2 MPa, as compared to 35 MPa for simple concrete without fibers. We advance a mechanism by which the fiber structure can be affected by gamma irradiation resulting in the compressive strength improvement of the concrete.