| 摘要 |
Fiber additives for addition to proportioned concrete comprise a plurality of thermoplastic fibers having a profile geometry defined by equation (I), wherein the amplitude a0 falls within a range of from about 0.1 d f to 2.0 d f and the period .lambda. falls within a range of fro m about 2 d f to 15 d f for fibers having a diameter d f of from about 0.5 to about 1 mm; the peak pull-out stress .sigma.peak and the specific pull-out energy absorbed to a maximal displacement of 7.5 mm .PSI.peak, both increase linearly with a deformity factor defined by equation (II), where .alpha. = 0.8 and .beta. = -1, such that the peak pull-out stress is defined by equation (III), and the specific pull-out energy is defined by equation (IV), the fiber additives having an optimum deformity D optimum ~ (0.5 to 1)D critical, D critical being that deformity where the ultimate tensile strength of the fiber equals k1 D critical + C, and where loads are measured in N; energy in N-mm; length dimensions are in mm, and the values of k1, k2, C and C1 are determined based upon the ultimate tensile strength of the fiber and by plotting deformation versus pull-out stress to obtain the value for D critical. The present invention also provides concrete having improved crack resistance and a method for improving the bondslip performance of fibers in concrete utilizing the sinusoidally configured fibers of the present invention. |
