Graded fiber design and concrete reinforced therewith

摘要

Graded fiber additives for addition to proportioned concrete comprising a mixture of fibers having deniers ranging from about 3 to about 5000 and lengths ranging from about 0.0625 to 3 inches (0.16 to 7.6 cm), graded to provide pluralities of different fiber designs comprising variations in at least three of lengths, widths, thicknesses, deniers, fibrillations, cross-sections or aspect ratios, prior to their addition to concrete, or at least two of lengths, widths, thicknesses, deniers, fibrillations or aspect ratios, prior to their addition to concrete, or at least two of widths, thicknesses, deniers, fibrillations, cross- sections or aspect ratios, prior to their addition to the concrete, so as to accommodate the mortar factions within proportioned concrete containing graded aggregate, provide a continuous distribution of fibers therein and thereby inhibit the initiation of cracking. The present invention also provides concrete having improved crack resistance consisting essentially of concrete; and from about 0.025 to 1 percent by volume of a graded, synthetic fiber mixture, having deniers ranging from about 3 to about 5000 and lengths ranging from about 0.0625 to 3 inches (0.16 to 7.6 cm), as described hereinabove, whereby initiation of cracking of the concrete is inhibited as compared to concrete reinforced by the addition of single length fibers. The present invention further provides methods for improving the crack resistance of concrete and for inhibiting the initiation of cracking thereof.