Polyester Though not as widely used as polypropylene fibers, polyester fibers are offered by several manufacturers. The fiber bundles come only in mono filament form in lengths from 0.75 to 2 inches.
Nylon Like poly-ester fibers, nylon fibers come only in mono filament form. What primarily distinguishes them from polypropylene and polyester fibers is their hydrophilic nature. Nylon fiber manufacturers also report that their fibres have higher aspect ratios (ratio of length to diameter) than those made of polypropylene. Therefore, they can be added in smaller dosages to produce the same reinforcing effects. Usually no more than 1 pound per cubic yard is needed.
Mixing Fibers can be added with the coarse and fine aggregate at the batch plant or to the central or truck mixer at the jobsite. If adding the fibers with other mix ingredients, no extra mixing time is needed. If adding the fibers to mixed concrete, agitate the concrete an additional 3 to 7 to disperse the fibers thoroughly.
II. Mechanical Properties of fiber
2.1 COMPRESSION The presence of fibers may alter the failure mode of cylinders, but the fiber effect will be minor on the improvement of compressive strength values (0 to 15 %).
STEEL FIBER The presence of fibers may alter the failure mode of concrete, but the fibers effect will be minor on the improvement of compressive strength values (0 to 15 percent).
The strain of SFRC corresponding to peak compressive strength increases as the volume fraction of fibers increases. As aspect ratio increases, the compressive strength of SFRC also increases marginally.
As the load increases, the deflection also increases. However the area under the load–deflection curve also increases substantially depending on the type and amount of fibers added.