Q. How are Nycon nylon fibers different from polypropylene fibers?
There are three principle differences between the two fibers:

Nycon nylon fibers have a specific gravity of 1.16, whereas polypropylene fibers have a specific gravity of 0.91. This means that volume displaced and fiber count can be different for the two materials. In general the fiber count for the Nycon RC and MultiMesh are much higher than the polypropylene fibers both monofilament and fibrillated. RC has a fiber count of approximately 34 million =" long fibers in 1.0 pound and MultiMesh has close to 18 million =" long fibers in 1.0 pound.

The tensile strength of nylon is listed at 140,000 pounds per square inch in Table 4.1 of ACI 544.1R. While the tensile strength for polypropylene is listed as 20,000 to 100,000 pounds per square inch in the same table.

The final major difference is that nylon is hydrophilic and polypropylene is hydrophobic. The moisture gain in the nylon, although very slight, has at least one benefit. The benefit is enhanced hydration of the cement particles within the contact zone with the discrete nylon fibers, which would increase the bond between the mortar and nylon fiber. This benefit is evident in the reported reduction of volume change for Nycon nylon reinforced concrete subject to moisture change. This slight moisture gain may also contribute to the excellent finishing properties of Nycon nylon fibers by attracting the mortar to the fiber surface.

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