Plastic fibers for improved concrete
A monofilament plastic fiber useful in reducing plastic shrinkage cracking of concrete articles has been discovered. The fiber has a core that is a polyolefin that is at least partially enveloped by a sheath that is a copolymer of an olefin and at least one olefinically unsaturated comonomer selected from the group consisting of an unsaturated carboxylic acid, alkyl acrylate, alkyl methacrylate and vinyl ester.
1. A concrete article comprised of concrete having therein a monofilament reinforcing fiber comprised of a core that is a polyolefin, that is at least partially enveloped by a sheath, that is a copolymer of an olefin and at least one olefinically unsaturated comonomer selected from an unsaturated carboxylic acid, alkyl acrylate, alkyl methacrylate and vinyl ester wherein the fiber has a denier of at most 12.
2. The concrete article of claim 1 wherein the fiber is present in the article in an amount of 0.01 to 0.2 percent by volume.
3. The concrete article of claim 2 the polyolefin is polypropylene and the olefin is ethylene and the comonomer is acrylic acid.
4. The concrete article of claim 3 wherein the copolymer has at least 0.1 percent to at most 50 percent by weight of acrylic acid.
5. The concrete article of claim 3 wherein the fiber has a denier of at least 0.1.
6. The concrete article of claim) 5 wherein the denier is at most about 8.
7. The concrete article of claim 6 wherein the denier is at least 1.
8. The concrete article of claim 1 wherein the olefin is ethylene and the copolymer has at least 0.1 percent to at most 50 percent by weight of the olefinically unsaturated comonomer.