Epoxy Coated Seven-Wire Strand for Prestressed Concrete

Abstract

W hen a ruling by the Federal Highway Administration early in 1981 banned the use of uncoated strand in certain prestressed concrete members because of a lack of effective corrosion resistance, Florida Wire & Cable Company began a program for the development of a corrosion resistant strand. As a first step, samples of strand were submitted for coating to a number of plants already engaged in coating reinforcing bars. Examination of the resultant coatings showed that none of the bar coating procedures provided or could be altered to provide a satisfactory coating on strands. The coatings were not sufficiently ductile to meet bending and stretching of a strand, or they did not bridge the gap between the outer wires, or the coating process impaired some of the desired properties of the high strength cold-worked wires of the strand. After numerous trials and rejections of coatings that did not have all of the required properties or that impaired the properties of the strand during application, an ideal coating and coating procedure were developed. Coated strand of all sizes from % in. through 0.60 in. (9.5 through 15.2 mm) diameter is now available on a production basis. Coated wire is also available. Fig. 1 is a photograph of a 1/2 in. (12.7 mm) diameter strand which has been cut with a carborundum disc. The coating