The development of PC Strands and Prestressed steel products anchorage systems

Prestressed steel products has made great progress since 1950s of the last century, there are two main points in its development trajectory. First, the strength of the material gradually increases, so that reduced the size and weight of prestressed components,even decreased the project cost ; Second, on the basis of improving strength, we should pay attention to the development of materials with high anti-corrosion performance, so as to improve the durability of prestressed steel components and save the maintenance costs.

As far as high-strength and low-relaxation steel strands are concerned, their development process is roughly divided into four stages: ordinary smooth&plain steel strands - galvanized steel strands and unbonded steel strands - unbonded galvanized steel strands - epoxy steel strands. In the first three stages of development, the anchor working clips matched with the steel strand are roughly the same; Its design, processing and production have become large-scale. The fourth stage of development, that is, epoxy steel strand, there are currently three types of epoxy steel strand in the international and domestic markets. One is a single-wire thin-layer epoxy steel strand, that is, seven steel wires in the steel strand are coated with epoxy coating separately, and the coating thickness is thin (about 0.1~0.2mm); The second is the coated epoxy coated steel strand, that is, the outer layer of the steel strand is coated with epoxy coating, and there is no epoxy resin filling in the gap between the steel strands, and the thickness of the outer epoxy coating is (about 0.65~1.15mm); The third is the filled epoxy coated steel strand, which is filled with epoxy resin on the outer layer and in the gap, and is the only epoxy steel strand that meets both ASTM A882/A882M-04a and ISO14655:1999 standards.

The prestressed anchorage system is gradually developed with the development of prestressed steel, both are inseparable. With gradual maturity of filler epoxy coated steel strand technology, its anchoring system has also been gradually developed and improved. The two cooperate with each other, and have been applied to many highway bridge construction projects such as cable-stayed bridges, partial cable-stayed bridges, external prestressing, arch bridge tie rods and rock stone staggering.

Univac New Material Tech.Manufacturing Co., Ltd. is a professional manufacturer and distributor of high-strength and low-relaxation prestressed steel strands, prestressed steel wires, hot-dip galvanized steel strands, unbonded steel strands, epoxy-coated steel strands and their supporting anchoring systems, the quality of prestressed steel products fully meets the international standards BS 5896:2012, FprEN 10138:2009, ASTM A416/416M:2012, ISO 14655:1999 "Epoxy Coated Steel Grain Wire for Prestressed Concrete" and the requirements of the American standard ASTM A882/A882M-04a "Standard Specification for Filled Epoxy Coated Seven Wire Prestressed Steel Strands"; The anchoring system has successfully developed the cable-stayed cable system, the cable-stayed system for some cable-stayed bridges, the external prestressing system, the arch bridge tie system and the geotechnical anchorage system, which has been applied in many projects.