Recent development of epoxy coated and filled prestressing strand and behavior upon a wire break

Abstract

Insufficient PC grout in PC sheath has been a worldwide problem recently. In Japan, 15.2 mm and 15.7 mm 7-wire Epoxy Coated and Filled prestressing strand (ECF strand) are used as the anti-corrosion PC cable effectively. The 21.8 mm 7-wire ECF high strength strand was developed in order to fulfill the need for greater load-carrying capacity. The 21.8 mm 7-wire ECF high strength strand has a maximum load of 573 kN and 0.2% proof load of 495 kN, which are equal to conventional 21.8 mm 19-wire bare strand (JIS G 3536). Furthermore, the anchorage system for the 21.8 mm ECF high strength strand was also developed in order to apply for actual bridges in Japan. In addition, when some wires of ECF strand and bare strand with a tension of 0.6 Pu were intentionally broken, their behavior were observed. Although epoxy resin and PC wires of ECF strand firmly adhere to each other, the strand did not break at once, and the load decreased gradually in step with the breakage of each wire. When a break is observed due to corrosion resulting from insufficient grout filling, the results of the load decrease obtained by this test can be used as a reference to examine residual prestressing force, etc. This paper describes the new developments of the 21.8 mm 7-wire ECF high strength strand and the behavior of the ECF and bare strand breakage.