1996 年 45 巻 9 号 p. 1021-1026
The after-set type prestressing tendon is newly developed for post-tensioning of concrete. Without grouting, this tendon has the same structural properties as the grouted tendon. This paper presents the properties of after-set type prestressing tendon and the flexural behavior of concrete beams using the new tendon.
After-set type prestressing tendon is composed of prestressing steel coated with a cold setting epoxy resin in a corrugated polyethylene sheath. The hardening time of the resin can be controlled by the amount of curing catalyst that hardens after stressing and then bonding with concrete occurs through the sheath. The concrete specimens embedding the tendon and the beams reinforced with the tendon were prepared. The pull-out test, fire resistance test and flexural test of the beams were carried out. In conclusion, the bond strength of after-set type prestressing tendon is equal or superior to that of the prestressing steel with cement grout. The concrete cover of after-set type prestressing tendon needs about 55mm, 65mm and 75mm for 30 minutes, 1 and 2 hours of fire resistance periods respectively. The concrete beams using the after-set type tendon show the flexural behavior similar to the concrete beams using the prestressing steel with cement grout.