Effect of grout conditions and tendon location on corrosion pattern in PS tendon in grout

Abstract

Pre-stressed Concrete (PSC) has various engineering advantages like reduction of dead load, enhancement of shear strength, and reducing crack, however tendon corrosion in grout caused by deficient grout and intrusion of chlorides causes a tendon break and the related structural problems. It is important to understand the corrosion pattern varying with grout properties and placement conditions. In the work, TG (Tendon-Grout) systems are prepared considering grout quality, bleeding, tendon location, and crack width. In order to evaluate corrosion pattern in TG systems in a short period, ICM (Impressed Current Method) is adopted for corrosion acceleration for 2 and 4 days of duration. For two types of grout (conventional one and improved grout with reduced water to cement ratio and silica fume), corrosion current and its amounts are evaluated for various conditions. In the TG system with crack, corrosion greatly increases with extension of test duration for both types of grout since crack width on grout is a main channel for ion intrusion. In spite of crack effect, improved grout has better resistance to corrosion considering crack and bleeding condition. When TG system has eccentricity of tendon with small cover depth, no significant differences between conventional and improved grout are measured since cover depth is too small to protect chlorides from outside. Various effects like bleeding, crack, tendon location, and grout quality are discussed in the work. The improved properties in IG like porosity, strength, absorption ratio, and expansion rate are also investigated.