Effects of corrosion on the behaviour of precast concrete floor systems

Results show that the service and the ultimate performance of pretensioned concrete joists are not affected for corrosion levels below approximately 2%. For higher degrees, concrete cracking starts developing resulting into bond degradation and consequent loss of effective prestressing force and counter deflection reduction. Tensile tests of corroded prestressing wires suggest a more relevant reduction of the material average maximum strain than strength. Loading tests of the joist specimens show that for corrosion levels above 15%-20% the ultimate loading capacity can be reduced up to 10% of that of the uncorroded specimens.