Deterioration of an industrial reinforced concrete structure exposed to high temperatures and dry-wet cycles

This paper presents the results of an in-situ test and experimental study on a reinforced concrete wet quenching tower that had been exposed to high temperature and dry-wet cycles for 34 years. Fourteen concrete cylinder samples were drilled along the height. The variations in the carbonation depth, compressive strength, pH, phase compositions, substance contents and morphologies of concrete along the height and depth of the tower were tested. The carbonation depth of concrete at the top of the tower was 2.3 times greater than the bottom, and the compressive strength of concrete at the top was only about 30% of the bottom. Variations of pH with the content of CaCO3 in different depths have been quantified. The pH at different depths of concrete in the severe dry-wet cycle zone fluctuated around 9.0, the content of CaCO3 was around 8%. Calcium carbonate coexisted with gypsum in the transition zone of carbonated concrete. A modified stochastic carbonation depth model is proposed for concrete exposed to high temperatures with dry-wet cycles and was in acceptable agreement with natural carbonation test results.