Case studies of concrete deterioration in reinforced concrete chimneys

This paper discusses the site investigations and follow-up laboratory tests on three reinforced concrete chimneys - two in central and one in southern India. In the first case, a 2 year old reinforced concrete chimney in central India showed blistering of the outer surface of concrete in many locations, which indicated a possible acid attack that should have progressed outward from the inner surface of the chimney shell. Additionally, the reinforcing bars in these locations showed signs of extensive corrosion, which led to the formation of rust stains on the outer surface. The details of the inspection, analyses, and recommendations are presented in this paper. The second chimney in central India was actually under construction, and poor quality of concrete was noticed at the 90 m level. Site investigation and interviews, followed by laboratory evaluation of cores removed from the structure were able to reveal that the poor quality was a mixture of slow hydrating cement and inadequate construction practices. The analyses and recommendations are presented. In the final case, the failure of the acid resistant brick lining on the top levels of a reinforced concrete chimney in southern India led to an extensive laboratory investigation on the quality of the chimney concrete, using cores removed from the chimney. A combination of chemical and physical tests was used to evaluate the quality, and the details of the methods and results are presented. © 2012 Taylor & Francis Group.