Reinforced concrete cooling towers exposed to harsh operating environments can develop severe corrosion of embedded steel reinforcing, concrete delamination and spalling. Condition assessment of cooling towers is challenging due to their size, geometry and operational constraints but careful investigation can provide critical knowledge to effectively characterize structural health, plan maintenance, and prioritize repairs to maximize service life. A case history is presented to illustrate how assessment data was collected, interpreted, and used to develop and implement repair strategies for two 400 foot (121 m) tall hyperbolic shell cooling towers exhibiting widespread corrosion-induced deterioration. Evaluation of concrete properties, corrosion rate and desired service-life objectives were considered in the decision to utilize impressed current cathodic protection (ICCP) and galvanic cathodic protection (GCP) as part of the repair program. Review of the design and installation of the ICCP and GCP systems highlight the unique challenges associated with repair and protection of reinforced concrete cooling towers.
Key words: Natural Draft Cooling Towers, Reinforced Concrete, Concrete Assessment, Concrete Repair, Alkali-Silica Reaction, Petrography, Service Life Modeling, Impressed Current Cathodic Protection, Galvanic Cathodic Protection