A 32-year old prilling tower exhibited some major cracks and a few minor cracks at certain locations. During its service life, the maintenance work was carried out periodically by carrying out some minor repairs. Subsequently, two major vertical narrow cracks were noticed on the prilling tower. The cause of cracking and the present condition of the concrete and the reinforcement with regard to physical, chemical and electrochemical parameters were investigated. Assessment made from rebound hammer, ultrasonic pulse velocity and half cell potential tests did not show any evidence of material degradation as the cause of cracking. However, the concrete core test results indicated lower compressive strength values. A theoretical analysis of the prilling tower was made to find the cause of cracking. The available details obtained at the site showed that certain alterations were made in the prilling tower in the form of some additional construction and consequent loading. Based on a detailed computational stress analysis by incorporating the changes made on the tower, the cause of cracking was identified. It was mainly due to additional loads and the temperature effect. The paper describes the details of the investigative work carried out using non destructive techniques and theoretical analysis by finite element method. The results of investigations carried out are included and recommendations on strengthening measures are given.
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