Structural Assesment Of Concrete Strength For Ageing Konar Dam, Jharkhand, India

US Vidyarthi, Ravi Agarwal, S K Dwivedi, N Sivakumar

Interactions of concrete with persistentprevailing environmental conditions will alter its material properties and cause deteriorations. Such phenomenon is very common in various elements of dams. Konar dam is an earthen dam with concrete spillway built across the Konar river (23.9411° N, 85.7750° E) in Hazaribag district of Jharkhand, India. It is 3,549 m long and 49 m high dam with 110 m long concrete spillway.The project was commissioned in 1955.  Besides providing irrigation facilities to 45,000 hectares of agricultural land, it supplies clean water to the thermal power plant located at Bokaro. Observation of horizontal cracks of 2-4 mm width extending continuously all along the upstream as well as downstream facesin the galleries from one end to other necessitated evaluation of the quality of concrete with regard to its strength and other associated properties.  For initial broad spectrum diagnosis and overall assessment of the status of concrete,ultrasonic pulse velocity technique was adopted. Based on the test observations,locations for extraction of cores for further investigationswere identified on upstream as well as downstream faces of galleries. This paper presents the outcome of various investigations that were carried out for structural assessment of different grades of concrete used in the dam.