Evaluation of Strength of Existing Structure by using NDT Techniques

Reinforced concrete that has been used for long time should be evaluated to determine the current strength, durability and to know how long it can be with stand all possible loads. Poor quality of reinforced concrete will cause discomfort to customers, safety will be affected and strength will be reduced. In this paper we are using existing polytechnic building belonging to Adichunchanagiri Shikshana Trust, Chikmagalur is taken as the case study. It is a reinforced cement concrete framed structure comprising of ground floor, First floor and second floor. It is reported that the building was constructed about 30 years back and since then it is occupied was investigated for their strength and quality. The pulse velocity test and rebound hammer tests were used to determine the current strength and also the properties of the concrete. From the data it was found that the building achieves 14 to 18 MPa compressive strength in the current condition. On the basis of test results, the above said reinforced concrete building shows consistent strength, meets moderate quality and still safe in all ways. Further this paper proposes the Ultrasonic Pulse Velocity (UPV) and Rebound Hammer tests for the two grades of concrete casted in the laboratory viz: M20 and M25 for evaluating the compressive strength.