NON- DESTRUCTIVE EVALUATION OF IN-SITU STRENGTH OF HIGH STRENGTH CONCRETE STRUCTURES

This paper deals with the evaluation of in-situ strength of high strength concrete (HSC) structures using Non Destructive Evaluation (NDE) techniques like Ultrasonic Pulse Velocity (UPV) Rebound Hammer test and combined methods. An experimental research was carried out, involving both destructive and non destructive methods applied to different concrete mixes, with compressive strength varying from 50 up to 130 MPa. Both cubic and cylindrical standard specimens and bigger blocks were cast with water cement ratio of 0.30. Just before conducting destructive test, UPV and Rebound Hammer tests were conducted on the same cubes as per IS 13311 (Part-1&2). The results of all the tests were utilized to obtain correlation curves between destructive and non-destructive parameters. For all the experimental values, design curves were drawn for correlating the compressive strength with the UPV and Rebound Number. Regression analysis was performed for assessment of in-situ strength of high strength concrete structures. Cores were also taken from the columns of the buildings for compressive strength. The results shows NDE techniques like pulse velocity, surface hardness and combined methods are suitable for evaluation of compressive strength of high strength concrete structures up to compressive strength of 130 MPa.