RESPONSE OF STRESSED CONCRETE TO REBOUND NUMBER

Abstract

In case of existing concrete structures, the strength was mainly defected by destructive tests. Now, with the development in non-destructive techniques it is very to know the strength and other properties about reinforcement, crack depths etc. For the compressive strength the rebound hammer test is very handy and easy. With the help of NUT techniques it is possible to know the strength of the structure without impairing its future usefulness within ± 25% of accuracy. In the first part of present study, the properties of the constituents materials used were investigated further the compressive strength of the different type of concrete have been determined by the destructive test. The control specimens used for investigation were cubes, cylinder and beams. To investigate the effect of moisture half of cubes and cylinders are dried in oven for 24 hrs. In the second part of the study, attempt have been made to predict the properties of concrete by non-destructive test namely rebound hammer test. It is obvious that he rebound number are effected by number of factors. In this study, experimental investigation have been conducted to study the effect of moisture and stress. Lastly based upon the test results, correlation between the compressive strength Tck' and the rebound number 'R' have been established and best fit compression are proposed for different cases (wet and dry). The validation of the proposed correlation has been done by comparing the actual compressive strength with the predicted compressive strength by non-destructive test. The results have shown that it is possible to predict the concrete properties with in a difference of -±20% of the actual value obtained experimentally.