Determinação da resistência à compressão em concretos expostos a altas temperaturas por meio de ensaios não destrutivos

Abstract

Despite the fire situation is considered rarity in a building, it?s subject to this event at any stage of life, causing a reduction in the mechanical properties of concrete, including the compressive strength. It is necessary to evaluation of a professional as to the efficiency of the structure as a whole, where destructive or non-destructive tests can be used for the analysis of the concrete, but the destructive ones have disadvantages in relation to the non-destructive ones. For this reason, this study aims to correlate the results of the main non-destructive testing methods (ultrasonic pulse and rebound hammer) to destructive testing (compressive strength) in concrete. For this, samples of concrete with fck equal to 20 MPa, 30 MPa and 50 MPa, at ages of 7, 21 and 28 days were exposed at environment temperature (as a base for analysis), 150 ° C, 300 ° C, 450 ° C, 600 ° C, 750 ° C and 900 ° C, after removed from the oven the specimens were cooled slowly (to the air free) and abruptly (submerged in water), 24 hours later the ultrasound velocity and the sclerometric index were read, with a subsequent compressive strength test. Finally, a correlation value was obtained between ultrasonic velocities and compressive strengths of 0.859, while between sclerometric index and compressive strength it was 0.638. However, analyzing according to concrete class or cooling form, the values of correlations of the ultrasonic velocity proved better than for the sclerometric index