Post-fire assessment of mechanical properties of concrete with the use of the impact-echo method

The paper presents the nature of elastic wave transition obtained in the time domain and the wave propagation velocity for the impact-echo method employed on the surface of concrete cubes 0.15 x 0.15 x 0.15 m(3) subjected to heating in the temperature range of 200-1000 degrees C. The relations between the characteristics of the obtained impact-echo signal and the mechanical properties of concrete subjected to high temperature were presented as regression curves. The paper proposes certain formulas to be employed while assessing fire-damaged concrete element. The results obtained on fire damaged concrete slab 1.2 x 1.0 x 0.3 m(3) indicate a strong relation between the impact-echo parameters and the mechanical properties of concrete. (C) 2015 Elsevier Ltd. All rights reserved.