The colorimetry method in assessing fire-damaged concrete

Abstract

Fast and accurate assessment of fire-damaged concrete structures is of great significance for later maintenance and reuse. The traditional methods require large amount of experimental efforts, and some other new technologies are expensive and their applicability still needs further investigation. In view of this, a colorimetric method based on the optical analysis is proposed to evaluate the fire damage of the concrete in terms of the translation of the color coordinates in the chromaticity diagram. Fire damage experiment was first conducted on concrete cubes with two different strengths. Photos were then taken under the conditions of daylight vs. fluorescent light, and manual white balance vs. auto white balance. The chromaticity diagram is constructed to represent the relationship between the coordinates of the concrete colors and the maximum temperature that concrete was subject to. The conditions under the daylight and the manual white balance are recommended for taking photos to construct the chromaticity diagram, and a linear equation was obtained to estimate the heating duration and the maximum temperature that the concrete exposed to from the coordinates of the concrete color. The results of this study will advance the technology of non-destructively assessing the fire-damaged structures.