Quantifying the colour alteration of concrete exposed to fire with a flatbed scanner

In this paper two techniques are discussed to measure the colour of concrete samples after fire exposure, namely a spectrophotometer and a calibrated flatbed scanner. These techniques are used to trace the temperature history of the concrete, from which the corresponding fire damage can be assessed. A spectro-photometer allows to measure colours in a fast and device independent way, resulting in absolute colours usable as a reference in both laboratory and field explorations. A flatbed scanner is less portable, but can be coupled to image analysis software by which focus is possible solely on the cement matrix. With increasing the colour of traditional and self-compacting concrete is studied in the CIE Lab colour space. With increasing temperature not only a shift to red is considered, but also the development of a colour path