Study the surface color of sewage sludge mortar at high temperature

In this study, with the help of digital image analysis method, the surface color changes of sludge ash mortar specimens at various elevated temperatures are studied. Moreover, the influences of temperatures on surface color changes of mortars are investigated. Selected portions of cement are replaced by three different amounts of sewage sludge ash and six varied temperatures are then assigned. Results indicate that the addition of sludge ash in the mortar has significant influence on the surface color changes. Intensities of red, green, and blue are reduced with the ash additives. Our study also shows that the grayscale of sand could be one of the important factors in assessing the high temperatures of fire. Distributions of colors and brightness of mortar surface with temperatures quantified by image analysis can serve as a useful tool in detecting properties of mortars at high temperatures.