Burnt Building Material Carbonation Evaluation Using Primary Color Analysis

When exposed to events such as fires or elevated temperatures, carbonation is an eventual outcome in cementitious building materials and can compromise the structural integrity of the material. Monitoring the pH levels in cement-based materials using color dyes, such as phenolphthalein, can offer insights into their chemical stability and the potential for early aging. These chemicals are traditionally used to detect carbonation depth in concrete, and recently, it has been suggested that they be applied to the concrete surface to determine the pH levels and the associated changes within these materials after heat treatment. This study utilizes image processing techniques to analyze the extent of fire damage by evaluating the primary color changes induced by phenolphthalein in cemented clay-based building materials. The primary color analysis can reduce the complexity in image processing, and while analyzing the color changes, it is found that the CMYK color model is superior to the RGB model for the cemented clay brick samples analyzed. The objective of this study is to develop rapid image processing techniques to automate the detection of carbonation in heat-treated cementitious materials. This study highlighted significant color transformations across different temperature exposures, providing valuable insights into the carbonation processes in burnt building materials. This study also identified the temperature range limitation (100 °C to 400 °C) of phenolphthalein indicators, which was not previously identified, and suggested the need for more robust carbonation indicators.