Spectrophotometer-Based Novel Models for Detection of Fire Damage in Stone Monuments

Fires are one of the biggest threats to the transfer of cultural heritage to future generations. Sudden thermal differences endanger cultural heritage by causing changes in the chemical and physical properties of stones. Rapidly estimating the changes in the physical and strength properties of building stones after a fire is vital for restoration work. Colour changes occurring in building blocks after chemical processes can be an important tool in predicting the physical properties of the blocks. For this purpose, the samples were first subjected to heat treatment at different temperatures in a laboratory environment, and non-destructive tests (P-wave velocity, spectrophotometer, and Karsten tube) were performed for each stage. Colour differences occurring in the samples after heat treatment were digitized using a spectrophotometer. The relationships between these data and the physical properties obtained in the laboratory were modelled. Then, using the proposed models, the temperatures to which the in-situ building blocks were exposed during the fire and the changes in their physical properties were determined. Finally, the correlation between the predicted values and on-site non-destructive testing (NDT) measurements was examined. According to the findings obtained from the study, it was revealed that the proposed method predicts the change in physical properties due to in-situ fire temperature with a high correlation coefficient.