Development of cement composite with high-temperature detection performance using green earth

This study proposed cement composites with natural green earth to detect elevated and abnormal temperatures. The thermochromic properties of the green earth pigment were examined with increasing temperature, and mixed cement composites were designed based on the pigment content and elevated temperatures. Cement composites with a pigment content of at least 3% demonstrated an irreversible color transition from grayish green to brown. The transition range of the temperature and the change in RGB values depended on the pigment content The color transition ranged from 250° to 350°C for specimens with pigment contents of 3% and 6% and from 200° to 300°C for specimens with a pigment content of 9%. In addition, the specimens with pigments showed a significant drop in weight between 200 and 250 °C, followed by a gradually decreasing rate similar to that of the control specimen. The change in the compressive strength at room temperature was minimal, regardless of the pigment content in the cement composites. After subjected to elevated high temperatures, the compressive strength was reduced by approximately 31.4% for the control specimen and 53.2% for specimens with pigments. The pigment content had minimal effect on the loss of strength.