The detection of high-strength concrete exposed to high temperatures using infrared thermal imaging technique

Abstract

Based on the detection principle regarding physical and chemical changes of the internal structure of concrete at elevated temperatures, and with the application of infrared thermal imaging technique, laboratory investigations related to infrared thermal image inspection and compressive strength test on C80 high-strength concrete (with or without polypropylene fibres) were carried out under thoroughly heated conditions. With the application of SEM and XRD analysis, the microstructure and organisational structure of the concrete could be seen. Also, data analysis could help identify their relationship in cases with polypropylene fibres added or not. The results showed that the elevated temperature through infrared images generally exhibits an upward trend with increasing temperature. Only slight damages were detected below 400°C, whereas more and more severe deterioration events were expected when the temperature was over 500°C. Meanwhile, the compressive strength kept decreasing as the temperature increased. Additionally, the addition of polypropylene fibres with appropriate length, diameter and quantity contributed to the improvement of high-temperature resistance of high-strength concrete.

Keywords:

• High-strength concrete
• Polypropylene fibre
• High temperature
• Infrared thermal imaging technique
• Compressive strength ratio

Acknowledgements

Financially supports from the National Natural Science Foundation of China (51278325), and Shanxi Province Natural Science Foundation (2011011024-2) are acknowledged.