Ultrasonic characterization of damage induced by temperature variations in concrete medium treated with nanosilica

Concrete is widely used as construction material in civil infrastructures. Generally, this type of material can deteriorate due to several reasons, such as temperature variations. It is essential to monitor the changes inside the concrete medium using a suitable technique. In this study, six concrete specimens (three prisms and three cylinders) with different nanosilica contents were made and tested using the ultrasonic pulse velocity (UPV) method. These specimens were evaluated under the effect of daily freeze-thaw (F-T) cycle (71 cycles) under controlled laboratory conditions. A new evaluation approach based on selected frequency bands is proposed to analyze the signal spectra to monitor the damage development inside the concrete medium under temperature variations and compared with other conventional procedures. The results obtained show that the proposed approach could capture the damage progress better than other procedures used to evaluate damage propagation in concrete medium. It is shown that the band with high frequencies (42–65 kHz) is more robust to capture damage in all concrete specimens tested in this study in comparison with the UPV methods. In conclusion, the findings of this study indicate that the proposed new approach can be applied to monitor damage propagation in concrete medium under laboratory and field conditions.