Abstract

Concrete is the most preferred construction material. Besides the aggregates and sands, the cement is one of its primary constituents. During hydration, cement composite is developed over a period of time after going through various chemical reactions. In the present study, ultrasonic testing is carried out in the cement composite in transmission mode. Acoustic signal was actuated using the ultrasonic transducer excited at different frequencies and the received signal was acquired on the other side of the specimen. Different frequencies of the input signal helped to choose the most responsive frequency range for the cement composite inspection. The non-destructive testing and evaluation (NDT&E) was carried out on different days of curing. The obtained signals were processed to analyze the change in signal characteristics during different stages of curing. It is interesting to observe that the peak frequencies obtained from the Fast Fourier Transform (FFT) were not very distinctive. However, more sophisticated signal processing tools like S- Transform and Hilbert Huang Transformation (HHT) showed promising results. Nonlinear ultrasonic method which is very efficient for providing information on minor damages (which cannot, generally, be done using linear ultrasonic techniques), was also tried out. It was found that the nonlinear ultrasonic technique called side band peak count (SPC) which is derived from the frequency spectra of FFT exhibits clear distinction among the cement composite specimens with different ages of curing. The present study shows that the S- Transform, Hilbert Huang Transformation and SPC can provide appropriate parameters to characterize the cement composite.

How to Cite:

Amjad, U., Sasmal, S., Alnuaimi, H. & Kundu, T., (2019) “Linear and nonlinear ultrasonic techniques for investigations of cement composites of different ages”, Review of Progress in Quantitative Nondestructive Evaluation .