An acousto-ultrasonic approach for the determination of water-to-cement ratio in concrete

A novel nondestructive procedure for the evaluation of water-to-cement (w/c) ratio in concrete is presented. The experimental setup is based on the method of acousto-ultrasonics; data analysis, however, and recognition of concrete composition from the waveform transmitted through specimen thickness, are achieved by simple time and frequency domain schemes used in this work. Experiments were performed in a number of concrete specimens made at various w/c ratios and at a number of ages starting from 2 up to 90 days. Recognition results were satisfactory and the algorithm introduced was successful in identifying the correct w/c ratio in more than 90% of the test cases. The use of existing spectral analysis techniques such as the coherence function has also proved to be more efficient and fits the purpose. The possibility of water content determination in fresh paste is also discussed along with preliminary evidence from initial tests.