The Effect of Water-Cement Ratio on Acousto-Ultrasonic Characteristics in Mortar

A self-improved and debugged acousto-ultrasonic system was used to investigate the effect of water cement ratio (w/c ratio) on ultrasonic pulse wave propagation and find more accurate and effective evaluation parameters than the traditional ultrasonic pulse velocity (UPV). An experimental study on the uniaxial compression test and acousto-ultrasonic test of mortar cylinder with different w/c ratios (0.4, 0.5, 0.6) was presented. The results showed that the increase of w/c ratios deteriorated the mortar mechanical properties with the compressive strength decreased and reduced the UPV. The high w/c ratio also leaded high attention of wave amplitude and energy. Through analysis of the ultrasonic pulse waveforms, the maximum peak amplitude (AE parameter) couldn't reflect the real change of the waveforms. The parameter energy, which is mainly determined by the average amplitude, showed a higher sensitivity to the mortar w/c ratio and more accurate reflection of the changes of the waveforms with different w/c ratios. Compared with other parameters, the energy could be used to evaluate the cement based material properties changes caused by the changes of composition and external effect.