Versatility of Piezoelectric Ring Actuator Technique (P-RAT) for Characterization of Cement Paste and Mortar

Piezoelectric ring-actuator technique (P-RAT) enables the measurement of shear wave (S-wave) velocity (Vs) of a cement-based material, which is directly related to its elastic shear modulus (G). The P-RAT can produce high quality signals with low energetic primary waves (P-waves), thus resulting in precise measurements of S-wave velocity. This paper checked the reliability of the P-RAT to monitor the setting time using the frequency spectrum of the received signals. A possibility of using the P-RAT to monitor the elastic shear modulus of the cement pastes and mortars starting at an early age was studied. This paper also discussed signal processing techniques, including phase shift correction and the first arrival time that can be used to determine the variation of Vs of cement paste and mortar, which can be interpreted to determine setting time. In total, 16 cement paste and mortar mixtures proportioned with different water-to-cement ratios (w/c), high-range water-reducing admixture dosages, and sand volume fractions were investigated. In addition to Vs measurements, the frequency content of the received signals was shown to offer another alternative to determine setting time of cement paste and mortar. To monitor the elastic shear modulus of cement paste and mortar from 1 up to 56 days, a test setup with two P-RAT sensors mounted on opposite sides of a clamping vice was developed for measuring Vs of different hardened material in shape and thickness