As a non-destructive technique to evaluate the homogeneity of
concrete, UPV testing is based on the fact that the velocities of
ultrasonic pulses traveling in a solid depend on the density and elastic
properties of the material [3]. The average UPVs in the SCC mixtures
after 3, 7, 14, and 28 days are presented in Fig. 6. The UPVs, which
varied between 1.5 and 3.9 km/s, depended on the degree of
densification within the internal structure of the SCC mixtures.