Ultrasonic structural health monitoring of cement paste is of great interest both scientifically and practically, because cement is a complex acoustic medium, whose structure affects the propagation of ultrasound, which offers a great wealth for structural monitoring in a non-viscous fluid. In this paper, the effect of water content on the ultrasonic signal of cement was studied. The immersion transmission technique is used to study the relationship between water content and durability of cement. Therefore, this experimental technique investigates the dispersion curves of cement paste prepared with different percentages of water, based on the ultrasonic signal transmitted through the cement paste recorded at different angular orientations, which allows the durability of the cement paste to be controlled by finding the critical angle in order to calculate the ultrasonic velocity. Overall, the result of this analysis shows that the water content has a significant effect on the ultrasonic velocity and durability of the cement paste.