Comment on the paper: "Water content and its effect on ultrasound   propagation in concrete- the possibility of NDE". Ultrasonic 38(2000) 546-552   by Etsuzo Ohdaira and Nobuyoshi Masuzawa
  The fundamental application of the ultrasonic pulse velocity method (UPV) in the study of concrete, consist in the analysis and estimation of the mechanical properties (compressive strength). The precission of the estimation may be dependent on the incidence of various factors, one of which is the water content acquired by the sample of concrete. In [Etsuzo] a lineal dependence of the UPV in terms of the water content for different dosifications of concrete is proposed. This paper presents an analysis of that dependence proving that an exponential model describes better the behavior of the velocity as function of water content. 
Manuel Rodriguez Gonzalez, Rolando Bonal Caceres