ABSTRACT
Hydration of cement materials, because of its practical and economic importance, as well as its complexity, triggers a lots of research. The trend is toward better understanding of both basic hydration mechanisms and structure evolution-property relations. The nondestructive testing methods, and especially ultrasonic NDT methods serve in this respect. The advance of computers and instrumentation in past years enabled in-depth investigation of cement materials by various ultrasonic techniques. Consequently, the focus of investigation, at least in laboratory conditions, moved toward better understanding of the whole ultrasonic signal received, or extraction of some useful parameters from it. Those parameters, e.g. amplitude, duration, frequency shift, wave energy etc. aid in better detection of early damage of the material, determination of porosity, water to cement ratio or improved strength correlations. This work will outline a simple procedure for extracting several meaningful parameters from the transmitted ultrasonic signal. The combination of parameters is proportional to the maximum stress accompanying longitudinal ultrasonic wave propagation through the material and to the measured compressive strengths.
