Acoustic monitoring of the curing process in cement and concrete

Abstract

Acoustic wave velocity and attenuation measurements are used to monitor cement and concrete during hardening. The measured acoustic parameters can then be used to investigate the curing process. The goal of this work is to determine the time required for a given mixture of concrete to be hard enough for the removal of the molds, in order to speed up the construction process. Currently this removal time is unpredictable. In addition concrete, mortar, and cement, before hardening, can be considered as examples of granular materials. The shear, rigidity moduli, and acoustic wave velocity of these materials can differ from the values obtained by applying effective-medium theories and Biots theory. The complete description of the mechanical properties of these materials requires the consideration of discrete nature of the solid constituents and the effects of contacts between the grains. These effects are included in the theoretical description of the process. The methods of acoustic microscopy are also applied to investigate the surface and subsurface physical changes of cement during hardening. Theoretical and experimental results of this investigation will be presented.