Ultrasonic determination of elastic moduli in cement during hydrostatic loading to 1 GPa

Abstract An ultrasonic methodology has been developed for determination of the elastic constants of porous, cementitious materials as a function of applied hydrostatic pressures up to 1 GPa. The methodology can be performed upon bulk samples and in a fashion, which is more controlled than traditional impact (shock wave) testing. In addition, data can be acquired during both the application and release of the pressure. The data for mortar and cement paste samples, with porosity ranging from 13.7 to 24.1% by volume, indicate that during the initial application of pressure there is an irreversible, approximately linear, increase in the elastic moduli associated with the compaction of the pores. During subsequent cycling of the pressure, a slight ‘hysteresis’ was observed, with sound wave velocities and elastic moduli being slightly lower during the application of the pressure than during the release of the pressure. This effect was observed to be reproducible, and is consistent with a weak bonding between crack or pore faces forced into contact by the applied pressure. Use of the proposed ultrasonic methodology for quantification of the effects of pressure on the elastic moduli in cement-based materials will provide the foundation for accurate modeling of the behavior of cementitious materials during a broad range of high-strain inducing conditions such as ballistic impact (military) or geological instability (civilian).