The relationships among elastic modulus, sound velocity and porosity (P) were investigated by theoretical elastic model and experimental results obtained by acoustic pulse method. Young's modulus (shear modulus) decreased with increasing P as (E₀-K_E⋅P)·(1-P), where K_E and E₀ are experimental constants.
The square of sound velocity was as a function of P. The calculated sound velocity using the relation corresponded to the measured sound velocity against P. Furthermore, it was clarified that elastic modulus against P can be calculated using the square of sound velocities at P=0 and two experimental constants.
In these relations, the experimental constants of elastic modulus and sound velocity changed at critical porosity where pore morphology changes. When the critical porosity was considered to the fitting curve calculated using the equation derived in this study, good agreement with the fitting curve and measured data of Poisson′s ratio was obtained.