| Current methods of determining the elastic modulus and Poisson's ratio for geopolymeric materials are limited by the destructive nature of compressive strength and bending testing analysis techniques. Since these tests are not repeatable, there is no means of evaluating whether measured properties are a result of the actual materials or the effect of possible mechanical defects. This study applies a relationship between the speed of sound through a material and its elastic properties to determine the elastic modulus and Poisson's ratio of geopolymeric samples. In addition to these elastic properties, the density, percent pore volume, average pore diameter and standard deviation of pore diameter were also evaluated. These material characteristics were determined as a relationship to the Si:Al ratio of sodium activated metakaolin based geopolymers with Si:Al ranging from 1.49 to 6.4. It was found that lower Si:Al values were consistently around 8.5 GPA while the elastic modulus experienced a decrease to around 5.5 GPa in samples above 3.1 Si:Al ratio. The Poisson's ratio for each sample dereased proportionally to the Si:Al ratio with a maximum value of 0.22 and a minimum value of 0.05. |
