This paper presents a new methodology for determining the elastic moduli of swelling clay minerals based on the
combination of two original elements: (a) a natural multi-millimetric vermiculite crystal considered as a model
system of swelling clay minerals and (b) a mechanical device that allows for mechanical compression in a
controlled hydric state while concomitantly measuring the resulting strain field using the digital image correlation
(DIC) method. Following this approach, the DIC method can (a) identify anomalous areas of the strain field to be
excluded from an elastic analysis and (b) not introduce any assumptions for Poisson's ratio, as often required in
other techniques (e.g., nanoindentation).
This approach was applied to a vermiculite crystal, with dimensions of 5 × 5 mm2 and a thickness of 1 mm; the
value obtained for the undrained uniaxial Young's modulus was 32.3 ± 3.9 GPa. To the authors' knowledge, this is
the first value for Young's modulus proposed in the literature for a natural and pure swelling clay mineral and is
consistent with those obtained from synthetic samples and molecular dynamics simulations