Fractal nature of bentonite–water–NaCl gel systems evidenced by viscoelastic properties and model of gels

The effect of ionic strength on the viscoelastic behaviour of bentonite dispersion has been investigated and quantified by the elastic modulus (G′) to insure the fractal nature of the bentonite–water–NaCl gel systems. Whatever the ionic strength of the medium, this rheological parameter followed a scaling law as a function of the bentonite volume fraction. Shih's fractal model (strong-link regime) was used to better fit the experimental data in coagulated and non-coagulated gels. A good agreement between the experimental results at different ionic strength and calculated data was obtained. The fractal dimension (D) varied with ionic strength and had a minimum value at maximum coagulation which is in agreement with the fractal nature of the bentonite gels.