GELATION OF A CLAY COLLOID SUSPENSION

A colloidal suspension of clay particles is modeled by a system of infinitely thin disks carrying a point quadrupole, which results from the electric double layer around the clay platelets. Monte Carlo simulations show that, at sufficiently large values of the quadrupole moment, the system undergoes a transition from a low concentration phase, where disks assemble into elongated clusters, to a space filling gel phase at higher concentrations. The gel phase exhibits a nearly incompressible network structure similar to the ''house-of-cards'' structure conjectured to be typical of clay gelation.