Plastic Concrete Bentonite: Description & Applications Plastic concrete bentonite is one of the most important materials in Plastic concretes due to causes to fill voids of concretes. Creating an impermeable barrier (cut-off wall) for containment. Seepage control in highly permeable dam foundations. Has enough compressive strength, tensile strength and shear strength. Designed to undergo deformations compatible with those in the surrounding soil without development of cracks.