The multiple-charge phosphate-based additives affected the rheology of bentonite gels differently. The yield stress decreased with increasing concentration of additives. However for the triple-charge additives, PO43− and cyclic P3O93− the maximum extent of yield stress reduction was only about 50%. For the higher multiple-charge additives, P2O74−, P3O105− and (PO3−)17 the decrease was >95% where yield stress of
