The present invention provides methods and compositions for treating clay-bearing aggregates, particularly those used for construction purposes, whereby inclusion of fines is maximized due to minimization of clay washing which tends to remove such fines, and whereby performance of the aggregate-containing construction material is enhanced. Exemplary methods comprise introducing to clay a water-soluble, functionalized polyamine comprising a water-soluble polyamine formed by reacting an amine compound with an epoxy compound, the polyamine thus reacted being functionalized through the use of certain halide, sulfate, or epoxy compounds.