INFLUENCE OF THE POLYELECTROLYTE CRD-186 ON AGGREGATION AND OTHER PHYSICAL PROPERTIES OF SOME CALIFORNIA AND ISRAELI SOILS AND SOME CLAY MINERALS

Abstract

Effects of adding Monsanto''s CRD-186 (calcium salt of polyvinyl acetate-maleic acid copolymer, VAMA) conditioner to several California and Israeli soils were studied with respect to their aggregation and water retention. The treated soils possessed more and larger aggregates than the untreated; air-drying after conditioner addition was unnecessary for aggregate formation. Pressure of retention v. water content curves of treated and untreated soils were significantly different only for pressures< 1 atmosphere, over which range VAMA treatment lowered water retention. Mechanical stirring of water (suspensions) of VAMA-treated soils diminished the aggregating effect of VAMA. Polyelectrolyte addition failed to influence significantly the interplanar spacings as revealed by X-rays, of Ca- and Na-bentonites and of extracted soils'' clays, although the treated materials gave clearer patterns. A definite amount of VAMA is needed to give full aggregation and it is suggested that a coorientation of mineral particles and polymer molecules takes place to produce water stable aggregation.