A new polymeric system has been applied for structural modification of (noncompactable) sandy soils. The system is based on a water-borne styrene acrylic polymeric formulation (emulsion) containing varying amounts of solid polymer. The present work deals with system optimization and measurements designed to examine the effects of polymer content on hydraulic conductivity and compressive strength. Samples were prepared from prescribed amounts of polymer, water, and sand by using two different preparations methods (mixing and spraying). Measurements of hydraulic conductivity for both sets of samples were conducted in a flexible membrane test apparatus. For the first set of samples, the permeability coefficient of the sand was noted to be reduced 10-fold (from 10(-5) to 10(-6) M s(-1)) upon the incorporation of about 2% polymer. In the second set (samples prepared with the spraying method), the hydraulic conductivity was further reduced to 7.2 x 10(-7) at a polymer concentration of about 2%. Stress-strain measurements made on dry cylindrical specimens disclosed remarkable enhancement in the mechanical behavior of the system. For both types of preparation methods, the compressive strength and modulus of elasticity increased linearly with the polymer concentration in the sample. Scanning electron microscopic examination revealed that the dramatic reduction in the permeability and the improved mechanical properties are attributed to the polymer coverage of the sand particles and the development of interconnecting ties between them. (C) 2003 Wiley Periodicals, Inc.