Investigation of the Stabilization of a Selected Expansive Soil in North Cyprus Using an Aqueous Polymer

In this research, co-polymer of Butyl Acrylate and Styrene (CBAS) is utilized to improve volume change behaviour, undrained shear strength and internal stability of a cohesive soil obtained from Famagusta Bay, Cyprus. CBAS has low viscosity improving its adsorption in the soil microstructure and its ionic structure enhances its interaction within the soil fabric. The ease of application of CBAS, by shallow mixing or direct spraying onto soils, makes it favorable for engineered fills or just to be used as a wind or water erosion measure. Treatment of the soil samples with CBAS indicated significant improvement in the shrinkage and compressibility characteristics when it is added up to 5% of dry mass of soil, whereas the swelling behaviour is improved with further addition. The secondary compression rate is reduced down to approximately a quarter of the rate obtained from untreated specimens. The unconfined compressive strength is increased significantly even at low percentages of treatment. A similar efficacy is also observed from the results of internal stability tests. The mode of the collapse of specimens in the internal stability tests changed from being `gradual cracking and slaking` to `explosive` when CBAS is used. The cyclic wetting and drying behaviour is also tested, which indicated delay in the drying periods and a reduced swelling potential for the treated specimens. Microstructural changes in the soil fabric are observed with the use of scanning electron microscopy, which indicated that an effective formation of polymer soil interaction is achieved. X-Ray Diffraction analysis and Fourier Transform Infrared Spectroscopy are performed for observation of the effect of CBAS on microstructural interactions such as electrostatic bonding and changes in soil fabric.