Improvement of Internal Stability of Alluvial Clay from Famagusta Bay, Cyprus, Using Copolymer of Butyl Acrylate and Styrene

Abstract

The internal stability of alluvial clays may be significantly compromised during a heavy rainfall due to infiltration of surface water causing sudden inundation, softening, and loss of erosion resistance or mechanical strength. Most of the available stabilization methods for clay soils employ pozzolanic or other cementitious binders, creating a chemically bound clay-admixture matrix. These admixtures commonly require a curing period after placement and compaction. Alternatively, aqueous polymers can be used in diluted form without any need for a curing period. Aqueous polymers can form agglomerations of clay particles enclosed in a matrix of polymer chains, held together by electrostatic and hydrogen bonding, improving erosion resistance. In this research, an aqueous polymer, namely, copolymer of butyl acrylate and styrene (CBAS), is mixed with alluvial clay sampled from Famagusta Bay, Cyprus, and the clay stability test is performed as a basis for assessing the degree of improvement on erosion resistance. A time-dependent approach for the evaluation of test results is followed to increase the accuracy of the analysis of the actual behavior observed during the test. A significant improvement in the erosion resistance is observed in treated test specimens. The mode of collapse of specimens during the clay soil stability test when aqueous polymer is used also changed from being gradual cracking and slaking to explosive. The swelling behavior and the effect of drying on the erosion resistance are also observed in the testing program. 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.