Effect of salinity on geotechnical properties of soft marine clay

Marine clays are soft clays with low shear strength and high compressibility. These soils are prone to seawater intrusion, due to which their engineering properties may be altered. Therefore, the effect of salinity on engineering properties of marine clay has to be investigated prior to any engineering activity in those areas. In this paper, an attempt has been made to study the effect of salinity on various geotechnical properties of Cochin marine clay. As sodium chloride is the most abundant mineral salt in seawater, the effect of 0%, 0.5%, 1%, 2%, 3% and 4% sodium chloride on marine clay for different curing periods were studied. The results of the study show that liquid limit decreases whereas the strength and compressibility characteristics improve as the concentration of salinity increases. Leaching, however, reverses these improvements, amplifying compressibility by 30% and decreasing pre-consolidation pressure by almost 50%. ITherefore, prior to design of any foundation structures on coastal areas prone to salt water intrusion, the behaviour of clay with variation in salinity should be investigated.