Characterization of Ariake and other marine clays

Characterisation of marine clays is an important aspect of understanding their behaviour. Investigation showed that there is a good linear relationship between percent clay and liquid limit and plastic limit. Sand and silt fraction has only diluted the magnitude of liquid limit and plastic limit. The ratio of plastic limit to liquid limit is almost a constant irrespective of percent sand fraction and is a function of clay mineral type or mixture of clay minerals, associated cations and ion concentration. Marine clays of Japan around Ariake bay (Hachirogata, Ariake – Ushiya, Meguri, Okishin and Yamaashi)have shown good correlation between plastic and liquid limits and this ratio ranged between 0.35 to 0.50 as against 0.07 (Limontmorillonite)to 0.88 (halloysite) of pure clay minerals. Cochin marine clay behaviour compares well with Ariake-Ushiya, although their geological history is entirely different. The revised plasticity chart with liquid limit and plastic limit as coordinates appears to be a better representation of fine grained soils