Experimental study on physical properties of clays with organic matter soluble and insoluble in water

Abstract Six natural clays with a predominant clay mineral of illite and two pure clay minerals (kaolinite and smectite) were mixed with organic matter to prepare 64 samples of organic clays containing different organic compounds at different contents. The organic compounds are classified into two categories (insoluble and soluble in water) for studying their effects on physical properties of organic clays investigated. When original clays are mixed with organic material insoluble in water, the particle size distributions and the particle densities of organic clays can be approximately determined pro ratio of each component. Adding humic acid into original clays causes little aggregate or disperse action on solid particles. The Atterberg limits of organic clays containing organic matter insoluble in water vary with organic content in a nonlinear fashion, and its changing rate depends on the liquid limits of original clays. On the other hand, when original clays are mixed with organic compounds soluble in water, dissolved organic matter in pore water should be taken into account for measuring their Atterberg's limits. Atterberg's limits of organic clays containing organic matter soluble in water are greatly affected by the predominant clay mineral of original clays. For the original clays with a predominant clay mineral of illite and kaolinite, liquid limit increases with the increase in organic content, but contrary changing fashion is found for smectite.