Estimating liquid limits of mixed soils

A large number of mixed soils exist in nature, including sand–clay mixtures, silt–clay mixtures and clay–clay mixtures. The physical parameters of soils are the basis for investigating their mechanical properties (compression, permeability, strength). More importantly, the liquid limits play an important role in establishing the relationships between physical and mechanical properties. The liquid limit tests of sand–clay mixtures were performed on different kinds of original clays with different sand contents. These data together with those compiled from the literature were used to investigate the change in liquid limits of mixed soils. The results show that the liquid limits of mixed soils are influenced by the types of original soils and the contents of each constituent. In sand–clay mixtures, the liquid limits increase with the increasing clay contents. The empirical equation is proposed to predict the liquid limits of sand–clay mixtures based on the liquid limits of original clays and clay contents. By analogy, the method for predicting liquid limits of mixed soils including two types of original soils with known liquid limits is acquired, such as silt–clay mixtures and clay–clay​ mixtures. Such a method is also extrapolated to the mixed soils with more types of original soils.