THE INFLUENCE OF CUP FRICTION AND GRADING ON THE LIQUID LIMITS OF SOME GHANAIAN SOILS (ABRIDGMENT)

An investigation was made of the limitations of the conventional liquid limit test. Since the shear strength of a soil at the liquid limit may fall within a small but measurable range of values, the first part of this study was concerned with the establishment of a range of shear strength values for some typical plastic Ghanaian clays. Two groups of soils were then tested. The first group was composed of plastic clays of sedimentary or residual origin. These soils do not slip in the liquid limit cup and therefore give fairly reproducible results. The second group of soils included the residual soils derived from the chemical decomposition of local rocks, particularly granites. Liquid limits of these selected plastic clays and silty and micaceous soils were determined using both the conventional liquid limit cup and the roughened cup. Plastic limits were also determined for these soils as well as their undrained shear strengths, which were measured at various consistencies. The influence of maximum particle size on the liquid and plastic limits of the soils was also studied.