The relationship between drained friction angles and Atterberg limits of natural soils

The note briefly describes the results of a series of direct shear tests on soils with plasticity limits verifying over a wide range. The tests were conducted to investigate the correlation between residual friction angle and plasticity index. The soils consisted of monomineralic soils, some natural soils and the goose lake flour - a commercial standard soil used in research at Soil Mechanics Laboratory of University of Illinois. The tests were conducted at normal stress ranging from 0.1 to 3.5 kg/sq.cm and values of residual friction angle were plotted against plasticity index. It is seen from the tests that there is a correlation between peak and residual friction angle and plasticity index. /TRRL/