Atterberg Limits and Remolded Shear Strength--Water Content Relationships

The remolded undrained shear strength (sur) is of importance in many geotechnical applications. This paper uses published regression analyses for strength variation with water content (w) to draw some generalized conclusions on soil strength behavior, including values of sur mobilized for the Casagrande liquid limit (LL) and plastic limit (PL) conditions and, hence, the shear strength variation occurring over the plastic range. Reported methods of deducing strengths from measured values of water content (w) at the Atterberg limits are reviewed, many of which assume a strength variation of 100 over the plastic range. Regression analysis of reported log w: log sur correlations for 14 mineral soils and four organic sediments indicated that the strength variation is generally not 100 and can vary significantly between soils. Hence, a new approach is proposed for predicting values of remolded undrained strength mobilized for different water contents. Whereas existing formulations are based on empirical sur values associated with the Atterberg limits, the proposed approach is based on direct strength measurements along with water contents for two test specimens.