An index value for characterizing hardsetting soils by fall-cone penetration

Abstract

The measurement of fall-cone penetration on air-dried and slowly rewetted subsamples (< 1 mm) at different water contents characterizes hardsetting and non-hardsetting soils by differences in their maximum resistance to penetration (RP max), the water content (WC max) at RP max, and the amount of water adsorbed between the two values of 0.5 × RP max, called ‘insensitivity’ I. The insensitivity I is strongly correlated with the contents of organic matter and iron oxides which are considered as soil components improving aggregation. The insensitivity may be used to identify hardsetting soils. These have I-values < 7, whereas non-hardsetting soils have I-values > 10.