AN INDEX VALUE FOR CHARACTERIZING HARDSETTING SOILS BY FALL-CONE PENETRATION

The measurement of fall-cone penetration on air-dried and slowly rewet ted subsamples (< 1 mm) at different water contents characterizes hard setting and non-hardsetting soils by differences in their maximum resi stance to penetration (RP(max)), the water content (WCmax) at RP(max), and the amount of water adsorbed between the two values of 0.5 x RP(m ax), called 'insensitivity' l. The insensitivity I is strongly correla ted with the contents of organic matter and iron oxides which are cons idered as soil components improving aggregation. The insensitivity may be used to identify hardsetting soils. These have I-values < 7, where as non-hardsetting soils have I-values > 10.