  The difficulty of measuring and controlling suction in unsaturated soils is
one of the reasons why the development of the mechanics of unsaturated soils
has not been as advanced as that of saturated soils. However, significant
developments have been carried out in the last decade in this regard. In this
paper, a re-view of some developments carried out in the techniques of
controlling suction by using the axis translation, the osmotic method and the
vapour control technique is presented. The paper also deals with some recent
de-velopments in the direct measurement of suction by using high capacity
tensiometers and in the measurement of high suction by using high range
psychrometers. The recent progresses made in these techniques have been
significant and will certainly help further experimental investigation of the
hydromechanical behaviour of un-saturated soils.
