1. Test techniques and methods

1.1 General

Two suction control techniques were presented in the article Water in unsaturated soils :

• in the "axis translation" technique ( § 2.3), a controlled air pressure is applied to the sample, while the water pressure is kept at zero;

• in the osmotic technique ( § 2.4), we use a semi-permeable membrane and a solution of large molecules unable to cross the membrane.

These two techniques have been applied to various types of soil mechanics laboratory tests.