ABSTRACT
The most important pathologies that occur in civil constructions are a consequence of the foundations. Expansive soils are among the most problematic soils, being the cause of some of these pathologies. It is possible to design foundations that can resist and restrict the action of expansive soils. One of the alternatives that could be applied to some constructions is to mix the soil with an additive. In this paper, the additive used to modify the swelling properties of an expansive Patagonian soil is lignin, a calcium lignosulphonate (CLS). CLS was analysed considering its influence on the behaviour of the soil. A series of tests were carried out to get a better understanding of the impact the addition of lignin produces on the soil. Tests performed were focused on the physicochemical and microstructure characterization (XR diffractometry, mercury intrusion porosimeter and scanning electronic microscope), volumetric behaviour upon wetting (free swelling), hydraulic behaviour (water retention test using dew-point potentiometer and permeability test) and mechanical behaviour (uniaxial compression test). Time of contact clay-CLS was considered as a variable to analyse the stability of the mixture.
