<p>Sand mixed with fines content is always found in the soils projects and represent a discussion subject in many research items in the literature. This article aims to study the behaviour of soils representing by two different sands containing plastic fines content, emphasizing the variation of important parameters in soils behaviour in terms of stress/strain variation, compressibility and consolidation. Bentonite was used in particular to introduce the sands (Chlef sand and standard sand). A series of oedometric and a rectilinear box shear tests carried out to study how sand and bentonite mixtures behave together. To achieve this objective, fines content of 10, 20 and 30% have been highlighted, and compared therefor with pure sand or bentonite. From the oedometric tests, the tests results showed that the increase on bentonite content leads to an increment in the intergranular compression index (same behaviour has been recorded for compression index), the swelling index and the consolidation coefficient. On the other hand, the preconsolidation stress and the oedometric modulus decrease when the bentonite content increases. It has been observed from the direct shear tests that the shear strength increases when the bentonite amount increases until a limit or a threshold of <i>F</i>_<i>B</i> = 20% bentonite content for both Chlef and standard sands. The improvement of the mixtures’ strength is accompanied by a minimization of its contractiveness, which consequently increases the dilatant character for the different mixtures under study. Above <i>F</i>_<i>B</i> = 20% bentonite content, a slight decrease in the bentonite contribution on stress/strain behaviour has been recorded. Thus, the treatment of soils by introducing cohesive soils would be a curiously arrangement to bargain with the powdery soils instability and deformability taking in account an adequate combination of the materials.</p>