This experimental study is to find a solution to reduce the amount of waste and at the same time improve the geotechnical properties of fine soils. Compaction, odometer, direct shear tests, and unconfined compression tests were carried out on a clay with a very high degree of plasticity mixed with 0%, 10%, 20%, 30%, and 40% of recycled concrete aggregates (RCA). The addition of concrete aggregates to the clayey soil shows an increase in the maximum dry density and a reduction in the optimum water content. The odometer tests results showed that the increase in the recycled material content leads to a decrease in the compression index, swelling index and creep index. On the other hand, the pre-consolidation stress, the odometric modulus, the consolidation coefficient and the permeability coefficient increase with increasing RCA content. According to the direct shear test, the higher RCA content provided an improvement in shear strength which is accompanied by an increase in the dilatant character. For different curing times and for a content of 10% recycled concrete aggregate, the unconfined compressive strength increased compared to the untreated soil.