Improving rheological and mechanical properties of non-plastic clay soil from Bensmim region (Morocco) using bentonite additions: Suitability for building application

The present study aims to develop an innovative scientific methodology for adjusting the physicochemical composition of any clay soil to make it appropriate for construction applications. The realized research was carried out on unexploited clayey soil extracted from Bensmim village (Morocco). Another clay sample from "Extrabrick" brick manufactory was also used as a reference since it is used to produce high-quality bricks. Raw materials physicochemical and geotechnical properties were determined. Results demonstrated that the studied clay is an unsuitable raw material for clay bricks production. This is due to its low plasticity resulting from its significant sand content, low clay fraction, and absence of swelling clay. Therefore, improving the plasticity of our clay was taken as a critical factor to enhance the properties of this clay. Different percentages of bentonite, which is known for its high plasticity, ranging from 0 to 10%, were added to study the effect of this addition on the characteristics of the studied clay. The rheological and mechanical analysis showed that increasing the percentage of bentonite has a beneficial effect on the properties of the studied clay bricks. In fact, the addition of 10% bentonite showed an increase in the yield stress, viscosity, and the mixture exhibited a rheological behavior very close to the reference sample. The founded results were fitted to Herschel-Bulkley classical. The findings suggest that the addition of bentonite decreases the flow index value and increases the consistency index of the studied clay. Furthermore, compressive strength went from 5.3 MPa for the studied clay without additive to 19.33 MPa after 10% of bentonite addition. This value of compressive strength is very close to the compressive strength of the reference brick 23.83 MPa. These results confirmed that rheology could be a powerful tool to tune the formulation of construction materials.