Microstructure and Mineralogy of Compressed Earth Bricks Incorporating Shea Butter Wastes Stabilized with Cement

Abstract

The current context of sustainable development encourages the development of materials with low environmental impact, which explains the renewed interest in earthen constructions. This study is therefore a contribution to the valorization of clay raw materials from Côte d'Ivoire and agro-industrial waste in eco-construction. The aims of this study was studied the effect of shea butter wastes on the mineralogy and microstructure of Compressed Earth Bricks (CEB) stabilized with cement. To do this, two clay raw materials denoted F (Fronan) and K (Katiola) were sampled and then characterized. Various geotechnical and physicochemical tests have shown that these soils are loamy sand of class A2 and essentially contain quartz, kaolinite, mica and ferric compounds. As for shea butter wastes, it is mainly rich in lignin (32%); cellulose (28%) and hemicellulose (19%). Several samples of bricks with different percentages by mass of clay and shea butter wastes (0-10%), stabilized with 5% cement were prepared and then characterized. The results of the mechanical tests showed that the clay-cement matrix could contain 4% shea butter wastes for the formulations with clay F against 6% with clay K. The corresponding optimal formulations are F₉₁TK₄C₅ and K₈₉TK₆C₅ with clays F and K respectively. The SEM images showed a less dense microstructure for the optimal formulation F₉₁TK₄C₅ compared to that of the clay-cement matrix unlike K₈₉TK₆C₅ where the microstructure remained always dense. X-ray diffraction did not allow to observe mineralogical modifications with the incorporation of shea butter wastes into the clay-cement matrix due to their low quantities in the optimal formulations.