Chemico-microstructural changes in earthen building materials containing calcium carbide residue and rice husk ash

Physico-chemical and mineralogical characterization of clay materials suitable for production of stabilized compressed earth blocks

“…10b show that the initial EC (after 1 hour) of the clay materials mixed with 10 % and 20 % CCR respectively reached at least 5.8 mS/cm and 6.0 mS/cm. The dissolution of portlandite (Ca(OH)2) from CCR into Ca 2+ and OHwas responsible for this drastic increase of the initial pH and EC [26,47]. The EC of all mixtures decreased over the curing time, at similar rate in the first 3 days, after which a clear difference was recorded for different clay materials and CCR contents (Fig.…”

“…The pH reached the apparent maximum values of 11.7 for Kamboinse, 11.4 for Pabre, 11.3 for Kossodo, and 11.4 for Saaba after 1 hour of addition of 2 % CCR compared to the pH of 11.6 for the solution of 2 % CCR alone. This suggests that at least 2 % CCR is necessary to satisfy the short term modification and increase the pH of all clay materials [26]. This is related to the predominance of low activity clay mineral, such as kaolinite, in all clay materials.…”

“…Many efforts have been made to improve the physico-mechanical performances of CEBs in dry and saturated conditions as well as their long term durability. This is mainly achieved by stabilization with chemical binders such cement, lime, geopolymer as well as by-product materials [6][7]15,18,[24][25][26]. The stabilization of CEBs with by-product materials in partial or full substitution to classic binders not only improves the technical performance but also can potentially improve the sustainability and economic benefits of stabilized CEBs [8,24,[27][28].…”

“…The improvement of the compressive strength was related to the formation of cementitious products such as calcium silicate hydrates (CSH) and calcium aluminate hydrates (CAH), either from the hydration reaction of cement or pozzolanic reaction between lime and aluminosilicate minerals such as kaolinite and fine particles of quartz (<50 µm) in the clay material [6,19,29,[30][31]. More recently, calcium carbide residue (CCR), an industrial by-product rich in lime (Ca(OH)2), showed the potential to improve the compressive strength of CEBs through the chemical interactions with the clayey earthen material [24,26]. Therefore the suitability of clay materials should be characterized prior to the production of stabilized CEBs given that their performance is largely influenced by the characteristics of the earthen material, type and content of stabilizer as well as the production and curing process.…”

“…Clay materials from this region are basically used for road pavement and in some cases for the artisanal production of adobe; although some small enterprises such as Zi-Matériau and CC3D offer services of production, commercialization and construction with CEBs in the major cities. In fact, current research on earth for building construction in Burkina Faso mainly reports on adobes and only a limited number of studies are reported on CEBs [10,11,14,[24][25][26].…”