Mineralogy, Physical and Mechanical Properties of Adobes Stabilized with Cement and Rice Husk Ash

A Burkina Faso clay referenced SAB has been characterized to be used as raw material in the making of adobes. Mineralogical studies (by XRD, DTA-TG), chemical and geotechnical studies (Atterberg limits, particle size distribution) carried out on this clay have shown that it is composed of kaolinite (62 wt%), quartz (30 wt%) and goethite (18 wt%). It is a sandy-silty clay of medium plasticity containing no swelling minerals. Its particles are mainly clay (19 wt%), silt (36 wt%), fine and coarse sand (45 wt%). It is thus suitable for the development of adobes for habitats. The adobes elaborated with SAB clay have been stabilized with an optimal cement content of 10 wt%, which offers a mechanical strength greater than 2 MPa; minimum value for single-level constructions. In order to improve the physical properties (density, porosity, water absorption by capillarity, erosion resistance, compressive and flexural strengths) of these adobes and to reduce cement consumption as much as possible, the cement (10 wt%) was partially or totallysubstitutedby rice husk ash. This substitution contributed to the improvement of the physical and mechanical properties of the adobes, due on the one hand to the effect of micro-filling of the ash and on the other hand to the increase of the CSH resulting from the pozzolanic reactivity between the released portlandite by the hydration of the cement and the amorphous silica of the rice husk ash.