Thermal, hydric and mechanical behaviours of adobes stabilized with cement

- Cement additions to raw material induced CSH formation by pozzolanic reactions.
- Physical and mechanical properties of adobes amended by cement are improved.
- Raw material grinding has effect on physical and mechanical properties of adobes.
- Cement amended adobes are less eroded by water comparing to raw adobe.
- Elaborated adobes were suitable as building materials with good thermal comfort.

The main objectives of this work were to manufacture adobes with good mechanical properties, even in a wet environment, and low thermal conductivity so as to give the population homes that provided better thermal comfort than cement-based constructions. For this purpose, clayey raw material from Burkina Faso, mainly composed of quartz (49 wt%), kaolinite (28 wt%), goethite (7 wt%) and muscovite (9 wt%) was mixed with up to 12 wt% of cement to manufacture adobes. Various characterization techniques were implemented to assess the microstructure of these materials: X-ray diffraction, infrared spectrometry, differential scanning calorimetry, scanning electron microscopy and energy dispersive spectrometry. Their physical properties were also investigated (through water absorption, spray test, apparent density, porosity and thermal conductivity) as their mechanical characteristics (compressive and flexural strengths). It was found that the addition of cement resulted in the formation of calcium silicate hydrate (CSH) (I), ettringite and calcite. The CSH was formed partly through the hydration of anhydrous cement compounds (alite and belite) and also through pozzolanic reactions strongly involving finely crushed quartz and, to a lesser extent, kaolinite. These cement-stabilized adobes were particularly distinguished by good mechanical resistance even in a wet environment, and low thermal conductivity. These results indicate that adobes stabilized with 2 wt% of cement are suitable for use as building materials for mass housing.