The main objective of this study is to characterize the physico-chemical and mineral properties of clay materials from Burkina Faso to produce stabilized compressed earth blocks (CEBs). The reactivity of the clay materials was tested based on the electrical conductivity of solutions and the compressive strength of CEBs stabilized with 0-20 wt% CCR (calcium carbide residue) and cured for 45 days at 40±2 °C. Pabre and Kossodo respectively contain the highest fractions of clay (20-30%) and gravel (40%). Saaba and Pabre contain the highest content of kaolinite (60˗70%) and quartz (45-60%) and recorded the highest and lowest reactivity, respectively. The compressive strength of CEBs stabilized with 20% CCR improved tenfold (0.8 to 8.3 MPa) for Saaba and only 2.6 (2 to 7.1 MPa) for Pabre. The clay materials in the present study are suitable to produce CCRstabilized CEBs for load-bearing construction.

Earth stabilization, using two by-products available in Burkina Faso: Calcium Carbide Residue (CCR) and Rice Husk Ash (RHA), improved the performance of compressed earth blocks (CEBs). The effect of adding CCR or CCR: RHA (in various ratios) to the clayey earth was investigated. CEBs were molded by manually compressing moisturized mixtures of earthen materials and 0-15 % CCR or CCR: RHA (various ratios) with respect to the weight of earthen material. The results showed that, with 15 % CCR: RHA in 7: 3 ratio, the compressive strength of CEBs (6.6 MPa) is three times that of the CEBs containing 15 % CCR alone (2.2 MPa). This improvement was related to the pozzolanic reaction between CCR, clay and RHA. These CEBs comply with the requirement for wall construction of two-storey housing.

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This paper investigates the stabilization effect on compressed earth blocks (CEB) produced from quartz-kaolinite rich earthen material stabilized with 0% -25% calcium carbide residue (CCR). The paper evaluated various physico-thermal properties of the stabilized CEB and thermal comfort in the model building made of CEB masonry. The optical properties of CEB were evaluated from the mineral composition of the earthen material and CCR and apparent density of the CEB. A simulation was carried out on naturally ventilated model building whose masonry is made of CCR stabilized CEB comparing to the so-called conventional cementitious materials such as cement blocks and concrete. The results showed a decrease of the apparent density of the CEB from 2100 kg•m −3 for unstabilized CEB (0% CCR) to 1600 kg•m −3 for 25% CCR stabilized CEB. The thermal conductivity and depth of penetration of the heat flux on a 24 hours period of CEB respectively decreased from 1 W•m −1 •K −1 and 12.7 cm for 0% CCR-CEB to 0.5 W•m −1 •K −1 and 10.2 cm for 25% CCR-CEB. The emissivity, solar absorptivity and visible absorptivity of the CEB respectively decreased from 0.82, 0.82 and 0.82 for 0% CCR-CEB to 0.80, 0.64 and 0.64 for 25% CCR-CEB. The number of hours of warm and humid thermal discomfort was impacted for stabilized CEB based masonry in comparison with cement based masonry. The warm discomfort in building made of 20% CCR-CEB masonry was 400 hours lesser than that in building made of hollow cement blocks masonry.

This study investigated the effect of production and curing parameters on the mechanical performance of compressed earth blocks (CEBs) stabilized with 0-20 wt % CCR (calcium carbide residue). Kaolinite (K) and quartz (Q)-rich earthen materials were mixed with the CCR and used to mould CEBs at optimum moisture content (OMC) and OMC+2 % of the dry mixtures, cured at 20 °C, ambient temperature in the lab (30±5 °C) and 40 °C for 0-90 days. After curing, the reactivity of the materials and compressive strength of dry CEBs were tested. Increasing the moulding moisture from OMC to OMC+2 decreased the compressive strength 0.3 times (4.4 to 3.3 MPa) for the CEBs stabilized with 20 % CCR cured at 30±5 °C for 45 days. Similarly, the compressive strength (4.4 MPa) was reached by CEBs stabilized with 10 and 20 % CCR after 28 and 45 days of curing, respectively. At 40 °C, the compressive strength increased 3.3 times (1.1 to 4.7 MPa with 0 to 20 % CCR) for K-rich and 2.5 times (2 to 7.1 MPa) for Q˗rich materials. At 20 °C, the compressive strength increased only 1.3 times (1.1 to 2.5 MPa) for K˗rich and barely 0.7 times (2 to 3.4 MPa) for Q-rich materials. These suggest that CCR is useful for stabilization and improving the performances of CEBs in hot regions.

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