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.

No abstract

This study investigated the impact of the design of wall systems, mainly made of compressed earth blocks (CEB), on the indoor thermal comfort of naturally ventilated housing in hot climates of Burkina Faso. Conventional housing was modeled and calibrated using the WUFI® Plus dynamic simulation tool based on typical field surveys and the literature. This allowed testing the ability of different wall designs to impact thermal comfort. Thermal discomfort was assessed through an adaptive approach and was based on the annual weighted exceedance hours of overheating. Six designs of walls made of CEB and other locally available materials were simulated and compared to those made of classical hollow concrete blocks. The results of the simulation reveal that the profiles of thermal discomfort vary depending on the wall designs and building spaces. Thus, the wall made, from the outside toward the inside surface, of plywood of 2 cm, an insulation layer of 5 cm and a CEB layer of 29 cm thickness is the most suitable for an annual reduction in overheating for the living room. Regarding the bedroom, the most suitable wall is made of a 14 cm CEB layer, 5 cm insulating layer and 2 cm wood layer from the outside toward the inside surface.

Municipal wastes such as water sachets and agricultural by-products in Burkina Faso need proper management to limit their hazards to the environment. This study investigated the effect of incorporation of fibres from agricultural by-products (okra plant fibre) and water sachet wastes (polymer fibre) on thermophysical and mechanical properties of stabilized compressed earth blocks (CEBs). The CEBs were moulded from moistened mixtures of clayey earthen material stabilized with 10 wt.% CCR (calcium carbide residue) and incorporated with 0 to 1.2 wt.% fibre of each type. The CEBs were cured in a closed environment, at room temperature in the lab (30 ± 5°C) for 45 days. Cured CEBs were dried (40 ± 2°C) and tested for the thermophysical and mechanical properties. The experimental results showed that the average bulk density of CEBs decreased in the range of 1690-1565 kg/m 3 with the incorporation of 0-1.2% fibre. The thermal conductivity and diffusivity also decreased, respectively, in the ranges of 0.84 to 0.63 W/m.K and 6.1E-7 to 4.2E-7 m 2 /s with plant fibres and 0.84 to 0.38 W/m.K and 54E-7 to 2.3E-7 m 2 /s with polymer fibres. This resulted in evolution of the depth of penetration of the thermal flux from 0.12 to 0.07 m which is smaller than the total thickness of the CEBs (0.14 m). This shows the improvement of the thermal performance of the CEBs incorporated with fibres in the context of the warm climate of Burkina Faso. However, the dry and wet compressive strength respectively decreased from 4.3 to 2.9 MPa and 2.7 to 1.3 MPa, which were respectively greater than 2 and 1 MPa required for the construction of non-load bearing buildings. These results suggest that CEBs containing by-product fibres are useful to improve the thermal efficiency of one-storey building.

No abstract

No abstract

This study explores the logics, motivations and issues related to the construction of sustainable housing made of compressed earth blocks (CEB) material in the city of Ouagadougou. In Burkina Faso, a landlocked country with limited natural resources and predominantly warm dry climate, most buildings are made of local materials. Historically, people built their habitats using mud brick (adobe). However, with the irreversible process of urbanization, the construction sector recorded changes with an increase in concrete-based, hollow cement blocks (HCB) constructions. Besides this trend, individualistic strategies are moving towards other types of materials such as CEB. Throughout a qualitative approach, the present study intends to show that the use of eco-materials, like the CEB, is the concern of middle class population who has broken with the "all in concrete" in the construction of their housing. This study also reveals that the owners of CEB-based housing are mostly city dwellers endowed with considerable cultural and economic capital. It also briefly reveals that the logic behind the use of the CEB is based on the social distinction of city dwellers, having both a romantic and Romanesque vision of earth-based construction. Moreover, this mode of construction is associated with a post-modern vision of sustainable development (less energy and resources consuming constructions, reduction of the electricity bill, etc.), but also with an ecological reasoning that cannot be afforded by the common population in Burkina Faso.

No abstract