Optimizing thermal and mechanical performance of compressed earth blocks (CEB)

• High bulk density compressed earth blocks (CEB) have good compression strength but a relatively high thermal conductivity.
• The variation of compaction pressure changes bulk density of CEB and modifies their thermal and mechanical properties.
• The decrease of bulk density CEB must be limited, else they lose their cohesion and no longer have sufficient compression strength.
• Optimizing bulk density of CEB makes possible to reach a dual objective of reducing thermal conductivity and to provide sufficient mechanical compression strength.

Compressed earth blocks (CEB) were used for the construction, always and until now systematically with a bulk density of about 1800 and 2100 kg m−3. These earth construction materials have a relatively high thermal conductivity of about 1.1 W m−1 K−1. This study aims to obtain lightweight CEB by varying their bulk density in order to modify their porosity and consequently to act on their thermal conductivity. The approach adopted here involves an experimental study of the influence of compaction pressure on the bulk density of the compressed earth block (CEB) and its effects on their thermal performance (thermal conductivity and thermal effusivity) and mechanical properties (compressive strength and modulus of elasticity). Results show that bulk density has a strong influence on thermal and mechanical behavior of CEB. The decrease in the bulk density of CEB was accompanied by a significant reduction in their thermal conductivity and their thermal effusivity. This variation in thermal properties as a function of bulk density is performed linearly. However, the bulk density should not decrease under certain minimum values below which the CEB lose their cohesion and compressive strength.