Strength and elasto-plastic properties of non-industrial building materials manufactured with clay as a natural binder

The objective of this article is to study the mechanical performances of non-industrial materials made with soils containing argillaceous minerals as the sole binder (materials referred to as earthen). The renewed interest in earthen construction requires, in the current context, a scientific approach to these materials and a re-examination of certain techniques such as that of adobes. These adobes are obtained starting with very argillaceous soil saturated with water and poured into wooden moulds. Thus with a soil containing 25% clay, two types of adobe were studied: traditional adobe and Pressed Adobe Blocks (PABs). They were made with a variation in moulding water. Once dried, they were subjected to an unconfined compression test with three loaded and unloaded cycles at 30% of the compressive strength. This test, which takes into account the specificity of adobes, made it possible to determine their compressive strength, initial tangent modulus (E_t) and equivalent modulus during cycles (E_eq). From the results obtained, it appears that the mechanical performances of adobes depend on the moulding water content (W_m) and the manufacturing process used. The PABs with a lower W_m have a higher compressive strength than the adobes. Moreover, they are more homogeneous, although both types of adobe have an elastoplastic behavior. Therefore, for laboratory testing the use of PABs is recommended rather than the use of adobe.