Influence of straw content on the mechanical and thermal properties of bio-based earth composites

Abstract

Construction is one of the most polluting sectors of industry, which is the reason why developing sustainable building materials is of world-wide interest. Earth is being increasingly studied as a building material because of its low environmental impact and its abilities to regulate indoor moisture and to improve building users’ comfort. However, very few studies deal with unfired earth bricks with plant aggregates incorporated into the earth matrix to lighten the material and improve some properties of the composite. In response to such issues, the Bioterra ANR project aims to develop and characterize bio-based earth composites. In this paper, the mechanical and thermal properties of earthen bricks with barley straw are investigated. The proportions of straw used in the present study were 3% and 6% by weight of the earth, which was made of fines from aggregate washing sludge (FWAS). The results showed that the addition of 3% and 6% of straw decreased the compressive strength by 20% and 5% respectively. Concerning thermal insulation, the thermal conductivity of the specimens with 6% of straw decreased by 75%.