Assessment of Durability of Bio-based Earth Composites

Bio-based earth composites present various environmental benefits, such as usable wastes, coproducts, abundant or renewable materials, etc. Moreover, the incorporation of bioaggregates in the earth matrix allows the buildings to act as an effective carbon sink. A growing number of studies are now focusing on the mechanical and hygrothermal properties of bio-based earth building materials. However, the durability of these types of material is a major concern, and knowledge of their various aspects is essential to anticipate maintenance and sustain the performance levels. Here, the durability of compressed earth composites, valorizing discarded earth containing 3% of barley straw, hemp shiv, or rice husk, is investigated. Due to the lack of internationally recognized standards to assess the durability of earthen materials and products, we proposed some testing procedures and discussed their relevance. The addition of these three bioaggregates decreases stiffness, as estimated by ultrasound velocity, and improves the resistance to impact and erosion by water. However, water absorption under low pressure is increased, and dry abrasion resistance is decreased. Moreover, the rice husk composite presents the best compromise.