Recent Advancements on the Effect of Bio-Stabilisation on the Mechanical and Hygrothermal Properties of Earthen Building Materials

© The Author(s), under exclusive license to Springer Nature Switzerland AG 2026. Raw earth is a viable alternative to traditional energy intensive building materials like concrete and fired clayey materials. It can be locally sourced and serves as an excellent hygrothermal buffer, regulating indoor temperature and relative humidity. Unlike mainstream building materials, earth is also fully recyclable at the end of its life cycle. However, stabilisation – the addition of supplementary material to enhance mixture stability – is often required to enhance the durability of earthen building products and their resistance to liquid water erosion, typically increasing their environmental impact. To mitigate this impact, various bio-based stabilisation methods have recently been explored by the scientific community. These involve the addition of biopolymers, bio-fibres or the triggering of bio-mineralisation processes. Still, the effects of these novel bio-stabilisation methods on the mechanical and hygrothermal behaviour of earthen building composites/products require further investigation. This paper provides an overview of existing experimental methods for measuring the mechanical, hygroscopic and thermal properties of bio-stabilised earthen composites and products, along with key findings from the literature. Insights from this review can help guide future research on bio-stabilised earthen products.