Sustainable earthen plasters: surface resistance enhancement via thermal treatments

The construction sector contributes approximately 37% of global embodied carbon from materials. Earth-based materials offer a more sustainable alternative, and using recycled aggregates as sand substitutes further reduces environmental impact by limiting raw material extraction. However, these materials are often vulnerable to erosion and water action. This study investigates low-temperature thermal treatments (200–600 °C) of 10 and 60 minutes and bio-based polymer coatings to enhance the durability of clay-based mixtures with recycled aggregates. Treatments at 500–600 °C significantly improved resistance, with short treatments at 600 °C performing comparably to longer ones. In contrast, bio-based coatings were less effective due to superficial application and film discontinuities. Results highlight the potential of in situ thermal stabilization as a sustainable and efficient method to improve the durability of earthen construction materials and promote their use as a viable alternative in sustainable building practices. • Higher clay content improves erosion resistance of surface; • thermal treatments at 500–600°C enhance surface resistance and durability; • surface enhancement of earth based plasters has been obtained; • bio-based polymer coatings offer limited durability; • in situ thermal stabilization reduces raw material use and supply chain impact.