Bio and Geo-Sourced Additives Influence on the Hygrothermal Properties of Earth Plaster Derived from Excavated Soil in Reunion Island

In Reunion Island, the valorization of excavated soil from civil engineering projects as construction materials emerges as an innovative approach to tackle the current challenges of material scarcity and the high demand for housing. This research evaluates the effectiveness of various earth-based formulations, incorporating both bio-sourced and geo-sourced materials, for using these excavated soils in plaster for walls. The study focuses on assessing the impact of these incorporations on the hygrothermal properties of the materials, aiming to identify the most suitable formulation to ensure optimal comfort in the island’s tropical climate. Preliminary results indicate significant improvements in hygrothermal properties following the addition of these elements to excavated soils. Notably, a decrease in relative humidity has been observed, suggesting that the composite material acts as an effective hygroscopic buffer. This capacity to regulate indoor humidity presents a promising solution for enhancing indoor thermal conditions by minimizing fluctuations in relative humidity. These findings pave the way for practical applications to improve the sustainability and energy efficiency of constructions on the island, thereby contributing to more ecological management of local resources.