Thermal, Hygrothermal, Mechanical and Environmental Study of Stabilized Earth with GGBS-Based Binders

Earth materials are recognized for their excellent thermal and hygrothermal properties but exhibit low mechanical resistance. Binder stabilization improves compressive strength but often increases the carbon footprint. This study evaluates the mechanical, thermal, hygrothermal, and environmental properties of 12 stabilized earth concrete formulations. The samples were prepared using four types of excavated earths (A, B, C, and D) with varying granular distributions and chemical compositions, stabilized with three industrial binders: two low-carbon activated GGBS-based binders (LN and LW) and a CEM II cement. The samples were cured at 20 °C and 100% relative humidity. Density, porosity, thermal conductivity, specific heat capacity, and Moisture Buffer Value (MBV) were measured at 28 days of curing, using standard methods from concrete and geotechnical fields, while compressive strength tests were performed at 7, 28, and 90 days. The results revealed that gravel-rich earths (A and B) demonstrated higher densities and compressive strengths compared to fine-rich earths (C and D). GGBS-stabilized earths exhibited superior mechanical performance (1.7–14.8 MPa) compared to cement-stabilized earths (0.8–3.8 MPa). Despite low binder content (7%), thermal and hygrothermal properties were largely influenced by the earth’s composition. Thermal conductivity (0.48–0.59 W·m−1·K−1), volumetric heat capacity (1661–2031 J·m−3·K−1), and MBV (0.9–1.9 g·m−2·%RH−1) were consistent with raw earth values, supporting thermal inertia and humidity regulation. The carbon footprint analysis showed that both LN and LW binders had the lowest emissions (29–34 kg CO2·eq/m3), with LN binders demonstrating consistent normalized performance (5.2–6.2 kg CO2·eq/m3·/MPa) and LW binders exhibiting superior mechanical performance and a lower normalized indicator (2.3–5.4 kg CO2·eq/m3/MPa). Conversely, CEM II-stabilized formulations displayed the highest emissions (70–86 kg CO2·eq/m3) and the least favorable compressive strength-to-carbon ratios. These findings emphasize the potential of stabilized earth concretes, particularly those with low-carbon GGBS binders, for sustainable and energy-efficient construction practices.

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