Building with Rammed Earth: Characterization and Optimization of Earth Mixes from a Monticello d’Alba Case Study

This study explores the potential of rammed earth (RE) as a sustainable construction material by evaluating the mechanical and compositional properties of an earth-based mixture designed for structural applications. The investigation focuses on "Casa del Thè," a pavilion built using a tailored RE mixture (Tmix), combining quarry waste-soil (Tb) and vineyard soil (Tv). Comprehensive geotechnical (Atterberg Limits, Specific Gravity, Granulometry) and chemical and materials characterizations (ATR-FTIR, TGA, XRD, XRF) characterized the constituents. Optimal water content for compaction was determined using Standard Proctor tests, for both Tb and Tmix, followed by UCS tests to compare their mechanical behaviors. To evaluate the compressive strength (UCS) of the mixture, cylindrical samples were made at the construction site. The mixture was then recreated in the laboratory using the same ratios to ensure better control over the preparation methodology. A granulometric optimization was achieved computationally by blending Tb with other soils to approximate an ideal grain size distribution for RE, resulting in an optimized mixture with an average UCS of 0.99 MPa. Results indicated that while the initial Tmix yielded a UCS of 1.67 MPa, the optimized mixture demonstrated a slight UCS reduction, highlighting a trade-off between granulometric refinement and compressive strength. Comparative analysis of on-site and lab-prepared samples revealed that Tb and Tmix achieved UCS values of 1.44 MPa and 1.24 MPa, respectively, underscoring the influence of preparation methods on material performance. Overall, the findings suggest that with targeted adjustments in soil composition and compaction, rammed earth can be effectively adapted for broader, sustainable structural applications.