Holistic Comparison of Bio-Stabilized Rammed Earth for Building Construction

Rammed earth (RE) walls are built by compacting soil into formwork layer by layer. Clay is the only binder in the mixture that compacted at optimum water content provides a load-bearing material. Adding cement to the soil can improve the durability and the mechanical performances of RE, with consequent increment of the environmental impact and reduction of the recyclability and hygrothermal properties. The use of bio-stabilizers from waste, by-products or plant extract represents a promising alternative to the use of chemical stabilizers. The addition of biopolymers affects the porosity distribution of the soil and can modify both hygrothermal, mechanical and water resistance performances. Therefore, the performances at building scale are also affected, influencing the heating demand, summer thermal comfort and passive regulation of relative humidity. Considering all these elements, how to perform an overall assessment of the impact of bio-stabilization? The present study proposes a holistic approach using performance indicators to compare the impact of three different biopolymers for RE stabilization.