Rethinking excavated-earth concrete: water transport in sustainable earthcretes

Durability plays a fundamental role for ensuring environmental resilience, structural integrity, long-term functionality, and economic sustainability. On the other hand, earth-based constructions materials are known to be sensitive to wet environments, especially in presence of wet-to-dry cycles. This study examines the interaction of water with Shot-Earth, an innovative earth-based composite suitable for realizing structural elements like reinforced walls, beams, vaults and slabs. To this aim, two Shot-Earth mixtures were analysed through capillary absorption, water permeability, and microstructural analyses, and their performances were compared with an Ordinary Portland Cement (OPC) concrete. Capillary absorption coefficients were found to range from 0.8 kg/(m2h0.5) to 3 kg/(m2h0.5) over 24 h, reflecting the influence of water-soil affinity, binder content, porosity, and internal cohesion. It is found that high stabilizer contents reduce voids, and, in turn, high densities allow to reduce the absorption coefficient to 0.2 kg/(m2h0.5), like for an OPC concrete. Moreover, water permeability for Shot-Earth typically ranges between 1.965 × 10−16 m2 and 3.373 × 10−16 m2, exceeding those of OPC by more than one order of magnitude. Experimental results were supported by both FE modeling and predictive formulas, providing reliable tools to forecast and optimize the durability of earth-based materials. These findings demonstrated that Shot-Earth can achieve durability performances compatible with structural applications, contributing to the development of low-carbon construction materials.