How Moisture Transport Governs Mechanical Degradation in Stabilized Earthen Materials: From Pore Structure to Structural Design

Although moisture-induced degradation is widely recognized, the relationships between pore structure, water transport, mechanical degradation, and structural performance remain insufficiently quantified for engineering design. This study investigates these relationships through an integrated experimental and analytical framework applied to stabilized earthen materials, with particular focus on Shot-Earth. Moisture transport was characterized through capillary absorption, full immersion, and wetting–drying tests and interpreted using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). Mechanical degradation was assessed through compressive strength and Young’s modulus measurements at different degrees of saturation. Results show that moisture transport and the resulting mechanical degradation are strongly associated with pore-network characteristics, which reflect the combined effects of material composition and processing conditions. In particular, under full saturation, stabilized earthen materials lost up to 50% of their compressive strength and elastic modulus, whereas ordinary concrete experienced significantly lower degradation (~10%). Although moisture exposure significantly reduced mechanical performance at critical locations, particularly wall bases, safety factors against compressive failure remained between 10 and 20 even under full saturation. The main contribution of this study is an integrated engineering framework that connects experimentally characterized moisture states to mechanical degradation and propagates the resulting moisture-dependent properties to structural assessment. This framework provides a basis for incorporating moisture-induced mechanical degradation into the durability-oriented structural assessment of stabilized earthen materials.