From Real Soils to 3D-Printed Soils: Reproduction of Complex Pore Network at the Real Size in a Silty-Loam Soil

Pore complexity and micro-heterogeneity are pivotal in characterizing biogeochemical processes in soils. Recent advances in X-ray computed microtomography (microCT) allow the 3D soil morphology characterization of undisturbed samples, although its geometrical reproduction at very small spatial scales is still challenging. Here, by combining X-ray microCT with 3D multijet printing technology, we aimed to evaluate the reproducibility of 3D-printing soil structures at the original scale with a resolution of 80 mm and compare the hydraulic properties of original soil samples with those obtained from the soil-like prototypes. Results showed that soil-like prototypes were similar to the original samples in terms of total porosity and pore shape. By contrast the pore connectivity was reduced by incomplete wax removal from pore cavities after the 3D printing procedure. Encouraging results were also obtained in terms of hydraulic conductivity since measurements were successfully conducted on five out of six samples, showing positive correlation with experimental data. We are confident that future developments of 3D-printing technologies and of their combination with microCT will help to further the understanding of soil micro-heterogeneity and its effects on soil-water dynamics.