Three‐Dimensional Printing of Macropore Networks of an Undisturbed Soil Sample

Abstract

Macropore systems predominantly determine rapid water flow and solute transport in undisturbed soils. Repeated experiments are needed to investigate the relationship between the nature of the macropore network and the resulting water and solute transport under different hydraulic initial and boundary conditions. However, the large heterogeneity in soil macropore network structures renders each soil sample unique and multiple identical samples impossible. In addition, the fragile nature of soil strongly limits the possible number of repeated experiments on one individual sample. Micromodels that mimic the precise shape and location of the macropores in undisturbed soil are therefore necessary to allow repeated experiments. In this study we investigated whether such micromodels can be obtained using contemporary three‐dimensional (3‐D) printing techniques and materials. We used X‐ray computed tomography to digitize the 3‐D macropore structure of an undisturbed soil sample. We printed a subsection of this macropore system in five different materials. Four out of the five investigated materials had essential parts of their macropore system clogged with residual printing or printing‐aid material. Only one reprint, namely the prime‐gray sample that was printed using stereo lithography, exhibited no pore clogging and had the largest hydraulic conductivity of all investigated reprints. Prime gray showed subcritical water repellency with a medium contact angle of approximately 65°, which is similar to contact angles found in natural soil. We conclude that the 3‐D printing of undisturbed soil macropore systems is in principle possible with contemporary 3‐D printing systems.

Estimating the Permeability of Naturally Structured Soil From Percolation Theory and Pore Space Characteristics Imaged by X‐Ray

“…These images were taken before and after presaturation and K s measurement and show evidence of both pore space consolidation and shrinkage crack formation. One potential solution to this problem would be to make measurements on printed copies of X‐ray imaged samples, although some technical issues remain to be resolved (Bacher et al, ).…”

Understanding Preferential Flow in the Vadose Zone: Recent Advances and Future Prospects

“…However, it is often problematic to repeat experiments on the same soil sample because it may cause temporal changes in pore space properties. In such cases, it may prove advantageous to make use of more durable three‐dimensional printed copies of soil macropore networks imaged by X‐ray (e.g., Bacher et al, 2015). Further improvements in process understanding can also be expected from studies that use two or more complementary noninvasive imaging techniques.…”

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

“…This technology has been proposed in research as a tool to integrate virtual microCT information with real building models. In fact, the combination of such techniques make it possible to reconstruct complex microcosms with the heterogeneity discovered with microCT at a resolution of few micrometers, providing the opportunity to isolate the physical and chemical aspects that govern the biogeochemical and microbial processes in the soil (Otten et al, 2012;Ju et al, 2014;Bacher et al, 2015;Ringeisen et al, 2015). Nowadays, with 3D printing the diversified geometry encountered in a soil can be replicated at a resolution of tends of micrometers.…”