3D printing of rock analogues in sand: a tool for design and repeatable testing of geomechanical and transport properties

Abstract

Natural rocks can be heterogeneous due to complex diagenetic processes that affect mineralogy and pore architecture. Correlation of geomechanical and transport properties of rocks in three dimensions can lead to large variances in data when tested experimentally. 3D-printing of rock analogues in sand is a promising alternative for experimental testing that can be used to calibrate variables during geotechnical testing. While 3D-printed sand is a homogeneous material, the parameters for creating grain packing and pore infill can be tuned to mimic specific geomechanical and transport properties. Initially, 3D-printed specimens have a low density due to a loose distribution of grains. Herein, we present our efforts at increasing the density through incorporating a roller in the printing process to compact individual layers. We also propose introduction of a more heterogeneous sand mixture that encompasses a wide range of grain-size distributions. Lastly, a discussion between binder saturation (that infills the pore space) of 3D-printed specimens and the axial strength, dimensional control, and porosity is described within. 3D printing of rock analogues is critical in pursuing rigorous destructive tests required for geotechnical and geological engineering because it can provide repeatable, controlled data on rock properties.