Fabrication of Reactive Rocks with 3D Printing

Abstract:

Natural samples are inherently heterogenous, a challenge for understanding transport and reactive processes in these systems. In this work, we explore fabrication of reactive rocks through additive manufacturing by integrating reactive materials with polymer filaments to further the understanding of geochemical reactions in porous media. Here, 3D X-ray Computed Tomography (X-ray CT) images of a sandstone sample from the Paluxy formation in Mississippi were used as a template to 3D print a model of the system. Two methods for fabricating a rock structure consisting of a reactive phase that reflects the reactive properties of the real sample are explored here. The first method requires mixing calcite particles with HIPS pellets and extruding the customized reactive filament to be used for printing. The second method consists of dispersing calcite in THF and using the resultant mixture to coat a segment of PLA filament to be used for printing. After rock structures are printed, the relative success of each method is evaluated by optical microscopy, 2D Scanning Electron Microscopy, and 3D X-ray CT imaging. The calcite volume fractions and the exposed calcite surface area are determined in these images using ImageJ and MATLAB. Initial results show calcite accessible surface areas in samples fabricated with calcite-containing filament are comparable to real samples, albeit most of the calcite is inaccessible. This will be compared with accessible surface areas of samples printed with the calcite coated samples. These findings will be used to inform further pathways for utilizing 3D printing as a means of modelling reactive systems in pursuit of a solution that maximizes the exposed surface area of calcite.