3D PRINTING MUDROCKS: EXPERIMENTS IN VALIDATING THE 3D-PRINTING PROCESS WHEN USING KAOLINITE CLAY AS A BUILD MATERIAL

3D Printing technologies have the ability to turn digital, 3D designs into tangible, lab-testable objects. While 3D printing in plastic and granular materials is quite common now, new equipment has been developed that can 3D print using paste-like materials (e.g., clay, Portland cement). This study was initiated to characterize simple core-plug-sized models to evaluate whether this technology can be applied to producing 3D printed analogs for mudrocks. Most models produced were designed as solid one-inch diameter cylinders, one-inch tall in two different types of clay. Models were printed on a DeltaWASP 60100 with the DeltaWASP low-density material extruder kit.

Models displayed negligible dimensional loss after desiccation, but shrank considerably after first firing (8-12% loss for both height and diameter). Mass loss was 8-11% after first firing. A second firing yielded 5-6% loss for height and diameter, 0.1-0.2% mass loss. Models produced from Clay Type 1 reduced from ~39% porosity after desiccation to ~7% after first firing to ~1% after second firing. Clay Type2 reduced its porosity less with firing going from ~36% to ~23% to ~10%.

For Clay Type 1, mercury intrusion porosimetry experiments showed modal pore throat size decreased from ~2.5 microns to ~0.3 microns after first firing. After a second firing, this value decreased ~0.15 microns and second, smaller peak appeared at ~0.05 microns. Using the values provided in Nelson (2009, AAPG Bulletin), these size correlate with a fine siltstone/tight sandstone, tight sandstone, and a shale, respectively. The reduction in pore throat size suggests that the pore throat size distribution can be modified by adjusting the parameters of the firing process.