Fabrication, Characterization and Performance of 3D-Printed Sandstone Models

• Author / Creator

  Hodder, Kevin J

• Due to the natural heterogeneity of rock there exists a large variance between samples in geomechanical engineering testing. Additionally, the number of samples available for testing that meet the screening requirements for grain size, mineralogy, bedding orientation and moisture content can reduce the number of samples even further. Specifically, the unconfined compressive strength (UCS) and Young’s modulus, E, can vary considerably, making the repeatability of geomechanical experimental work questionable. 3D-printed model sandstone has been shown to be a viable prospect in minimizing the variance between geomechanical laboratory samples by providing a method of fabricating multiple samples with similar mechanical properties. However, although the macroscopic mechanical properties have been studied, the micromechanical properties governing the macroscopic behavior of 3D-printed sandstone is relatively unknown. Through a research paradigm encompassing processing, structure, properties and performance, 3D-printed sandstone was characterized on a microstructural level and the results reported herein. 3D-printed sandstone was compared and contrasted to Berea sandstone via ultra-violet (UV) fluorescence microscopy where it was found that 3D-printed sandstone contains higher porosity and a two phase organic/inorganic particle coupling that is unlike the crystallized bonds of natural sandstone. Due to the porosity of the samples and the binder jetting technique used to fabricate 3D-printed sandstone, a binder volume fraction limit was discovered via a thermogravimetric technique and a dimensional control study. It was found that samples containing more than 8 vol. % of binder were subject to bleeding through capillary action and pooling through gravity. Through determination of the binder volume fraction limit, the UCS of 3D-printed sandstone was increased by 77 % without any apparent loss of dimensional stability. Additionally, an innovative use of silane coupling agents (SCA) is described that provides a novel prospect of further increasing the UCS of 3D-printed sandstone. The results of a combination of atomic force microscopy (AFM) and nanoindentation techniques are described that present the Young’s modulus of the 3D-printed binder between sand grains, which may be used as a vital parameter in finite element analysis (FEA) modelling of geomaterials. As far as the author knows, the quantification of a micromechanical property between the particles of a geomaterial, although 3D-printed, is a novel prospect. Through quantification of the micromechanical properties of geomaterials, new opportunities for increasing the accuracy of FEA simulations and decreasing the burden on sampling from natural formations may be achieved. By using the information gathered from the processing, structure, property and performance-related studies described herein, the performance in UCS and Young’s Modulus of 3D-printed sandstone was improved and the micromechanical property relationships between binder volume fraction and macroscopic properties is presented.

• Subjects / Keywords

  • Binder
  • Nanoindentation
  • 3d printing
  • Unconfined compressive strength
  • Dimensional control
  • Atomic force microscopy

• Graduation date

  Spring 2018

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3ST7FC07

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.