The effect of differential mineral shrinkage on crack formation and network geometry

Jeremy E. Trageser (1), Chven A. Mitchell (2) (3), Reese E. Jones (4), Edward N. Matteo (3), Jessica M. Rimsza (5), Laura J. Pyrak-Nolte (2) (6) (7)
Scientific Reports. (23 December 2022). DOI: https://doi.org/10.1038/s41598-022-23789-3

Keywords

Civil engineering, geophysics, structural materials

Abstract

Rock, concrete, and other engineered materials are often composed of several minerals that change volumetrically in response to variations in the moisture content of the local environment. Such differential shrinkage is caused by varying shrinkage rates between mineral compositions during dehydration. Using both 3D X-ray imaging of geo-architected samples and peridynamic (PD) numerical simulations, we show that the spatial distribution of the clay affects the crack network geometry with distributed clay particles yielding the most complex crack networks and percent damage (99.56%), along with a 60% reduction in material strength. We also demonstrate that crack formation, growth, coalescence, and distribution during dehydration, are controlled by the differential shrinkage rates between a highly shrinkable clay and a homogeneous mortar matrix. Sensitivity tests performed with the PD models show a clay shrinkage parameter of 0.4 yields considerable damage, and reductions in the parameter can result in a significant reduction in fracturing and an increase in material strength. Additionally, isolated clay inclusions induced localized fracturing predominantly due to debonding between the clay and matrix. These insights indicate differential shrinkage is a source of potential failure in natural and engineered barriers used to sequester anthropogenic waste.

How Our Software Was Used

Initial data analysis involved thresholding segmentation to generate regions of interest (ROIs) for the extraction of different networks (unconnected round pores and connected cracks), quantification of sample properties (length, diameter, volume, porosity, damage), and comparison of the different sample types.

Author Affiliation

(1) Center for Computing Research, Sandia National Laboratories, Albuquerque, NM, USA
(2) Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA
(3) Nuclear Waste Disposal Research and Analysis, Sandia National Laboratories, Albuquerque, NM, USA
(4) Mechanics of Materials, Sandia National Laboratories, Livermore, CA, USA
(5) Geochemistry Department, Sandia National Laboratories, Albuquerque, NM, USA
(6) Department of Physics and Astronomy, Purdue University, West Lafayette, IN, USA
(7) Lyles School of Civil Engineering, Purdue University, West Lafayette, IN, USA