Modeling Drying of Cement-Clay Composites with Non-Local Peridynamics

Abstract:

Evaluation of the properties of clay-rich subsurface rocks and minerals are necessary for investigation of geological reservoirs for subsurface disposal and storage. Long term containment within these systems requires a detailed understanding of the swelling and drying nature of cement-clay composites. Modeling provides unique insight into how the distribution of clay in a cement matrix and the shrinkage behavior of each phase impacts the resulting fracture pattern during drying. Here, we use the recently developed nonlocal formulation of continuum mechanics, peridynamics, for investigation of cement-clay systems. Peridynamics uses integrals rather than differential operators to allow for simulation of intersecting and branching fractures that are more likely to occur in natural composite materials. Multiple composite models were developed with both distributed clay and localized clay inclusions and modeled with peridynamics, along with variable shrinkage rates to analyze the impact on the resulting fracture patterns. The modeling results indicate that the distribution of clay in the cement, including the relative difference in shrinkage rates and the size of the clay inclusions, controls the resulting fracture and strength of the material. When compared with experimental results on comparable composite systems, we see similarities in fracture rates and patterns. Our results confirm that peridynamics can be used as a non-local modeling method for evaluation of the impact of variation in shrinkage rates on the properties of cement-clay composites and highlights the most critical material properties in controlling fracture.

Acknowledgment: Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions, LLC., a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under Contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government. The experimental data is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Geosciences Research Program under Award Number (DE-FG02-09ER16022). SAND2020-7529A