Characterization of Pore Geometry of Indiana Limestone in Relation to Mechanical Compaction

Abstract

We studied the pore structure in intact and inelastically compacted Indiana limestone using X-ray microtomography imaging. Guided by detailed microstructural observations and using Otsu's global thresholding method, the 3D images acquired at voxel side length of 4 μm were segmented into three domains: solid grains, macropores and an intermediate zone dominated by microporosity. The macropores were individually identified by morphological processing and their shape quantified by their sphericity and equivalent diameter. Our new data revealed a significant reduction of the number of macropores in hydrostatically and triaxially compressed samples with respect to the intact material, in agreement with previous microstructural analysis. The intermediate (microporosity) domains remained interconnected in compacted samples. Our data suggest that the inelastic compaction in Indiana limestone is manifested as not only a decrease in the volume fraction of the microporosity backbone but also a corresponding decrease in its thickness. © 2012, IFP Energies nouvelles.