Three-dimensional mortars using real-shaped sand particles and uniform thickness interfacial transition zones: Artifacts seen in 2D slices

Published

November 11, 2019

Author(s)

Edward Garboczi, Yang Lu, Aminul Islam, Stephen Thomas

Abstract

All scanning electron microscopic (SEM) examination of mortars are based on two-dimensional (2D) slices through the true three-dimensional (3D) microstructure. Even though stereology guarantees that certain quantities are equal in 3D and in 2D slices of that 3D structure, such as 2D area fractions and 3D volume fractions, there are still many artifacts that are seen in 2D that are different from 3D reality. For example, 2D slices through a 3D random arrangement of monosized spheres gives circles with an apparent size distribution. A mortar containing a size distribution of randomly-shaped sand grains, with uniform thickness interfacial transition zones (ITZs) embedded in bulk cement paste, is much more complicated so that the 2D artifacts are expected to be more complicated. Using the Anm model, we generate mortar models with real (measured) sand particle size and shape distributions, surrounded by uniform thickness ITZs, and then examine 2D slices and discuss the multiple types of artifacts that are generated when real shape particles are used. Artifacts that are seen include: small particles that appear close together but really come from the same 3D particle, joined ITZs that really come from two parts of the same 3D particle, a distribution in apparent ITZ widths, ITZs that appear in the middle of a 2D particle, inner and outer parts of an ITZ that have apparently been inverted, and patches of pure ITZ (so less dense) material appearing by themselves in the middle of bulk cement paste. The Anm model shows the considerable variety of artifacts that can be observed in the 2D slices, which can be mistaken for real 3D features, when in fact they have only been generated by slicing the random 3D microstructure.

Citation

Cement and Concrete Composites

Volume

236

Pub Type

Journals

Download Paper

DOI Link

Keywords

mortar, Anm, interfacial transition zone, SEM, model

Citation

Garboczi, E. , Lu, Y. , Islam, A. and Thomas, S. (2019), Three-dimensional mortars using real-shaped sand particles and uniform thickness interfacial transition zones: Artifacts seen in 2D slices, Cement and Concrete Composites, [online], https://doi.org/10.1016/j.conbuildmat.2019.117590 (Accessed January 16, 2025)