Using fine sand shape metrics determined from X-ray microcomputed tomography to illustrate the influence of particle shape on the properties of dispersed mortars

Published

July 10, 2021

Author(s)

Edward Garboczi, Jeffrey W. Bullard, Olafur Wallevik, Pierre Estephane

Abstract

This study follows a first paper written on some three-dimensional geometrical quantities of a selection of sand particles from the United Arab Emirates (UAE), determined using a combination of X-ray microcomputed tomography (µCT) and spherical harmonic analysis, and their correlation to the properties of mortars made with these sands, with no added dispersant. This paper studies other shape metrics of these same sands, the degree of convexity and the Hoffman shape entropy, and the influence of particle shape, as judged from these shape parameters, on the water demand and other properties of dispersed mortars. Five sands from different sources were sampled, wet sieved, and classified into six sieve size classes: 20 µm to 75 µm, 75 µm to 150 µm, 150 µm to 300 µm, 300 µm to 600 µm, 600 µm to 1.18 mm and 1.18 mm to 2.36 mm. The paper discusses the methods of sample preparation, µCT scanning, and the classification of particles based on their shape. The mortars used a dispersant agent enabling experiments to be conducted at low levels of water to cement mass ratios. A cause and effect relation was established between sand particle shape, in the presence of a dispersant, and properties of mortars such as the wet packing density, the workability in the form of slump-flow, and the water demand. A relationship between plastic density, after the peak of packing, the volumetric water to cement mass ratio (vw/c), and workability, as measured by slump- flow, was developed.

Citation

Cement and Concrete Composites

Volume

123

Pub Type

Journals

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DOI Link

Keywords

mortar, sand, workability, particle shape, wet packing density, X-ray tomography, spherical harmonics, plastic density, slump flow, water demand, volumetric water to cement mass ratio

Citation

Garboczi, E. , Bullard, J. , Wallevik, O. and Estephane, P. (2021), Using fine sand shape metrics determined from X-ray microcomputed tomography to illustrate the influence of particle shape on the properties of dispersed mortars, Cement and Concrete Composites, [online], https://doi.org/10.1016/j.cemconcomp.2021.104176 (Accessed October 4, 2024)