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Relationship between fine aggregate size and the air void system of six mortars: I. Air void content and diameter distribution



Edward Garboczi, Kai Lyu, Yufeng Gao, Changwen Miao


The air void network, as part of the pore structure of cement-based materials, controls their freeze- thaw durability. Precisely determining the characteristics of the air void system is important in material design and freeze-thaw durability evaluation. In previous research, X-ray computed tomography (XCT) has been used in air void system characterization, since it is able to measure the 3D spatial arrangement of the voids. Though the factors influencing air void formation and arrangement have been well-studied, the role of fine aggregate size and gradation has mainly been ignored. In this paper, seven mortars were prepared with varying size distributions and blended proportions of sand and their air void system quantitatively characterized via XCT. The role of sand size distribution and blended proportions were combined via calculation of the fine aggregate specific surface area (SSA), and a roughly linear relationship between SSA and global void content was observed. Based on digital image processing methods and spherical harmonic (SH) functions, the 2D circle diameter distribution and 3D sphere diameter distribution were derived from 2D analysis of each slice and 3D analysis of the stacked 3D microstructure, respectively. The two different dimensional distributions were also calculated from each other using stereological methods and compared with the original experimental results. The air void size distributions for several of the mortars were obtained via high resolution (small voxel size, small scan volume) and low resolution (large voxel size, large scan volume) XCT scans, which were compared in a compatible size range in order to verify the reliability of the results.
Cement and Concrete Composites


air void, aggregate size and gradation, X-ray computed tomography, air void content, sand size distribution, air void size distribution, scan resolution, mortar


Garboczi, E. , Lyu, K. , Gao, Y. and Miao, C. (2022), Relationship between fine aggregate size and the air void system of six mortars: I. Air void content and diameter distribution, Cement and Concrete Composites, [online], (Accessed June 13, 2024)


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Created May 23, 2022, Updated February 7, 2023