Comparison of the pore size distributions of concretes with different air-entraining admixture dosages using 2D and 3D imaging approaches

Sang-Yeop Chung,Teresa Rucinska,Pawel Sikora,Mohamed Abd Elrahman,Dietmar Stephan

doi:10.1016/j.matchar.2020.110182

Abstract

This study aims to more accurately investigate the pore size distribution of air voids in cement-based materials. For this purpose, micro-computed tomography (micro-CT) images were used to describe the inner structure of target materials, without damaging them. Together with the data obtained and the imaging techniques used, the pore structures of the specimens were visualized in 3D, with the pore size distributions being investigated using a volume-based method. The chord-length distribution, another approach to describe heterogeneous pore characteristics, was computed from 3D micro-CT images and compared with the conventional method. A RapidAir 457, an automated air void analyzer, was also used as a reference, with the results obtained being quantitatively and qualitatively compared using several curve fitting algorithms. The correlation between the pore characteristics and the mechanical properties of the specimens was examined, with the results indicating that the pore size distribution described using chord-length distribution is more effective than the conventional volume-based method. The results obtained can be utilized to investigate and predict material properties.

Highlights

As concrete structures are exposed to various harmful environments, studies relating to the durability of cementitious composites have been receiving a great deal of attention
As expected, the density of fresh concrete was found to be negatively correlated to the air-entraining admixtures (AEA) content
As expected, more air bubbles were generated in plastic concrete with the addition of AEA

Summary

Introduction

As concrete structures are exposed to various harmful environments, studies relating to the durability of cementitious composites have been receiving a great deal of attention. The threat related to the deterioration of concrete through freeze-thaw cycles is of high importance in major applications such as pavements, dams, foundations or bridges [1]. The content, size, and distribution of air pores, are critical regarding durability and in reference to the physical/mechanical properties of concrete structures [2]. In addition to frost-related properties, other important properties of cement-based composites such as permeability, compressive strength, or thermal conductivity are strongly affected by the pore structures of a material [5,6,7,8,9]

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Results

Conclusion