Investigation of characteristics and responses of insulating cement paste specimens with Aer solids using X-ray micro-computed tomography

• Aer solids are used for cement paste specimens to enhance the insulating effect.
• Micro-CT and probability functions are used to characterize the void distribution of samples.
• Effect of Aer solids on the material property is examined using experiments and simulations.
• The relationship between the void distribution and the material property is investigated.

Insulating concrete is a type of material designed to enhance energy efficiency by reducing thermal conductivity. It contains numerous voids induced by the use of air-entraining admixtures or aggregates, and these voids strongly affect the characteristics and responses of the material. Thus, appropriate methods to examine the void distribution of materials are needed. Here, X-ray micro-computed tomography (micro-CT) is adopted to investigate the spatial distribution of voids in a material without destroying the specimen. By using micro-CT, a series of cross-sectional images with the micrometer range pixel size can be obtained. Then, void density contour and probabilistic description methods, such as two-point correlation and lineal-path functions, are used to describe the void distribution inside the specimen. In this study, Aer solids, small prefabricated hollow air bubbles, are used for insulating cement paste specimens to increase the insulating effect. The cement paste specimens with different void ratios and Aer solids are generated, and their void distribution characteristics are investigated using the methods mentioned above. The thermal and mechanical responses of the insulating specimens are also evaluated by experiments and numerical methods. The effect of Aer solids on the material characteristics and the relationship between void distribution and material responses are confirmed from the obtained results.