The Effect of Waste Mineral Powders on the Structure of Air Voids in Low-Strength Air-Entrained Concrete Floor Screeds

The purpose of the article is to present the results of the evaluation of the structure of air voids in low-strength air-entrained concrete (AEC) floor screeds modified with mineral powders sourced from industrial wastes. Quartz-feldspar and basalt powders were selected for aggregate quarry waste to replace 10%, 20%, and 30% of the mass of the binder. The principal aim of this study is to investigate the effect of adding selected powders on the structure of the air voids in AEC floor screeds. The structure of the air voids was measured using X-ray micro computed tomography (micro-CT). In the analysis, two methodologically different approaches were used, i.e., the volume-equivalent sphere diameter of the air voids and the local structure thickness of the air voids. It was seen that the structure of the air voids in the modified AEC floor screeds is different when compared to the reference AEC floor screeds without powders and non-AEC screeds. It was also shown that the microstructure differs for different amounts and types of used mineral powder.