Bleeding is a common problem in concrete slabs, and may lead to serious damage. The goal of this article is to understand the impact of alternative binders and their properties on the bleeding of concrete. Therefore, the impact of the type of binder on the bleeding process is investigated. The results show that the addition of granite powder or fly ash allows for the increased control of the bleeding process. It was found that a finer particle size distribution (PSD), an increased specific surface area (SSA), and a higher bulk density may reduce the amount of dispensed water in the concrete mix. Furthermore, the use of additives with an increased SSA leads to even a 30% reduction of the bleeding rate of mixes. The utilization of additives with a finer PSD than cement enables a 37% reduction of the bleeding rate of mixes. The influence of bleeding on compressive strength was assessed using destructive and non-destructive tests: Replacing 30% of cement with granite powder leads to a 30% reduction of concrete strength after 28 days of curing; on the other hand, replacing 30% of cement with siliceous fly ash leads to an 18% reduction of strength. Importantly, bleeding was also found to lead to the heterogeneity of the physical and mechanical properties across the concrete section. Consequently, the proper control of the bleeding process leads to more homogeneous properties of concrete across its cross-section.

Siliceous fly ash can be applied as a cement replacement material for mortars used in cement-based floor overlays. At present, there is no knowledge of the appropriate curing conditions that need to be applied on concrete floors. Moreover, previous research related to curing conditions has left research gaps related to the conditions in which such floors are cured. This study focuses on understanding the importance of the curing conditions that are typical for concrete overlays on the physical, chemical, mechanical, and microstructural properties of siliceous fly ash-modified mortars. The results indicate that curing conditions have a significant impact on these properties (particularly long-term effects). Differences were observed between siliceous fly ash-modified mortars cured in different conditions. In this research, we investigated the volume porosity, water absorption, microstructure, hydration process, pore segmentation, and strength of composites that have had cement partially replaced with the addition of fly ash. It should be noted that the use of siliceous fly ash in properly cured mortars that are applied in floor overlays could lead to a better use of green cementitious composites.