In the concrete manufacturing industry, a large amount of waste is generated. Such waste can be utilised in the production of more sustainable products with a low carbon footprint. In this study, concrete sludge, a difficult-to-utilise waste that is obtained from residual concrete by washing a concrete truck, was investigated. During washing, aggregates from the concrete mixture are separated, and the remaining insoluble fine particles combine with water to form concrete sludge. Dried and wet concrete sludge were used in the tests. Samples with different compositions were produced with dried and wet concrete sludge, cement, superplasticiser, and tap water. Seven cement pastes with different compositions were made by partially replacing cement with dried concrete sludge (0%, 5%, 10%, 15%, 20%, 25%, and 30%). In compositions with wet concrete sludge, cement was replaced by the same amounts as in the case of dried concrete sludge. The slump, setting time, and their changes with different amounts of concrete sludge were determined for fresh cement pastes. It was found that with different forms of concrete sludge, the technological properties of the mixtures change, and the setting time decreases. The density and compressive and flexural strength results were confirmed by SEM and XRD tests. The research results show that dry concrete sludge causes the deterioration of the mechanical properties of cement stone, while wet concrete sludge improves the mechanical properties of cement stone. However, it was found that replacing 5% cement with dry concrete sludge does not significantly affect the properties of hardened cement stone. In mixes with wet concrete sludge, the recommended amount of replaced cement is 10%, because the technological properties of the mixture are strongly influenced by larger amounts.

The article analyses what effect crystallization additive usage has on concrete physical and mechanical properties and shrinkage to find most effective concrete additive. Investigations of concrete properties with various amounts of crystallization admixture were performed. 9 concrete mixtures with different amounts of crystallizing admixtures were formed and admixtures were added to the concrete mixes from 0.6% to 1.4% of the cement mass, in increments of 0.1%. During the research, the influence of the amount of crystallization admixture the density of hardened concrete, flexural strength, compressive strength, and shrinkage was determined. After evaluating the physical, mechanical properties and shrinkage of the concrete, it was determined that the optimal amount of crystallizing admixture in the concrete mixture is 1% of the cement mass. Thus, it can be argued that the use of a crystallizing admixture has a positive effect i.e., reduces the shrinkage of concrete, because of which cracks in concrete structures can be avoided.

The growing global consumption of concrete is driving up the demand for cement, which has a negative environmental impact due to intensive CO₂ emissions. This impact can be reduced by replacing cement with reactive mineral industrial waste, simultaneously addressing the issue of waste accumulation in landfills. However, to ensure the effective use of such materials, it is essential to comprehensively investigate their influence on concrete durability. This study analyzes glass processing waste (GPW) generated during glass grinding. The waste is removed using water, resulting in the formation of glass processing waste. In the experiment, CEM I 42.5 R cement, GPW, sand, crushed dolomite stone, concrete sludge (CS), chemical admixtures, and water were used. In the tests, cement was replaced with glass processing waste in amounts ranging from 5% to 30%, analyzing a total of seven different compositions. The properties of the sustainable concrete mixture were evaluated, and the mechanical–physical properties of the hardened concrete were determined. Resistance to alkali–silica reaction was tested according to the RILEM AAR-4 methodology, while the environmental impact of glass processing waste was assessed using Life Cycle Assessment (LCA). The results showed that glass processing waste increases the concrete’s resistance to alkali corrosion: as the amount of waste increased, a smaller change in the linear dimensions of the specimens was recorded, and the lowest mass loss was found in the composition where 20% of the cement was replaced by glass processing waste. The environmental impact assessment confirmed a direct correlation—as the amount of glass waste increases, CO₂ emissions decrease proportionally. To produce sustainable concrete, it is recommended to use up to 20% glass processing waste: this allows for the maximum reduction in environmental impact while maintaining mechanical properties and high resistance to alkali–silica reaction.