Pocius Edvinas, Nagrockienė Džigita, Pundienė Ina
Department of Building Materials and Fire Safety, Faculty of Civil Engineering, Vilnius Gediminas Technical University, Sauletekio al. 11, LT-10223 Vilnius, Lithuania.
Materials (Basel). 2023 Mar 22;16(6):2531. doi: 10.3390/ma16062531.
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.
在混凝土制造业中，会产生大量废弃物。这类废弃物可用于生产碳足迹较低的更具可持续性的产品。在本研究中，对混凝土污泥进行了调查，混凝土污泥是一种难以利用的废弃物，它是通过冲洗混凝土搅拌车从残留混凝土中获得的。冲洗过程中，混凝土混合物中的骨料被分离出来，剩余的不溶性细颗粒与水结合形成混凝土污泥。试验中使用了干燥和湿润的混凝土污泥。用干燥和湿润的混凝土污泥、水泥、高效减水剂和自来水制备了不同成分的样品。通过用干燥混凝土污泥（0%、5%、10%、15%、20%、25%和30%）部分替代水泥，制备了七种不同成分的水泥浆体。在含有湿润混凝土污泥的成分中，水泥的替代量与干燥混凝土污泥的情况相同。测定了新鲜水泥浆体的坍落度、凝结时间以及它们随不同量混凝土污泥的变化情况。结果发现，随着混凝土污泥形式的不同，混合物的工艺性能会发生变化，凝结时间会缩短。通过扫描电子显微镜（SEM）和X射线衍射（XRD）试验证实了密度、抗压强度和抗折强度的结果。研究结果表明，干燥混凝土污泥会导致水泥石力学性能恶化，而湿润混凝土污泥则能改善水泥石的力学性能。然而，发现用5%的干燥混凝土污泥替代水泥对硬化水泥石的性能没有显著影响。在含有湿润混凝土污泥的混合料中，推荐的水泥替代量为10%，因为更大的替代量会对混合物的工艺性能产生强烈影响。
