Influence of the mixing processes in concrete with aggregates coarse recycled concrete

Abstract The reuse of construction waste is a strategy employed to achieve sustainability, however, only a small number of construction initiatives use it. The variability of concrete residue is an inherent condition of this product and it must be considered. The control of the production process of concrete produced with concrete waste can improve the quality of the final composite. This paper aims to evaluate the effect of the mixing process and the mixer type on the fragility of recycled coarse aggregate concrete and to investigate their influence on compressive strength. This study also evaluates the effect of the mixer on concrete performance. Recycled coarse aggregate concrete was used as a total replacement for natural coarse aggregate. The results showed no significant differences between concrete produced from different types of mixtures, however, both yielded satisfactory compressive strength results at 28 days. However, the mixtures made in the vertical shaft mixer were more efficient than the mixtures produced in the inclined axis mixer, as the concrete produced by the former presented a lower variation coefficient. The study concluded that the equipment's characteristics contributed to better uniformity, leading to less variability in the resulting concrete.摘要 建筑垃圾资源化再利用是实现建筑业可持续发展的重要策略，但当前仅有少数建筑工程项目实践采用该技术路径。废弃混凝土料的变异性是该类再生材料的固有属性，必须在生产过程中予以充分考量。对以废弃混凝土制备再生混凝土的生产流程进行管控，可有效提升最终复合建材的质量。 本研究旨在探究搅拌工艺与搅拌设备类型对再生粗骨料混凝土（Recycled Coarse Aggregate Concrete）脆性性能的影响，并分析二者对抗压强度的作用机制；同时考察搅拌设备类型对混凝土综合性能的影响。本试验采用再生粗骨料完全替代天然粗骨料，制备再生混凝土试样。 试验结果表明，不同搅拌工艺制备的混凝土未呈现显著性能差异，但二者在标准养护28天时均获得了令人满意的抗压强度表现。相较于斜轴搅拌机制备的混凝土拌合物，立轴搅拌机制备的拌合物性能更优，前者所制混凝土的变异系数更低。 本研究最终得出结论：搅拌设备的自身特性有助于提升拌合物均匀性，进而降低最终再生混凝土的性能离散程度。