Recycling coarse aggregates from construction and demolition waste is essential for sustainable construction practices. However, the quality of recycled coarse aggregates (RCA) often fluctuates significantly, in contrast to the more stable quality of natural aggregates. Contaminants in RCA notably compromise its quality and usability. Therefore, automating the quality control of RCA is necessary for the recycling industry. This study introduces an industry-focused, innovative, and rapid quality control system that combines Laser-Induced Breakdown Spectroscopy (LIBS) with 3D scanning technologies to enhance the detection of contaminants in RCA streams. The system involves a synchronized application of LIBS for spectral analysis and 3D scanning for the physical characterization of different materials. Results reveal that the dependability of single-shot LIBS analysis has been enhanced, thus elevating the precision of contaminant detection. This improvement is achieved by accounting for the laser shot's angle of incidence and focal length adjustments. The introduced technology holds potential for application in the real-time examination of substantial volumes of RCA, facilitating a rapid and reliable quality control method. This rapid assessment technique delivers online data about the concentration of contaminants in RCA, including recycled fine aggregates, cement paste, bricks, foam, glass, gypsum, mineral fibers, plastics, and wood. This data is both essential and sufficient for choosing a cost-effective mortar recipe and guaranteeing the performance of the final concrete product in terms of strength and durability in construction projects. The system can monitor the quality of RCA flows at throughputs of 50 tons per hour per conveyor, characterizing approximately 4000 particles in every ton of RCA, in this way signaling the most critical contaminants at levels of less than 50 parts per million. With these characteristics, the system could also become relevant for other applications, such as characterizing mining waste or solid biofuels for power plants.

中文翻译：

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回收粗骨料 （RCA） 流的快速质量控制：多传感器集成，实现高级污染物检测


从建筑和拆除废料中回收粗骨料对于可持续建筑实践至关重要。然而，与更稳定的天然骨料质量相比，回收粗骨料 （RCA） 的质量经常波动很大。RCA 中的污染物会严重损害其质量和可用性。因此，自动化 RCA 的质量控制对于回收行业是必要的。本研究介绍了一种以行业为中心、创新和快速的质量控制系统，该系统将激光诱导击穿光谱 （LIBS） 与 3D 扫描技术相结合，以增强对 RCA 流中污染物的检测。该系统涉及 LIBS 的同步应用，用于光谱分析和 3D 扫描，用于不同材料的物理表征。结果表明，单次 LIBS 分析的可靠性得到了增强，从而提高了污染物检测的精度。这种改进是通过考虑激光射击的入射角和焦距调整来实现的。引入的技术具有应用于实时检查大量 RCA 的潜力，有助于实现快速可靠的质量控制方法。这种快速评估技术提供有关 RCA 中污染物浓度的在线数据，包括回收的细骨料、水泥浆、砖块、泡沫、玻璃、石膏、矿物纤维、塑料和木材。这些数据对于选择具有成本效益的砂浆配方和保证最终混凝土产品在建筑项目中的强度和耐久性方面的性能既重要又充分。 该系统可以以每小时 50 吨/小时的速度监测 RCA 流量的质量，表征每吨 RCA 中大约 4000 个颗粒，从而以低于百万分之 50 的水平发出最关键污染物的信号。凭借这些特性，该系统还可以与其他应用相关，例如表征发电厂的采矿废料或固体生物燃料。