Hung Vu Quoc, Jayarathne Ayomi, Gallage Chaminda, Dawes Les, Egodawatta Prasanna, Jayakody Shiran
Faculty of Engineering, Queensland University of Technology (QUT), GPO Box 2434, Brisbane, 4001, Queensland, Australia.
Hydraulic Construction Faculty, National University of Civil Engineering, 55 Giai Phong Road, Hai Ba Trung District, Hanoi, Viet Nam.
Heliyon. 2024 Apr 30;10(9):e30407. doi: 10.1016/j.heliyon.2024.e30407. eCollection 2024 May 15.
Recycled concrete aggregates (RCA) and reclaimed asphalt pavements (RAP) are two construction waste products that are commonly used in the road construction industry. Besides many advantages, pollutants leaching from RCA and RAP are highlighted as the most concerning environmental issue. This study investigated metals leaching characteristics from RCA and RAP due to the variations in key influential factors of pH, dissolved organic carbon (DOC), compaction and liquid to solid ratio (L/S). The leaching tests for RCA and RAP were carried out separately and additionally, the standard leaching test was conducted as the benchmark for leaching investigations. Study outcomes revealed that the combined influences of factors are variable for RCA and RAP, while influences are also variable for individual metals. L/S ratios considerably affect the release of metals from RCA under saturated conditions, facilitating high metal concentrations in the leachate. On the other hand, acidic solutions are more favourable for leaching of metals from RAP. The influence of DOC in solution was minimal on the metal leachability. Interestingly, the increased degree of compaction with a higher density of materials presented the highest negative influence on metal leachability, suggesting that the metal leachability can significantly reduce, in particular when the RCA and RAP are used for the sub-base layers of road structure with a higher degree of compaction. However, the use of these recycled materials under field conditions should be further studied as there is an increasing concern of metal leaching from RCA and RAP with respect to recreational and drinking water thresholds.
再生混凝土骨料（RCA）和再生沥青路面材料（RAP）是道路建设行业常用的两种建筑废料。除了许多优点外，RCA和RAP中污染物的浸出被视为最令人担忧的环境问题。本研究调查了由于pH值、溶解有机碳（DOC）、压实度和液固比（L/S）等关键影响因素的变化，RCA和RAP中金属的浸出特性。分别对RCA和RAP进行了浸出试验，此外，还进行了标准浸出试验作为浸出研究的基准。研究结果表明，这些因素对RCA和RAP的综合影响各不相同，对单个金属的影响也各不相同。在饱和条件下，L/S比显著影响RCA中金属的释放，使得渗滤液中的金属浓度较高。另一方面，酸性溶液更有利于从RAP中浸出金属。溶液中DOC对金属浸出性的影响最小。有趣的是，材料密度越高，压实度增加对金属浸出性的负面影响越大，这表明金属浸出性会显著降低，特别是当RCA和RAP用于压实度较高的道路结构基层时。然而，由于人们越来越关注RCA和RAP中金属相对于娱乐用水和饮用水阈值的浸出情况，因此应进一步研究这些再生材料在现场条件下的使用情况。
