Recycled concrete aggregates (RCA) are a widely used recycled building material. RCA materials have many uses such as a road base or backfilling trenches. Our study investigated the potential water-contamination risks of water exposed to RCA materials. We recirculated water for 60 min through four different treatments. Two treatments were a PVC gutter filled with different size grades of RCA material (20 mm and 45 mm), the third treatment was a clean PVC gutter and the fourth and final treatment was an unused concrete water pipe. Results showed that RCA material exposed to water released a suite of contaminants that could be ecologically hazardous to aquatic species. RCA leached metals over the 60-min recirculation (aluminium, arsenic, barium, chromium, lead, manganese, molybdenum, titanium, lithium and strontium). Water exposed to RCA material exceeded aquatic ecosystem guidelines for aluminium by 50 times and lead by up to 12 times. RCA materials increased pH by up to 4.35 pH units and electrical conductivity (EC) by up to 11 times the starting EC (mean 27.9 µs cm−1). We suggest that RCA materials need to be used with caution in settings that could be exposed to water and flow to waterways of conservation value.

中文翻译：

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再生混凝土骨料对水的潜在污染

再生混凝土骨料（RCA）是一种广泛使用的再生建筑材料。RCA 材料有许多用途，例如用作路基或回填沟渠。我们的研究调查了暴露于 RCA 材料的水的潜在水污染风险。我们通过四种不同的处理方法循环水 60 分钟。两种处理是填充不同尺寸等级的 RCA 材料（20 毫米和 45 毫米）的 PVC 排水沟，第三次处理是干净的 PVC 排水沟，第四次也是最后一次处理是未使用的混凝土水管。结果表明，暴露于水中的 RCA 材料会释放出一系列污染物，这些污染物可能对水生物种造成生态危害。RCA 在 60 分钟的再循环过程中浸出金属（铝、砷、钡、铬、铅、锰、钼、钛、锂和锶）。暴露于 RCA 材料的水比铝的水生生态系统指南高出 50 倍，铅高出 12 倍。RCA 材料将 pH 值提高了 4.35 个 pH 单位，电导率 (EC) 提高了起始 EC 的 11 倍（平均 27.9 µs cm-1）。我们建议在可能暴露于水和流向具有保护价值的水道的环境中，需要谨慎使用 RCA 材料。