Air-cooled blast furnace slag (ACBFS) is often used as road construction aggregate. Several incidences of adverse environmental effects have been reported in Indiana where unbound slag has been used. The aggregates that caused issues in the field had been previously approved for use by passing State of Indiana standard slag leaching procedures. The study goal was to test several hypotheses posed to the Indiana Department of Transportation and authors by the industry about slag leaching, and to better understand water quality impacts. Ten slags from two suppliers underwent leaching procedures adopted by two U.S. states, but additional test procedures and material and leachate chemical characterization were also conducted to better interpret results. Aggregates varied in size and age (24 h to 2 years old). Like prior literature reports, the chemical composition among the slag samples was similar. However, water quality impacts observed at the bench-scale in this study differed substantially across the slags. Results were consistent with those previously reported at Indiana field sites, but not with literature reported results from standardized leaching tests (i.e., TCLP, percolation, etc.). In the present study, no relationship was found between slag age and leachate composition. Leachate pH, conductivity, and color levels exceeded thresholds of regulatory and aquatic toxicity significance. For one slag, leachate pH reached 12.9, but the effluent was colorless. During both stagnation and rinsing tests, aqueous chloride, sulfate, and zinc concentrations sometimes exceeded regulatory water quality and aquatic toxicity levels. Repeated rinsing of the slag resulted in water conductivity and sulfate concentration differences. To better understand and predict the impacts of unbound ACBFS, additional fundamental studies and field investigations are recommended. Unbound ACBFS is not recommended for use near environmentally sensitive areas, drinking water sources, habituated areas, and where it may have water contact (i.e., waterways, wetlands, reservoirs, and groundwater).

中文翻译：

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用于道路建设的无结合风冷高炉渣对水质影响的预测差距


风冷式高炉炉渣 （ACBFS） 通常用作道路建设骨料。印第安纳州报告了几起不良环境影响事件，那里使用了未结合的炉渣。在现场引起问题的骨料之前已通过印第安纳州标准炉渣浸出程序批准使用。该研究的目标是检验向印第安纳州交通部和行业作者提出的关于炉渣浸出的几个假设，并更好地了解水质影响。来自两个供应商的 10 个炉渣经过了美国两个州采用的浸出程序，但还进行了额外的测试程序以及材料和渗滤液化学表征，以更好地解释结果。聚集体的大小和年龄各不相同（24 小时至 2 年）。与以前的文献报道一样，炉渣样品之间的化学成分相似。然而，在这项研究中，在实验室规模上观察到的水质影响在炉渣之间差异很大。结果与之前在印第安纳州田间现场报道的结果一致，但与文献报道的标准化浸出测试（即 TCLP、渗滤等）的结果不一致。在本研究中，未发现炉渣年龄与渗滤液成分之间存在关系。渗滤液 pH 值、电导率和色度水平超过了调节和水生毒性显著性的阈值。对于一个炉渣，渗滤液 pH 值达到 12.9，但出水是无色的。在停滞和冲洗测试期间，氯化物、硫酸盐和锌水溶液的浓度有时会超过规定的水质和水生毒性水平。炉渣的反复冲洗导致水电导率和硫酸盐浓度差异。 为了更好地理解和预测未结合的 ACBFS 的影响，建议进行额外的基础研究和实地调查。不建议在环境敏感区域、饮用水源、居民居住区以及可能与水接触的地方（即水道、湿地、水库和地下水）附近使用未结合的 ACBFS。