Recycling of heavy metal contaminated river sludge into unfired green bricks: Strength, water resistance, and heavy metals leaching behavior – A laboratory simulation study
Recycling of heavy metal contaminated river sludge into unfired green bricks: Strength, water resistance, and heavy metals leaching behavior – A laboratory simulation study
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DOI：
10.1016/j.jclepro.2022.130882
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发表时间：
2022-02
影响因子：
11.1
通讯作者：
Y. Maierdan;Kang Gu;Bing-Xin Chen;M. Haque;Y. Zhang;Ling Zhao
中科院分区：
文献类型：
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作者：
Y. Maierdan;Kang Gu;Bing-Xin Chen;M. Haque;Y. Zhang;Ling Zhao
将污泥回收用于建筑材料是降低建筑成本和环境污染的一种有前景的方法。然而，当污泥作为原料时，应考虑污泥的机械特性和环境风险。在这项研究中，将重金属污染的河流污泥（CRS）与半水磷石膏（HPG）、磨碎的粒化高炉矿渣（GGBFS）和波特兰水泥（PC）结合到未烧生砖的生产中。通过无侧限抗压强度（UCS）和耐水性测试确定砖试件的力学性能，同时通过 XRD、TGA 和 SEM-EDS 研究检测水化产物和强度形成机制。此外，TCLP和SPLP测试用于评估重金属释放行为。探索结果表明，随着GGBFS对PC的替代水平的提高，样本的UCS增加。使用 60% CRS、20% HPG 以及 17% GGBFS 和 3% PC 的组合，砖的最高 UCS 和软化系数分别为 15.24 MPa 和 0.94。微观结构分析表明HPG可以与GGBFS和PC反应生成块状钙矾石（AFt）。这些AFt可以桥接石膏晶体以形成致密的网络微结构。此外，本研究中制备的样本表现出优异的重金属固定能力。最佳混合物的重金属固定化率均高于99.41%。
Recycling the sludge in building materials is a promising approach to reduce construction costs and environmental pollution. However, when the sludge is used as a raw material the mechanical properties and environmental risks of sludge should be taken into consideration. In this study, heavy metals contaminated river sludge (CRS) incorporated into the production of unfired green bricks with the combination of hemihydrate phosphogypsum (HPG), ground granulated blast furnace slag (GGBFS), and Portland cement (PC). The mechanical properties of brick specimens were determined by conducting unconfined compressive strength (UCS) and water resistance tests, while the hydration products and strength formation mechanism were detected by XRD, TGA, and SEM-EDS investigation. Furthermore, the TCLP and SPLP tests were used to assess the heavy metals releasing behavior. The explored results show that the UCS of samples increases with the rise of the replacement level of PC by GGBFS. The highest UCS and softening coefficient of bricks were 15.24 MPa and 0.94 using the combinations of 60% CRS, 20% HPG along with 17% GGBFS and 3% PC. The microstructural analysis revealed that HPG could react with GGBFS and PC to generate massive ettringite (AFt). These AFt may bridge gypsum crystals to form a dense network microstructure. Additionally, specimens prepared in this study exhibited an excellent fixing capacity for heavy metals. The heavy metal immobilization rates of the optimal mixture were all higher than 99.41%.