Resourceful utilization of quarry tailings in the preparation of non-sintered high-strength lightweight aggregates
Resourceful utilization of quarry tailings in the preparation of non-sintered high-strength lightweight aggregates
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DOI：
10.1016/j.conbuildmat.2022.127444
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发表时间：
2022-06
影响因子：
7.4
通讯作者：
Shunfeng Wang;Long Yu;Fei Yang;Weikang Zhang;Linglin Xu;Kai Wu;L. Tang;Zhenghong Yang
中科院分区：
文献类型：
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作者：
Shunfeng Wang;Long Yu;Fei Yang;Weikang Zhang;Linglin Xu;Kai Wu;L. Tang;Zhenghong Yang
采石场尾矿由于其在100 °C以下的稳定晶体结构和丰富的来源而通常被堆放，导致严重的环境影响和高生态风险。以粉煤灰和尾矿为主要原料，研究了粉煤灰和尾矿制备土木工程用轻集料的工艺。提出了一种新的固化制度（高压釜技术），以获得更高的抗压强度的轻骨料。系统研究了养护参数（包括温度和蒸汽压力）对轻集料的抗压强度、吸水率、松装密度、相组成、孔结构和微观结构等性能的影响。另一方面，本研究亦探讨水泥掺量对轻集料基本性质之影响，水泥掺量由30%降低至10%，以降低二氧化碳排放量。结果表明，随着养护温度从25 ° C升高到190 °C，强度从2.48 MPa急剧增加到11.95 MPa，吸水率从11.2%下降到2.09%。在190 °C下，以70%的固体废弃物（粉煤灰和尾矿）为原料制备的轻集料强度最高（11.95 MPa），松散体积密度较低（1160 kg/m3），符合GB/T 17431.1-2010的要求。除样品T25外，LWA的吸水率均低于5%。当水泥含量从10wt%增加到30wt%时，轻骨料的总孔隙率在150 °C时从39.65%降低到26.32%，在190 °C时从42.54%降低到27.24%。同时，孔隙（>50 nm）的百分比也逐渐降低。当养护温度、压力和水泥用量分别高于150 °C、1.00 MPa和10 wt%时，将促进新相组成（方沸石）的形成。这也进一步增加了无害孔隙和少量有害孔隙的强度和百分比。因此，这项研究提供了一种新的固化方法，用于从70至90重量%的固体废物中生产LWA，并且是大规模回收采石场尾矿的快速和可持续的解决方案。
Quarry tailings are usually stockpiled due to stable crystalline structures below 100 °C and abundant sources, which lead to a serious environmental impacts and high ecological risks. This paper presents a study of transforming the fly ash and quarry tailings as the main raw materials into lightweight aggregates (LWAs) for using in civil engineering. A novel curing regime (autoclave technology) has been proposed to obtain higher compressive strength of LWAs. The effects of curing parameters (including temperature and steam pressure) on the properties (compressive strength, water absorption, loose bulk density, phase composition, pore structure and microstructure) of LWAs were systematically evaluated. On the other hand, this research also studies the effect of cement content on the basic properties of LWAs, which was decreased from 30 to 10 wt% for declining the CO2emission. Results show that the strength sharply increases from 2.48 to 11.95 MPa and the water absorption decreases from 11.2 to 2.09% with increasing the elevated curing temperature from 25 to 190 °C. The LWA prepared with 70 wt% solid wastes (fly ash and quarry tailings) at 190 °C achieved the highest strength (11.95 MPa) and the lower loose bulk density (1160 kg/m3), which could meet the requirement of Chinese LWAs standard (GB/T 17431.1-2010). The water absorption of LWAs is below 5% except sample T25. The total porosity of LWAs decreases from 39.65% to 26.32% at 150 °C and from 42.54% to 27.24% at 190 °C while the cement content increases form 10 wt% to 30 wt%. At the same time, the percentage of pores (>50 nm) also gradually decreases. While the curing temperature, pressure and cement usage are above 150 °C, 1.00 MPa and 10 wt% respectively, will promote the formation of new phase composition (analcime). That also further increases the strength and percentage of harmless pores and few harmful pores. Therefore, this research offers a new curing method for producing LWAs from 70 to 90 wt% solid waste and is a rapid and sustainable solution for the large-scale recycling of quarry tailings.