摘要
为大规模消纳生活垃圾焚烧灰渣,采用飞灰为原材料制备地聚合物,并论证地聚合物代替水泥用于稳定尾渣路基填料的可行性。首先,以基础材料(飞灰和偏高岭土)和碱激发剂(NaOH和Na_(2)SiO_(3))为原材料,改变A(SiO_(2)与Al_(2)O_(3)的质量比)、B(Na_(2)O与SiO_(2)的质量比)和C(水与基础材料的质量比)3个参数,采用正交试验设计了16种地聚合物配比,并基于抗压强度和重金属浸出浓度确定其最佳配比;其次,研究了陈化时间、搅拌时间和固化温度对地聚合物抗压强度的影响,并采用微观测试考察了飞灰地聚合物的化学组成、官能团以及表面微观结构;最后,测试飞灰地聚合物稳定尾渣的加州承载比(CBR)和有害重金属浸出浓度。研究结果表明:飞灰地聚合物的最佳配合比为A=7.0、B=0.82、C=0.66,最佳配合比下的飞灰地聚合物3 d和28 d抗压强度分别为14.54、15.78 MPa;制备地聚合物时,陈化时间宜为3 h、搅拌时间宜为1 min、固化温度宜为60℃;反应生成的C—S—H、N—A—S—H、钙矾石(AFt)以及CaCO_(3)等互相搭接形成三维网状结构,是地聚合物强度形成的主要原因;有害重金属通过物理吸附和化学键合的双重作用被固封在网状结构中;地聚合物稳定尾渣的CBR满足高等级公路技术要求,当聚合物掺量为6%和12%时,地聚合物稳定尾渣的有害重金属浸出浓度分别满足Ⅳ类和Ⅲ类地下水质量标准。
To promote the large-scale utilization of fly ash and tailings left from domestic waste incineration slag,the possibility of using geopolymers prepared from fly ash instead of cement to stabilize tailing as subgrade filler was studied.The base materials(fly ash and kaolin)and alkali activators(NaOH and Na_(2)SiO_(3))were selected as raw materials for the preparation of fly-ash based geopolymers.Sixteen geopolymer proportions were designed using orthogonal tests with three parameters:A(mass ratio of SiO_(2)to Al_(2)O_(3)),B(mass ratio of Na_(2)O to SiO_(2)),and C(mass ratio of water to base material).The compressive strength and heavy metal leaching concentration of the 16 geopolymers were investigated to determine the optimal geopolymer proportion.The effects of aging time,mixing time,and curing temperature on the strength of the 16 geopolymers were investigated.The chemical composition,functional groups,and surface microstructures of the prepared geopolymers were investigated using microscopic tests.Finally,the California bearing ratio(CBR)and leaching concentration of harmful heavy metals in geopolymer-stabilized tailings were tested.The recommended optimal proportion of the fly-ash based geopolymer is A=7.0,B=0.82,and C=0.66,with the compressive strengths when cured for 3 d and 28 d being 14.54 MPa and 15.78 MPa,respectively.When preparing geopolymers,an aging time of 3-8 h,a mixing time of 1 min,and a curing temperature of 60℃are appropriate.The C-S-H,N-A-S-H,ettringite(AFt),and CaCO_(3)produced by the reaction overlap to form a three-dimensional network structure,which primarily contributes to the strength of the geopolymer.Harmful heavy metals are fixed in the network structure through the dual roles of physical adsorption and chemical bonding.The CBR of geopolymer-stabilized tailings satisfies the technical requirements for high-grade highways.When the geopolymer contents are 6%and 12%,the harmful heavy-metal leaching concentrations of the geopolymer-stabilized tailings meet the quality standards for Cla
作者
纪小平
刘杰
董鑫泽
朱世煜
李晓娟
JI Xiao-ping;LIU Jie;DONG Xin-ze;ZHU Shi-yu;LI Xiao-juan(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China;Xinjiang Transportation Planning,Survey,Design and Research Institute Co.Ltd.,Urumqi 830006,Xinjiang,China;College of Civil Engineering and Architecture,Xinjiang University,Urumqi 830046,Xinjiang,China;Hefei Municipal Design and Research Institute Co.Ltd.,Hefei 230041,Anhui,China;Shaanxi Jiaokong Technology Development Group Co.Ltd.,Xi'an 710075,Shaanxi,China)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2023年第10期30-41,共12页
China Journal of Highway and Transport
基金
陕西省重点研发计划项目(2023-YBSF-390)
新疆交通设计院公司科研基金项目(KY2022080901,KY2022042501)
陕西省交通科技项目(23-97k)。
关键词
路基工程
飞灰地聚合物
微观测试
力学强度
重金属浸出浓度
生活垃圾焚烧灰渣
subgrade engineering
fly ash-based geopolymer
microscopic test
mechanical strength
heavy metal leaching concentration
domestic waste incineration slag
