摘要
采用浸没燃烧工艺产生的生活垃圾卫生填埋场浓缩液污泥具有含水率高、有机质含量和重金属含量低,但含盐量极高的特点。选用硫铝酸盐水泥作为主固化剂,垃圾焚烧飞灰和底渣作为辅助固化剂,制备不同水泥、飞灰和底渣掺量的固化污泥试样,进行一系列的无侧限抗压试验、水稳定性试验和微观测试试验,以定量分析不同固化剂对浓缩液污泥的固化效果,探索固化污泥强度演化规律和浸水劣化机制的宏微观耦合控制机制。试验结果表明:单掺10%水泥,固化污泥的7 d无侧限抗压强度大于50 kPa,即可达到填埋的强度要求;当单掺50%以上的水泥时,28 d龄期的固化污泥才具有满足填埋强度要求的水稳定性;飞灰和底渣对水泥固化试样28d强度的提升存在一个最优掺量,分别为5%(水泥掺量<40%)和10%(水泥掺量≥40%);在水稳定性方面,复掺底渣较复掺飞灰有效。扫描电镜(SEM)和X射线衍射(XRD)微观测试结果表明:水泥与一定量的飞灰或底渣共同生成的针柱状钙矾石晶体与水泥水化产物形成空间镶嵌互锁结构,是掺飞灰或底渣固化试样水稳定性提高的主要原因。
The concentrated solution sludge(CSS)produced by submersion combustion process has special characteristics,such as high water content,low organic matter and heavy metals content and extremely high salinity.In this study,sulfoaluminate cement(SAC)was used as the main curing agent,and two kinds of waste incineration fly ash and bottom ash were added as auxiliary curing agents to quantificationally investigate the influence of different curing agents on the solidification effectiveness of CSS,and various solidified CSS samples with a variety of curing agent combinations were prepared for a series of unconfined compressive strength tests,water stability tests and microscopic observation tests.The results show that the strength of CSS solidified with 10%SAC can meet the strength requirement(50 kPa)of landfill under the condition of 7 d curing age;the 28 d strength of the cement solidified samples meet the requirement of water stability as the SAC content exceeds 50%.The optimal dosages of fly ash and bottom ash of 28 d solidified samples are 5%(SAC content<40%)and 10%(SAC content≥40%).Bottom ash is more effective than fly ash for improving water stability of solidified samples.The SEM and XRD results show that the formation of interlocked structure composed of hydration product of cement and ettringite crystal generated from the interaction between SAC and fly ash or bottom ash,is the major factor improving the water stability of solidified samples with a certain dosage of fly ash or bottom ash.
作者
梁仕华
冯德銮
LIANG Shi-hua;FENG De-luan(School of Civil and Transportation Engineering,Guangdong University of Technology,Guangzhou,Guangdong 510006,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2022年第6期1453-1468,共16页
Rock and Soil Mechanics
基金
国家自然科学基金(No.52078142)
广州市科技计划项目(No.202002030194)。
关键词
浓缩液污泥
极高含盐量
固化稳定化
垃圾焚烧副产物
水稳定性
concentrated solution sludge
extremely high salinity
solidification/stabilization
waste incineration by-products
water stability
