疏浚淤泥与焚烧底灰混合固化方法的试验研究

针对疏浚泥黏粒含量多、含水率高、强度低等特性,利用生活垃圾焚烧底灰的骨架作用、吸水性能及火山灰活性将其掺加到疏浚淤泥中,以水泥为固化剂,开展固化试验研究。首先对焚烧底灰和疏浚淤泥的理化特性进行了测试和研究,分析了焚烧底灰掺量对疏浚淤泥颗粒级配的改善效果及减水效果。通过不同焚烧底灰掺量的混合料的击实试验及直剪实验,确定了焚烧底灰与疏浚淤泥的最佳配合比为3∶7,此时混合料击实密度最大,减容效果最好。对不同初始含水率的疏浚淤泥采用不同掺量的水泥开展固化配方试验,测试了7~28 d龄期的固化淤泥的抗压强度。测试结果表明:对于初始含水率50%~70%的疏浚淤泥,4%水泥掺量及30%焚烧底灰掺量的固化淤泥抗压强度大于无侧限抗压强度,满足填土材料的强度要求。以水泥为固化剂的焚烧底灰和疏浚泥混合固化技术具有较好的技术和经济可行性,有望应用于工程实践。

Experimental study on solidification method for dredged mud mixed with MSWI

The dredged mud is high in clay content and water content, and it is low in permeability and shear strength. Experimental study on the solidification of dredged mud was carried out by using bottom ash of municipal solid waste incinerator (MSWI) as aggregate material and using cement as solidification material. The physical and chemical properties of MSWI bottom ash and dredged mud were measured. The measurements show that the MSWI bottom ash has properties of aggregates, a significant water absorption ability and a certain volcano ash activity. The addition of MSWI bottom ash into dredged mud will improve its grain size distribution and reduce its water content. Compaction tests and direct shear tests were carried out on the mixture of MSWI bottom ash and dredged mud to determine the optimum mixture ratio. The test results demonstrate that when the ratio of MSWI bottom ash to dredged mud was 3:7, the mixture can be compacted to the maximum dry density,and the volume reduction reached the maximum. Solidification tests were carried out on the dredged mud with different values of initial water content by adding different percentages of cement. Measurements of compressive strength were conducted on the solidified specimens with different curing duration ranging from 7 d to 28 d. The experimental study demonstrate that the addition of 4% cement and 30% MSWI bottom ash into the dredged mud with water content ranging from 50% to 70% produced a solidified material with a compressive strength being greater than 50 kPa, which can be reused for embankment filling materials. The experimental study indicates that the solidification method by adding MSWI bottom ash and cement into dredged mud is cost effective, and can be used in engineering practice.