新型城市污泥固化土工程特性及微观机理

通过污泥固化技术可以将城市污泥转化为一种新型城市污泥固化土。为了研究污泥固化土工程特性，对新型城市污泥固化土进行无侧限强度试验、收缩特性试验、浸出毒性试验以及X射线衍射试验与微观结构测试。试验结果表明，城市污泥固化土无侧限抗压强度随期龄增加而增长，28 d后基本稳定；新型城市污泥固化土的线缩率随龄期的增大而增大，且28 d后趋于稳定值；与消化后城市污泥相比，城市污泥固化土中的浸出毒性明显减少，重金属浸出量均符合国家规范要求。消化城市污泥衍射峰中氢氧化钙峰值很高，但随着养护期龄的增长，城市污泥固化土中氢氧化钙的衍射峰值减小，碳酸钙的衍射峰值增大，说明固化土各成分反应越充分，强度越高。微结构测试研究表明，污泥固化土SEM图像中有大量的纤维状物质联结着土颗粒和颗粒团块，形成土骨架纤维的交互空间结构，提高了土体强度。

Study of engineering properties and micromechanism of new municipal sludge solidified soil

Through the sludge solidification technology, the municipal sludge is transformed into a new type of municipal sludge solidified soil. In order to study the engineering properties of the sludge solidified soil, the unconfined strength test, shrinkage test, leaching toxicity test and microstructure test are carried out on the new type of municipal sewage sludge solidified soil. The test results show that the unconfined compressive strength of urban sludge solidified soil increases with the aging period, and basically stable after 28 days. The linear shrinkage of new city sludge solidified soil increases with age, and 28 days later tend to a stable value; compared with city sludge solidified soil after digestion, the leaching toxicity of city sludge solidification in soil decreased, the leaching amount of heavy metals are in line with the requirements of national standard. The peak of calcium hydroxide in the urban sludge after lime digestion diffraction peak is very high; but with the increase of curing age, the diffraction peak of calcium hydroxide in the city sludge solidified soil decreased; the diffraction peak of calcium carbonate increased. Microstructure studies show that there is a large number of fibrous material associated with soil particles and agglomerates of particles of city sludge solidified soil in SEM images, interactive spatial structure of soil skeleton fiber, which improves the strength of the soil.