市政污泥焚烧飞灰的工程性质

通过室内土工试验等方法分析了与市政污泥焚烧飞灰收集、运输和填埋处置相关的工程性质.结果表明,污泥焚烧飞灰含水率大多低于1.5%,比重为2.15~2.72,渗透性较强;飞灰粒径均值小于100μm,除旋风除尘器灰介于细粒土和粗粒土之间外,飞灰均属于细粒土,粒径分布较为均匀,但大多飞灰级配不良;飞灰的自然休止角为38.8~55.0°,流动性较差,在一定范围内粒径和含水率增加会使休止角减小;飞灰具有较高的界限含水率,但黏性较差;飞灰的最佳含水率与塑限接近,但最大干密度仅0.86~1.20g/cm³,且含水率小于30%时,水分的增加对干密度影响较小;飞灰颗粒较为稳定、难变形,压缩系数小;飞灰的无侧限抗压强度大多随着含水率增加而增大;飞灰与水接触时具有较强的热效应,在填埋体中可能造成堆体温度升高,产生破坏.

Geotechnical properties of sewage sludge incineration ash

The significant increase of sewage sludge incineration presents challenges for the proper management of emerging sewage sludge incineration ash (SSA). The engineering properties of SSA related to collection, transportation and disposal were analyzed by indoor geotechnical tests. The results showed that the moisture contents of SSA were mostly less than 1.5%, the specific gravities were 2.15~2.72, and their permeability was strong. The SSA samples had average particle sizes of less than 100μm, mostly classified as fine-grained soil. Their particle size distribution was relatively uniform, but most SSA were poorly graded. The natural repose angles of SSA were 38.8~55.0°, with poor fluidity. The increase of moisture content reduces the angle of repose. The SSA exhibited high limit moisture contents, but poor viscosity. The optimum moisture content of SSA for compaction was close to the plastic limit, while the maximum dry density was only 0.86~1.20g/cm³. When the moisture content was less than 30%, the increase of moisture had little effect on the dry density. The SSA particles were relatively stable and the compression coefficients were small. The SSA had a strong thermal effect when contacting with water, which could enhance landfill temperature and geotechnical damage.