Development of composite geomaterials with immobilization effect of harmful substance and evaluation of recycle efficiency of wastes

在岩土工程领域，已经开发了使用废弃材料的岩土材料。明确这些地质材料对有害物质的固定作用和对环境的负荷程度是十分重要的。在这项研究中，实验室测试调查的渗滤液和机械性能进行了四种类型的岩土材料与固定处理的重金属：水泥处理土，固化材料烘干，塑料熔融固化材料和与木炭的混合物考虑到废物的利用和制造过程中的CO2排放，地质材料以城市生活垃圾焚烧底灰为原料，计算了复合土工材料的回收利用率，评价了其环境影响，制备了不同重金属固定化处理的土工材料，并进行了室内试验。并对废弃物土工材料的生态影响进行了讨论。结果表明：（1）水泥固化土、焙烧固化材料、塑料熔融固化材料和木炭混合物对重金属的固定效果较好;（2）水泥固化土和焙烧固化材料对重金属污染的桑迪具有较好的固定效果，粘土的加入使其固定效果更好。3）基于LCA的概念，计算了垃圾焚烧底灰作为土工材料的CO_2排放量。4）提出了一个表征回收效率的参数。结果表明，该计算方法可用于评价各种岩土材料的再生利用效率。

Geomaterials using waste materials have been developed in the geotechnical engineering field. It is important to clarify immobilisation effect of harmful substances and the extent of environmental load of these geomate-rials. In this study, laboratory tests for investigating the leachate and mechanical properties are carried out on four types of geomaterials with immobilisation treatments for heavy metals : cement-treated soil, baking solidification material, plastic melting solidification material and mixture with charcoal A parameter for representing recycling efficiency is proposed in consideration of the utilisation of waste and CO2 emission in the manufacturing process of the geomaterials. The recycling efficiency of composite geomaterials is calculated using MSW(Municipal Solid Waste) incineration bottom ash, and its environmental impact is evaluated.Geomaterials with various immobilisation treat-ments for heavy metals are produced and several laboratory tests have been carried out. The environ-mental impact of the geomaterials using wastes is also discussed. The following conclusions are ob-tained from this study :1)The immobilisation effects of heavy metals on the cement-treated soil, baking solidification mate-rial, plastic melting solidification material and mix-ture with charcoal are clarified by the results of the leaching test.2)Cement-treated soil and baking solidification material are effective for the immobilisation treat-ment of polluted sandy soil with heavy metals and their effect becomes much greater by mixing clay. Plastic melting solidification material and mixture with charcoal are also effective as new treatment methods.3)CO_2 emission of the geomaterials using MSW incineration bottom ash is calculated based on the concept of LCA.4)A parameter for representing recycling effi-ciency is proposed. It is confirmed that the recycling efficiency of various geomaterials can be evaluated from this calculation method.