Municipal waste incineration ash contains heavy metals, and the safety of its disposal and reuse is an important issue. In this study, we discussed a safe recycling technology for bottom ash (BA) by utilizing the excellent heavy metal immobilization feature of geopolymer (GP). First, the differences in chemical compositions, physical properties, and heavy metal contents of BAs discharged in different months were investigated. Next, the reaction products and strength of the mixture of BA and alkali-activator (AA) solution were examined to clarify the reactivity of BA in the AA solution. We also investigated the effects of the discharge time of BA, ingredients of AA solution, curing method and mixing ratio of BFS on the setting time, strength and heavy metal immobilization capacity of GP mortar using ground granulated blast furnace slag (BFS) and coal fly ash (CFA) as precursors, and BA as fine aggregate, and discussed reaction products and micro-structure of the GP mortar. The main results are as follows: 1) BA contained a small amount of amorphous phase. Hardened GP monolith using BA and AA solution was not dense and had a very low strength. 2) The BFS/CFA-based GP mortar with BA as fine aggregate had a higher strength and a longer setting time when sodium silicate solution (WG) was used as AA solution than when sodium hydroxide was added or used entirely. The GP mortars using the BAs discharged in the warm season had longer setting time and higher strength. The reaction products of the GP mortar with WG solution and BA were mainly C-A-S-H gels. The leaching of heavy metal elements (HME) from the GP mortars increased with decreasing the alkalinity of leachate, but the effect of BA’s discharge season was not found in this study. The HME leaching concentrations from the GP mortars in non-acidic water environment were less than the HME leaching limits specified for recycled construction materials directly contacting with water, thus the GP materials with BA can be used in dry or non-acidic water environment. However, when used in acidic water environment, the BA content in the GP materials should be reduced.

市政垃圾焚烧灰渣中含有重金属，其处置和再利用的安全性是重要的问题。在这项研究中，我们讨论了利用地质聚合物（GP）优异的重金属固定特性来安全回收底灰（BA）的技术。首先，调查了不同月份排放的BA的化学组成，物理性质和重金属含量的差异。接下来，检查BA和碱活化剂（AA）溶液的混合物的反应产物和强度，以澄清BA在AA溶液中的反应性。我们还研究了BA的排出时间，AA溶液的成分，固化方法和BFS的混合比例对固化时间的影响，以磨碎的高炉矿渣（BFS）和粉煤灰（CFA）为前驱体，BA为细骨料的GP砂浆的强度和重金属固定能力，并讨论了GP砂浆的反应产物和微观结构。主要结果如下：1）BA含有少量的非晶相。使用BA和AA溶液硬化的GP整体块不致密且强度非常低。2）当使用硅酸钠溶液（WG）作为AA溶液时，与添加或完全使用氢氧化钠相比，以BA为细骨料的BFS / CFA基GP砂浆具有更高的强度和更长的凝固时间。使用在温暖季节排放的BA的GP砂浆的凝结时间更长，强度更高。GP砂浆与WG溶液和BA的反应产物主要是CASH凝胶。GP砂浆中重金属元素（HME）的浸出随着渗滤液碱度的降低而增加，但本研究未发现BA排放季节的影响。非酸性水环境中GP砂浆的HME浸出浓度低于直接与水接触的再生建筑材料的HME浸出极限，因此具有BA的GP材料可用于干燥或非酸性水环境中。但是，在酸性水环境中使用时，应降低GP材料中的BA含量。非酸性水环境中GP砂浆的HME浸出浓度低于直接与水接触的再生建筑材料的HME浸出极限，因此具有BA的GP材料可用于干燥或非酸性水环境中。但是，在酸性水环境中使用时，应降低GP材料中的BA含量。非酸性水环境中GP砂浆的HME浸出浓度低于直接与水接触的再生建筑材料的HME浸出极限，因此具有BA的GP材料可用于干燥或非酸性水环境中。但是，在酸性水环境中使用时，应降低GP材料中的BA含量。