報告書番号

V08031

タイトル（和文）

埋立処分された石炭灰の再資源化に関する研究－既成灰の性状と土工材料としての適用性－

タイトル（英文）

Recycling of landfill coal fly ash - Properties and applicability for geomaterials -

概要 （図表や脚注は「報告書全文」に掲載しております）

石炭灰埋立地において，埋立後12～21年が経過した石炭灰(既成灰)30試料を採取し，化学性状と土工材料としての適用性を調査した。pHの高い既成灰の表面または周囲には，アルミノシリケート水和物やセメント水和物の形成がみられ，BET比表面積が大きくなる傾向がみられた。既成灰にセメントを添加・養生後，基礎物性を調べ，以下を得た。1)最大乾燥密度は0.9～1.1g/cm3程度で，CaO含有量の多い既成灰ほど軽量になる傾向がみられた。2)一軸圧縮強度(qu7)は300kN/m2以上あり，盛土材としても使用できる。3)有害物質の溶出に関しては，3%程度のセメント添加率で土壌環境基準値を満たした。

概要 （英文）

To use a large amount of coal fly ash as a material for construction, flexible fly ash supply systems are needed. This is a point that landfill ash has been receiving attention. But fresh ash and weathered ash may have different properties. In this paper, we investigated chemical properties of weathered ash and its applicability for geomaterials. Weathered ashes that were landfilled 12 to 21 years ago were obtained from a coal ash landfill site. Most weathered ashes contained less Na than fresh fly ashes, and weathered ashes landfilled more than 20 years before contained less SO3. But there was no remarkable difference in other elements. The aluminosilicate hydrate and/or cement hydrate were observed in the alkaline weathered fly ashes so that BET of weathered fly ash increased with high pH. The maximum dry densities of weathered ashes mixed with cement were 0.9 - 1.1 g/cm3, and the density was lowered in the ash with high CaO content. The unconfined compressive strength (qu.7) of weathered ashes mixed with cement was more than 300kPa. The leaching amount of trace elements from weathered ashes showed a decreasing tendency with increasing cement content and that tendency was more remarkable than that from fresh ashes.

報告者

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