| 摘要: | 最終處置場為長期貯存具高放射性用過核子燃料之設施，有效及安全的將用過核子燃料進行儲放為各國高度重視的長期安全性議題。處置場地下設施所使用之混凝土，為避免影響緩衝材料的預期成效，各國傾向採用低鹼性混凝土。目前低鹼性混凝土(Low pH concrete)係由瑞典、芬蘭及日本等各國進行國際合作研究所獲得成果為基礎，主要以使用矽灰、飛灰、爐石粉等礦物摻料，進行重量比例取代卜特蘭水泥製成。
為了瞭解處置場用混凝土與其他障壁材料及場外周邊環境之交互作用，
以及礦物摻料(矽灰、飛灰)對降低處置場混凝土孔隙溶液pH 值及其他工程特性之影響，本研究分別進行處置場低鹼性封塞用自充填混凝土(SCC)於使用不同礦物摻料下之工程特性，以及透過文獻蒐集彙整之方式瞭解混凝土與處置場周邊環境之互動關係，並於工程特性探討部分，使用礦物摻料矽灰及飛灰部分取代水泥，對混凝土之新拌性質、硬固性質及耐久性質等試驗進行分析與探討。
於處置場環境互動關係部分，國際文獻對混凝土孔隙溶液長期模擬結果顯示，其對處置場膨潤土影響範圍僅落在交界面10 cm 之範圍內，並在30,000 年時不再有更進一步影響範圍。膨潤土及混凝土鄰近之交界面處孔隙率變化反應水力傳輸之趨勢。
處置場封塞用SCC 工程特性部分，總取代量達50 %，且在固定矽灰取代水泥比例35 %之情況下，混凝土之強度、體積穩定性、耐久性及水密性等表現皆較普通混凝土佳，並且能在28 天齡期即符合處置場低鹼性混凝土pH 值≤ 11 之要求；在提高膠結材料總量上亦有相同之性質表現。;Final disposal depository is where nuclear canister been replaced. To let the radioactive waste safety and efficiently disposed on the long term is an important issue for world wide. Due to the depth of repository, concrete might have influence on near field, buffer and backfill material. Low pH concrete has been obtained by Sweden, Finland, Japan, and other countries during an international cooperation research. It is mainly made of fly ash, slag, and silica fume with different weight replace on cement.
In this study, the engineering characteristics of self-compacting concrete (SCC) with different mineral materials mixed for low pH concrete plug, and the interaction between concrete-bentonite, and concrete-near field materials are being studied by having mechanical tests ,and collecting research separately.
After a long-term evaluation on the pore solution of concrete-bentonite interface, the impact range on bentonite only fell within 10 cm of the interface, and no longer had any further influence at 30,000 years. The change of porosity at the interface between bentonite and concrete implies the water transport trend between materials.
While the total replacement reach 50% with silica fume replace at 35% to cement, strength, volume stability, durability, and water permeability are more advance than Portland concrete. Also, the requirement of pH ≤ 11can be fulfill at age of 28 at this mix design. The same characteristics were found on a higher binder percentage of concrete. |
