硫酸鹽侵蝕對低放處置場障壁混凝土之劣化及推估研究

The degradation and estimation of sulfate attacked for barrier concrete of low-level disposal field

邱耀輝(Yao-huei Ciou)

指導教授 ： 黃偉慶

國立中央大學/工學院/土木工程學系/碩士(2011年)

摘要

低放射性處置場主體由混凝土構成，由於台灣地區多雨且四面臨海，因此易因海水、地下水、酸雨以及乾濕循環的作用而造成障壁混凝土材料遭受硫酸鹽侵蝕劣化，處置場在此種服務環境下，可能對障壁混凝土造成損害或劣化而影響其耐久性。
本研究針對低放射性廢棄物處置場所使用之混凝土材料，以實驗室模擬混凝土材料長期受硫酸鹽侵蝕作用下，探討障壁混凝土材料長期在此環境下的行為，分析其可能劣化機制及對耐久性之影響。試驗結果得知: (1)混凝土受硫酸鹽侵蝕時，其入侵之深度及濃度皆隨著歷時時間增加，以卜作嵐材料取代部分水泥及降低水膠比，可提升混凝土緻密性進而改善抗硫酸鹽侵蝕能力；(2)將試驗結果依據費克第二定律(Fick’s second law)加以擬合可推估硫酸根離子擴散係數，藉以評估卜作嵐材料取代水泥之影響；(3)由微觀分析結果顯示，水泥漿體受硫酸鹽侵蝕歷時作用下，其內部微結構明顯可發現侵蝕產物，造成混凝土體積變化。另外，運用硫酸鹽侵蝕模型比對硫酸鹽侵蝕試驗之結果，可預估砂漿棒達劣化所需之時間。

關鍵字

障壁混凝土 ； 硫酸鹽侵蝕 ； 擴散係數

並列摘要

The proposed engineered barrier for low-level radioactive wastes disposal site is made of concrete. Since Taiwan is surrounded by the sea, the low-level radioactive wastes disposal site is very possible to suffer from the attack of different elements of the environment, such as sea water, ground water, acid rain, wet-dry cycle, and sulfate attack.
The attack by sulfate on concrete material used at the low-level radioactive wastes disposal site was simulated in the laboratory to determine the long-term durability of concrete material. The possible degradation mechanism of concrete under sulfate attack and the influence on its durability are carefully examined in this study. The results of the laboratory works show that: (1) the depth of sulfate penetration increases with elapsed time of sulfate attack; (2) the replacement of a portion of Portland cement with pozzolanic materials and use of low w/b were found to help the concrete to resist the sulfate attack; (3) the diffusion coefficient can be determined from the sulfate profile experimental result according to Fick’s second law, such that the effect of replacement of a portion of Portland cement with pozzlanic materials can be assessed; (4) the product of sulfate attack to concrete was found in the specimens and resulted in peel-off and cracking, as demonstrated by microstructural observations.

並列關鍵字

concrete barrier ； sulfate attack ； diffusivity

參考文獻

黃兆龍，1999，「混凝土性質及行為」，詹氏書局。

吳清哲，2006，「低放射性廢棄物處置場障壁受硫酸鹽侵蝕之劣化模式評估」，碩士論文，國立中央大學土木工程研究所，中壢。

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