低放射性最終處置場障壁混凝土以熱養護提升品質之研究

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Title:	低放射性最終處置場障壁混凝土以熱養護提升品質之研究
Authors:	陳雅文;Chen, Ya-Wen
Contributors:	土木工程學系
Keywords:	氯離子擴散;服務年限;熱養護;表面電阻率
Date:	2018-07-18
Issue Date:	2018-08-31 11:23:22 (UTC+8)
Publisher:	國立中央大學
Abstract:	延續先前研究團隊針對可能低放射性廢棄物盛裝容器混凝土配比HIC-C、HIC-M之氯離子長期浸泡試驗(改自AASHTO T259)及配比C、配比M之氯離子浸泡試驗(ASTM C1556)分別增加第七年及第三年之實驗數據，利用長時間之實驗結果探討擴散係數發展趨勢以及推估更準確之服務年限。以最保守估計盛裝容器於製作完成後立即受氯離子入侵，推估於容器厚度一半(35mm)深度於500年後之氯離子含量仍低於腐蝕門檻值0.05%，表示盛裝容器混凝土配比之服務年限超過500年。低放射性最終處置工程障壁混凝土以安全性為首要要求，為了探討是否有其他方法能使其品質再提升，故本研究藉由熱養護方式分別採用80℃熱水養護三天及四天進行一系列試驗，與23℃常溫養護進行比較。結果顯示經80℃熱養護3天及4天後，能加速混凝土水化反應減少試體內部孔隙，相較於常溫養護試體其試體內部較為緻密，故在品質提昇方面有明顯的效果。由表面電阻率與混凝土、水泥漿體孔隙率試驗結果發現，電阻率與兩個試驗之間有良好相關性，表示以表面電阻率評估本研究配比混凝土品質應為可行的，而與抗壓強度因試驗機理不同所產生之相關性較差，故不建議以電阻率評估混凝土之抗壓強度。 ;Safety is the most important consideration in the development of concrete mix for containment of low-level radioactive wastes. So this study intends to find methods to improve the durability of the concrete mix by thermal curing in 80°C hot water for 3 or 4 days. To evaluate the effectiveness of the improvement by thermal curing of the concrete mixes, the chloride ion diffusion, mechanical, durability and non-destructive test results were compared with those cured at room temperature of 23°C. It was found that heat curing can speed up the pozzolanic reaction and accelerate cement hydration so as to fill the pores in the concrete and produce a denser structure. Compared with room temperature curing, heat curing can effectively improve the concrete quality. Continuing the long-term study on chloride ion penetration measurements of the potential mixes (HIC-C, HIC-M) to be used for highly integrated containers (HIC), the seventh year’s profile was determined and the time factor for diffusion re-evaluated using updated data. And the instantaneous chloride diffusion coefficient of mix C and M was determined for 3-year’s specimens. Based on long-term measurements on the concrete mixes, a more reliable estimation on the service life of HIC was made possible. Surface resistivity and porosity test results on concrete mixes C and M show that there is a good correlation between the two tests. Since the durability of concrete is known to be highly influenced by the porosity and pore size distribution. The surface resistivity measurement is found to be feasible method for estimating the durability of barrier concrete.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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