臺灣博碩士論文加值系統

本研究係利用加速氯離子傳輸試驗ACMT探討非穩態與穩態傳輸性質之關係，藉此評估初始電流與電量在非穩態階段與穩態階段之適用性，及探討加速氯離子傳輸試驗與鹽水浸漬試驗Ponding test之關係。本試驗材料變數為水膠比 (0.35, 0.45, 0.55, 0.65)，飛灰、爐石與飛灰加爐石分別取代 、 與 之水泥量，養護齡期分別為28天、56天與91天。
ACMT是根據ASTM C1202-97及AASHTO T277-96修改其試驗條件，而得到之試驗，將電壓60V 修改成24V，以避免熱效應對試體孔隙結構產生影響，將溶液槽由250ml 加大至4750ml 以方便取得累積氯離子濃度，由ACMT可得到非穩態傳輸係數(Mnc)與穩態傳輸係數(Ms)，非穩態傳輸係數所代表的機理為微量的氯離子濃度剛通過混凝土試片進入到陽極槽，令此微量氯離子濃度所對應的時間為氯離子穿過混凝土試片所需的時間稱之為穿透時間(breakthrough time)，根據modified Fick's second law計算得到非穩態傳輸係數，利用非穩態傳輸係數來評估氯離子進入混凝土內部之傳輸性質，穩態傳輸係數所代表的機理為隨著試驗時間的增加混凝土孔隙充滿氯離子溶液，各孔隙傳輸途徑之累積氯離子濃度皆以相同的速度前進至陽極槽溶液，根據Nernst-Planck equation計算得到穩態傳輸係數，利用穩態傳輸係數評估混凝土抵抗氯離子穿透之能力，研究結果顯示非穩態傳輸係數與穩態傳輸係數兩者間有良好的線性關係，非穩態傳輸係數較穩態傳輸係數大。評估初始電流與電量之研究顯示，孔隙溶液中離子溶度影響其電流值大小，離子移動速率及導電度的不同在非穩態階段與穩態階段產生了不同的結果，研究結果顯示非穩態階段的電流大部份由OH- 主導，穩態階段電流由Cl-主導，利用初始電流與電量評估氯離子滲透在穩態階段較非穩態階段適合。加速氯離子傳輸試驗與鹽水浸漬試驗結果顯示，由加速氯離子傳輸試驗中得到的非穩態傳輸係數和穩態傳輸係數與鹽水浸漬試驗所得到的傳輸係數隨著養護齡期的增加有良好的線性關係，非穩態傳輸係數和穩態傳輸係數皆大於鹽水浸漬試驗所得到的擴散係數。增加鋼筋保護層厚度對於延緩結構物產生腐蝕之初始時間其效果明顯的較混凝土中添加摻料與提高養護齡期好。

In this study, the electrochemical technique is applied to accelerate chloride migration in concrete to estimate chloride transport properties in non-steady-state and steady-state. Concrete containing different types of mineral admixtures (fly ash and slag) with different water-to-binder ratios (0.35, 0.45, 0.55, and 0.65) were produced and cured in water for 28, 56, 91days respectively.The accelerate chloride migration test is a modified version of the ASTM C1202-97 or AASHTO T277-96 (RCPT) method. The voltage applied between the two electrodes is limited to 24V to avoid any abnormal heating of the sample and to reduce the risk of chloride oxidation on the anode. The cell volume is 4750 ml in ACMT rather than 250ml in RCPT. The increasing solution may reduce the Joule effect on the test result and the accumulative chloride-ion concentration can be measured periodically. According to breakthrough time can be obtained non-steady-state migration coefficient. The non-steady-state migration coefficient is calculated from a modified version of Fick's second law. The chloride flux J measured by the slope of the linear increase in chloride concentration in anode cell. According to chloride flux can be obtained steady-state migration coefficient. The steady-state migration coefficient is calculated on the basis of the Nernst-Planck equation. The results show that non-steady-state migration coefficient and steady-state migration coefficient have a good line correlation in the later age. Non-steady-state migration coefficient is up to 2.8 times higher than steady-state migration coefficient. The non-steady-state and steady-state migration coefficient obtained from ACMT and diffusion coefficient obtained from ponding test have a good line correlation. Non-steady-state and steady-state migration coefficient are higher than diffusion coefficient obtained from Ponding test. The current is controlled by OH-in non-steady-state. Using the initial current or charge passed to estimate chloride penetration capacity in non-steady-state is not an appropriate method. Increasing depth of layer is better than increasing curing age and mineral admixture to retard corrosion in reinforcement structure.

目錄
摘要.........................................i
Abstract...................................iii
目錄.........................................v
表目錄....................................viii
圖目錄......................................ix
第一章 前言..................................1
第二章 文獻回顧..............................3
2-1混凝土添加礦物摻料抵抗氯離子穿透之機理....3
2-2 混凝土孔隙溶液之導電度...................4
2-3 加速氯離子傳輸試驗中離子移動之情形.......5
2-4 加速氯離子傳輸試驗中影響導電度之因素.....8
2-5 加速氯離子傳輸試驗中濃度梯度的變化.......9
2-6 利用外加電場評估氯離子滲透試驗...........9
2-6-1 非穩態傳輸試驗........................10
2-6-2 穩態擴散試驗..........................11
2-6-3 加速氯離子穿透試驗(RCPT ).............11
第三章 試驗計畫............................13
3-1試驗材料變數.............................13
3-2試驗方法與儀器設備.......................16
3-2-1加速氯離子傳輸試驗.....................16
3-2-2氯離子濃度量測-電位滴定法..............20
3-2-3 Ponding test ......................... 21
第四章結果與討論............................23
4-1氯離子的傳輸過程.........................23
4-2非穩態傳輸係數(Mnc ).....................27
4-2-1非穩態傳輸係數之計算...................27
4-2-2過渡時期階段之累積氯離子濃度...........30
4-2-3非穩態傳輸係數與水膠比之關係...........35
4-2-4非穩態傳輸係數與養護齡期之關係.........39
4-3穩態傳輸係數(Ms )........................40
4-3-1穩態傳輸係數計算.......................40
4-3-2氯離子的穿透速率(K)....................42
4-3-3穩態傳輸係數與水膠比之關係.............49
4-3-4穩態傳輸係數與養護齡期之關係...........56
4-4穩態傳輸係數(Ms)與非穩態傳輸係數(Mnc)之關係
............................................57
4-4-1比較穩態傳輸係數與非穩態傳輸係數之機理.57
4-4-2比較穩態傳輸係數與非穩態傳輸係數之差異.60
4-5傳輸係數與初始電流和電量之關係...........63
4-5-1傳輸係數與初始電流之關係...............63
4-5-2傳輸係數與電量之關係...................68
4-6 ACMT與Ponding test之關係................71
4-6-1Ponding test...........................71
4-6-2非穩態傳輸係數與Ponding test擴散係數之關係
............................................72
4-6-3穩態傳輸係數與Ponding test 擴散係數之關係
............................................74
4-7預測鋼筋混凝土結構物產生腐蝕之初始時間...76
4-7-1鋼筋混凝土結構物產生腐蝕之初始時間計算.76
4-7-2水膠比與鋼筋混凝土結構物產生腐蝕之初始時間
之關係......................................78
4-7-3養護齡期與鋼筋混凝土結構物產生腐蝕之初始時
間之關係....................................80
4-7-4鋼筋保護層厚度與鋼筋混凝土結構物產生腐蝕之
初始時間之關係..............................82
4-8抗壓強度.................................86
第五章 結論............................... 88
參考文獻....................................90

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