臺灣博碩士論文加值系統

本論文在探討混凝土孔隙率對氯離子擴散性與電導性之影響。在固定骨材使用量與無添加礦物掺料條件之下，一般水泥(OPC)混凝土與砂漿試體配比各採用八組不同之水灰比(w/c)。壓汞試驗的結果顯示出水灰比對於水泥基材料的孔隙率與孔隙結構扮演著重要的影響因素。同時水灰比對於混凝土的各種性質也有明顯的影響。毛細孔隙率、孔隙的分布與孔隙連通性等孔隙結構因素對控制氯離子的擴散性扮演著主要的角色，研究中同時建立了氯離子擴散性與毛細孔隙率間之函數關係式，利用此函數關係式可以得到氯離子擴散與孔徑範圍在10-500 nm的孔隙率存在著最佳對應關係。藉由水泥基材料的電阻性與孔隙率之關聯性，研究結果也得到RCPT試驗的總電荷量與總孔隙率的函數關係式，而此兩者之間也存在著一個良好的對應關係。對一般水泥混凝土，RCPT試驗得到的總電荷量與90天浸漬試驗得到的氯離子擴散係數之間亦存在著非常良好之線性關係。最後，應用四個一般常用之抗壓強度與孔隙率之關係式，研究結果顯示四個關係式均具有良好之真確性。

The purpose of this thesis presents the results of an investigation on the relationship of porosity with chloride ions diffusivity and electrical-conductivity of concrete. Eight different water/cement (w/c) ratios ordinary Portland cement (OPC) concrete and mortar specimens with constant aggregates and free mineral additives were used. The MIP measurements showed that water/cement ratio was an important factor in determining the porosity and microstructure of cement-based materials. Water/cement ratio was also significantly to control concrete various properties. The capillary porosity, pore size distribution, and connectivity of pores exerted major control factors on the chloride ions diffusivity of concrete. Correlation between the diffusion coefficient and capillary porosity was found and the best fit of diffusion coefficient with porosity at pore size distribution between 10 and 500 nm was obtained. Based on the porosity-electrical resistivity relation, fit to the experimental results of total porosity as a function of charge passed was addressed, meanwhile, a well correlation between total porosity and charge passed was also obtained. The total charge passed from RCPT has fair well corresponding to the diffusion coefficient from salt ponding test was observed for ordinary Portland cement concrete. Four common porosity-strength equations: Balshin’s, Ryshkewitch’s, Schiller’s, and Hassellman’s fit the experimental results of mineral-free OPC concretes with sufficient accuracy.

摘要…………………………………………………………………… Ⅰ
Abstract……………………………………………………………… Ⅱ
Content………………………………………………………………… Ⅲ
Tables………………………………………………………………… Ⅵ
Figures………………………………………………………………… Ⅶ
1. Introduction……………………………………………… 1
2. Literature Review……………………………………… 3
2.1 Microstructure of hydrated cement paste………… 3
2.1.1 Hydration of cement past……………………………… 3
2.1.2 Pore system in hydrated cement paste……………… 3
2.1.3 Effect of water/cement ratio………………………… 5
2.1.4 Effect of mineral admixture………………………… 7
2.1.5 Effect of superplasticizer…………………………… 9
2.2 Mechanism of ionic transportation in concrete… 10
2.3 Test methods of chloride penetration of concrete……… 14
2.3.1 AASHTO T259 salt ponding test……………………… 14
2.3.2 Rapid chloride permeability test (RCPT)……… 16
2.3.3 Acceleration Chloride Migration Test (ACMT)…… 19
2.3.4 Mercury intrusion porosimetric test (MIP)……… 21
3. Experimental Details………………………………… 24
3.1 Mixture details………………………………………… 24
3.2 Material details……………………………………… 26
3.3 Test details…………………………………………… 29
3.3.1 90-day Salt ponding test…………………………… 29
3.3.2 Rapid chloride permeability test (RCPT)………… 31
3.3.3 Mercury intrusion porosimetric test (MIP)……… 34
3.3.4 Compressive strength test…………………………… 36
4. Results and Discussion……………………………… 37
4.1 Mercury intrusion porosimetric test (MIP)……… 37
4.1.1 Total intrusion pore volume and porosity……… 37
4.1.2 Critical pore diameter……………………………… 44
4.1.3 Pore size distribution……………………………… 47
4.2 90-day salt ponding test…………………………… 50
4.2.1 Relationship between diffusion coefficient and w/c ratio… 56
4.3 Rapid chloride permeability test (RCPT) ……… 58

4.3.1 Relationship between charge passed and w/c ratio……… 60
4.3.2 Relationship between total charge passed and initial current…………………………………………………… 61
4.4 Compressive strength test…………………………… 62
4.5 Relationship between pore structure and chloride ions diffusivity…………………………………………………… 64
4.5.1 Porosity and diffusivity relationship…………… 64
4.5.2 Connectivity and diffusivity relationship……… 69
4.6 Porosity and electric-conductivity relationship…… 71
4.7 Relationship between 90-day salt ponding test and RCPT…… 75
4.8 Relationship between compressive strength and porosity…… 77
5. Conclusion……………………………………………… 81
6. Suggestion……………………………………………… 82
Reference……………………………………………………………… 83
Appendix……………………………………………………………… 90

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