Luận án tiến sĩ: Mô hình xâm nhập clorua vào BTCT dưới tải trọng & môi trường biển

แบบจําลองการแทรกซึมของคลอไรดเขาสูโครงสรางคอนกรีตเสริมเหล็กภายใตน้ําหนักกระทํา และสภาวะแวดลอมทางทะเล นาย วูฮวาง ควอค วิทยานิพนธนี้เปนสวนหนึ่งของการศึกษาตามหลักสูตรปริญญาวิศวกรรมศาสตรดุษฎีบัณฑิต สาขาวิชาวิศวกรรมโยธา ภาควิชาวิศวกรรมโยธา คณะวิศวกรรมศาสตร จุฬาลงกรณมหาวิทยาลัย ปการศึกษา 2554 ลิขสิทธิ์ของจุฬาลงกรณมหาวิทยาลัย MODEL FOR CHLORIDE INGRESS INTO REINFORCED CONCRETE STRUCTURE UNDER LOAD AND MARINE ENVIRONMENT Mr. Quoc Vu Hoang A Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Program in Civil Engineering Department of Civil Engineering Faculty of Engineering Chulalongkorn University Academic Year 2011 Copyright of Chulalongkorn University vi ACKNOWLEDGEMENTS I would like to acknowledge all the contributions from the following persons. Without their support, this thesis would not have been completed. First of all I would like to express my thank to my family, my love and deepest gratitude to my wife - Thu, and to my daughter, little angle - Bina, for their enormous contribution, constant support and encouragement throughout completion of this thesis.

I would like to thank Japan International Cooperation Agency (JICA) through AUN/SEED-Net program for giving me the opportunity to pursue a PhD Degree in Civil Engineering in the field of Structural Engineering. I express my gratitude to Chulalongkorn University for providing a wonderful educational environment for studying. I also thank the Environmental Material Engineering (EME) Laboratory at Hokkaido University for its supporting programs. I wish to express my gratitude to my supervisor, Asso.

Boonchai Stitmannaitum, for his support, guidance, and encouragement. My thanks also go to my co-advisor, Prof. Sugiyama Takafumi at Hokkaido University, for his assistance in experiments in his lab that forms an essential part of this research. My sincere thanks to all committee members, namely, Prof.

Teerapong Senjuntichai, Asso. Phoonsak Pheinsusom, Asst. Withit Pansuk, and Asst. Their challenging questions and orientation on my proposal report have strengthened the framework of this research.

Finally, I would like to express my special thanks to my friends, Mr. Oran Laungpetcharaporn in concrete lab at Chulalongkorn University, and my friends in EME lab at Hokkaido University for their helps. CONTENTS Page Abstract in Thai.………………iv Abstract in English.………………vii List of Tables.x List of Figures……………………………………………….xi CHAPTER I INTRODUCTION…………………………………………………………….2 Statement of Problems. 2 CHAPTER II LITERATURE REVIEW …………………………………………………….1 Chloride induced corrosion in cracked concrete .1 Corrosion mechanisms of steel reinforcement in concrete .2 The effect of crack on the steel reinforcement corrosion in concrete.2 Transport mechanisms of chloride through cracked concrete.2 Permeation of salt solution .3 Background of correlations of crack to chloride ingress .1 Crack generation method .2 Influence of crack width and crack depth on chloride diffusion .3 Crack tortuosity and crack constrictivity .4 The loading and marine environment .5 Models for chloride ingress into cracked concrete .7 The objectives of study .8 The scopes of study.

27 CHAPTER III DEVELOPMENT OF MODEL ………………………………………………29 3.1 Two dimensional chloride diffusivity model of cracked reinforced concrete .1 The movement mechanism of bulk salt solution .2 The diffusion mechanism of chloride ions into cracked concrete .2 Model for chloride diffusion at crack location of reinforced concrete. 32 CHAPTER IV SIMULATION OF CHLORIDE PENETRATION INTO CRACKED REINFORCED CONCRETE…………………………………………………37 4.1 Simulation for chloride diffusion at crack location of reinforced concrete .2 Simulation for 2D chloride diffusivity in crack concrete .1 Model for 2D chloride diffusivity.2 Model for chloride diffusivity only perpendicular crack plane. 49 CHAPTER V MODEL VALIDATION …………………………………………………….1 Experiment procedures to perform the effect of crack depth on the chloride penetration .2 Determination for chloride profile by chemical analysis method .3 Determination for chloride profile by EPMA test .1 Correlation of the applied load (SR) to crack width opening .2 The correlation between crack depth and crack width.3 The influence of water-cement ratio (W/C) on the chloride penetration depth .4 The influence of crack depth on the chloride penetration depth .5 The influence of residual crack width on the chloride concentration depth .6 The influence of crack depth on the chloride diffusion coefficient at crack location.7 The tortuosity and constrictivity of crack .1 Validation for model of chloride diffusion at crack location of reinforced concrete .2 Two dimensional chloride ingress in cracked concrete. 81 CHAPTER VI DISCUSIONS AND CONCLUSIONS …………………………………….2 Limitations and Directions for Future Research .105 APPENDIX ……………………………………………………………………………………111 BIOGRAPHY …………………………………………………………………………………119 x LIST OF TABLES Page Table 2.

Maximum permissible crack width (ACI-224-01, 2001). Permissible crack width and minimum concrete cover.3 The lower and upper threshold values of crack width influencing on chloride diffusion. The input data for analytical computation following 1D chloride diffusivity model. The input data for ANSYS program analysis.1 Mix proportion per 1 cubic meter of concrete.

The different characteristics of crack and the affected coefficients. The surface chloride content and chloride diffusion coefficient at crack and uncrack locations. The deviation between predicted and experimental results. 71 xi LIST OF FIGURES Page Figure 2.

The anodic and cathodic reactions in the corrosion of steel bar in concrete (Broomfield, 2007). Volumetric expansion like a result of metallic iron (Broomfield, 2007). Schematic representation of two types for corrosion process in crack region (Schiessl and Raupach, 1997). Feedback controlled slitting test and water permeability test setup (Aldea et al.

The artificial crack (notch) by Marsavina (Marsavina et al. Controlled splitting test (Djerbi et al. The wedge splitting test (Karihaloo et al. Crack crated by the bending test (Gowripalan et al.

The sample and the expansive core (Ismail et al. Correlation of chloride threshold level to Wcr /C (Gowripalan et al. Diffusion coefficient and crack width tested with mortar specimens (Takewaka, Yamaguchi and Maeda, 2003). The chloride concentration profile collected at location of surface and perpendicular-to-crack wall (Ismail et al.

Study on chloride diffusion into cracks on concrete and steel specimens (Kato et al. Correlation of crack width to diffusion coefficient of crack (Djerbi et al. The definition of the tortuosity. The directional diffusion tortuosity along the x-axis by three simple capillary tube models by (Promentilla et al.

The concept for the constrictivity. Effect of crack width on crack constrictivity parameter (Ishida et al. Rapid chloride permeability under different stress-strength ratio (Lim et al. Chloride diffusion coefficient at different compressive stress level (Wang et al.

21 xii Page Figure 2. chloride diffusion coefficient at different tension stress level (Wang et al. The chloride diffusion coefficient in tension zone and compressive zone under flexural loading (Mien, 2008). The schematic representation of crack spacing l and crack width W (Boulfiza et al.

Concept for crack zone (Kato et al. The space domain for model of chloride diffusion in cracked concrete, (Paulsson-Tralla and Silfwerbrand, 2002). Chloride ions spread in two (three) dimension (Paulsson-Tralla and Silfwerbrand, 2002). The two-dimensional chloride diffusion coefficient.

The concept of the 2D surface content and diffusion coefficient of chloride for cracked concrete. Definition for crack and uncrack locations. The concept for the influence of crack depth on the chloride profile. The illustration of updating chloride diffusion coefficient.

The concept for chloride diffusion coefficient at crack location of reinforced concrete. Predicting chloride profile of beam series 1 after 2-week immersion in salt solution 38 Figure 4. Predicting chloride profile of beam series 2 after 2-week immersion in salt solution 39 Figure 4. Predicting chloride profile of beam series 3 after 2-week immersion in salt solution 39 Figure 4.

Predicting chloride profile of beam series 2 and 3 after 4-week immersion in solution. Predicting chloride profile of beam series 1 after 6-week immersion in salt solution 40 Figure 4. Predicting chloride profile of beam series 2 after 6-week immersion in salt solution 40 Figure 4. Predicting chloride profile of beam series 3 after 6-week immersion in salt solution 40 Figure 4.

Predicting chloride profile of beam series 1 after 8-week immersion in salt solution 41 Figure 4. Predicting chloride profile of beams after 8-week immersion in salt solution. 41 xiii Page Figure 4. Predicting chloride profile of beam series 2 after 16-week immersion in salt solution.

The elements of model by ANSYS. The surfaces exposed to chloride solution (2D chloride diffusivity). The analytical result of 2D chloride diffusivity of cracked concrete beam 1. The analytical result of 2D chloride diffusivity of cracked concrete beam 2.

The analytical result of 2D chloride diffusivity of cracked concrete beam 3. The analytical result of 2D chloride diffusivity of cracked concrete beam 4. The analytical result of 2D chloride diffusivity of cracked concrete beam 5. The analytical result of 2D chloride diffusivity of cracked concrete beam 7.

The crack plane surface exposed to chloride solution. The analytical result for chloride diffusivity perpendicular to crack plane of beam 6. The analytical result for chloride diffusivity perpendicular to crack plane of beam 8. The sketch of process research.

Set up of short-term diffusion test combined by ASTM C1202 and Nordtest NT 492. The concept of the penetration depth at crack location of reinforced concrete. The schematically experimental procedure. An example of results for the correlation between crack width and crack depth.

The mechanism and technology of EPMA (http://jp. Cracked reinforced concrete beam with coated epoxy layers. The location of the slice for EPMA test. The correlation between load level (SR) and residual crack mouth opening.

The correlation between respective crack depth and residual crack width. The chloride penetration depth at uncrack location versus the W/C ratio. The chloride concentration depth of specimens with (a) and without (b) steel bars. 60 xiv Page Figure 5.

The chloride penetration depth at uncrack (a) and crack (b) locations. The chloride penetration depth at crack location versus the respective crack depth 61 Figure 5. The influence of crack width on the chloride concentration depth. The influence of crack depth on the chloride diffusion coefficient by STDT.The artificial crack by Marsavina (Marsavina et al.

Influence of the notch depth on chloride penetration depth (W=0.2 mm) (Marsavina et al. Influence of the notch depth on chloride penetration depth (W=0.3 mm) (Marsavina et al. The influence of crack depth on the chloride penetration depth after converted by the tortuosity and constrictivity parameters of crack. Immersion (a) and after immersion (b) of cracked beam in salt solution.

The location for collecting the concrete powder to analyze chloride content. Comparison between the predicted results and experimental results affected by crack mouth. Comparison between the predicted results and experimental results affected by crack depth. Comparision between predicted and experimental results (Beam series 1, crack 1) 72 Figure 5.

Comparision between predicted and experimental results (Beam series 1, crack 2) 73 Figure 5. Comparision between predicted and experimental results (Beam series 1, crack 3) 73 Figure 5. Comparision between predicted and experimental results (Beam series 2, crack 1) 73 Figure 5. Comparision between predicted and experimental results (Beam series 2, crack 2) 74 Figure 5.

Comparision between predicted and experimental results (Beam series 3, crack 1) 74 Figure 5. Comparision between predicted and experimental results (Beam series 3, crack 2) 74 Figure 5. Comparision between predicted and experimental results (Beam series 3, crack 3) 75 Figure 5. Comparision between predicted and experimental results (Beam series 2, crack 1) 75 Figure 5.

Comparision between predicted and experimental results (Beam series 3, crack 1) 75 xv Page Figure 5. Comparision between predicted and experimental results (Beam series 1, crack 1) 76 Figure 5. Comparision between predicted and experimental results (Beam series 1, crack 2) 76 Figure 5. Comparision between predicted and experimental results (Beam series 1, crack 3) 76 Figure 5.

Comparision between predicted and experimental results (Beam series 2, crack 1) 77 Figure 5. Comparision between predicted and experimental results (Beam series 2, crack 2) 77 Figure 5. Comparision between predicted and experimental results (Beam series 2, crack 3) 77 Figure 5. Comparision between predicted and experimental results (Beam series 3, crack 1) 78 Figure 5.

Comparision between predicted and experimental results (Beam series 3, crack 2) 78 Figure 5. Comparision between predicted and experimental results (Beam series 3, crack 3) 78 Figure 5. Comparision between predicted and experimental results (Beam series 1, crack 1) 79 Figure 5.