Development of a system to select rehabilitation methods for deteriorated concrete marine structures | |
| Author | Sarayoot Thongyot |
| Call Number | AIT Thesis no.ST-00-4 |
| Subject(s) | Concrete construction--Deterioration Offshore structures |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | Reinforced concrete has been used widely in the marine environment during this century. The concrete has excellent durability and provides a satisfactory level of protection of the steel embedded inside. However, marine environment is very aggressive condition so that corrosion of the steel reinforcement cannot be avoided. Therefore, the proper rehabilitation methods should be applied to repair the structures. But the problem is how to select the suitable rehabilitation methods. The purpose of this research is development of the system to select rehabilitation methods. Firstly, the degradation curves of structural performances are evaluated. Three performances that are load bearing capacity, safety perception for third parties and aesthetics performance are considered. The load bearing capacity is evaluated theoretically, while safety perception for third parties and aesthetics performance are evaluated from the results obtained by online questionnaire. Furthermore, the selection of rehabilitation methods is also gathered from the opinion of the skillful engineers how to repair the structures by using online questionnaire also. The results show that load bearing capacity is degraded with time due to chloride attack. The degradation rate of load bearing capacity depends on many factors such as cover thickness, reinforcement diameter and reinforcing arrangement. Degradation rate will be large if using small size of diameter, and the corrosion will start very soon if using small cover thickness. Therefore, large diameter of steel with enough concrete cover is suggested. It is clearly shown that the change of failure mode from flexural mode to shear mode can occur in corrosion process if much larger corrosion amount occurs on shear reinforcement compared with flexural reinforcement. Degradation in safety perception for third parties and aesthetics performance will be different when the structures is deteriorated from different sources. The aesthetics performance is degraded largely in case of color changing when compared with safety perception for third parties. However, they are degraded closely in case of cracking and spalling. Both performances are rapidly degraded in case of spalling and degradation level is very high. The repair is strongly needed to recover both performances when the spalling occurs. The need of repair action is decreased respectively in case of cracking and color changing. The engineers require only coating to recover the aesthetics performance when the structures are deteriorated from color changing. For cracking, the crackfilling with coating is mostly required as rehabilitation methods. In addition, the strengthening is also preferred in repairing of large cracks. For spalling, the crackfilling, coating, patching and electrochemical methods are suggested to use. Especially, the electrochemical are noticeably suggested in the repair of spalling. The cyclic repair is required increasingly to repair the structures deteriorated from color changing, cracking and spatting respectively. |
| Year | 2000 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Takewaka, Koji; |
| Examination Committee(s) | Nii, Kazuyoshi ;Worsak Kanok-Nukulchai; |
| Scholarship Donor(s) | Asian Institute of Technology (Partial Scholarship) |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2000 |