Fabrication and Non-Destructive Evaluation of Reinforced Concrete Specimens Containing Delaminated Cracks and Repaired Cracks

• Main Authors: Jiunn-Hong Wu, 吳俊鴻
• Other Authors: Chia-Chi Cheng
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/85712539651784483568

碩士 === 朝陽科技大學 === 營建工程系碩士班 === 93 === For the needs of developing techniques for the safety assessment of concrete structures in nuclear facilities, the present project focuses on constructing concrete specimens containing naturally developed delaminated cracks with various crack depths. The specimens can be used for evaluating the repairing techniques which may be applied in the nuclear facilities and be provided for establishing the database for various non-destructive testing techniques. Four specimens with dimensions 1 m by 2.1 m by 0.4 m were constructed. Among them, two are unreinforced specimen and the others contain lattice-arranged steel reinforcing bars. One unreinforced and one reinforced plates are provided for future repairing works and the rest of the specimens were used for present study. In the specimen-design, the concrete strength, size and arrangement of steel bars are all simulating those in the base floor of nuclear power plant. The delaminated cracks are at the depth which was typically appeared in the base floor of nuclear power plant. The method for creating cracks is as following. First, inject strong expansive cement paste into the pre-split carefully arranged plastic tubes buried inside the concrete specimens. And then wait for several hours for expansive cement storing enough force to crack the surrounding concrete. After the cracks open to the designed crack width, the expansive cement were extract from the tube and stop the crack growth. As the results, delaminated cracks with width 1mm, 3mm and 5mm were successfully created. The specimens can be provided for various NDT methods including impact-echo, ultrasound, short-pulse radar, and ultrasound matrix. Among them, the responses of impact-echo tests will be transferred into the transfer function for more valuable analyses. The matrix ultrasound evaluation is the cutting edge technology for evaluating the damaged and repaired concrete structures.