Detection of rebar corrosion by ultrasonic wave | |
| Author | Anawat Chotesuwan |
| Call Number | AIT Thesis no.ST-07-14 |
| Subject(s) | Ultrasonic waves Reinforced concrete--Corrosion |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technololgy |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ST-07-14 |
| Abstract | This research studies the possibility to use ultrasonic wave in order to investigate corrosion of rebar in reinforced concrete structures with the basic concept that corrosion generates small cracking around the surface of rebar which could modify the ultrasonic signal. Reflection type ultrasonic measurement is used in measurements of rectangular prismatic concrete specimens with rebar embedded inside. Corrosion of rebar is accelerated by the mean of galvanic acceleration. Signal changes are considered comparatively to the change of voltage reading by half-cell potential. There are two parts of experiment in this study. Preliminary testing were conducted in order to make the author gets used to with the ultrasonic equipment. And later, the main part of experiment focusing on corrosion of rebar was tested. Experiments in preliminary part consist of three testing. Measurement of pulse-echo ultrasonic wave on concrete with steel pipe and reinforcing bar embedding inside with also evaluation of crack depth testing were conducted in order to practice the equipment usage. Study on the effect of compressive load on the change in the amplitude of ultrasonic signal was performed in order to confirm the assumption that changes in micro structure affects the amplitude of ultrasonic signal. The first preliminary testing on the measurement of pulse-echo ultrasonic wave on concrete with steel pipe and reinforcing bar embedding inside gives the overview picture of how does the recorded wave look like. Measurements were conducted on the surface of specimen at three positions, over plain concrete zone, over rebar zone and over steel pipe zone. Reflection from another surface of specimen is observed at the same time for measurements over plain concrete zone and rebar. Another reflection from rebar itself is observed in measurement over rebar zone. However, in the measurement over steel pipe, only one reflection from pipe is observed which means the wave cannot penetrate through air. The testing on evaluation of crack depth was not accomplished, the author cannot observe the wave which likely to be the interesting wave. And for the study on the effect of compressive load on the change in the amplitude of ultrasonic signal, compressive load testing was done to cubic concrete specimens in several loading and load releasing steps. Decrease in amplitude of ultrasonic signal is observed in overall testing; however, at some steps compression load increase the amplitude of recorded wave. This can confirm the assumption which the amplitude of recorded signal is affected by internal change in micro structure of concrete. The main experiments on corrosion of reinforcing bar were conducted with three types of specimens - reinforced concrete, ferro-cement and reinforced cement paste. With all three types of specimens, changes in the amplitude of recorded ultrasonic signal are observed. And finally, the author tried to set up some index values for evaluating corrosion; however, the result is still unsatisfied. |
| Year | 2007 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. ST-07-14 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Structural Engineering (STE) /Former Name = Structural Engineering and Construction (ST) |
| Chairperson(s) | Kato, Yoshitaka; |
| Examination Committee(s) | Worsak Kanok-Nukulchai;Pennung Wamitchai;Raktipong Sahamitmongkol; |
| Scholarship Donor(s) | RTG Fellowship; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2007 |