Dissertation/ Thesis
Bond deterioration of reinforcing steel in concrete due to corrosion
| العنوان: | Bond deterioration of reinforcing steel in concrete due to corrosion |
|---|---|
| المؤلفون: | Amleh, Lamya. |
| Thesis Advisors: | Mirza, M. S. (advisor) |
| بيانات النشر: | McGill University, 2000. |
| سنة النشر: | 2000 |
| المجموعة: | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| مصطلحات موضوعية: | Engineering, Civil. |
| جغرافية الموضوع: | Doctor of Philosophy (Department of Civil Engineering and Applied Mechanics.) |
| الوصف: | This research program consists of laboratory studies of the corrosion phenomenon and field study of the deterioration due to corrosion of the Dickson Bridge. The laboratory studies examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various cements and mix proportions influence the corrosion of the reinforcement as well as the chloride ion penetration. The corrosion resistance of the fly ash concrete is examined and compared with that of plain concrete to determine the effects of cement type, w/c ratio, cover thickness, and the use of different classes of fly ash on the durability of the concrete mix. An accelerated electrochemical corrosion procedure was developed with the objective of "completely" corroding the bar in a period of 15--20 weeks. The influence of corrosion on the bond between the reinforcing steel and concrete was studied using two types of tests ---the pullout and tension test. Eight levels of corrosion, ranging from no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. The phenomena of tension cracking and tension stiffening in tension specimens subjected to corrosion were also examined. The bond behaviour is influenced by the deterioration of the reinforcing bar ribs and by the reduced adhesion and cohesion of the reinforcing bar due to the widening of the longitudinal splitting crack resulting from corrosion. It was noted that low levels of corrosion (about 1--3% mass loss) lead to slight improvement of bond strength. However, bond strength decreases rapidly with an increase in the corrosion level, especially in the case of any severe localized corrosion. Analysis of the test results showed that a 5% mass loss resulted in a 9 percent decrease of the nominal bond stress. While with over 25 percent mass loss due to corrosion, a 90 percent loss of the nominal bond stress was noted. The results indicate that the use of high volume fly ash (three different mixtures) was very effective in delaying the corrosion process as compared to that of the normal portland cement. However, the direct tensile strength of fly ash concrete as calculated from the response of the tension tests was noted to be weaker than that of normal portland cement concrete. Also, the bond performance of the steel bars embedded in the normal portland cement concrete mixtures with a low water-cement ratio of 0.32 was found to be superior than that with a concrete mixture with a larger water-cement ratio. This research program was a part of a detailed strategic program to determine why the Dickson Bridge in Montreal deteriorated so prematurely and to create a data bank from many electrochemical, chemical, physical and mechanical tests on the various bridge components. This thesis includes the results of very detailed tests on four randomly selected 6 m by 5 m segments of the bridge, with some of the basic tests being undertaken on a grid of 0.25 m by 0.25 m. The field test data corroborates the results of six other investigators who undertook similar tests on different parts of the bridge and also repeated some of the tests to ensure reproduction of the results. An evaluation of the steel bar mass loss and the chloride content at the steel-concrete interface in the field showed considerable scatter because of the leaching of the chlorides deeper into the deck. However, an analysis of this data for steel bar mass loss of less then 15% showed good correlation between the field test results and the laboratory data from the tension specimens constructed using the same concrete as the Dickson Bridge. Although more research is needed in this area, presently it is possible to determine the steel bar mass loss from measurement of the chloride contents in its vicinity. |
| Original Identifier: | oai:collectionscanada.gc.ca:QMM.36868 |
| نوع الوثيقة: | Electronic Thesis or Dissertation |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | alephsysno: 001808719; proquestno: NQ69964; Theses scanned by UMI/ProQuest. |
| الاتاحة: | http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36868 |
| Rights: | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| رقم الانضمام: | edsndl.LACETR.oai.collectionscanada.gc.ca.QMM.36868 |
| قاعدة البيانات: | Networked Digital Library of Theses & Dissertations |
| الوصف غير متاح. |