Thesis (M.S.) in Civil and Environmental Engineering--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 102-105).

Thesis (M.A. Sc.)--Dept. of Civil Engineering, Concordia University, 1995. / Includes bibliographical references (leaves 141-145). Available also on the Internet.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed May 23, 2007). PDF text: v, 326 p. : ill. (some col.) ; 3.85Mb UMI publication number: AAT 3237557. Includes bibliographical references. Also available in microfilm and microfiche formats.

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The transportation engineering community of the United States faces a tremendous problem: the gradual deterioration of the nation's bridges. A major component of the overall bridge deterioration problem is the corrosion-induced deterioration of reinforced concrete bridge components that are exposed to de-icing salts. The progression of events resulting from corrosion of the reinforcing steel includes cracking, delamination, spalling, and patching of the surface concrete. Bridge components reach the end of their functional service life when the level of damage warrants rehabilitation. The objective of this study was to determine the end of functional service life for concrete bridge decks, piers, and abutments by quantifying terminal levels of physical damage. The approach for quantifying terminal damage levels involved obtaining recommendations from state Department of Transportation (DOT) bridge engineers via an opinion survey. A field study of 18 existing concrete bridges that had been designated for rehabilitation was conducted to develop concrete bridge component maps showing areas of physical damage. Deck damage maps were produced using a ground-based photogrammetry system developed in this study, while pier and abutment damage maps were drawn by hand in the field. Survey Kits based on the component damage maps were distributed to bridge engineers in 25 states that use de-icing salts. The engineers evaluated the maps and recommended when each component should be, or should have been, rehabilitated~ Based on the engineers' responses, linear regression prediction models were developed to relate the recommended bridge component rehabilitation time point to the physical damage level. Based on the prediction models, two viable terminal damage levels for concrete bridge decks, and a partial terminal damage level for concrete bridge piers, were quantified. / Master of Science

Hydrodemolition is the use of a high pressure water-jet to remove concrete. It is a new method of concrete removal which is becoming increasing specified by state Departments of Transportation for bridge rehabilitation work. The technical, financial and contractual aspects of using hydrodemolition are examined and a brief explanation of salt induced concrete deterioration in bridges is presented. Interviews were conducted with state DOT engineers, general contractors, specialty hydrodemolition subcontractors and hydrodemolition equipment manufacturers. These interviews identified problems encountered with using hydrodemolition. Possible solutions to these problems are presented. These possible solutions are based on both suggestions made by the persons interviewed and the author. / Master of Science

In order to predict the future needs of existing bridges, Bridge Management Systems use models to predict the time when damage will reach a level to cause repair, rehabilitation, or replacement of the structure. One such model is the deterioration model, which has three distinct phases. The second phase of the model, the corrosion phase, is the focus of this study. During the corrosion phase, chloride ion concentration reaches a threshold level at the depth of the reinforcing steel which initiates corrosion. The corrosion continues until sufficient pressure is exerted on the surrounding concrete to cause cracking. This study is a continuation of a study implemented in the Materials Division at Va Tech. The study includes the monitoring of the corrosion rate of steel reinforcing bars placed in simulated bridge decks. The corrosion rates were varied by placing between 0 - 9.6 Ibs/yd³ of chloride ions in the concrete to produce six different series. Also, the depth of concrete cover, bar spacing, bar size, and exposure conditions were varied. The specimens were monitored until the time that the cracking of the concrete was observed. At that time, samples of the steel reinforcing bars were removed and the actual amount of corrosion which had occurred was determined as the weight loss of the steel. The actual weight loss of the steel reinforcing bars was then compared to the predicted weight loss from the corrosion rate measurement devices. The time to cracking and the mode of cracking was compared to Bazant's equations for cracking which are the basis for the corrosion phase of the deterioration model. Although only one series cracked during the study, corrections in the use of Bazant's equations were proposed. / Master of Science

This thesis presents both an analytical and an experimental evaluation of the feasibility of using infrared thermographic techniques to detect subsurface damage in concrete. Various methods of artificial heating, required to effectively apply this technique, are presented. Four major conclusions are reached in this study. 1) Normal ambient diurnal atmospheric temperature changes are not generally sufficient to produce a measurable response in bridge substructures. 2) Heating by an infrared heat source is a technically viable artificial method provided some type of surface preparation is made to assure uniform emissivity. 3) Hot air heating is a viable technical alternative which does not require surface preparation prior to the application of heat. However, this method does require some type of enclosure to produce a hot air pocket. 4) Artificial heating methods based on heating blankets are not a feasible method due to local nonuniform heating effects. / Master of Science