| Description |
xii, 146 leaves : illustrations ; 28 cm + 1 CD-ROM. |
| Notes |
System requirements: Adobe Acrobat Reader. |
| Summary |
"This study involved the investigation of the causes of spalling observed in several partial-depth precast prestressed bridge decks in the state of Missouri. Recently it has been observed that several bridges in Missouri with this type of construction have experienced spalling of concrete at the edges of the panels revealing an extreme condition of corrosion in the prestressing tendons, some to the point of rupture. Ground penetrating radar (GPR), which has been shown to be successful in bridge deck evaluation, was used to determine the relative condition of the prestressing tendons as well as the relative condition of the concrete throughout the deck in order to identify areas of cracking and corrosion. Particular techniques were used in an attempt to identify areas of delamination at the interface between the precast panels and cast-in-place topping slab, namely the acquisition of data from both the top and bottom deck surfaces as well as specialized data interpretation techniques. Core control and visual inspection were utilized to interpret and validate the GPR data. Half-cell, resistivity and rebound hammer testing was performed on bridge deck panels to determine the corrosion levels of the prestressing strands and material properties of the panels. Findings indicate that spalling in the PPC panels is the result of the penetration of water and chlorides through the reflective cracking in the CIP topping, to the interface between the CIP topping and the PPC panels, then through the PPC panels to the prestressing tendons located near the panel joints. Increased crack control in the CIP topping delays the onset of spalling at the panel joints. Most deterioration is occurring near the area of reflective cracking in the CIP topping and not in the area of concrete over the middle of the panels. Some delamination is occurring at the CIP topping and panel interface"--Abstract, leaf iii. |
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