An analysis of practices for concrete bridge deck durability
| dc.creator | Yasmin, Ashfia | |
| dc.date.available | 2011-02-18T19:09:07Z | |
| dc.date.issued | 2000-12 | |
| dc.degree.department | Civil Engineering | en_US |
| dc.description.abstract | With increasing roadway congestion, there is increasing pressure to open newly constructed concrete bridge decks to full traffic early. Generally, highway agencies open bridge decks as soon as possible to traffic without sacrificing long-term durability of the structure. Thus, there is a ''critical loading age" at which time applied design loads have no applicable detrimental effect on the long-term durability of concrete bridge deck. Currently, there are no specific methods to determine this critical loading age for different concrete mixes or for site cast concrete. So, difficulties arise when one attempts to (a) define this critical loading age for a number of concrete mixes and (b) determine when site cast concrete actually reaches this critical loading age. This thesis analyzes the current practice for loading age of concrete. Typically, after a minimum number of days of wet mat curing and a given compressive strength (f'c) are reached, traffic is allowed on a concrete bridge deck. In Texas, the requirement for wet mat curing is 8 days for decks with Type I cement and 10 days for decks with Type II or I/II cement or mixtures containing fly ash. The most recent Special Provision to Item 420, "Concrete Structures," effective 9-98, allows opening to traffic after design strength is achieved and concrete surface treatment has been applied. This allows opening to all traffic after specification requirement of 8-10 days wet mat curing plus a day for the surface to dry and a day to apply concrete surface treatment, for a total of 10 to 12 days. In the past, the minimum number of days before full traffic load has been 30 days is 1982 specification and 21 days, as stated in the 1995 specification. The longer time of loading was preferred because of concerns that the concrete would reach it critical loading age at some point before opening the deck to traffic. The main problem the concrete shows at the early age if it is open to traffic earlier than the critical loading age is the appearance of micro-cracks. Significant efforts have been made to develop concrete mix designs to improve early strength and durability of concrete in recent years. However, the minimum number of wet mat curing days to achieve sufficient concrete durability is not known yet. | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | http://hdl.handle.net/2346/9628 | en_US |
| dc.language.iso | eng | |
| dc.publisher | Texas Tech University | en_US |
| dc.rights.availability | Unrestricted. | |
| dc.subject | Concrete | en_US |
| dc.subject | Bridges | en_US |
| dc.title | An analysis of practices for concrete bridge deck durability | |
| dc.type | Thesis | |
| thesis.degree.department | Civil Engineering | |
| thesis.degree.department | Civil and Environmental Engineering | |
| thesis.degree.discipline | Civil Engineering | |
| thesis.degree.grantor | Texas Tech University | |
| thesis.degree.level | Masters | |
| thesis.degree.name | M.S.C.E. |
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