Post-tensioned (PT) bridge technology was first introduced in France in the 1930?s as
described in the post-tensioned concrete bridges: Anglo-French liaison report by
Highway Agency and is widely used in Europe and the US. PT bridge technology is
advantageous over other bridge-type structures due to its larger span-to-depth ratio and
reduced construction costs and time. This technology however faces several challenges
due to potential corrosion of the prestressing steel.
PT bridges constructed in the US during the 1970?s used cementitious grouts to fill
the empty spaces in the PT ducts in order to protect the strands from corrosion. This
grout in the ducts was intended to protect the strands from being attacked by aggressive
agents and to prevent corrosion. A mixture of ASTM Type I cement and water was used
as the grouting material for construction of PT bridges. In Texas, four major PT
structures have been in place for more than 10 years. Recent investigations of the PT
bridges in Texas did not identify any strand failures. However, the visual inspections
identified voids in many of the ducts, especially at the ends of the bridge spans. These voids are believed to have been formed as a result of grout bleeding, poor grouting
materials, and poor grouting techniques.
One of the main performance requirements sought from PT grouts is their ability to
fill existing voids in the existing ducts. Currently, many prepackaged grouts are
available for PT application that are reported to not bleed and provide better flowability
as compared to the older ASTM Type I cement grout. However, the current standard
specifications for approving grout materials have limited requirements for evaluating the
?fillability? of these pre-packaged PT grouts. This research is being performed to
provide modifications to the existing PT specifications such that PT repair grouts can be
objectively assessed for fillability and long-term performance.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2008-08-50 |
| Date | 16 January 2010 |
| Creators | Kataria, Suresh |
| Contributors | Trejo, David |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis |
| Format | application/pdf |
Page generated in 0.0019 seconds