Latest Edition Gives New Perspective on Design-Build Project

This issue of HPC Bridge Views focuses on one design-build project from the perspectives of the owner, designer, general contractor, and concrete supplier.

For its largest and most complex bridge project ever completed, the South Carolina Department of Transportation set high design standards: 100 year service life at the lowest life-cycle cost. The design objectives were met not only through the use of HPC, but also through a hig- performance contract between the owner and the contractor.

The designer’s main challenge was that there was no code to follow for a 100-year design. Through extensive research and considerable engineering judgment, they devised a combination of low-permeability concrete and minimum concrete cover to assure long service life. The use of performance-based specifications allowed complete freedom to the contractor to come up with the most economical concrete mix design.

Due to high performance requirements placement limitations, the contractor was faced with the use of every imaginable placement technique: hoppers, pumps, tremie concrete, and mass concrete. The excellent partnering with the owner allowed the contractor to use the best technology to get the job done.

The concrete supplier had his own challenges to produce over 320,000 cu yd of concrete including high strength, high early strength, low permeability, extended set times, extended transportation times, and control of initial concrete temperatures. Again, the design-build process allowed the flexibility to select the mix design to construct the best bridge possible. The $531 million project was completed more than one year ahead of schedule.

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HPC Works for Every-Day Bridges

High-performance concrete is not just for high-profile megaprojects. You can use it for routine highway overpasses such as SR18 over SR516 in King County, Washington. For today's emphasis on construction zone safety and reduced traffic delays, you can "stay out" by building with maintenance free, long-lasting, and durable HPC.

Washington State Department of Transportation (WSDOT) has developed and used high-performance concrete (HPC) mixes containing fly ash and silica fume in several highway bridges since 1992. The concrete has high compressive strength attaining 10,000 psi (69 MPa) by 28 days, low chloride permeability averaging less than 1,000 coulombs by 56 days, and generally lower shrinkage and creep values than conventional concrete. More.

Avoiding Strand Corrosion

Dr. Andrea Schokker of Penn State University recently conducted research on the issue of strand corrosion in sealed environment. The research found that:

• Corrosion could occur in a sealed environment despite the initial high pH of the grout bleed water and the low levels of chlorides in the system.


• The corrosion mechanism is most likely a carbonation reaction involving carbon dioxide in the air and calcium hydroxide in the grout bleed water. This reaction creates regions of low pH at the surface of the bleed water where the passivity of the steel is lost and corrosion subsequently occurs.

• Measures should be taken to eliminate the bleeding of grouts used in post-tensioned construction, even in traditionally noncorrosive environments. High quality antibleed grouts should be used to ensure tendon durability. The motivation for using bleed-resistant grouts has focused previously on grout bleed voids as potential locations for chloride ingress and subsequent corrosion initiation. The present research indicates that even the presence of grout bleed water in the tendon can initiate corrosion in the absence of chlorides.


• Post-tensioned tendon anchorage protection systems, which completely encapsulate the anchorage hardware and strand ends, should be used to prevent air, water, or chlorides from entering the tendon.

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Bridge Tour Added to CBC

A site visit to the Galena Creek Bridge currently under construction will take place on
Sunday, May 7, 2006 (1:00 - 4:30pm). When completed the main span of 689 ft. will be the longest concrete arch span in the U.S. The construction of the arch will utilize an innovative method called the pilot truss method in which a steel truss used as a support during construction becomes a composite part of the completed concrete arch. Nevada DOT engineers will be on hand to provide an overview of the project and answer questions.

The 2006 Concrete Bridge Conference will be held May 7-10, 2006, at the Nugget Resort Hotel in Reno, Nevada, in conjunction with the 2006 Post-Tensioning Institute (PTI) Technical Conference and Exhibition. Your registration will enable you to attend both conferences. More than 600 attendees are expected. More.

SAFETEA-LU Becomes Law

Officially dubbed the "Safe, Accountable, Flexible, and Efficient Transportation Equity Act: A Legacy for Users," the new $286.4 billion, six-year highway bill was signed into law by President Bush on August 10, 2005. The bill authorizes $16.5 million for research and technology transfer of high-performance concrete bridges. PCA, the Precast/Prestressed Concrete Institute, and other members of NCBC will work closely with the Federal Highway Administration to achieve the objectives set forth in NCBC's Building a New Generation of Bridges - A Strategic Perspective for the Nation, the advocacy document produced in support of the research program. More.

Take 1/3 Off New Guide Specification for High Performance Concrete for Bridges

This guide specification is for all high-performance concretes supplied for highway bridges, whether produced by a ready mix supplier, a general contractor, or in a permanent plant of a precast concrete manufacturer. The document provides mandatory language that the specifier can cut and paste into project specifications. It also includes guidance on what characteristics and limits should be specified to ensure satisfactory performance for a given element or environment.
EB233—Regular price $30
Now only $20 until October 31, 2005.

Question: What is match curing and can I use it to determine specified release strengths and design strengths?

Answer: Match curing is a system in which a standard concrete cylinder—usually 4x8 in. (102 x 203 mm)—is cured at the same temperature as that measured in a concrete member. The system includes a temperature sensor in the member, a controller, a special insulated cylinder mold with a built-in heating system, and a temperature sensor in the mold. Whether or not the match-curing technique can be used to determine specified strengths will depend on the specifications. More.