Newsletter Delivers Latest in HPC Developments

Published jointly by the Federal Highway Administration (FHWA) and the National Concrete Bridge Council (NCBC) HPC Bridge Views was introduced in 1999 to provide relevant, reliable information on all aspects of High Performance Concrete (HPC). It is the result of a cooperative agreement to develop and implement means to enhance the use and quality of concrete materials and bridge systems in order to achieve a more cost-effective highway system.

Printed issues are mailed 6 times a year to partners in the HPC for Bridges implementation effort including the AASHTO HPC Lead States Team, State DOTs, universities, ready-mixed concrete suppliers, the prestressed concrete industry, materail and admixture suppliers, contractors, consultants, and FHWA. Click here to view back issues.

This is the first time the newsletter will be sent electronically, as well. Future issues of this Bridges e-newsletter will contain links to the printed versions.

In the cover article, Oregon feels that the money spent up front is well worth the investment if its bridges last for a hundred or more years! So, in its most demanding environments, the solution is HPC together with stainless reinforcement. In Texas, parallel bridges with ages of 45 and 56 years were replaced and designed to last much longer – 100 years. In a very demanding environment, the TxDOT approach was somewhat different – HPC, inhibitors, low design stresses, and "generous structural proportioning." Sulfates are one of the enemies waiting to attack concrete. In her article on testing, Rachel Detwiler describes the current tests to determine sulfate levels and measures to mitigate sulfate attack. This is the fourth in a series of articles describing tests applicable to HPC. Self-consolidating concrete is becoming quite common in the public sector; but just how common? This issue's Q&A probes that very question. Articles Include:

• 120-Year Bridge Service Life, Is It Possible? by Tarif M. Jaber
• Galveston Bay Bridges by Kevin Pruski
• HPC Tests – Sulfate Resistance by Rachel Detwiler
• Q&A: What is the status on the use of self-consolidating concrete in bridges?

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HPC: Build Fast, Build to Last

The National Concrete Bridge Council is pleased to announce the 2006 Concrete Bridge Conference to be held May 7-10, 2006 at the Nugget Resort Hotel in Reno, Nevada. CBC has quickly become the premier national venue for the exchange of ideas and information on all aspects of concrete bridge design and construction. The last two conferences held in 2002 and 2004 were a great success. Typically, over 300 bridge engineers including FHWA, DOT, and consulting engineers, academia, contractors, and industry attend CBC. An extra day has been added in 2006 for a workshop on Rapid Bridge Construction. More.

The 2006 Concrete Bridge Conference (CBC) is being held in conjunction with the 2006 Post-Tensioning Institute (PTI) Technical Conference and Exhibition. Your registration will enable you to attend both conferences. Up to 600 attendees are expected.

The 2004 Conference Bridge Proceedings, featuring 90 papers are available on a CD. More.

Still Time to Attend Bridge Design Seminar for University Professors

By 2007, all bridges receiving federal funding must be designed by the AASHTO LFRD Bridge Design Specifications. The subject seminar emphasis is on the new state-of-the-art design methods in the LRFD Specifications that are relatively unfamiliar and significantly different than the current methods in the Standard Bridge Design Specifications.

Since 1999, PCA has conducted an annual LRFD Concrete Bridge Design Seminar to provide information on the latest concrete industry developments to university professors to assist them introduce new or update existing courses in concrete bridge design.

The seminar will be held August 4-5, 2005 in Skokie, IL and is open to all university professors from Canada and the U.S. As in the past, there is no seminar registration fee. For more information contact cjohnsen@cement.org.

Save 20% on AASHTO LRFD Strut-and-Tie Model Design Examples

This publication identifies disturbed regions of structures resulting from geometric or force discontinuities where STM must be used. A step-by-step procedure for STM is provided. Five detailed design examples are also provided; they include: (1) Design of cap beam, (2) Design of footing, (3) Design of pile cap, (4) Design of dapped end region of girder, and (5) Design of hammerhead pier.
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Question: Are there quantitative measurements for HPC?

Answer: The most common measurement for HPC is concrete compressive strength. The American Concrete Institute recognizes that concrete with a specified compressive strength of 6000 psi (41 MPa) or greater is a high strength concrete and, therefore, a high performance concrete.

However, there are many other measurements that can be used to specify HPC. For structural properties, these may include tensile strength, modulus of elast i c i t y, shrinkage, or creep. For durability, performance can be measured using freeze-thaw resistance, de-icer scaling, abrasion resistance, or chloride permeability. Concretes may also require a special density or low heat of hydration. The goal is to specify quantifiable performance to match the intended application. In many cases, this will mean that performance requirements other than strength will be specified.

Corrosion From Bleed Water In Grouted Post-Tensioned Tendons

Bleeding of grouts used in post-tensioned concrete construction is problematic because the bleed water tends to migrate to the tendon high points and form a void in the grout. This report details a study investigating the corrosive nature of bleed water from grouts with certain cement-admixture combinations. Research findings showed significant corrosion in most of the specimens. A suspected corrosion mechanism is discussed and recommendations for avoiding this type of corrosion are presented (RD137). More.