Editor's note: For more than a dozen years, there's been a slow but steady effort to promote the quality of concrete bridge construction. In this article reprinted from the Federal Highway Administration's and National Concrete Bridge Council's, HPC Bridge Views, No. 53, we learn how widespread the acceptance of new concrete techniques has been. Initiatives such as deploying high-performance concrete technologies will surely help producers secure our fair share of the current stimulus funding and the next major transportation bill due in late fall.
The 1990s laid the groundwork for high-performance concrete (HPC) technology to develop and blossom into a bona fide bridge material through the efforts of the Federal Highway Administration (FHWA), state agencies, consulting engineers, the concrete industry, and academia. This continuing dedicated partnership will play a critical role in the widespread use of HPC.
In 1997, the FHWA High-Performance Concrete Technology Deployment Team (TDT) was created to assist state departments of transportation and other agencies with deploying HPC technology.
In 2003-04, the team's national survey of HPC usage showed that almost every agency had either incorporated HPC into their standard specifications or had at least tried it during the previous 10 years. However, on the extent of HPC usage by each agency, the results were inconclusive.
A second survey was made three years later. This version attempted to bridge that gap by soliciting information on number of bridges built with an HPC element, as well as percentages of projects built since the first survey with an HPC bridge element.
The survey was distributed to all 50 state DOTs, Puerto Rico, the District of Columbia, and the Federal Lands Bridge Office. All 53 agencies returned the survey to the TDT for processing, although some agencies did not respond to all questions. The survey included sections on general HPC use, its permeability and strength benefits, self-consolidating concrete (SCC), lightweight HPC, and various types of corrosion-resistant reinforcing bars.
The map shows there is still much work to be done if HPC is to successfully impact the new and rehabilitated U.S. bridge infrastructure in the 21st century. An aggressive training effort will still be necessary for the total workforce involved with bridge design and construction-engineers, inspectors, and contractors. Undergraduate and graduate school curricula must also adapt to give students the tools needed to understand the behavior of HPC constituent materials.
Here is a summary of the key results.
General Usage of HPC
The recent survey asked about the usage since 2003 of HPC for major bridge components-deck overlays, deck slabs, superstructures, and/or substructures. On average, about 15% of the agencies used HPC for these components in more than 50 bridges, 20% in 10 to 50 bridges, 30% in one to 10 bridges, with the remainder not using it at all or not responding.
On a project basis, on average, 16 agencies used HPC on up to 10% of their bridge projects, 19 agencies used HPC on 10% to 80%, and 15 agencies used HPC on more than 80%.