A new innovation by AltusGroup could reportedly reduce maintenance costs and extend the lifespan of bridges from 50 years to upwards of 75 to 100 years by improving their corrosion resistance through the use of carbon fiber reinforced polymer (CFRP) grid in precast concrete bridge piles.
In this technology, CFRP mesh surrounding a composite support structure with a plurality of support strands is encapsulated in concrete to provide high corrosive resistance and provide increased ability to withstand compressive, tensile and shear loading as compared with carbon steel spirals commonly used in piles today.
This extension of the CarbonCast line introduces AltusGroup’s technology to the pile market sector. Although the brand is already producing CarbonCast enclosure systems for building exteriors and CarbonCast double tees for structured parking, this new bridge pile would be the first CarbonCast technology to enter the DOT and transportation segment.
The CFRP grid aims to deliver increased corrosion-resistance and a greater ability to withstand compressive, tensile and shear loading compared with the conventional steel spirals and reinforcing bar it would replace, making it a particularly attractive option in in coastal and marine environments where the presence of salt often amplifies the possibility and speed of corrosion, a major problem identified by many DOTs.
The CFRP grid resists the extreme corrosion common in the splash zone of a pile where it is most susceptible to impact, damage and cracking. The corrosion of conventional steel, on the other hand, expands and damages the concrete encasing it, which in turn compromises the integrity of the bridge itself.
The American Society of Civil Engineers’ 2013 Report Card for America’s Infrastructure rates one in nine of the nation’s bridges as structurally deficient. Of the nation’s 607,380 bridges, the average age of a bridge is 42 years, and most have a design life of only 50. Targeting the commercial construction sector of the market for initial technology commercialization, AltusGroup plans to work closely with many states’ DOTs, especially those with coastal zones and exposure conditions that are in need of improved and enhanced durability.
Dr. Sami Rizkalla, of the North Carolina State University Constructed Facilities Laboratory in Raleigh, N.C. performed initial testing of the pile concept and confinement of CFRP grid versus steel spirals. Florida DOT’s structural research and testing facility, the Marcus H. Ansley Structures Research Center Laboratory in Tallahassee, Fla., performed subsequent testing, including pile load testing and driving in known soil conditions.
AltusGroup was founded in 2003 as the first-ever international partnership of precast companies with the goal of developing, manufacturing and marketing precast innovations. The 16 North American and three international AltusGroup companies have more than two dozen structural and architectural locations in the U.S., offering architects, engineers and contractors a network of manufacturing plants, technical staff and sales personnel. For more information, visit www.altusprecast.com.
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