THE CONCRETE BRIDGE MAGAZINE

WINTER 2012

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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ASPIRE , Winter 2012 | 37 concrete mixture design, and construction practices in concrete placement, finishing, and curing. Methods for crack repair are also provided in the circular. A list of about 150 references is provided. FHWA Webinar On September 15, 2011, FHWA in cooperation with the National Highway Institute (NHI) conducted a webinar on "Control of Concrete Cracking in Bridges and Pavements." The webinar was co-sponsored by FHWA's Highways for LIFE program, NHI, and TRB as part of the ongoing Innovations series. T h e w e b i n a r wa s m o d e r a t e d b y M y i n t Lwin, director of the FHWA Office of Bridge Technology and Ben Graybeal, FHWA research structural engineer. Three featured speakers shared their knowledge and experience on three topics: • C a u s e s , Te s t i n g , a n d D e t e c t i o n o f Cracking • Controlling Cracks • Prevention of Cracks in Concrete A recording of the webinar may be viewed at http://fhwa.adobeconnect.com/n134083201109. Closing Remarks By virtue of its low tensile strength, concrete cracking is natural and often unavoidable. Proper structural design and detailing, selection of materials, mixture design, and construction practices can keep cracking to an acceptable level. Understanding the causes of cracking can lead to finding effective ways to prevent, control, and repair cracks. National standards, such as those by AASHTO and ACI, and reports such as those by PCI, have provisions for crack control and repair to assure serviceability, aesthetics, and economy of bridges. The Charenton Canal Bridge, La., was constructed in 1999 and inspected 4 years later for cracks in the deck. The only cracks observed were transverse ones in the negative moment region over the intermediate piers. Photo: Louisiana Department of Transportation and Development. The Route 104 Bridge, Bristol, N.H., was constructed in 1996. A bridge deck survey 8 years later showed only two longitudinal cracks with a total length of 10 ft. Photo: New Hampshire Department of Transportation. Book_Win12.indb 37 12/29/11 11:12 AM

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