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Founded in 1904 and headquartered in Farmington Hills, Michigan, USA, the American Concrete Institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensus-based standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design, construction, and materials, who share a commitment to pursuing the best use of concrete.
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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Title: Lessons Learned from Bridge Repair with Steel Fiber-Reinforced Shotcrete and Overlays
Author(s): J. Wong and P. D. Carter
Publication: Special Publication
Appears on pages(s): 139-154
Keywords: corrosion protection; high-performance concrete; overlays; repair cracking; shotcrete; steel fiber-reinforced concrete.
Abstract:The use of steel fiber-reinforced, silica-fume-modified concrete overlays and shotcrete for bridge repairs has long been the standard for Alberta Transportation (AT). Approximately 200 provincial bridges have been repaired with steel fiber reinforced, silica-fume-modified materials since 1984, mostly to decks, which had been exposed to aggressive conditions including freezing and thawing, de-icing salts, and moisture. The purpose of using steel fiber in bridge concrete repair materials was primarily to prevent or reduce repair cracks and to improve durability. Standard fiber lengths were 25 mm (1 in.) for shotcrete and 50 mm (2 in.) for overlays with standard fiber dosages of 60 km/m3 (100 pounds/yd3). Most of the repairs were done with superplasticized, silica-fume-modified, low water-cement ratio concrete mixes. This paper reports on the early historical development of the repair method basics and the lessons learned from monitoring bridge repairs. Conclusions are presented from AT’s Level 1 and Level 2 inspection data. Level 2 data quantifies several repair performance indicators, such as wide cracks, stains, delamination, spalls, patches, and debonds, as well as a breakdown
of numerical condition ratings on important bridge elements. Crack data from Level 2 inspections was available from 154 silica fume modified bridge deck overlays, 124 of which contained steel fiber. The crack data was analyzed to assess the performance of fibers in reducing the amount of easily visible cracks: those wider than 0.3 mm (0.012 in.). The results showed that the steel fibers resulted in significant crack reduction and improved overlay durability and service life.
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