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Preventing
rebar corrosion in concrete structures
This article reviews the issue of rebar
corrosion, discusses some of the preventive technologies available,
and presents information on recent studies conducted by NRC's Institute
for Research in Construction. (NRC
Institute for Research in Construction, September 2004, 8 p.)
Electrodeposition
as a rehabilitation method for concrete materials
Electrodeposition was used to rehabilitate cracked reinforced
concrete both in the laboratory and under field conditions. First the
chloride-induced specimens were cracked by applying a bending load,
then the samples were immersed in a zinc sulfate solution, and a constant
current was applied between the reinforcing steel and the external electrode.
The results obtained in the laboratory showed that electrodeposition
effectively repaired cracks in the concrete specimen; therefore, field
investigations were performed on a 35-year old structure that had been
damaged by corrosion to assess the feasibility of using this technique
in field conditions. The field results indicate that the electro deposits
formed on the concrete surface closed the cracks in the concrete. In
addition, the application of electro deposition had beneficial effects
on the electrochemical property of the reinforcing steel in concrete.
(Canadian Journal of Civil Engineering, October 2004,
pp. 776-781.)
Critical
Literature Review of High-Performance Corrosion Reinforcements in Concrete
Bridge Applications
A critical literature review regarding high-performance
reinforcement for concrete bridge applications was conducted. This included
(1) an overview of the corrosion-induced concrete deterioration process,
(2) corrosion control alternatives, (3) the utility of corrosion (pitting)
resistant alloys for applications in chloride containing environments,
(4) a review of the pitting mechanism, and (5) performance of various
metallic reinforcement types in aqueous solutions, cementitious embedments,
test yard exposures, and actual structures. (FHWA
Report FHWA-HRT-04-093, July 2004, 54 p.)
Long-Term
Performance of Epoxy-Coated Reinforcing Steel in Heavy Salt-Contaminated
Concrete
This report describes long-term natural weathering exposure
testing of the remaining 31 post-Southern Exposure (SE) test slabs that
were not autopsied during the 1993–1998 Federal Highway Administration
(FHWA) research project. The samples were exposed from September 1998
to December 2002 at an outdoor test yard in Northbrook, IL. The 1993–1998
research program involved testing more than 52 different bar materials
and, consequently, 12 different bar types were selected for long-term
durability tests in concrete exposed to the very aggressive SE test,
which involved alternating wetting with 15 weight percent NaCl solution
and drying cycles for 96 weeks. (FHWA Report
FHWA-HRT-04-090, May 2004, 132 p.)
Remaining
Life of Reinforced Concrete Beams with Diagonal-Tension Cracks
This report concerns the initial efforts of a research
study investigating the remaining capacity and life of cast-in-place
reinforced concrete deck-girder (RCDG) bridges with diagonal tension
cracks. A database of 442 bridges constructed from 1947 to 1962 was
developed to identify salient parameters related to bridges with diagonal
tension cracks in the Oregon Department of Transportation bridge inventory.
The database was queried to provide summary details for individual parameters
and relationships between parameters. In additional, a bridge analysis
was conducted on an in-service RCDG bridge with diagonal tension cracks.
A linear finite element model of the bridge provided reasonable prediction
of cracking. (Oregon Dept. of Transportation
Report SPR #341, April 2004, 124 p.)
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Cost-Effective
Practices for Off-System and Local Interest Bridges