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For FY 2000, the Federal Highway Administration (FHWA) was
directed by Congress to fund a program of research and
implementation of lithium-based technologies for the mitigation
of alkali-silica reactivity (ASR) in Portland cement concrete.
Two types of field trials will be considered: (1) New
construction or reconstruction projects using lithium-based
technologies to prevent ASR, and (2) Application of
lithium-based technologies on existing concrete to mitigate ASR.
The objective of these field trial studies is to demonstrate the
use of lithium-based technologies to (DOT) agencies and to
document field performance of these technologies.
ASR takes place between certain reactive siliceous aggregates
(e.g., opal, chalcedony and volcanic glass) and the alkali from
Portland cement paste or external source. A reaction product gel
forms that, in the presence of water, expands and may cause
cracking of mortar and concrete. These surface cracks are
aggravated by winter deicing salts and freeze-thaw action,
leading to shallow delamination, rebar corrosion, potholes, and
other serious problems including structural failure. Recent
studies have shown that adding lithium compounds to concrete in
the plastic state to be effective in the control of ASR.
However, lithium-based
technology has not been widely applied to existing and aged
concrete bridge decks and pavements. The development of
materials and application procedures is urgently needed for
field implementation using lithium compounds in arresting ASR in
existing concrete pavements.
A stretch of N. first Street in Norfolk,
Nebraska, has been selected for lithium treatment. The 8-year
old concrete pavement is 8 inches in thickness. Originally
constructed in 1995. This project is proposed to be a joint
effort of Nebraska Department of Roads (NDOR), the U.S.Army
Corps of Engineers, Omaha District (USACE), and the University
of Nebraska-Lincoln (UNL), in that the project will be managed
by NDOR, in-situ testing and petrographic examinations of
lithium-treated and untreated concrete samples will be performed
by USACE, laboratory testing will be conducted at UNL, and the
lithium treatment procedures will be jointly developed by the
research team.
sponsored by: Federal
Highway Administration (FHWA/HIPT)Lithium Field Implementation
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