Frequently Asked Questions
Cement & Concrete
Technology Home > FAQs > Lightweight
concrete for bridge construction
Q: Can lightweight concrete be used for bridge
construction?
A: Lightweight concrete can be and
has been used for bridge construction for decades. There are many
examples of lightweight concrete bridge construction in different
environments:
- Upper deck of the Oakland Bay Bridge constructed in 1936 (still
in service)
- William Preston Lane, Jr. Bridge, Chesapeake Bay, Maryland,
constructed in 1952 (still in service)
Of course any concrete mixture considered for a specific application
should always be evaluated for the service environment in which
it will be placed. Concrete used in bridge construction in severe
weathering regions typically requires low permeability to provide
protection for the steel reinforcement in the structure as the use
of deicing chemicals increases the risk of corrosion of any steel
reinforcement. Corrosion of the steel is a primary concern for the
long term durability of this type of structure. Low permeability
and high strength are closely related concrete properties; as strength
increases permeability decreases.
Concrete strengths used in bridges typically equal or exceed 5000
psi and some bridge specifications require permeability testing
using the “Standard Test Method for Electrical Indication
of Concrete’s Ability to Resist Chloride Ion Penetration,"
ASTM C1202. These minimum precautions should be implemented regardless
of the type of concrete being considered.
In summary lightweight concrete that has been properly tested to
assure that it provides the required properties for the specific
structure in question can be used for bridge construction.
Reference:
Criteria for Designing Lightweight Concrete Bridges, FHWA-RD-085-045,
TY Lin International, FHWA, Aug. 1985.
Available from NTIS at 1-800-553-6847 or orders@ntis.fedworld.gov
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