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salts and not oilborne preservatives such as creosote. Evaluate the cost and
availability of timber piles and other members for the project.
When protected against corrosion by the use of coal tar epoxy or other marine
coatings and cathodic protection systems, steel construction may be considered
for all types of marine structures. Active cathodic systems are difficult to design,
construct, and maintain properly, therefore, passive systems are preferred.
Additional steel thickness may be provided as a sacrificial corrosion allowance.
Steel is particularly adaptable for use: in template and jack-up barge construction
at advance base facilities; as piles for structures located in deep water where
high lateral forces must be resisted; as fender piles and fender panels; as piles
for structures located in areas of high seismic activity; and where difficult driving
is anticipated. When the utilization of other construction materials is considered
feasible, the use of steel construction may be restricted due to cost and
For piers and wharves, concrete is generally the best material for construction.
Properly designed and constructed facilities are highly durable in the marine
environment. New advances in concrete technology have improved concrete
durability. Concrete enhanced with fly ash, silica fume and corrosion inhibitors
has demonstrated superior performance and should be used whenever possible.
The use epoxy coated reinforcement is recommended. UFGS 03311 Marine
Concrete calls for the use of the latest generation of epoxy coated rebar, known
as "purple bar" as specified in ASTM A934. Concrete is immune to marine borer
and insect attack and is incombustible. Concrete is also ideal for deck
construction in open-type piers and wharves and, when properly designed, is
more economical for floating structures. Proprietary stainless steel reinforcement
bars, wires, and strands have been developed for use in concrete construction
where nonmagnetic properties are desired as in Magnetic Treatment and
Electromagnetic Roll piers.
Precast Concrete Piles.
Precast concrete piles should preferably be prestressed to resist the tensile
forces frequently encountered during driving. Corrosion of reinforcement in
prestressed concrete piles can be controlled by proper mix design and, in
extreme cases, by epoxy coating the reinforcement. However, exercise sufficient
control during driving of concrete piles to minimize cracking. Where difficult
driving into very compact sands, gravels, or rock is anticipated, the tip of the piles
may be equipped with a WF-shape or H-pile "stinger" to achieve needed
penetration. Very large hollow cylindrical piles (48-in. diameter and larger) have
also been successfully employed for waterfront construction on the East coast.