19 June 2001
Floating structures use reinforced concrete for pontoons, quays,
wharves, piers, and facilities for small boats.
Drydocks are made of reinforced concrete.
seawater is due to corrosion of the reinforcement. This corrosion can be
accelerated due to improper concrete mix, insufficient concrete cover (thickness
of concrete over the reinforcing steel), improper curing, operational loads,
chemical attack, and volume changes. Using well established mix designs and
construction practices, however, will enhance reinforced concrete durability.
Reinforced concrete in waterfront facilities must meet the criteria set by
the American Concrete Institute (ACI) Standard 318, Building Code
Requirements for Reinforced Concrete. This standard covers the building code
requirements for concrete with and without reinforcing. Additional design
information, with emphasis on waterfront facilities, is included in NAVFAC MIL-
HDBK-1025/6, General Criteria for Waterfront Construction. These manuals
provide general design and application data for a variety of waterfront structures.
Unified Facilities Guide Specification UFGS-03311, Marine Concrete, provides
guidance for cast-in-place concrete subject to exposure to the marine
environment. Unified Facilities Guide Specifications UFGS-02459N, Cast-in-
Place Concrete Piles, UFGS-02395N, Prestressed Concrete Fender Piles, and
UFGS-02456N, Prestressed Concrete Piles, provide guidelines on concrete
Components of Concrete. Concrete is a mixture of Portland cement,
coarse and fine aggregate, and water. Various admixtures, and pozzolans may
be used to improve the strength, workability, and service life. Preparation and
proportioning of concrete mixtures should follow the recommendations of the
Portland Cement Association's, Principles of Quality Concrete, and ACI 211,
Recommended Practice for Selecting Proportions for Concrete
3-3.2.1 Cement. Five types of Portland cement are described in ASTM C
150A, Cement, Portland. For concrete structures exposed to seawater, Types II
and V should be used. Type II is a sulfate-resisting cement. Type V, however, is
no longer being produced. Low alkali cements should be used with potentially
Do not use any product containing sodium or calcium, as it will likely
accelerate the onset of rebar corrosion.
3-3.2.2 Aggregates. Aggregates are used in concrete mixtures to improve
durability and reduce costs. They usually make up 60 to 80 percent of the volume
of the concrete. The shape and size of the aggregate should meet the
requirements specified in ASTM C 330. Aggregates are a mixture of sand and
rock. Marine aggregates, such as coral, should not be used. However, if marine