Special Concrete Finishes

MIL-HDBK-1011/1

aggressive

environments.

Extra cover cannot be a substitute for quality

concrete.

3.10.5

Chlorides. Although research and experience to date have

demonstrated that unbonded tendons exposed to seawater and other aggressive

environments are durable, do not use unbonded tendons in applications directly

exposed to seawater. In addition, do not use admixtures containing calcium or

aggregates containing chlorides in posttensioned structures. This restriction

refers also to the mortar used to patch or fill stressing pocket recesses.

3.10.6

Design Considerations. If higher prestress forces are used to

create watertight concrete, incorporate allowances for elastic shortening as

well as creep and shrinkage in the design.

3.11

Special Concrete Finishes, It is important, however, to be aware

of mildew problems that exist, especially on untreated, exterior, textured

surfaces. In areas subjected to salt-laden, wind borne exposures, specify

long-life surface coatings, such as concrete and masonry block filler with two

finish coats of exterior-grade paint, for all exposed concrete.

3.12

Concrete Cover. See Table 1 for recommended minimum concrete cover

over non-coated reinforcing steel in tropical environments.

Table 1

Reinforcing Steel Concrete Cover

LOCATION

CAST-IN-PLACE

CONCRETE TYPE

PRESTRESSED

PRECAST

Exposed to the Weather

3 inches

2 inches

Interior Beams and

2 inches

Columns (to Ties)

Interior Walls and Slabs

1 inch

1-1/2 inches

(Except Nos. 14 and 18

Bars)

Slabs on Grade (Wire

1/2 thickness of slab but not less than 2 inches

Fabric)

Waterfront (10 Feet

3 inches

2 inches

Below and 10 Feet Above

Mean Low Tide)

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