The air contents specified are for concrete that
will be subjected to freezing weather and the
possible action of deicing chemicals. In climates
where freezing is not a factor but where air
entrainment is used in local commercial practice to
improve the workability and placability of concrete,
concrete having air content of 4-1/2 plus or minus
1-1/2 percent may be specified as Contractor's
option to nonairentrained concrete.
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Unless otherwise specified, concrete and reinforced concrete shall conform
to the requirements for [_____] MPa psi concrete under Section [03300A
CAST-IN-PLACE STRUCTURAL CONCRETE][03300N CAST-IN-PLACE CONCRETE]. The
concrete mixture shall have air content by volume of concrete, based on
measurements made immediately after discharge from the mixer, of 5 to 7
percent when maximum size of coarse aggregate exceeds 37.5 mm. 1-1/2 inches.
Air content shall be determined in accordance with ASTM C 231. The
concrete covering over steel reinforcing shall not be less than 25 mm 1 inch
thick for covers and not less than 40 mm 1-1/2 inches thick for walls and
flooring. Concrete covering deposited directly against the ground shall
have a thickness of at least 75 mm 3 inches between steel and ground.
Expansion-joint filler material shall conform to ASTM D 1751, or ASTM D 1752,
or shall be resin-impregnated fiberboard conforming to the physical
requirements of ASTM D 1752.
2.3.2
Mortar
Mortar for pipe joints, connections to other drainage structures, and brick
or block construction shall conform to ASTM C 270, Type M, except that the
maximum placement time shall be 1 hour. The quantity of water in the
mixture shall be sufficient to produce a stiff workable mortar but in no
case shall exceed [_____] liters gallons of water per sack of cement.
Water shall be clean and free of harmful acids, alkalies, and organic
impurities. The mortar shall be used within 30 minutes after the
ingredients are mixed with water. The inside of the joint shall be wiped
clean and finished smooth. The mortar head on the outside shall be
protected from air and sun with a proper covering until satisfactorily
cured.
2.3.3
Precast Concrete Segmental Blocks
Precast concrete segmental block shall conform to ASTM C 139, not more than
200 mm (8 inches) 8 inches thick, not less than 200 mm (8 inches) 8 inches
long, and of such shape that joints can be sealed effectively and bonded
with cement mortar.
2.3.4
Brick
Brick shall conform to ASTM C 62, Grade SW; ASTM C 55, Grade S-I or S-II;
or ASTM C 32, Grade MS. Mortar for jointing and plastering shall consist
of one part portland cement and two parts fine sand. Lime may be added to
the mortar in a quantity not more than 25 percent of the volume of cement.
The joints shall be filled completely and shall be smooth and free from
surplus mortar on the inside of the structure. Brick structures shall be
plastered with 10 mm 1/2 inch of mortar over the entire outside surface of
the walls. For square or rectangular structures, brick shall be laid in
stretcher courses with a header course every sixth course. For round
SECTION 02630
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