Construction Methods. Sidewalk shall be constructed on a prepared,
compacted smooth subgrade of uniform density formed by trenching or
filling, to the required elevation. Large boulders and ledge rock
found in the subgrade shall be removed to a minimum depth of 6 inches
below the finished subgrade elevation and the space shall be backfilled
with suitable material which shall then be thoroughly compacted.
The forms shall be of either metal or wood and shall be straight,
free from warp, smooth-faced, of sufficient strength to support the
work during construction, and of a height equal to the depth to the
sidewalk or sidewalk apron to be constructed. Wood forms shall have
a minimum nominal thickness of 1-1/2 inches. Metal forms shall be
of adequate type and shall have a flat top surface. The forms shall
be cleaned, well oiled, securely staked, braced, and held to the required
line and grade before any concrete is deposited. Sidewalk shall slope
1/4 inch per foot toward the roadway, unless conditions warrant otherwise.
The concrete shall be deposited between the forms on moistened
subgrade, shall be struck off to a minimum 4 inch thickness, and shall
be worked sufficiently to bring the mortar to the surface. At driveway
crossings, sidewalk thickness shall be increased to either nine inches
(9") of concrete, or six inches (6") of concrete on six inches (6")
of compacted DGA. The surface shall then be made smooth and even by
proper means and given a broom finish. All edges shall be rounded
with an edging tool to 1/4 inch radius. The surface shall be divided
into rectangular panels by means of a jointer having a radius of 1/4
inch and forming a groove not less than 1 inch in depth for the full
width of the walk. The length of the panels formed shall not exceed
the width of the sidewalk being constructed, unless otherwise specified
by the Engineer.
Joints may be sawed at the discretion of the Engineer. Ensure
that sawed joints are of uniform width throughout. Use sawing equipment
to cut the joint in strict conformity with the required alignment
and depth. Do not saw the joints until the concrete has hardened to
the extent that tearing and raveling will not occur, but as soon as
necessary to preclude random cracking.
When the sidewalk is constructed integral with the curb, ensure
that the width and spacing of the joints conform to that in the curb.
Round the edges of the sidewalk at all expansion joints with an approved
edging tool to a 1/4 inch radius. Install 1/2-inch premolded expansion
joint material to the full depth of the sidewalk where the sidewalk
abuts any rigid structure or fixture, such as curbs, columns, castings,
buildings, and light standards.
When sidewalks cross a driveway, delineate the extent of the
sidewalk by jointing as directed by the Engineer.
The developer shall install 1/2 inch premolded full-depth expansion
material at intervals not to exceed 40 feet, and where the sidewalk
abuts any rigid structure or fixtures such as curbs, columns, castings,
buildings, light standards, existing sidewalks or pavements, etc.
Flexible, non-extruding, expansion-contraction joint filler
material approved by the Engineer shall be used on all expansion joints.
If any type of closed-cell material is used, an elastomeric sealing
compound shall be applied to the top surface to seal the joint. Sealing
compounds shall be applied in accordance with manufacturer's recommendations,
and shall be approved by the Engineer. Zip-strips or other preformed
expansion joint materials may only be used with approval of the Engineer.
Sidewalk and aprons shall be cured in the same manner as specified
for concrete pavement.
After the concrete has set sufficiently, the developer shall
remove the forms and shall backfill the space on each side of the
walk. The earth shall be compacted and graded in a satisfactory manner.