The purpose of this chapter is to outline requirements for proper
design, construction, and inspection of concrete sidewalks, curb and
gutter.
Shall be in accordance with the following specifications and
subject to approval by the Engineer.
Shall be constructed of Portland Cement Concrete in accordance
with the requirements shown on the plans and the provisions of this
specification.
4.2.1.
Material. Concrete shall have a minimum 28 day compressive strength
of 3500 psi. Air-entraining admixture shall be used. No reinforcing
steel or wire mesh shall be installed in sidewalks, curbs, or curb
and gutter unless directed by the Engineer.
Expansion joint material shall conform to the requirements of
KYTC Standard Specifications current edition.
4.2.2.
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.
All curb and curb and gutter shall be Portland cement concrete.
Concrete shall have a minimum 28 day compressive strength of 4,000
psi. Air-entraining admixture shall be used.
4.3.1.
Subgrade. Subgrade for curb and gutter shall be at least four inches
(4") of compacted DGA.
When curb and gutter is constructed prior to establishment of
the street subgrade, the curb and gutter subgrade may be compacted
by approved methods. The width of the subgrade shall be not less than
the width of the curb and gutter plus six (6) inches on each side.
No curb and gutter concrete shall be placed until the subgrade has
been inspected.
4.3.2.
Construction. All curbs shall be placed by a continuous pouring (extruding)
curb machine with an approved mold and jointed on ten foot (10') centers.
Joints shall meet the requirements of Section 4.2.2 above, and may
be sawed at the discretion of the Engineer. Where radii, tie-ins or
other conditions make extruded curb impractical, curbs may be constructed
using forms and methods approved by the Engineer, and shall be finished
in a manner that matches adjacent extruded curb.
When indicated on the plans or directed by the Engineer, entrance
and drainage openings of the required dimensions shall be formed through
the curbing at the designated location. The back of curb and gutter
may be depressed as approved by the Engineer to provide vehicle entrance
and exit to private property.
Forms shall be removed in not less than 6 hours nor more than
24 hours after the concrete has been placed.
4.3.3.
Concrete Placement. Moisten prepared subgrade before the concrete
is placed. Immediately after placement by machine, the concrete shall
be floated to a smooth and consistent surface and lightly broomed.
Reinforcing steel is not normally allowed, but when required
by the Engineer, it shall be placed in accordance with the details
shown on the plans.
Expansion joints shall not be used except at catch basins or
inlets, or as deemed necessary by the Engineer.
4.3.4.
Concrete Finishing. The top surfaces of the curbs and gutters shall
be given a uniform float finish and the edges shall be rounded with
an edging tool having a radius of 1/4 inch. All honeycombed areas
shall be corrected by filling with mortar, composed of 1/2 mixture
by volume of cement and sand. Plastering will not be permitted. The
top and face of all curbing shall be finished while the concrete is
still green by wetting and rubbing. The face of header curbs shall
be finished to the ground line. The concrete shall be finished to
a smooth surface, presenting a uniform texture and color and be given
a final broom finish. Concrete surfaces within the right of way shall
not be stained, stamped or receive other than a broom finish.
4.3.5.
Protection and Curing. Concrete shall be cured for a period of not
less than 7 days after pouring. The method used to provide curing
shall be approved by the Engineer. Membrane curing, plastic sheet
curing, and wetted burlap curing will be considered satisfactory.
If at any time during the seven (7) day curing period, the air
temperature is 40 degrees F. or less, concrete shall be insulated
and/or heated as directed by the Engineer to aid curing and to prevent
freezing. Protective covering which will protect the surface of freshly
placed concrete from rain shall be readily available at the site of
the work. Concrete damaged as a result of failure on the part of the
developer to adequately protect the concrete from rain or freezing
shall be removed and replaced at the expense of the developer.
Ramps for handicapped shall be included in curb and gutter and
sidewalk construction as provided by KRS 66.660. All new curbs and
all existing curbs which are a part of any reconstruction, within
any block which is contiguous to any highway and in which fifty per
cent (50%) of the territory is devoted to or zoned for business, commercial,
or industrial use, shall be so constructed to enable persons using
wheelchairs to travel freely and without assistance. At each cross-walk
a ramp with nonslip surface shall be built into the curb so that the
sidewalk and street blend to a common level. Such a ramp shall not
be less than 48 inches wide. In all ramps there shall be a gradual
rounding at the bottom of the slope.
Maximum ramp slope in new construction shall be 1:12, except
that in areas where ramps are retrofitted into existing sidewalks,
grades of 1:8 for no more than two feet or 1:10 for no more than five
feet are permissible. Ramps should provide a minimum four foot square
landing area (no more than five percent grade or cross slope) at street
level and at other locations as required by ADA Standards. Provide
truncated domes or other devices or surface finishes in accordance
with ADA Standards.
See Exhibits 4-2 and 4-3 for construction guidelines and details.[1]
[1]
Editor's Note: The Exhibits are included as an attachment to this chapter.
