The work covered by this specification consists
of furnishing all plant, labor, equipment, appliances and materials,
and in performing all operations in connection with the furnishing
and installing of concrete curbs and sidewalks.
A.
Concrete shall be premixed certified concrete having
a twenty-eight-day compressive strength of not less than 3,000 psi.
B.
Forms may be either steel or a good straight timber,
planed on the side adjacent to the concrete and oiled. Timber forms
shall be not less than two inches in thickness, except curb radius
forms, which shall be prefabricated or plywood to the proper radius.
Forms shall be straight, free from warp, and of sufficient strength,
when staked to resist the pressure of the concrete without springing.
A.
Excavation shall be made to the required depth, and
through whatever material encountered, and the material upon which
the work is to be constructed shall be compacted to a firm, even surface.
All topsoil and soft yielding material shall be removed and replaced
with suitable material. Wherever it is necessary to remove old concrete
work, care shall be taken not to damage adjacent concrete work, which
is to remain, and all broken concrete and excess material shall be
removed and disposed of by the contractor.
B.
Curbs shall be either slant curb or straight curb
as specified, of the cross-section and dimensions shown on Exhibits
1 and 2 herein.[1] Concrete shall be placed in the form in horizontal layers
not to exceed five inches, and spaded sufficiently to eliminate all
voids. An approved vibrator may be used when permitted by the Township
Engineer. Where necessary or directed, drainage openings shall be
made through the curbline at the elevation and of the size required.
Straight curb shall be depressed as indicated or directed. The top
surface of the curb shall be finished true to line and grade in a
smooth, neat, and even manner by means of wood floats, and the edges
of the face and back shall be rounded to a radius of not more than
1/2 of an inch while the concrete is still plastic.
(1)
The curb shall be constructed in continuous
lengths not to exceed 30 feet, with contraction joints scored at the
ten-foot intervals, and templates shall be pulled while the concrete
is still plastic so that there shall not be a complete separation
between sections. Premolded asphalt expansion joints 1/2 of an inch
in thickness shall be placed at the end of each pour, but in no case
at intervals exceeding 30 feet.
(2)
Two No. 4 deformed reinforcing bar dowels 24
inches in length shall be provided at all expansion joints. These
bars shall be placed as shown on Exhibits 1 and 2,[2] and shall exceed 12 inches on each side of the joint.
One end of the bars shall be rendered bondless with an approved material,
and enclosed, in part, in approved tubes or caps, which will provide
positive clearance of at least 1/2 of an inch. Bar dowels shall be
provided at all expansion joints as well as where tangent curb meets
radii curb.
[2]
Editor's Note: Said exhibits are included at the end of this
chapter.
(3)
Expansion joints shall be provided at the beginning
and end of all curb radii. One-half of an inch premolded asphalt expansion
joint material shall separate all curb from sidewalk poured directly
back of curb, and shall separate all curb and/or sidewalk from utility
poles, fire hydrants, walls, steps, and other permanent structures
abutting the work.
[1]
Editor's Note: Said exhibits are included at the end of this
chapter.
A.
Sidewalks shall be plain concrete four inches in thickness,
with 6 x 6 W2.1 x W2.1 welded wire fabric, except under driveways,
where the thickness shall be six inches and industrial drives where
the thickness shall be eight inches. The subgrade for the sidewalk
shall be 2B stone (four inches thick), and it shall be carefully graded,
and where necessary tamped, to provide an even, solid support. Sidewalks
shall be constructed in separate slabs 30 feet in length, separated
by premolded asphalt expansion joints 1/2 of an inch in thickness
for the full depth of the concrete. Between expansion joints, the
slabs shall be scored every five feet. Premolded asphalt expansion
joints shall separate the sidewalk from the curb, and from any existing
building, stairs, other pavement, utility poles, fire hydrants, or
other permanent structure.
B.
Normally sidewalk shall slope 1/4 of an inch per foot
toward the street, and where a grass plot is provided, sidewalk, grade
shall permit 1/4 of an inch per foot slope across the grass plot to
the top of straight curb of 1/2 to 3/4 of an inch per foot slope across
grass plot to the top of rolled or slant curb.
The forms shall not be removed within 12 hours
after the concrete has been placed. No rubbing to correct irregularities
will be permitted until the full curing period has elapsed. Any irregular
surface shall be corrected by rubbing with a carborundum stone. Brush
finishing or plastering will not be permitted and all rejected curb
shall be promptly removed and replaced. All joints in the curb shall
be opened from top to bottom immediately after the forms are removed
and the edges adjacent to the joints shall be sharp and clean-cut.
After the forms are removed, minor defects shall be filled with mortar
composed of one part cement and two parts fine aggregate.
Straight curb across existing driveways, whether
paved or not, shall be depressed approximately six inches in depth.
Where unusual grade conditions exist, such that the established curb
and sidewalk grade may not meet the existing driveway grade, the contractor
shall call the condition to the attention of the inspector prior to
placing forms so that any adjustment of grade may be made at the direction
of the inspector.
Where curb or sidewalk is constructed at a street
intersection, particularly where either street grade is in excess
of 5%, it may be necessary to adjust the grade, particularly the sidewalk
grade, to properly fit the grade of the intersecting streets. Generally,
it will be necessary to depart from the normal 1/4 of inch per foot
fall on the sidewalk, either raising or lowering the back edge of
sidewalk, in order to make a smooth grade transition in the vicinity
of the street intersection.
All curbs and sidewalks at intersection of streets
or avenues being constructed, reconstructed or altered for any reason
shall provide curb cut ramps for the physically handicapped except
as noted below in Subsection D.
A.
The curb cut ramps should be as close to the intersection
as possible to keep the widths of crosswalks to a minimum.
B.
The ramps at intersections shall be constructed as
illustrated in Exhibit 3[1] by depressing the curbs and sidewalks to the height necessary
to achieve the necessary ramp slopes and provide safe pedestrian and
wheelchair movement.
[1]
Editor's Note: Said exhibit is included at the end of this chapter.
C.
Existing driveway ramps near street intersections
should be considered for use as wheelchair ramps where curbs are being
constructed or reconstructed.
D.
On very narrow sidewalks, where curb cuts cannot be
constructed in accordance with Exhibit 3 curb cut ramps should be
placed at locations where a need exists.[2] Where such need cannot be demonstrated, curb cut ramps
should not be installed. Also, where a need does not exist, curb cuts
need not be constructed at locations such as very steep sidewalks,
where unavoidable trees or other obstructions exist and where safe
operation or a wheelchair cannot be ensured at the point of gradient
intersection of the pavement and the ramp.
[2]
Editor's Note: Said exhibit is included at the end of this chapter.
All concrete work shall be cured in strict accordance
with PennDOT Form 408, latest revision. Either membrane curing or
water curing will be permitted. For water curing, the curing period
shall be not less than seven days.
After concrete has retained the required strength,
the work shall be promptly backfilled with clean earth or other approved
material in layers of not less than four inches in depth, and shall
be thoroughly compacted mechanically to the required elevation and
cross section. Curbing shall be backfilled on the street side to street
subgrade either with clean earth or crushed stone. Grass plot areas
and areas to the rear of sidewalk shall be backfilled with clean earth
to within four inches of finished grade; at least four inches of clean
topsoil shall be spread as the last layer, to the proper grade to
meet the finished curb and sidewalk grade. To the rear of the sidewalk,
in fill areas, the backfill shall be carried level for a distance
of 12 inches behind the rear line of the sidewalk, and then sloped
down on two horizontal to one vertical slope to meet the existing
grade. If water pockets are formed, the contractor shall call this
to the attention of the inspector, so that an adjustment in backfill
can be made. In cut areas, the area to rear of sidewalk will be sloped
1 1/2 horizontal to one vertical to meet the existing grade.
The topsoil areas shall be hand raked to an even grade without water
pockets.
The following limitation shall apply when the
mean daily temperature is below 50° F.
A.
No concrete pours shall be permitted from December
1 to March 1 unless prior approval is received from East Manchester
Township.
B.
No concrete pours shall be permitted from December
1 to March 1 unless prior approval is received from East Manchester
Township.
C.
No concrete pours shall be allowed when the mean daily
temperature will fall below 32° F. within five days of the pour.
All concrete materials and all reinforcement, forms, fillers, and
ground with which the concrete is to come in contact with, shall be
free from frost.
D.
When the mean daily temperature is between 32°
F. and 50° F., all concrete place in the forms shall have a temperature
of between 70° F. and 80° F., and adequate means shall be
provided for maintaining a temperature of not less than 70° F.
for two days or 50° F. for three days or for as much more time
as is necessary to insure proper curing of the concrete. The housing,
covering or other protection used in connection with curing shall
remain in place in intact at least 24 hours after the artificial heating
is discontinued. No dependence shall be placed on salt or other chemicals
for the prevention of freezing.
E.
Adequate equipment shall be provided for heating the
concrete materials and protecting the concrete during freezing or
near-freezing weather. No frozen materials or materials containing
ice shall be used.
Where directed by the Township or the Township Engineer, a six-inch
concrete slab in conjunction with the curb and sidewalk shall be placed
across an access drive, private/public street, driveways, etc., all
to be constructed within the public right-of-way.