All work and materials shall be in accordance with the Pennsylvania
Department of Transportation Publication 408, except as herein provided
or as approved by the Borough Engineer.
A.
Cement concrete curb shall be 18 inches in depth, with 10 inches
below street grade, and as shown on the accompanying details.
B.
Replacement cement concrete curb shall be constructed to the size
and shape of the adjoining cement concrete curb. The exception being
the height of the curb above the gutter line shall be a minimum of
six inches and a maximum of nine inches.
Concrete shall conform to Class A cement concrete for cement
concrete curb. Type A concrete shall have a minimum compressive strength
of 3,300 psi after 28 days. For slip-forming, the concrete shall be
designed with a slump of up to 1 1/2 inches.
A.
Forms for the curb shall be of metal, except wood forms may be used
on sharp curves and short tangent sections when approved by the Borough
Engineer. Forms shall be straight, free from warp, and of sufficient
strength when staked to resist the pressure of the concrete without
springing. At least three stakes shall be provided for each 10 feet
of form. Metal forms shall be of approved section and shall have a
flat surface on top and wood forms shall be nominal two-inch surfaced
planks. These forms shall be of a depth equal to the depth of the
curb, designed to permit secure fastening of the face and back forms
at the tops. These fastenings shall be constructed in a manner that
will not obstruct satisfactory finishing and edging of the top of
the curb but will permit removal of the inside or face forms. The
outside of back forms shall be straight from top to bottom. The inside
of the face forms shall have a batter from the top of the curb to
the finished surface line of the pavement, as shown on accompanying
details, and shall be straight from this line to the bottom.
B.
All forms and templates shall be thoroughly cleaned and treated with
an approved material, as required, to prevent the concrete from adhering
thereto. Oil, bituminous paper or other material which will adhere
to or discolor the concrete shall not be used. Forms and templates
which are worn, bent, warped or broken shall not be used. The forms
shall be accurately set to line and grade in a manner to prevent settlement
or displacement.
A.
Materials requiring excavation such as old sidewalk, curbing, excess
earth, tree roots, paving and other materials that cannot be used
shall become the property of the contractor and disposed of by the
contractor at no additional cost to the owner.
B.
The existing cartway paving and cement concrete shall be saw cut
as required and the excavation made to the required depth. The material
upon which the curb is to be constructed shall be compacted to a firm,
even surface.
C.
In the event that overexcavation of the trench is necessary, the
trench shall be backfilled to the required grade with 2B stone and
thoroughly compacted to a firm, even surface at the contractor's expense.
The concrete shall be placed in the forms 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 Borough
Engineer. Where indicated or directed, downspout opening shall be
made through the curb as shown on accompanying details. 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 3/4 inch
and 1/4 inch, respectively, while the concrete is still plastic.
A.
Plain cement concrete may be placed with a self-propelling machine
consisting of a hopper, power-drive screw or screws, and a metering
device.
B.
Concrete shall be uniformly fed to the machine and, after extrusion,
the concrete shall maintain the shape of the section without slumping.
C.
The finished curb shall have a surface free from voids and honeycomb.
Any additional surface finishing required shall be performed immediately
after extrusion.
A.
Contraction joints shall be spaced in uniform lengths or sections
of 15 1/2 feet maximum, except where shorter sections are necessary
for closures or curbs, but no section shall be less than four feet.
B.
Contraction joints may be either hand-formed or saw-jointed. They
shall be three-sixteenth-inch wide and two inches deep. Sawing of
joints shall be done as soon as practicable after the concrete has
set sufficiently to preclude raveling during the sawing and before
any shrinkage cracking occurs in the concrete. The saw-cut depth may
be decreased at the edge adjacent to the pavement to obtain a maximum
depth that will avoid damage to the pavement. Contraction joints shall
have tooled edges.
C.
The three-fourths-inch premolded expansion joint material shall be
cut to conform to the cross-sectional area and be placed at structures
and at the end of a day's work.
D.
Existing abutting concrete structures shall also have the three-fourths-inch
premolded expansion joint material installed between the new and existing
concrete.
A.
The height of the curb may be lowered 6 1/2 inches at all places
where driveways enter the street and at such other places as directed
by the Borough Engineer.
B.
In no case shall a depressed curb section extend beyond a property
line. Where a driveway is adjacent to a property line the depressed
section of curb must terminate inside of the property line.
C.
Construction of depressed curb sections in excess of 20 feet in length
shall not be permitted unless specifically approved by the Borough.
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 or
plastering will not be permitted, and all rejected curb shall be promptly
removed and replaced at no expense to the Borough.
A.
The newly poured curb shall be cured and protected. In cool weather,
temperatures below 35° F., curb shall be cured as directed by
the Borough Engineer.
B.
In warm weather, the curb shall be kept moist for a period of not
less than three days, or longer if directed, and shall be protected
from the elements by a burlap covering which is not less than seven
ounces per square yard in weight or polyethylene sheeting with a total
nominal thickness of the two layers not less than four mils, in a
manner satisfactory to the Borough Engineer.
A.
As soon as possible after the removal of forms, the spaces in front
and back of the curb shall be backfilled with suitable materials in
layers of not more than four inches in depth, which shall be thoroughly
compacted mechanically to the required elevation and cross section.
The layers shall be placed by alternating between the front and back
of the curb.
B.
Paving restoration shall be done in accordance with the accompanying
details.
Curb returns for streets shall be constructed as shown on the
accompanying detail for typical curb ending or to meet existing field
conditions.
Depressed curbs for handicapped/pedestrian ramps shall be installed
at the locations directed by the Borough.
Engineering specifications for cement concrete curbs are illustrated
on a detail sheet prepared by the Borough Engineer, which is hereby
declared to be part of this article, and the notations, references
and other data shown thereon are as much a part of this article as
if the same were fully set forth herein.
