ITEM 609 CURBING, CONCRETE MEDIANS, AND TRAFFIC ISLANDS
609.01
Description
609.02
Materials
609.03 Stone
Curb
609.04
Cast-in-Place Concrete Curb and Combination Curb and Gutter
609.05 Asphalt
Concrete Curb
609.06 Concrete
Median and Traffic Island
609.07 Method
of Measurement
609.08 Basis of
Payment
609.01 Description. This work consists of furnishing
and constructing curb, combination curb and gutter, medians, and traffic
islands. This work also consists of excavating, backfilling, furnishing
and installing joint materials, and disposing of surplus excavation and
discarded materials according to Item 203.
609.02 Materials. Furnish materials conforming to:
Concrete,
Class QC Misc or QC
1*......................................... 499
Preformed
filler................................................... 705.03
Tie bar steel, epoxy
coated
..........................................
709.00, 709.01,
709.03, 709.05
Coated dowel
bars................................................... 709.13
* Replacing Coarse aggregate in the concrete mixes with Recycled
Concrete Aggregate conforming to Supplement 1117
is an option
Furnish
the best quality of Berea or Amherst gray sandstone, or sandstone of equal
quality.
Furnish
asphalt concrete curb conforming to a 448 Type 1
intermediate course, designed for medium traffic, using a PG 64‑22.
Conform the asphalt concrete to the composition
requirements with the fine aggregate content set at the maximum allowed under
this composition. Provided the Contractor meets the composition
requirements, the Contractor may add mineral filler conforming to 703.07. Add the mineral filler using a
method approved by the Laboratory.
A. Cutting and Dressing. Ensure that 95 percent of all straight curb
pieces are at least 5-feet (1.5 m) long, with no pieces less than 42 inches
(1.1 m). The Contractor may use a piece as short as 30 inches (0.8 m) for
closure. For curves with a radius of 50 feet (15 m) or greater, the
Contractor may use radially jointed straight curb pieces between 36 and 42
inches (0.9 and 1.1 m) long. For curves and corners with a radius of less
than 50 feet (15 m), use pieces a minimum of 36-inches (0.9 m) long, and dress,
joint, and set pieces to the radii specified. For all curves and corners,
use curb sections that are approximately uniform in length.
Dress all curb to a
straight edge on top and on the exposed face and ends to a depth of at least 6
inches (150 mm) below the gutter elevation. Dress the ends at right
angles to the face for straight curb and radially for curb on curves. Do
not allow slack or hollow joints. Do not leave any projections after
dressing the ends of any curb section that exceed 1/8 inch (3 mm) from the
plane of the end of that section. Cut the edge next to the gutter to a
3-inch (75 mm) radius and dress the top to a 1/4-inch (6 mm) bevel rising from
the exposed face. Use a pitching tool on the edge at the back to hand
dress curb to the specified width.
B. Setting. Set the curb on a thoroughly compacted subgrade
and with a 1 in 20 batter from the vertical backward from the gutter. If
the subgrade consists of clay soils or soils of a character that do not allow
free drainage, place a minimum 3-inch (75 mm) thick firm bed of porous material
as a foundation for the curb. Use a heavy rammer to settle the curb into
place. Place and compact a minimum 4-inch (100 mm) wide porous backfill
behind the curb to within 6 inches (150 mm) of the top. Bring the balance
of the backfill to the level of the top of the curb for a distance of 2 feet
(0.6 m) behind the curb with soil or other acceptable material.
Thoroughly tamp the backing in layers not exceeding 6 inches (150 mm) in
thickness, loose measurement, with an approved tamper or rammer. Perform
as much of the backfilling and tamping as is consistent with alignment of the
curb at the time the stone is first set. Set circular curb in plastic
concrete 6-inches (150 mm) thick as shown on the plans. Extend concrete
the width of the curb plus 6 inches (150 mm) behind the curb, and bring
concrete up behind the curb to within 4 inches (100 mm) of the top.
C. Joints. Set curbs such that below the dressed portions the
space between ends of adjacent sections of curbing is not less than 1/8 inch (3
mm) at any point and not more than 4 inches (100 mm). Cushion the joints
between the dressed portions of adjacent sections of curbing with 1/8-inch (3
mm) thick expansion joint material. Trim expansion joint material flush
with the curbing on all edges.
If placing sandstone
curb after placing pavement, fill remaining joints with dry sand to within 2
inches (50 mm) of the surface of the pavement, and fill to the pavement surface
with asphalt concrete. Take care in filling this joint so that no asphalt
concrete comes in contact with the exposed surface of the curb.
D. Reusing Existing as New Curb. If specifically allowed by the plans,
and to the extent available, use acceptable stone curb sections removed under
Item 202 instead of furnishing new stone
curb. Use salvaged curb at locations designated by the Engineer.
Place all salvaged sections of curb continuously without interspersing salvaged
and new curb sections. Haul and store salvaged curb as necessary.
Cut, dress, set, and install joints in salvaged curbs according to the
requirements for new curbs.
609.04 Cast-in-Place Concrete Curb and Combination Curb and Gutter.
A. Forms and Joints. Use approved steel forms for curbs.
Securely brace and hold forms to the line and grade shown on the plans.
The Contractor may use approved flexible forms of steel or wood to construct
the radius of a circular curb 200 feet (60 m) or less. Immediately before
placing concrete, clean the inner surface of the forms, and coat this surface
with a form release agent.
Where curb and
combination curb and gutter is not constructed integral with, or tied to, the
base or pavement, construct 1/4-inch (6 mm) wide contraction joints at 10-feet
(3 m) intervals using steel separator plates, a grooving tool, or a saw
according to Item 451. For combination curb
and gutter, construct the joint to an average depth of 2 inches (50 mm) or
more. For curb, construct the joint to an average depth of one-fifth or
more of the curb height. Where expansion joints occur
in the abutting pavement, separate the section being placed with 1-inch (25 mm)
705.03 preformed filler.
Where the curb is
integral with, or tied to, the base or pavement, construct the same type of
joints as used in the pavement. Space joints
identically with the joints in the base or pavement.
Leave curb forms in
place until their removal will not crack, shatter, or otherwise injure the
concrete. Do not seal transverse joints in cast-in-place concrete curb
and combination curb and gutter.
If curbs are to later
serve as a support for a finishing machine in the placing of a surface course,
align supporting edges so that the distance between the curbs is within 1/2
inch (13 mm) from that specified.
B. Placing. Place concrete in forms prepared as described
above, and vibrate the concrete to eliminate all
voids.
Place concrete for
curb that is integral with the concrete base or pavement while the base or
pavement concrete is plastic. Where the presence of the finishing
equipment on the forms at the end of the day’s run prevents completing the
curb, install No. 5 (No. 16M) tie bars vertically in the pavement at 1-foot
(0.3 m) intervals and in a line 3 inches (75 mm) inside of and parallel to the
pavement edge. Install these tie bars to within 1 1/2 inches (38 mm) of
the subgrade or subbase and 2 inches (50 mm) above
the concrete base or pavement surface. Water cure this horizontal
construction joint between the concrete base or pavement and the curb, or
membrane cure the concrete base or pavement and remove the membrane before
placing the curb. Immediately before placing the concrete curb, brush
mortar (consisting of one part cement to two parts sand with enough water to
form a workable mortar) into the surface area of the hardened concrete pavement
or base where the curb is to be placed. Do not allow the mortar to dry
before placing the curb on top of it.
C. Slip-Form Placement. The Contractor may use a self-propelled machine
to place concrete curb or curb and gutter. Force the concrete through a
mold of the proper cross-section to obtain the proper density and
cross-section. If using a track, set and secure the track on which the
machine operates to the exact line and grade given by the Engineer. Use
concrete of a consistency that provides the desired shape and remains as placed
without slumping of the vertical faces.
D. Finishing. Without adding extra mortar, float the top of
the curb to thoroughly compact the concrete and produce a smooth and even
surface. Round the edges of the curb using a tool specially designed for
this purpose. Immediately after removing the forms, rub the exposed face
of the curb with a float to eliminate unnecessary tool marks. Provide a
finished surface free of irregularities and waves, and uniform in texture.
E. Protection. Cure concrete according to Item 451.
609.05 Asphalt Concrete Curb. Use one
of the following methods, or other method approved by the Engineer, to furnish
and place an asphalt concrete curb of the required cross-section.
A.
Method A. After completing the surface course, paint or
spray only the area to be occupied by the asphalt concrete curb with asphalt
material conforming to 407.02.
Apply the asphalt material at the rate of 0.15 gallon per square yard (0.7 L/m2).
Place the curb with a hand-operated or self-propelled machine consisting of a
hopper and power-driven screw, which forces the material through an extrusion
tube. Force the material through a die attached to the end of the
extrusion tube to obtain the proper density and cross-section.
B. Method B. As an
independent operation preceding the final rolling of the asphalt concrete
surface course that the curb is placed, place loose asphalt concrete of
sufficient height and shape by hand methods using suitable templates or by
other means to produce the specified cross-section. Compact the loose
asphalt concrete using a hand-operated mechanical vibrating tamper equipped
with a compacting shoe of such shape that will produce the specified final
cross-section dimensions of the curb.
609.06 Concrete Median and Traffic Island
A. Forms and Joints. Securely brace and hold approved steel forms to
the line and grade shown on the plans. The Contractor may use approved
flexible forms of steel or wood to construct a radius of 200 feet (60 m) or
less. Immediately before placing concrete, clean the inner surface of the
forms, and coat this surface with a form release agent.
Where medians and
traffic islands are not anchored to the pavement, construct contraction joints
at 10-foot (3 m) intervals using steel separator plates, a grooving tool, or
saw according to Item 451. Construct the
joint using steel separator plates, a grooving tool, or saw according to Item 451. Construct the joint to a minimum depth of
2 inches (50 mm).
Where, as shown on
the plans, the medians or traffic islands are anchored to the pavement,
construct the same type of joints in the median or traffic island as used in
the pavement. Space the joints identically with the joints in the
pavement.
Leave forms in place
until their removal will not crack, shatter, or otherwise injure the concrete.
B. Placing. Before placing a concrete median or traffic
island on subgrade, sprinkle the subgrade with water until thoroughly moistened
at times and in a manner directed by the Engineer.
Place the concrete in
forms prepared as described above, and vibrate the concrete to eliminate all
voids.
C. Slip-Form Placement. The Contractor may use a self-propelled machine
to place medians and traffic islands. Force the concrete through a mold
of the proper cross-section to obtain the proper density and
cross-section. If using a track, set and secure the track on which the
machine operates to the exact line and grade given by the Engineer. Use
concrete of a consistency that provides the desired shape and remains as placed
without slumping of the faces.
D. Finishing. Without adding extra mortar, finish the top of
the median or traffic island to a broom texture. Round the edges using a
tool specially designed for this purpose. Immediately after removing the
forms, rub the exposed faces with a float to eliminate unnecessary tool
marks. Provide a finished surface free of irregularities and waves, and a
uniform texture.
E. Protection. Cure concrete according to Item 451.
609.07 Method of Measurement. The
Department will measure Sandstone Curb, Curb, Combination Curb and Gutter, and
Asphalt Concrete Curb by the number of feet (meters) complete in place, measured
along the front face of the curb section.
The
Department will measure Concrete Traffic Island and Concrete Median by the
number of square yards (square meters) or the number of cubic yards (cubic
meters) complete in place.
609.08 Basis of Payment. The
Department will pay for accepted quantities at the contract prices as follows:
Item
Unit
Description
609
Foot
(Meter)
Sandstone Curb
609
Foot
(Meter)
Curb, Type ___
609
Foot
(Meter)
Combination Curb and Gutter, Type ___
609
Foot
(Meter)
Asphalt Concrete Curb, Type ___
609
Square Yard
or
Concrete Traffic Island
Cubic Yard
(Square Meter or
Cubic Meter)
609
Square Yard
or
Concrete Median
Cubic Yard
(Square Meter or
Cubic Meter)