422.08 Cover Aggregate Application
422.01
Description. This work consists of preparing and applying a
single or double chip seal.
422.02 Materials. Use an RS-2 emulsified bind conforming to 702.04 for projects with an ADT less than
500. Use polymer emulsified binder conforming to 702.16 Type A for projects
with an ADT greater than 500. When a
project has multiple pavements with ADTs above and below 500 use the polymer emulsified binder, 702.16.A.
For cover
aggregate material, use washed limestone or dolomite meeting the gradation
below and 703.05. Submit a letter to the
Engineer and DET
containing the JMF gradation of the cover aggregate showing all sieve
sizes. Determine the JMF gradation by
averaging five samples from different locations of an aggregate stockpile
immediately before starting the job. If
the five samples deviate more than ±3.0 percent passing on the No. 8 (2.36 mm)
sieve, rework the stockpile, take five new samples, and redetermine the JMF
gradation. Include in the JMF both a dry gradation value and a washed
gradation value for passing the No. 200 (75 mm) sieve.
Sieve Size |
Total Percent Passing |
1/2 inch (12.5 mm) |
100 |
3/8 inch (9.5 mm) |
90 to 100 |
No. 4 (4.75 mm) |
5 to 25 |
No. 8 (2.36 mm) |
0 to 10 |
No. 16 (1.18 mm) |
0 to 5 |
No. 200 (75 mm) |
2.0 max [1] |
[1] Washed gradation value |
422.03 Equipment. Provide equipment conforming to the requirements of this section. Obtain approval of equipment before starting
the job.
Use equipment for binder distribution
conforming to 407.03, except ensure that it has
a computerized rate control that automatically adjusts the binder pump to the
unit ground speed and has a gauge or meter in plain view for reading gallons
(liters). Use appropriate spray nozzles
for the material and rate specified.
Use Type II pneumatic tire rollers conforming
to 401.13, except the maximum capacity shall not
apply.
Use self-propelled aggregate spreaders with a
variable width aggregate hopper capable of placing from 8 to 16 feet (2.4 to
4.8 m) in any increment and a computerized rate control that automatically
adjusts the aggregate output to the unit ground speed. Equip spreaders with pneumatic tires, a
screen to remove oversized material, revolving cylinders, and adjustments
necessary to produce a uniform distribution of particles at the specified rate.
Use power
sweepers or rotary brooms in initial surface preparation and for removing loose
particles. Use pickup type sweepers in
areas where the aggregate shoulder does not exist. Do not sweep loose aggregate onto lawns,
curbed areas, or intersections.
Furnish
accurate thermometers for determining any of the applicable temperature
requirements of this specification.
422.04
Weather Limitations. Place the chip seal when the pavement and
atmospheric temperature is 60 °F (16 °C) or above and the atmospheric temperature is 70 °F (24 °C) or above..
Do not place chip seal if any of the following conditions exist:
A. Impending weather conditions do not allow
for proper curing or if temperatures are forecasted below 50 °F (10 °C) within 24 hours from the time of work.
B. The existing pavement temperature is 140 °F (60 °C) or above.
C. Before May 1 or after September 1.
422.05
Test Strip. Construct a continuous 1000-foot (300 m) long by lane width test
strip. The Engineer will
review the test strip the next workday.
Determine the binder application rate, aggregate application rate, and
aggregate gradation during the test strip.
If the review shows the test strip meets the requirements of 422.11 and the application rate and quality control tests
show all is in control compared to the JMF, then progress with the work. Should problems be noted, the Engineer may
require another test strip.
The Department will waive the test strip if
the Contractor has
constructed a Department accepted test strip using the same materials and JMF
in the previous 30 days.
422.06
Surface Preparation. Clean the pavement according to 407.05. If
necessary, clean areas of the pavement with a hand broom. Do not place material until the Engineer approves the surface.
422.07
Binder Application. Before applying binder, ensure that sufficient
cover aggregate is available for immediate application. For single chip seal, apply the binder at a
minimum rate of 0.37 gallon per square yard (1.68 L/m2). For double chip seal, apply the binder at a
minimum rate of 0.34 gallon per square yard (1.54 L/m2) for the
first course and 0.37 gallon per square yard (1.68 L/m2) for the
second course. Maintain the binder temperature
from 150 to 185 °F (65 to 85 °C) during construction, including the start of each day. Reheat the binder at a rate of no more than
25 °F (14 °C) per hour, when the binder is allowed to
cool below 150 °F (65 °C).
If the
application rate is not the optimum application rate to achieve proper stone
embedment, immediately notify the Engineer. Proper
stone embedment is typically 2/3 of the stone chip height and can be checked by
pulling out several chips by hand. Adjust and document the new application rate
by stationing. Recheck stone embedment
after adjustment and obtain the Engineers approval of the new rate.
Do not
allow the binder to streak on the road surface.
If the Engineer determines
that streaking is occurring, cease operations until the Engineer is satisfied
that streaking has been eliminated.
At the
beginning and at the end of a contract section, start and stop the application on
a removable protective cover (paper, metal sheets, or other suitable material)
sufficiently wide enough to allow full application on the surface being
treated. Make transverse and
longitudinal laps in such manner to ensure that the texture of the finished
surface is uniform and continuous. To
prevent lapping at transverse junctions, promptly shut off the binder spray at
the end of the application. Before
continuing the application, place a removable protective cover a sufficient
distance back from the joint on the cover aggregate so the sprayers are
operating at full force when the distributor has attained the predetermined
speed upon reaching the uncovered surface.
Upon completion, remove all removable protective covers.
422.08 Cover Aggregate Application. Immediately after applying the binder, apply
cover aggregate uniformly without ridges or laps at the specified rate adjusted
as directed by the Engineer to
produce a minimum of excess loose particles.
Spread the material in such manner that the tires of the truck or
aggregate spreader at no time contact the uncovered and newly applied
binder. Before rolling, correct
deficiencies in the application of cover aggregate in a manner satisfactory to
the Engineer.
After
rolling, protect the surface from traffic damage during the period required for
the binder to cure sufficiently and prevent dislodging of the aggregate
particles by normal traffic. During this
period and as directed by the Engineer, correct deficiencies in cover aggregate by
spreading additional aggregate or by light brooming.
Apply cover
aggregate at a rate necessary to provide full coverage of the binder and to
avoid tracking. If the target rate is
not the optimum application rate due to the gradation of the aggregate or due
to existing surface conditions of the pavement, immediately notify the Engineer and
document the new rate by stationing.
422.09
Construction Operation.
Establish stations at 1000-foot (300 m) intervals on the entire project
before placing materials. Clearly
identify and maintain the stations until project completion.
Keep the
binder distributor, aggregate spreader, and rollers as close to each other as
possible. Do not allow the binder
distributor to be more than 150 feet (45 m) ahead of the aggregate spreader.
Perform
rolling immediately after placing the aggregate, but before the binder sets
up. Do not leave aggregate unrolled for
more than 5 minutes. Perform a minimum
of two complete roller passes over the aggregate. A single complete pass is forward and
backward over the same path. For each
new pass, overlap the previous pass by about one-half the width of the
roller. Use a minimum of three rollers,
and roll in a longitudinal direction at a speed not greater than 5 miles per
hour (8 km/h). Do not operate rollers at
speeds that cause pick-up or dislodging of aggregate particles.
After the
binder sets, and before placing a second course for double chip seals, and
within 4 hours, sweep the pavement using a power broom or pickup sweeper as
needed to remove all loose aggregate. Extend sweeping 1 foot (0.3 m) beyond the
edge of the pavement to help prevent migration of loose aggregate back onto the
pavement. If the pavement cannot
be swept within the 4-hour period due to
problems associated with the stone moisture, binder, breaking, humidity, or
other unknown, the Engineer may
suspend the operation until the problem is resolved or more suitable conditions
are obtained to maintain the 4-hour time frame for sweeping.
The
Contractor is
responsible for claims of damage to vehicles until the pavement and shoulders
receive a final sweeping immediately before application of permanent pavement
markings or a fog seal, if a fog seal is required.
Before
placing the second course of a double chip seal, ensure that the first course
is cured, swept, and capable of withstanding construction traffic without
damage. Correct damage to the underlying
chip seal before placing the final chip seal.
Place the
longitudinal construction joint on a lane line or as directed by the Engineer. For
double chip seal, place the longitudinal construction joint for the first
course 6 inches (150 mm) off the centerline and place the second course so
the longitudinal joint is at the centerline.
Before
opening to traffic, post the roadway with “Loose Stone” signs and a “35 mph”
speed plaque mounted below the sign.
Ensure that signs conform to Item 614.
Place these signs at a maximum of 0.5-mile (0.8 km) intervals. Remove the signs as directed by the Engineer.
On two-lane
roads or pavements where traffic is maintained on a chip seal constructed that
workday, provide a traffic control pilot vehicle operated at no more than 25
miles per hour (40 km/h) in the immediate work area.
Protect all
utility castings, monument boxes, and other similar items using tarpaper or
other approved material. Remove
protection before sweeping and opening to traffic.
A. General. Use the methods described in this section to measure compliance. If test results exceed any of the identified quality control tolerances, stop placement and immediately notify the Engineer and DET. Identify the cause of exceeding any of the identified quality control tolerances and document in detail the corrective action necessary to bring the deficiency into compliance. Obtain the Engineer’s approval before resuming work. Upon resuming work, take another sample and immediately provide the test results to the Engineer. If the tolerances are exceeded, stop the work. Do not resume work until approved by the Engineer and DET. The DET can obtain samples of materials at any time.
B. Binder. Label and retain one sample per
day for the Department. For the binder
application rate, as determined by a yield check, do not exceed a tolerance of ±0.02 gallon per square yard (0.09 L/m2)
from the established application rate.
C. Coarse Aggregate. Sample and test aggregate
according to AASHTO T 2, AASHTO
T 248, and Supplement
1004 (AASHTO T 11 where
required). If problems persist with dry
gradation results, perform washed gradations.
Reject
truckloads of aggregate if water is seen coming from the truck bed.
Reject
aggregate that does not meet the following requirements:
No. 4 (4.75 mm) sieve from
JMF |
±5.0% |
No. 8 (2.36 mm) sieve from
JMF |
±3.0% |
No. 200 (75 mm) sieve from JMF |
±1.0%, 2.5% upper limit |
Aggregate moisture
content (by dry weight) |
4.0% max. for aggregates
with an Absorption > 2.0%, 3.0% max. for aggregates
with an Absorption ≤ 2.0% |
D. Documentation.
Provide the Engineer a daily
report with the following:
1. Control section, project number,
county, route, and Engineer.2. Date,
air temperature, pavement temperature, and humidity.
3. Binder temperature.
4. Beginning and ending stations.
5. Yield checks on binder
(three per day, minimum).
6. Yield checks on aggregate (three per day,
minimum).
7. Gradation, moisture
content, and station (one at the start of daily production, minimum).
8. Length, width, and total area.
9. Condition of “Loose Stone”
signs with “35 mph” speed plaques.
10. Contractor representative’s signature.
Provide a bill of lading for binder and
aggregate as requested or at project completion.
422.11
Acceptance. During the application of the chip seal, inspect the chip seal for
deficiencies resulting from poor workmanship, flushing, tracking from
equipment, surface patterns, loss of stone, and sweeping. Inspect workmanship for untreated areas,
minimum overlap on longitudinal joints, and minimum overlap on construction
joints.
Verify the
following for daily acceptance:
A. Finished surface has no more than four
tears or untreated areas greater than 1 inch (25 mm) wide and 4 inches
(100 mm) long in any 120-square yard (100 m2) area.
B. Joints appear neat and uniform without
buildup, uncovered areas, or unsightly appearance.
C. Longitudinal joints have less than a
2-inch (50 mm) overlap on the adjacent passes.
D. Transverse joints have no more than
1/4-inch (6 mm) difference in elevation across the joint as measured with a
6-foot (2 m) straightedge.
E. Chip seal edge is neat and uniform along
the roadway lane, shoulder, and curb lines.
F. Chip seal edge has no more than 2-inch (50
mm) variance in any 100 feet (30 m), along the roadway edge or shoulder.
G. Typical stone chip embedment is 2/3 of
typical stone chip height.
For project
acceptance, the Contractor and
Engineer will
review the completed work 25 to 35 days after placement. The finished work must meet the following
requirements:
Defect[1] |
Severity |
Surface patterns |
Alternate lean and heavy lines |
Bleeding/flushing |
Distinctive appearance |
Loss of cover aggregate |
Patches or lines of aggregate lost from surface |
[1] Do
not exceed the extent of any surface defect by more than 20 percent of any
120-square yard (100 m2) area.
The beginning of any 120-square yard (100 m2) area will be
the start of any individual defect. |
Perform all
corrective work to the satisfaction the Engineer.
422.12 Method of Measurement. The Department will measure Single Chip Seal Course or Double Chip Seal Course by the number of square yards (square meters), completed and accepted in place. The Department will determine the width by measuring the actual width of the chip seal. The Department will determine the length along the centerline of each roadway or ramp.
422.13
Basis of Payment. The Department will not pay for materials,
equipment, or labor to make corrections.
The
Department will pay for accepted quantities at the contract prices as follows:
Item unit Description
422 Square Yard Single Chip Seal
(Square Meter)
422 Square Yard Double Chip Seal
(Square Meter)