All of the material
requirements for 304
are located in section 703.17.
This section allows for the use of the following five material types:
1. Crushed Carbonate Stone (CCS).
2. Crushed gravel.
3. Crushed Air-Cooled Blast Furnace slag (ACBFS).
4. Granulated slag (GS).
5. Open Hearth slag (OH).
If Crushed Carbonate Stone
(CCS) is used, the material must meet the gradation and physical requirements
in 703.17. In rare cases these materials become soft
after a rain event or over the winter.
If crushed gravel is selected
for use as aggregate base, it must be manufactured from material retained on
the 1/2-inch (12.5 mm) sieve. It must
meet the gradation and physical requirements shown in 703.17. At times this material lacks some fine
material and becomes unstable.
If Air-Cooled Blast Furnace
slag is selected for use, ensure that the material meets the requirements of Supplement
1027. This material can cause
environmental concerns. The gradation
and physical requirements are detailed in 703.17.
If Granulated slag is
selected for use, the material must meet the requirements of 703.08.
If
Open Hearth slag is selected for use, ensure that the material meets the
gradation and physical requirements of 703.17
and the requirements of 703.14
which include:
1.
Deleterious
Substances.
2.
Identification of
OH slag.
3.
Verification of
Tufa performance.
4.
Aging and
stockpiling requirements.
5. Expansion testing.
1. Sample the material to be used.
a. Develop a moisture density curve per Supplement
1015.
2. Material Moisture.
a. The material must have reasonably uniform moisture
content.
b. Prior to spreading, use moisture content no less than
2 percent below optimum moisture.
c. Add water to the stockpile, if required.
3. Minimize segregation.
a. If segregation occurs, mix or re-grade the stockpile.
1. Do not spread on frozen surfaces.
2. Do not use frozen material.
3. Do not exceed a compacted lift thickness of:
a. Eight inches (200 mm) when using vibratory rollers greater
than 12 tons (11 metric tons).
b. Six inches (200 mm) with vibratory rollers weighing 10
to 12 tons (9 to 11 metric tons).
c. Four inches (100 mm) with no vibratory roller. If the
Contractor is compacting with a vibrating plate compactor, the maximum lift
thickness is 4 inches. If the Contractor
is compacting with a roller without any vibration, the maximum lift thickness
is 4 inches.
d. Can use a lighter roller with equivalent centrifugal
force.
e. Centrifugal force is the weight with vibration.
f. Contractor needs to document that the roller weight
requirements are met.
4. Place in equal lifts when the specified thickness
exceeds 8 inches (200 mm).
a. Example: if a 12-inch lift is specified, place in two
6-inch lifts.
Figure 304.A – Spreading
304 with a Dozer and Spreader Box
Figure 304.B – Spreading
304 with an Asphalt Paver
5. Use self-propelled spreading machines.
a. Capable of placing the 304
material true to line and grade.
b. Use a dozer with a spreader box or an asphalt paver.
i.
This operation
prevents segregation.
ii.
If an area
appears to be segregated, take in place gradation tests according to Supplement
1090.
iii.
Contractor is
only allowed to use dozers without spreader boxes, graders, or hand-placing
methods when the total area of the aggregate base is 2,000 square yards or less
or in small areas. Do not take in-place
gradation tests in small areas.
Figure 304.C – Spreading
304 with a Dozer May Result in Segregation
Figure 304.D – Spreading
304 with a Grader May Result in Segregation
Figure 304.E – Adding Water
to 304 Prior to Compaction
Figure 304.F – Compacting
304 with Vibratory Roller
1.
Add water or dry
out the material.
a. To bring material to within 2 percent of the optimum
moisture content.
b. Add water or dry the 304
prior to compaction.
i.
Material is too
dense to add water after compaction.
c. Maintain moisture during compaction.
d. Uniformly apply water throughout the lift.
e. Reduce when unstable.
2. Compact immediately after spreading.
Figure 304.G – Construct a
Test Section
Figure 304.H – Perform the
Compaction Tests
3. Construct a short test section.
a. Compaction testing according to Supplement
1015.
b. Use a minimum of eight passes in the test section.
i.
Minimizes getting
a false maximum.
4. Use and adjust the vibration.
a. Maximize density and stability.
b. When vibration at maximum can make any material
unstable.
5. Use 98 percent for the acceptance in the production
area.
a. Take three tests in the lot for acceptance.
b. Use the average of the results.
6. Use at least:
a. Same number of passes and compactive effort used to
obtain the test section maximum density for the production material.
i.
Increases passing
results in the production area.
7. At a minimum, use eight passes in the production area.
a. Increases passing results.
8. Reduce minimum passes if detrimental.
a. Do not over roll, it may cause cracking.
9. Construct a new test section when:
a. Material changes.
b. Supporting materials change (e.g., change from natural
soil to cement stabilized subgrade).
10. Check production material density.
a. Before or after the finishing operations.
11. Maintain the surface so the texture is:
a. Reasonably uniform.
b. Aggregate firmly keyed.
c. Hauling on the 304
will “Un-key” the material.
12. Scheduling 304
operations.
a. Cover the aggregate base with the next pavement layer
prior to the end of construction season.
b. If the Contractor doesn’t pave before the end of
construction season, then the Contractor is responsible for contamination,
damage, and instability of the base, subgrade, and underdrains.
13. Provide drainage and maintain the material according
to 203.04.A.
a. Maintain the cross-slope.
b. If it rains or material sits over the winter.
i.
Dry the 304
and subgrade.
ii.
Obtain and
maintain stability and density.
1. Finished surface should not vary:
a. More than 3/8 inch (10 mm).
i.
From a 10-foot (3
m) straightedge parallel to the centerline.
b. Or more than 1/2 inch (13 mm).
i.
From a template
conforming to the required cross-section.
2. Contractor to furnish straightedges, templates, or
other devices.
1. At the beginning of the spreading operation.
a. Contractor must adjust the spreader.
i.
Produce
sufficient loose depth to meet plan compacted thickness.
1. Determined after compaction.
ii.
Make occasional
checks.
1. During the spreading to ensure uniform depth after
compaction.
b. Purpose is to control spreading.
i.
Need not be
recorded.
2. After fine grading.
a. Make depth checks.
i.
At 500-foot (150
m) intervals.
ii.
Extended to 1,000
feet (300 m) if depth is consistent and meets plan depth.
b. Some variation in depth is expected.
i.
Tolerance of 3/4
inch (19 mm) between individual measurements.
c. If consistently less by any amount.
i.
Requirements have
not been met.
ii.
Take corrective
action.
d. If individual measurement.
i.
Less than 3/4
inch (19 mm) of plan depth.
1. Make measurement within 100 feet (30 m).
2. If greater than plan thickness.
a. Satisfactory.
3. If less than plan thickness.
a. Make checks at additional locations.
b. Define deficient area.
c. Require correction.
e. Record all depth measurements.
i.
With station
locations.
ii.
Place in the
project records.
1. Measurements of the width of base.
a. Need not be made prior to placement of overlying
courses because the width of base can readily be verified.
2.
After the
overlying pavement is placed, make a visual verification of the base width.
a. If it conforms to or exceeds the plan width, file a
statement in the project records.
1. Materials.
2. Roller weights.
3. Record lift thickness.
4. Segregation.
5. Roller passes.
6. Perform the compaction tests according to S-1015.
7. Verify cross-section and thickness.
8. In-place gradation tests according to S-1090,
if required.
9. Obtain weight ticket, if required. Tickets should be
totaled with initialed and dated tape attached.
Convert to cubic yards (cubic meters) as per 304.07
of the C&MS.
10. Pay and measure according to 304.07
and 304.08.
11. Document on the CA-EW-12,
CA-D-1, and CA-D-2. Do not duplicate
the information on these forms unless necessary.