SECTION 02740
ASPHALT PAVEMENT
PART 1
1.01
SECTION INCLUDES
A.
1.02
Section 02340 – Fly Ash Stabilization
QUALITY ASSURANCE
A.
Test samples will be taken in the field by the OWNER’s independent testing
service. Mix designs and material samples are to be submitted for review at least
4 weeks prior to material placement. All sampling and testing shall be done in
accordance with the latest methods of AASHTO, unless otherwise specified.
B.
When placing the asphalt trench patch, saw cutting of the existing asphalt will
not be permitted within the wheel path of a travel lane. All asphalt patches shall
conform to the specifications outlined in the City of Fort Collins Design and
Construction Standards for Streets of Public Right-of-way, “Construction
Details” section.
PART 2
2.01
This section covers paving of all new and existing asphalt surfaces. Existing
pavement is to be replaced with similar material as herein set forth.
RELATED SECTIONS
A.
1.03
GENERAL
PRODUCTS
MATERIALS
A.
Cationic Emulsified Asphalt: The cationic emulsified asphalt for the tack coat
shall be CSS-1h and shall meet the requirements of AASHTO M 208 (ASTM C
2397).
B.
Aggregate for Hot Plant Mix Bituminous Pavement:
1.
Description – The asphaltic concrete surface shall consist of a mineral
aggregate, uniformly mixed with asphalt cement.
2.
Materials:
a.
Crushed Gravel: The crushed gravel shall consist of clean, hard,
durable particles which have been crushed to the gradations
shown in Table 1 (in accordance with the Colorado Department
of Transportation Standard Specifications for Road and Bridge
Construction).
Aggregates for hot plant mix bituminous pavement shall be of uniform quality,
composed of clean, hard, durable particles of crushed stone, crushed gravel,
natural gravel, or crushed slag. Excess of fine material shall be wasted before
crushing. For Gradings S, SX, and SG, a percentage of the aggregate retained on
the 4.75 mm. (No. 4) sieve shall have at least two mechanically induced fractured
Poudre High School
02740-1
Asphalt Pavement
faces when tested in accordance with Colorado Procedure 45. This percentage
will be provided by the ENGINEER OWNER. The angularity of the fine
aggregate shall be a minimum of 45.0% when determined according to CP
L-5113, Method A. Aggregate samples representing each aggregate stockpile
shall be non-plastic if the percent of aggregate passing the Number 4 sieve is
greater than or equal to 10 percent by weight of the individual aggregate sample.
Plasticity will be determined in accordance with AASHTO 90.
Reclaimed material shall be of uniform quality. The maximum size of the
reclaimed asphalt pavement shall be 38 mm (1 1/2 inches) prior to introduction
into the mixer. The maximum aggregate size contained in the combination of
reclaimed asphalt pavement and new aggregate shall not exceed the maximum
specified in Table 1. The hot bituminous pavement shall not contain more than
15 percent reclaimed asphalt pavement.
The material shall not contain clay balls, vegetable matter, or other deleterious
substances. The aggregate for Gradings S, SX, and SG shall have a percentage
of wear of 45 or less when tested in accordance with AASHTO T 96.
TABLE 1
MASTER RANGE TABLE FOR
HOT BITUMINOUS PAVEMENT
Sieve Size
Percent by Weight Passing Square Mesh Sieves
Grading S
Grading SG
Grading SX
100
100
90 – 100
90 – 100
100
*
*
90 – 100
*
*
*
*
*
*
23 – 49
19 – 45
28 – 58
37.5 mm (1 1/2”)
25.0 mm (1”)
19.0 mm (3/4”)
12.5 mm (1/2”)
9.5 mm (3/8”)
4.75 mm (#4)
2.36 mm (#8)
1.18 mm (#16)
*
*
*
600 m (#30)
300 m (#50)
150 m (#100)
2–8
1–7
2 –10
75 m (#200)
* These additional Form 43 Screens will initially be established for the
Contractor’s Quality Control Testing using values from the As Used
Gradation shown on the Design Mix.
The crushed gravel shall show no detrimental amount of stripping when tested as
follows:
A test sample consisting of the aggregate and bitumen to be used in the paving
mixture shall be mixed at the temperature specified herein. The sample shall
then be spread in a loose, thin layer and allowed to air-season for 24 hours before
testing. A portion of the sample, not over ½ of the capacity of the
Poudre High School
02740-2
Asphalt Pavement
jar, shall be placed in a glass jar and completely covered with distilled water.
The jar shall be fitted with a tight screw cap and allowed to stand for a period of
24 hours. The jar shall be vigorously shaken for a period of 15 minutes and the
sample of the mixture shall then be examined for stripping. If stripping occurs,
the aggregate shall be rejected or an approved method of treating shall be
specified to change the material from a hydrophilic to a hydrophobic state as
directed by the ENGINEER OWNER.
Superpave Performance Graded Binders. Superpave Performance Graded
Binders shall conform to the requirements listed in Table 2. The oil to be used
shall be Performance Graded Binder 64-22.
TABLE 2
SUPERPAVE PERFORMANCE GRADED BINDERS
Requirement for PG Binder
58-22
58-28
58-34
64-22
64-28
70-28
76-28
AASHTO
Test No.
230
230
230
230
230
230
230
T 28
3
3
3
3
3
3
3
TP 48
58
58
58
64
64
70
76
TP 5
-
-
-
-
50
-
-
T 51
Toughness, joules (inch-lbs)
-
-
-
-
-
-
Tenacity, joules (inch-lbs)
-
-
-
-
-
-
*CP L2210
*CP L2210
T 240
1.00
1.00
1.00
1.00
1.00
1.00
1.00
T 240
58
58
58
64
64
70
76
TP 5
-
-
-
-
-
50
50
*CP L2211
Method A
-
-
-
-
20***
-
-
T 51
Property
Original Binder Properties
Flash Point Temp., °C, minimum
Viscosity at 135 °C, Pa●s, maximum
Dynamic Shear, Temp. °C, where
G*/Sin δ @ 10 rad/s ≥ 1.00 kPa
Ductility, 4 °C (5 cm/min.), cm
minimum
12.4
(110)
8.5
(75)
RTFO Residue Properties
Mass Loss, percent maximum
Dynamic Shear, Temp. °C, where
G*/Sin δ @ 10 rad/s ≥ 2.20 kPa
Elastic Recovery, 25 °C, percent min.
Ductility, 4 °C (5 cm/min.), cm
minimum
PAV Residue Properties, Aging
Temperature 100 °C
Dynamic Shear, Temp. °C, where
G*●Sin δ @ 10 rad/s ≤ 5000 kPa
Creep Stiffness, @ 60 s, Test
Temperature in °C
S, maximum, MPa
m-value, minimum
**Direct Tension, Temperature in °C,
@ 1 mm/min., where failure strain ≥
1.0 %
PP 1
22
19
16
25
22
25
28
TP 5
-12
-18
-24
-12
-18
-18
-18
300
300
300
300
300
300
300
TP 1
0.300
0.300
0.300
0.300
0.300
0.300
0.300
TP 1
-12
-18
-24
-12
-18
-18
-18
TP 3
*Colorado Procedure
**Direct tension measurements are required when needed to show conformance to AASHTO MP 1.
***If the PG 64-28 RTFO residue fails the ductility test, the binder will be accepted if the TFO residue (AASHTO T 179) has a
ductility of 25 cm or more.
Poudre High School
02740-3
Asphalt Pavement
2.02
PAVING PLANT REQUIREMENT
A.
General Requirements:
1.
Uniformity: The plants shall be so designed, coordinated and operated as
to produce a mixture within the job mix tolerances as covered in
paragraph 2.03C under “Preparation and Composition of the Mixture.”
2.
Equipment for Preparation of Asphalt: Tanks for storage of asphalt shall
be capable of heating the material, under effective and positive control at
all times, to temperature requirements set forth in the Specifications.
Heating shall be accomplished by steam coils, electricity, or other means
such that no flame shall come in contact with the heating tank. A
circulating system for the asphalt shall be provided of adequate size to
ensure the property and continuous circulation between storage tank and
mixer during the entire operating period. All pipelines and fittings shall
be steam jacketed or other properly insulated to prevent heat loss.
Storage tank capacity shall be sufficient for at least one day’s run.
3.
Dryer: A rotary dryer of any satisfactory design for drying and heating
the mineral aggregates shall be provided. The dryer shall be capable of
drying and heating the mineral aggregate to the temperature requirements
set forth in the Specifications.
4.
Screens: Plant screens, capable of screening all aggregates to the size
required for proportioning, and having normal capacities slightly in
excess of the full capacity of the mixer, shall be provided. The mesh of
the screens shall be approved by the ENGINEER OWNER before paving
operations.
5.
Bins: The plant shall include a minimum of 3 dry aggregate storage bins
with the total capacity of not less than 3 times the dead load capacity of
the mixer. Each bin shall be provided with an overflow pipe that shall be
of such size and at such locations as to prevent any backing up of
material into other bins. Each bin shall have a suitable convenient means
for sampling. The sampling openings shall be subject to the approval of
the ENGINEER OWNER.
6.
Thermometric Equipment: An armored thermometer reading from 200F
to 500F shall be fixed in the asphalt feed line at a suitable location from
the discharge valve at the mixer unit. The plant shall be further equipped
with an approved dial scale mercury actuated thermometer, an electric
pyrometer, or other approved thermometric instrument so placed at the
discharge chute of the dryer as to register automatically or indicate the
temperature of the heated aggregate.
7.
Dust Collectors: When plants are located in any vicinity where dust may
be objectionable, or when dust interferes with the efficient operation of
the plant, proper housing, mixer covers, dust collecting systems shall be
installed. Provision shall be made to waste the material so collected or to
return it uniformly to the mixture as the ENGINEER OWNER may
direct.
Poudre High School
02740-4
Asphalt Pavement
8.
B.
Safety Equipment: Adequate and safe stairways to the mixer platform
and guarded ladders to other plant units shall be placed at all points
required for accessibility to all plant operations. All gears, pulleys,
chains, sprockets, and other dangerous moving parts shall be thoroughly
guarded and protected. Ample and unobstructed passage shall be
maintained at all times in and around the truck loading space. This space
shall be kept free from drippings from the mixing platform.
Special Requirements of Batch Plants:
1.
Plant Scale: Scales for any weight box or hopper may be either of the
beam or springless dial type and shall be a standard make and design,
sensitive to ½ of 1% of the maximum load that may be required. When
of the beam type, there shall be a separate beam with telltale indicator for
each size aggregate and a tare beam for balancing the hopper.
2.
Control of Mixing Time: The plant shall be equipped with an approved
means to govern the time of mixing and to maintain it.
3.
Weight Box or Hopper: The equipment shall include a means for
accurately weighing each bin size to hold a full batch without hand
raking or running over. The weight box or hopper shall be supported on
fulcrums and knife edges so constructed that they will not be easily
thrown out of alignment or adjustment. Gates on both bins and hopper
shall be so constructed as to prevent leakage when they are closed.
4.
Asphalt Bucket: The asphalt bucket which is used for weighing the
asphalt cement shall have sufficient capacity to hold not less than 10% of
the weight of aggregate required for one batch. It shall be steam jacketed
or equipped with properly insulated electric heat units and shall be
suspended on dial scales or beam scales equipped with a telltale indicator
so that the tare weight of asphalt cement can be measured accurately to
within 2% above or below the weight required. The bucket shall be so
arranged that it will deliver the molten asphalt cement in a thin uniform
sheet or in multiple streams the full width of the mixer.
5.
Mixer Unit: The plant shall include a batch mixer of an approved twin
pugmill type or rotary drum type and shall be capable of producing a
uniform mixture within the job mix tolerances fixed by these
Specifications. It shall have a batch capacity of not less than 2,000
pounds.
If of the pugmill type, worn or improper pugmill paddles will not be
permitted. A mechanical batch counter shall be installed and shall be so
designed as to register upon only the actuation of the asphalt bucket
release and to preclude the register of any material through the operation
of pulling bins.
Poudre High School
02740-5
Asphalt Pavement
C.
Special Requirements for Continuous Mixing Plants:
1.
Gradation Control Unit: The plant shall include a means of accurately
proportioning each bin size of aggregate either by weighing or by
volumetric measurement. When gradation control is by volume, the unit
shall have an accurately controlled individual gate to form an orifice for
volumetrically measuring the material drawn from each respective bin
compartment. Indicators shall be provided on each gate to show the gate
opening in inches.
2.
Weight Calibration or Aggregate Feed: The plant shall include a means
for calibration of gate openings by means of weight test samples. The
materials fed out of the bins through individual orifices shall be bypassed
to a suitable test box, each compartment material confined in a separate
box section. The plant shall be equipped to handle conveniently such
test samples weighting up to 800 pounds and to weigh them on accurate
scales.
3.
Synchronization of Aggregate and Asphalt Feed: Satisfactory means
shall be provided to afford positive interlocking control between the flow
of aggregate from the bins and the flow of asphalt from the meter or
other proportioning sources. This control shall be accomplished by
interlocking mechanical means or any positive method under the control
of the ENGINEER OWNER.
4.
Mixer Unit for Continuous Method: The plant shall include a continuous
mixer of an approved twin pugmill type, and shall be capable of
producing a uniform mixture within the job mix tolerance fixed by these
Specifications. The paddles shall be of a type adjustable for angular
position on the shafts and reversible to retard the flow of the mix. The
mixer shall carry a manufacturer’s plate giving the net volumetric
contents of the mixer at the several heights inscribed on a permanent
gauge and also giving the rate of feed of aggregate per minute at plant
operating speed.
Unless otherwise required, determination of mixing time shall be by
weight methods under the following formula. The weights shall be
determined for the job by tests made by the ENGINEER OWNER.
Mixing time in seconds = Pugmill dead capacity in pounds
Pugmill output in pounds/seconds
The mixing time shall be approved by the ENGINEER OWNER.
2.03
PREPARATION OF MATERIAL
A.
Preparation of Asphalt Cement: The asphalt cement shall be heated at the paving
plant to a temperature not exceeding 325F. The penetration of the asphalt cement
shall be maintained within the limits of penetration specified through the period
of use.
B.
Preparation of Mineral Aggregates: The mineral aggregates shall be dried and
heated at the paving plant so that when delivered to the mixer, they shall be at as
Poudre High School
02740-6
Asphalt Pavement
low a temperature as is consistent with proper mixing and laying, and in no case
to exceed 350F. They may be fed simultaneously into the same drier but in all
cases, immediately after heating, they shall be screened into three or more bins.
The screen sizes shall be approved by the ENGINEER OWNER prior to the start
of construction.
C.
Preparation and Composition of the Mixture: Each size of hot aggregate, the
mineral filler and the asphalt cement shall be measured separately and accurately
to the proportions in which they are to be mixed. After the hot aggregate and
mineral filler have been charged into the mixer and thoroughly mixed as directed
by the ENGINEER OWNER, the asphalt cement shall be added and the mixing
continued for a period of at least 20 seconds, or longer if necessary, to produce a
homogeneous mixture, in which all particles of the mineral aggregates are coated
uniformly.
The constituents of the surface course shall be combined in such proportions to
produce a mixture conforming to the gradations shown in Table 1.
All mix furnished for the project shall conform to within the range of tolerances
shown in Table 3.
TABLE 3
MIX TOLERANCES
Bitumen Content
Asphalt Recycling Agent
Temperature of Mixture When Discharged from Mixer
0.3%
0.2%
10°C
1
Hot Bituminous Pavement
Passing the 9.5 mm (3/8 inch) and larger sievers
6%
2
Passing the 4.75 mm (No. 4 and 2.36 mm (No. 8 sieves)
5%
2
Passing the 600 m (No. 30) sieve
4%
2
Passing the 75 m (No. 200) sieve
2%
1
When 100% passing is designated, there shall be no tolerance. When
90-100% passing is designated, 90% shall be the minimum; no tolerance
shall be used.
2
These tolerances apply to the Contractor’s Quality Control Testing.
2
Superpave Performance Graded Binders shall conform to the requirements listed
in Table 4 at 75 gyrations.
Poudre High School
02740-7
Asphalt Pavement
TABLE 4
MIX DESIGN CRITERIA AT OPTIMUM OIL
Property
Asphalt Content (%)
Voids @ N (INI)
Voids @ N (DES)
Voids @ N (MAX)
V.M.A. (%)
% Voids Filled
Tensile Strength Retention
Dry Tensile Strength (psi)
Mixing Temperature
Compaction Temperature
D.
PART 3
3.01
3.02
Specification
+/-0.3%
11 Min.
3%-5%
2 Min.
14 Min.
65%-78%
80 Min.
30 Min.
325 Deg. F
300 Deg. F
Paving Plant Inspection: For the verification of weights or proportions and
character of materials and determination of temperatures used in the preparation
of the mixture, the ENGINEER OWNER or his authorized representative shall
have access at any time to all parts of the paving plant.
EXECUTION
SURFACE PREPARATION
A.
All final pavement cuts shall be made in straight lines using saw cut. Initial
pavement cuts may be made using wheel cut or other suitable method.
B.
Prior to placing the prime coat, the base course shall be thoroughly cleaned.
Loose material shall be removed from the existing surface as directed by the
ENGINEER OWNER.
PRIME COAT
A.
All previously prepared bases or existing surface shall be primed with a cationic
emulsified asphalt in accordance with the requirements of these Specifications,
and at the locations that are shown on the Plans or as directed by the ENGINEER
OWNER. The prime coat shall be placed by means of an approved pressure
distributor. Before application, the asphaltic oil shall be heated as directed by the
ENGINEER OWNER. However, it shall not be heated to more than 180F. In
general, the rate of application shall be from 0.25 to 0.35 gallons per square yard
as directed by the ENGINEER OWNER. The prime coat shall be carefully
applied, particularly around curbs and sidewalks. If excessive amounts of curb,
sidewalks, or other structures are sprayed with asphaltic oil, they shall be cleaned
as directed by the ENGINEER OWNER at the CONTRACTOR’s expense. All
vertical contact faces shall be primed by painting with cationic emulsified
asphaltic oil.
Poudre High School
02740-8
Asphalt Pavement
3.03
ASPHALTIC CONCRETE SURFACE
A.
Transportation of Mixture: The mixture shall be transported from the paving
plant to the work in vehicles equipped with tight metal compartments previously
cleaned of all foreign materials. When directed by the ENGINEER OWNER, the
compartments shall be sufficiently insulated and each load shall be covered with
canvas or other suitable materials of sufficient size to protect it from weather
conditions. The inside surface of all vehicle compartments used for hauling
mixture must be lightly lubricated with a tin oil or soap solution just before
loading, but excess lubricant will not be permitted. No load shall be sent out so
late in the day as to interfere with spreading and compacting the mixture during
daylight unless artificial light, satisfactory to the ENGINEER, is provided.
B.
General Conditions:
The mixture shall be laid only when the base is dry and
only when weather conditions are suitable. The mixture shall be laid when
atmospheric temperatures are consistent with the placement temperature
limitations as outlined in Table 5. Asphalt shall not be placed when frost exists
in the subgrade. Any material laid shall be rolled with pneumatic rollers in
addition to the specified rolling, as directed by the ENGINEER OWNER.
C.
Placing Asphalt Mixture: If traffic is allowed to use the prepared subgrade or
sub-base, the subgrade or sub-base shall be checked and corrected as needed
immediately ahead of placing bituminous materials. Prior to placement of the
bituminous surface, the base shall be cleaned of all dirt or other foreign matter.
When the new pavement abuts the old pavement, the Contractor shall cut the old
pavement as directed by the Engineer and paint the edge of the pavement with a
tack coat.
TABLE 5
PLACEMENT TEMPERATURE LIMITATIONS
Compacted
Layer
Thickness, in
mm (inches)
Minimum Air and Surface Temperature, °C(°F)
Top Layer of Payment
Note (1)
15 (60)
10 (50)
Note (2)
20 (70)
15 (60)
Layers Below Top Layer
Note (1)
10 (50)
5 (40)
Note (2)
15 (60)
10 (50)
25(1) or less
>25 to 75
(1 to 3)
>75 (3)
--0 (30)
5 (40)
Notes: Air Temperature is taken in the shade. Surface is defined as the existing base
on which the new pavement is to be placed.
(1)
Temperatures to be used when mix contains unmodified asphalt cement (PG 5828, PG 58-22, PG 64-22). Temperatures to be used with PG 76-28, PG 70-34,
PG 64-28 and Pg 58-40.
(2)
Temperature to be used when mix contains AC-20R [AC-20 (Rubberized)].
The asphaltic pavement shall be placed only when the base is stable and weather
conditions are suitable. The asphaltic pavement shall have a density of ninetytwo percent (92%) to ninety-six percent (96%) of the maximum theoretical
Poudre High School
02740-9
Asphalt Pavement
density, determined according to Colorado Procedure 51. Field density
determinations will be made in accordance with Colorado Procedure 44 or 81.
While the surface is being compacted and finished, the Contractor shall carefully
trim the outside edges of the pavement to the proper alignment.
Unless otherwise permitted by the ENGINEER OWNER, the mixture shall be
spread by means of a mechanical self-powered paver, capable of spreading the
mixture true to the line, grade, and crown set by the ENGINEER OWNER.
Pavers shall be equipped with hoppers and distributing screws of the reversing
type to place the mixture evenly in front of adjustable screeds. The mixture shall
be dumped in the center of the hoppers and care exercised to avoid overloading
and spilling over of the mixture upon the base. Pavers shall operate when laying
mixtures at such speed between 10 feet and 20 feet per minute, as may be
decided by the ENGINEER OWNER.
Pavers shall be equipped with a quick and efficient steering device and shall have
forward and reverse speeds of not less than 100 feet per minute.
Unless operating on fixed side forms, pavers shall employ mechanical devices
such as equalizing runners, straightedge runners, evener arms, or other
compensating devices to adjust the grade and confine the edges of the mixture to
true lines within the use of stationary side forms. The pavers shall be capable of
spreading the mixtures, without segregation, in thickness of from ½ inch to 3
inches, to a maximum width of 10 feet in increments of 1 foot or less and to a
minimum width of 8 feet. They shall be equipped with blending or joint leveling
devices for smoothing and adjusting all longitudinal joints between adjacent
strips of courses of the same thickness.
When asphalt concrete pavement thickness in excess of 2 inches is called for,
they shall be laid in separate courses of not less than 1 inch or more than 2 inches
or as directed by the ENGINEER OWNER.
The term “screed” includes a “strike-off” device operating by cutting, crawling,
or other practical action which is effective on the mixture at a workable
temperature without tearing, shoving, or gouging and which produces a finished
surface of the evenness and texture specified. The screed shall be adjustable as
to level and shall have an indicating level attached. Longitudinal and transverse
joints shall be made in a careful manner. Well bonded and sealed joints are
required. If necessary to obtain this result, joints shall be painted with cationic
emulsified asphaltic cement.
In making the joint along any adjoining edges such as curb, gutter, or an
adjoining pavement and after the hot mixture is placed by the finished machine,
just enough of the hot material shall be carried back to fill any space left open.
This joint shall be properly “set” up with the back of rake at proper height and
level to receive the maximum compression under rolling. The work of “setting
up” this joint shall be performed always by competent workmen who are capable
of making correct, clean, and neat joints.
Immediately after any course is screeded, and before roller compaction is started,
the surface shall be checked, any inequalities adjusted, all fat, sandy
accumulations from the screed removed by a rake or hoe, and all fat spots in any
Poudre High School
02740-10
Asphalt Pavement
course removed and replaced with satisfactory material. Irregularities in
alignment and grade along the outside edge shall also be corrected by the
addition or removal of mixture before the edge is rolled.
In narrow, deep, or irregular sections, intersections, turnouts, or driveways where
it is impractical to spread and finish the mixtures by machine methods, the
CONTRACTOR may used approved spreading equipment or acceptable hand
methods as directed by the ENGINEER OWNER.
When the mixture is to be spread by hand, upon arrival on the work it shall be
dumped upon a steel dump board outside the area on which it is to be spread.
Immediately thereafter it shall be distributed into place by means of hot shovels
and spread with hot rakes in a loose layer of uniform density and correct depth.
Tines of the rakes shall not be less than ½ inch longer than the loose depth of the
mixture, and spaces between tines shall not be less than the maximum diameter
of aggregate particle except that in no case should the spaces be less than 1 inch.
Loads shall not be dumped any faster than can be properly handled by the
shovelers.
The shovelers shall not distribute the dumped load faster than it can be properly
handled by the rakers.
The rakers will not be permitted to stand in the hot mixture while raking it,
except where necessary to correct errors in the first raking. The raking must be
carefully and skillfully done in such a manner that after the first passage of the
roller over the raked mixture, a minimum amount of back patching will be
required.
Placing mixtures shall be as continuous as possible and the roller shall pass over
the unprotected edge of the freshly laid mixture only when the laying of this
course is to be discontinued for such intervals of time as to permit the mixture to
become chilled.
D.
Joints: Joints between old and new pavements, or between successive days’
work, shall be carefully made in such a manner as to insure a thorough and
continuous bond between the old and new surfaces. The edge of the previously
laid course shall be cut back to its full depth so as to expose a fresh surface, after
which the hot surface mixture shall be placed in contact with it and raked to a
proper depth and grade. Hot smoothers or tampers shall be carefully used in such
a manner as to heat up the old pavement sufficiently (without burning it) to
insure a proper bond. Before placing mixture against them, all contact surfaces
of curbs, gutters, headers, manholes, etc., shall be painted with a thin uniform
coating of cationic emulsified asphaltic cement.
E.
Compaction of the Mixture: After spreading, the mixture shall be thoroughly and
uniformly compressed by a power-driven roller or rollers, weighing not less than
8 tons, as soon after being spread as it will bear the roller without undue
displacement. Delays in rolling freshly spread mixture will not be tolerated.
Rolling shall start longitudinally at the sides and shall proceed toward the center
of the pavement overlapping on successive trips by at least ½ the width of a rear
wheel. Alternate trips of the roller shall be of slightly different lengths. If the
width of the pavement permits, it shall, in addition, be rolled at right angles to the
center line.
Poudre High School
02740-11
Asphalt Pavement
The speed of the roller shall not exceed 3 miles per hour and shall, at all times, be
slow enough to avoid displacements of the hot mixture, and any displacement
occurring as a result of reversing the direction of the roller, or from any other
cause, shall at once be corrected by the use of rakes and of fresh mixture where
required. Rolling shall proceed continuously until all roller marks are eliminated.
To prevent adhesion of the mixture to the roller, the wheels shall be kept properly
moistened, but excess water will not be permitted.
The rollers shall be in good condition, capable of reversing without back-lash and
shall weight not less than 200 pounds to the inch of tread. They shall be operated
by competent and experienced rollermen and must be kept in continuous
operation as nearly as practicable in such a manner that all parts of the pavements
shall receive substantially equal compression.
Along curbs, headers, manholes, and similar structures, and all places not
accessible to the roller, thorough compactions must be secured by means of hot
tampers and at all contacts of this character, the joints between these structures
and the surface mixture must be effectively sealed.
The course, after final compaction, shall conform to the following requirements:
It shall be smooth and true to the established crown and grade. It shall have the
average thickness specified and shall at no point vary more than ¼ inch from the
thickness shown on the typical cross-section in the Plans. Any low or defective
places shall immediately be remedied by cutting out the course at such spots and
replacing it with fresh, hot mixture which shall be immediately compacted to
conform with the surrounding area and shall be free from depressions exceeding
¼-inch as measured with a 10-foot straightedge paralleling the centerline of the
roadway.
After final compaction, the finished surface course shall at no point have a
density less than 92% of the maximum density possible to be obtained in a
voidless pavement composed of the same materials in like proportions. Density
shall be determined from specimens cut from the finished pavement as directed
by the ENGINEER OWNER.
3.04
TEMPORARY ASPHALT COLD-PATCH
In the event the CONTRACTOR cannot install hot bituminous pavement, for whatever
reason, pursuant to the requirements of these documents, he shall install a temporary
asphalt cold-patch pursuant to said requirement and subsequently remove said cold-patch
and replace with hot bituminous pavement at the earliest possible date.
A.
Place suitably prepared base course.
B.
Minimum thickness: 2 inches on 6-1/2 inches of aggregate base course.
C.
The CONTRACTOR is responsible for maintaining cold-patch.
Poudre High School
02740-12
Asphalt Pavement
3.05
MANHOLE FRAMES AND VALVE BOXES
A.
Manhole frames and water valve vaults can be completed after paving operation
by using “plates.”
B.
Foreign matter which is introduced into manholes and valve vaults shall be
removed immediately to provide free access to the facilities.
C.
Valve vaults and manhole rings shall be straight and properly aligned.
Adjustments to be made with concrete rings and mortar only (maximum
tolerance is ¼”).
Valve boxes shall be inspected by placing a valve key on the operating nut to
assure a proper alignment.
END OF SECTION
Poudre High School
02740-13
Asphalt Pavement
THIS PAGE INTENTIONALLY LEFT BLANK.
Poudre High School
02740-14
Asphalt Pavement