A Mix Design Report is required for all paving except small
quantities. All materials must meet specifications before an MDR is
issued. Mn/DOT will verify two trial mix designs per mix designated in
the plan, per contract at no cost to the Contractor. Additional mix designs
will be verified for $2000 per design.
For city, county and other agency projects that have no federal or
state-aid funding, the Contractor shall provide to the District Materials
Laboratory a complete project proposal including typical sections,
addenda, supplemental agreements and change orders that affect mix
design. All test procedures and required forms are on file with the
Mn/DOT Bituminous Engineer.
0.4 Mixture Quality Management
A. Quality Control (QC) – The Contractor must provide and maintain a
quality control program. This includes all activities and documentation
including mix design, process control inspection, sampling and testing,
and necessary adjustments in the process that are related to the HMA
pavement which meets the requirements of the specification. This also
includes the development and maintenance of a certification plan.
The Contractor is required to provide qualified personnel, a laboratory
with calibrated equipment, and sampling and testing using specific
procedures as listed. The test results will be documented using control
charts, control limits, JMF adjustments, corrective actions and failing
materials. A Payment Schedule is included in the specification for the
various production failures.
B. Quality Assurance (QA) – Mn/DOT will perform QA testing as part of the
acceptance process. The Engineer is responsible for QA testing, records
and acceptance. Specific operations for QC and QA are laid out in the
As part of QA the Engineer will periodically witness the sampling
performed by the Contractor. If the Engineer observes that the sampling
and QC are not being performed properly or tests are not being done
correctly the Engineer may stop production until corrective action is taken.
All sampling and testing must be performed by a Certified Bituminous
(QM) Technician. The Engineer shall calibrate and correlate all laboratory
equipment in accordance with the latest version of the Mn/DOT
Bituminous Manual (14).
C. Verification Testing – Verification testing of the Contractor’s results shall
be performed daily. Verification testing is to be conducted as part of QA.
This testing includes one set of production tests and the taking of a
companion sample once per day. Test result tolerances are listed in Table
2360.4-M for the various items used for QC/QA. Verification testing is
very important to make sure the Contractor and Agency technicians are
running the QC/QA tests using the procedures within acceptable limits.
Resolution procedures are also laid out.
D. Sampling and Testing
Sampling is to be at the prescribed rate using random numbers to
determine the location of the samples.
E. Production Tests
Specific tests are listed for determining asphalt binder content, Bulk
Specific Gravity, Maximum Specific Gravity, Air Voids-Individual and
Isolated, Voids in the Mineral Aggregate (VMA), Gradation of the
blended aggregate, Field Moisture Damage, Aggregate Specific Gravity,
Coarse Aggregate Angularity, Fine Aggregate Angularity, and Moisture
Content. Asphalt Binder Samples must also be taken in the amount of 1
liter (1 quart) for every one million liters (250,000 gallons).
F. Documentation (Records)
The Contractor shall maintain control charts and records on an on-going
basis. Diaries should be kept and filed as directed and become the property
G. Documentation (Control Charts)
The following data are to be recorded on standard control charts:
1. Blended aggregate gradation with specification sieves.
2. Percent asphalt binder content
3. Maximum mixture specific gravity
4. Production air voids, percent
Both individual values and moving average of four are plotted.
H. JMF Adjustment
Procedures for adjusting the JMF during construction are presented.
I. Corrective Action
The procedures for taking corrective action when the mix goes out of the
specified limits are given. Testing rates are increased and if the problem is not
solved production is to stop.
J. Failing Materials
This section lays out how to handle failing materials, which are defined as
materials outside of the control limits. The following situations are covered:
• Moving Average Failure – Production Air Voids
• Moving Average Failure – Percent Asphalt Binder Content, VMA and
• Individual Failure – Production Air Voids, Percent Asphalt Content,
• Individual Failure – Gradation
Coarse and Fine Aggregate Crushing Failure
0.5 Construction Requirements
A. General – The construction requirements listed in the Specification
provide for the construction of all courses.
B. Restrictions – Work can only proceed after load restrictions have been
lifted in the spring. No paving can proceed if the Engineer feels damage
will be caused to the subgrade or the HMA. Generally, no paving should
be done after October 15 north of Browns Valley to Holyoke or after
November 1 south of that line.
C. Equipment – The Specification lays out requirements for asphalt mixing
plants and placement and hauling equipment, including asphalt pavers,
trucks and motor graders.
D. Treatment of the Surface – An asphalt tack coat shall be applied to
existing asphalt and concrete and all surfaces of each course or lift
constructed except for the final course or lift according to Mn/DOT
Specification 2357 (9).
E. Compaction Operations – Compaction shall be accomplished with
continuous operation so that all areas are compacted uniformly to the
required density. Rolling with steel-wheeled rollers will not be continued
if crushing of aggregates results. To secure a true surface, variations such
as depressions or high areas that may develop during rolling operations
and lean fat or segregated areas shall be corrected or removed.
F. Construction Joints – Joints must be thoroughly compacted to produce a
neat tightly bonded joint that meets surface tolerances. Both transverse
and longitudinal joints are subject to specified density requirements.
Randomly selected core locations may fall on the joint in which case the
cores will be taken tangent to the joint.
G. Asphalt Mixture Production – Mixture as produced is to be provided to
Mn/DOT for check testing.
0.6 Pavement Density
A. General – For the 2360 Plant Mixed Asphalt Pavement Combined
2360/2350 (Gyratory/Marshall Design) all mixtures are to be compacted
using the Maximum Density Method unless otherwise indicated. Some
mixes that would not require maximum density are lifts less than 39 mm
(1.5 in.) wedge sections, patching, driveways or non-traffic areas,
excluding shoulders. These exceptions will be compacted using the
“Ordinary” Compaction Procedure.
B. Maximum Density Determination – For the Maximum Density Method all
courses and layers will be compacted to the values listed in Table
2360.6-B2,. The mixture used for calculation of densities shall be a field-
manufactured mixture. The requirement may be reduced by 1% if the first
lift of a mix is to be placed on an unstable base. Such cases would be the
first lift on a cold recycled base, aggregate base or on a PCC slab that is
faulted or has mid-panel cracks or other problems. The payment schedule
for Maximum Density is presented in Table 2360.6-B4. The Table shows
that incentives can be obtained for higher densities. The payments for
density are based on cores. A lot is defined as about one day’s
production. The payment schedule is set up by lot. The density is a percent
of the Maximum Theoretical Density. The density of the cores is to be
determined using AASHTO Method T-166. Compaction must be
accomplished by eight (8) hours after the mixture is laid. Coring and
traffic control during the coring operation is the Contractor’s
Density and the resulting voids are very important to the
performance of an asphalt mixture. It is therefore important that specified
density be used to obtain a high quality mix.
C. Ordinary Compaction Method – In areas where the specified density
method is not required, then the Ordinary Compaction Method is used. For
this method a control strip is used to establish how much compaction
effort is needed to densify the mixture. Construction of the control strip
will be directed by the Engineer. It is to commence as soon as possible in
the job. It shall be on the same base conditions and HMA layer thickness
as planned for that section of the project. A growth curve of density versus
roller passes shall be used to establish when no more density can be
achieved. A portable nuclear density device calibrated properly can be
used to establish the growth curves. Specifications for steel-wheeled and
pneumatic-tired rollers to be used for Ordinary Compaction are given.
D. Mixture temperature requirements are listed when compaction is by the
Ordinary compaction method. The limits are based on the thickness of the
lift and the air temperature. Unless allowed by the Engineer, no paving is
allowed under the Ordinary Compaction Method when the air temperature
is below 32F.
0.7 Thickness and Surface Smoothness Requirements
The final thickness and smoothness of the HMA surface will affect the
performance of the pavement quite significantly.
A. Thickness – After compaction the thickness of each course shall be within
6 mm (0.25 in.) of the thickness shown in the plan unless automatic screed
controls are used on the first course placed. If the thickness is less than the
minimum specified, that course shall be replaced. If it is greater than the
plans then the excess will not be included in the payment.
B. Surface Requirements – After compaction, the finished surface shall be
free of open and torn sections and true to grade and cross sections shown
on the Plans using the following definitions:
• For leveling courses a tolerance of 15 mm (1/2 in.) shall be used.
• The surface of the non-wear and the wear course shall show no
variation greater than 3 mm (1/8 in.) from the edge of a 3 m (10 ft)
• The transverse slope shall not vary from the planned slope by more
than 0.4 percent.
• The distance to the edge of each course and the centerline shall not be
more than 75 mm (3 in.).
C. Pavement Smoothness
• General - Pavement smoothness is evaluated on the final mainline
pavement surface because it has been shown to affect the overall
performance of the pavement. Exceptions such as turn lanes,
shoulders, intersections, etc are listed in the specification .
• Smoothness Requirements – The smoothness requirements are based
on the type of original surface, base and timing of the project. The
limiting profiles are listed on three different tables within the
specification and show the levels of incentive and disincentive.
• Measurement – Smoothness will be measured with a 7.62 m [25 foot]
California type profilograph or an Inertial Profiler (IP), which
produces a profilogram (profile trace of the surface tested). One pass is
made 2.74 m (9 ft) from the centerline. The profilograph shall be
equipped with automatic data reduction capabilities. Segments of
roadway are defined in the Specification.
• Profile Index – The profile index is calculated for each defined
segment. A blanking band of 5 mm (0.2 in.) is used for the profile.
Bumps and dips equal to or exceeding 10.2 mm in 7.62 m (0.4 in. in
25 ft) are treated separately. Bump, dip and smoothness corrections
shall be done across the full width of the pavement. All corrective
work shall be made by diamond grinding or approved equivalent,
overlaying the area, by replacing or by inlaying.
• Payment – The cost of the smoothness testing and associated traffic
control will be incidental to the cost of the wear course.
The contractor can receive incentives and disincentives for each
segment. However, the total ride incentive for the surface cannot
exceed 15% of the total mix price. Also, the contractor cannot receive
an incentive for ride if more than 25% of all density lots fail to meet
minimum density requirements.
5.4.2. Field Control Procedures to Meet Specifications
The section procedures in the Mn/DOT Grading and Base, Geotechnical and
Bituminous Manuals (10, 5, 14) are presented. Checklists developed by the laboratory
and field staff are also summarized in the Field Notes for Construction Engineers and
Inspectors (11). Some discussion is also made as to which methods are the best to use for
field control of either granular or HMA materials. Field control procedures for cold in-
place recycling and full depth reclamation have not been finalized.
The next section reviews the procedures recommended for the QC/QA of granular
bases and the following will review those considered best practices for HMA materials.
As with other procedures for design and control of pavements, it is anticipated that the
procedures presented here will be improved over the years and therefore, the methods
presented should be up-dated periodically.
22.214.171.124. Granular Subbases and Aggregate Bases
The construction of granular subbases and aggregate bases involves the following
• Manufacture of the material from a gravel pit or quarry.
• Storage of the materials (stockpiling)
• Transport to the grade
• Placing of the material
The specifications require that the material be tested initially for general quality,
gradation and compaction. It must be determined that the material being tested is
uniform meaning that very little segregation has occurred. It is also important to make
sure the material being constructed is represented by the correct moisture-density test
if specified density is being used.
126.96.36.199.2. Schedule of Materials Control
A current schedule of materials control should be reviewed before each project to
• The specification applicable for that project
• The minimum required acceptance testing rate
• Form No.
• Minimum required sampling rate for laboratory testing
• Sample size required for laboratory testing
These requirements are listed for gradation, one-point density, Moisture-density,
relative density, relative moisture content, pulverization testing, percent crushing, and
aggregate quality testing.
The Schedule of Materials Control is Tab. A 5-692.100 in the Grading and Base
A standard sample identification card is also presented in the Grading and Base
Manual Fig. 1 5-692.101 (10).
Standard forms to use for Independent Assurance Sampling and Testing are also
188.8.131.52.3. Standard Methods of Testing
Standard methods of testing and procedures to be used by the contractor and
Mn/DOT for QC and QA are presented in Section 5-296.200 of the Grading and Base
Manual. It is very important that exactly the same procedures be used by both groups
when quality assurance and verification testing are performed.
Methods to correctly sample and test for statistically based specifications are
presented in Chapter 5-692.700 of the Grading and Base Manual. It is very important
to use the principles of statistics because all pavement construction materials are
variable. When a material is designed the variability is considered. Then in the field
the constructed material must be placed as uniformly as possible and within the
variability assumed during design. The MnPAVE Design procedure will include
variability as one of the conditions to consider in thickness design and generally will
show that a thinner pavement can be designed where less variability can be measured.
184.108.40.206.4. Methods of Compaction Control for Aggregate Bases
Three methods are included for Compaction Control of aggregate bases in the
• Specified Density
• Dynamic Cone Penetrometer
• Quality Compaction
Specified density is usually measured using the 150-mm (6-in.) Sand Cone
Method, ASTM D 1556-90. The larger cone is used to minimize side effects of the
hole. It is important to make sure that random sampling procedures are used for
selecting sample locations, that the material being tested has been moisture-density
tested and that the standard test procedure is used for the sand cone test.
The Dynamic Cone Penetrometer (DCP) has recently been added as a test
procedure for aggregate base construction control. This procedure is quicker and
easier to run than the sand cone density. Also, it gives a direct measure of the material
stiffness modulus. It is important to follow the test procedure carefully and to conduct
the test within 24 hours of compaction so that crusting does not occur. Statistical
procedures should again be used to establish the test location and analyze the data.
Quality Compaction should only be used if the equipment is not available to do either
Specified or DCP testing. If quality compaction is used, the inspector and engineer
should be experienced in the construction of aggregate base and embankment
materials. They must also observe the compaction operation continuously. This
method of compaction is appropriate only for very small areas where a limited
amount of material is being placed.
220.127.116.11.5. Job Guide for Aggregate Base Construction
The Mn/DOT Office of Construction, Technical Certification Section has
published Field Notes for Construction Engineers and Inspectors (11). This booklet
presents many items that an inspector should use to do a quality job of construction
control. The following are a portion of the checklist items presented for aggregate
1. Review the contractor/producer QC procedures and test results. Obtain the
completed Certification of Aggregates (form #24346) from the contractor.
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