Plant Mix Overview

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Plant Mix Overview

• MDT Training Conference
• Billings, Montana
• March 1 2, 2006

Presented By Matt Strizich and Danny Hood
2
Recent Plant Mix Use
3
Volumetrics Incentives

• 1.45 million or 2.85 in 2005
• 0.48 million or 3.16 so far in 2006
• Percentage of total spent on PMS that year

4
Ride Specification Incentives

• 0.39 in 2002
• 1.51 in 2003
• 0.9 /- from 2004-2006
• Percentage of total spent on PMS that year

5
Compaction Statistics
6
Compaction Issues

• Compaction incentives were 1.04 in 2003 and
  1.20 in 2004
• Dropped to 0.34 in 2005
• Have a net disincentive of 0.22 so far in 2006

7
Quick Notes

• Volumetrics and the Ride Specification are not
  included on all projects
• All end-result specifications

8
Contractors are Earning it!

• MDT is paying 3-5 of PMS costs in incentives
• Plant production has been slowed
• Seeing quality compete with production

9
Purpose

• Present potential future changes
• Provide reasoning behind changes
• Share information from last year
• Provide the opportunity to ask questions

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Topics

• Grade S Grade D Commercial Specification
  Revisions
• New ½ Grade S Policy
• Ride Specification Revisions
• Compaction Issues in 2005
• Aggregate Surface Treatment Experiment

11
MDT Staff

• Construction Reviewers
• Project Staff
• Internal Audit

12
Contractors

• Montana Contractors Association (MCA)
• Non-Uniformity Complaints
• Claims

13
Specification Change Process

• All specification revisions go through the
  Specification Section
• Dan Smith and Ryan Antonovich
• Defined process
• Standards Committee coming soon

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Change Process

• Ensures thorough review
• Reviewed by MDT staff and contractors

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Plant Mix Specifications

• Grade S and Grade D Commercial

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Grades of Plant Mix

• Grade S
• Volumetrics
• Non-Volumetrics

• Grade D Commercial
• Tested
• Non-Tested

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Why two versions?

• Contract administration
• Quality of the same grades of mix should be
  equal.
• Testing and frequency of testing varies

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Grade S

• Completely revised mix
• Grade S has been successful
• Moved to gyratory compactors
• Bob Weber and Scott Barnes deserve the credit

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Volumetrics

• Volumetrics is how MDT administers and controls
  the plant mix quality
• True end result specification
• Successfully encourages contracts to control
  their operations
• Want quality to be able to compete with production

20
Grade D Commercial

• Relatively new specification
• Always used on smaller projects
• Bill Fogarty leading the committee

21
Grade B

• Use for bike paths or other features not subject
  to heavy loading
• Consider using Grade D or S with chip seals
  instead

22
Grade C

• No longer needed
• Grade D Commercial should be used instead

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Change Process

• Plan to review specifications yearly
• Will continue to see the same issues if they are
  not identified
• Anyone can initiate change
• People doing the work need to identify the issues
• MDT Project staff
• Contractors
• Reviewers

24
Grade S Changes

• Changes are minimal
• Changes are the same for volumetrics and
  non-volumetrics versions

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Mix Designs

• 50 Gyration mixes have been eliminated
• SHRP recommendation for low volume roads
• Created issues with meeting Hamburg testing
  requirements

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Release Agents Specification

• a)                  Trucks. Remove trucks from
  service that leak fluids. When directed, cover
  each load with canvas or other approved material
  to protect the mix at Contractor expense. Do not
  use Diesel fuel as a truck bed release agent.
  Use a commercially manufactured release agent
  approved by the Project Manager.

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Release Agents - Specification

• b)                  Rollers. Furnish and use
  rollers that compact the plant mix to the
  specified density. Remove rollers that crush the
  paving aggregates or otherwise damage the plant
  mix and replace the damaged plant mix at
  contractor expense.
• Cleaning Agents. Do not use diesel fuel as a
  cleaning agent or as a release agent for any
  paving equipment or operations. Use a
  commercially manufactured release agent approved
  by the Project Manager.

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Release Agents - Justification

• Expands the existing restriction on diesel fuel
  to all equipment
• Need to be uniform in our enforcement.
• Contractors will include additional cost in bids
• Will eliminate having the issue every time paving
  starts

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Release Agents - Justification

• Plant Mix quality
• Employee safety
• Environmental concerns

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Tack

• The cost of SS-1 will be incidental to the cost
  of Plant Mix Surfacing
• Includes tack between lifts of paving and for
  sealing rumble strips
• Tack is still required in all instances it was
  previously used

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Tack

• SS-1 will still be a pay item for some uses
• Aggregate surface treatment
• Fog sealing
• Reasons for change
• The number of lifts is no longer specified
• Low cost item

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Grade D Commercial

• Mostly Clarifications
• Extensive revisions last year
• Previously relied only on compaction to control
• Not enough control so 5 penalties on specified
  properties was added

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Grade D Commercial

• Wording change
• Material. Provide Grade D Commercial Plant Mix
  Bituminous Surfacing with the specified asphalt
  binder, 1.4 hydrated lime, and meeting
  Table 701-15A requirements. Use fillers or
  additives as necessary.

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Grade D Commercial

• Clarification
• c) Sampling. Sample the PGAB meeting subsection
  402.03.2 (B). A sample is two one-pint (two 500
  ml) containers of PGAB. Sample fillers, hydrated
  lime, additives, aggregate treatment and tack in
  accordance with MT-601.

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Grade D Commercial

• Revised target air voids
• Percent Air Voids
• changed from 3-5 to 2-4
• Do not want drier mixes
• Cost of oil is included in the Grade D Commercial
  bid item

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Grade D Commercial

• Reweighing of vehicles is no longer mandatory
• It should still be done in most cases
• The Project Manager may randomly designate the
  re-weighing of loaded vehicles.

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Grade D Commercial

• Reduced the F factor from 12 to 6
• a)   Acceptance. Rescind Subsection 401.03.12 (E)
  and replace with the following
• Plant mix surfacing is evaluated for density on
  a lot-by-lot basis under Subsection105.03.2,
  except as noted in Subsection 401.03.12(B).
  Change the F factor for the Compaction element
  in Table 105-2 Table of Price Reduction Factors
  from 12 to 6 for plant mix furnished under this
  provision.

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F Factor Change

• Compaction is no longer the only measure for
  controlling quality
• Want to be consistent with other mixes
• Inflated prices due to haul
• Too much risk for Contractors

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Grade D Commercial

• Wording clarification
• A 5 percent price reduction (15 maximum), in the
  unit bid price for PMS Grade D Commercial will be
  applied for each test not meeting the Mix Design
  Stability, Flow, Percent Air Voids, Asphalt
  Binder Properties, Gradation, or Asphalt content
  specified. Price reductions will be assessed on
  the quantity of material represented by each
  failing sample. The quantity of material
  represented by each sample is the total tons of
  material produced divided by the total number of
  samples representing the material.

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Grade D Commercial

• The quantity of material represented by each
  sample is the total tons of material produced
  divided by the total number of samples
  representing the material.
• Changed to help keep administration uniform
• Fairer to the contractor

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Grade D Commercial Non Tested

• Many of the same changes as the tested version
• Price reductions are only assessed for obviously
  defective material
• Added the following Provide the Project Manager
  density testing results upon request.

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Contract Administration Tied Projects

• Issue has been identified
• Materials working with construction to develop
  guidance

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½ Grade S Policy
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Why?

• Compaction Concerns
• Reduced lift thicknesses
• Lower overall cost

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October 2003 Policy

• ½ Required for all lifts less than 60 mm
• Introduced in response to Grade S compaction
  concerns
• Followed SHRP recommendations

46
Revised Policy April 2005

• Limited use of ½ Grade S to low volume roads
• Reduced the overall use.

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January 2006 Revision

• Construction Memo
• Requires the use of ¾ PMS whenever 0.15 ft or
  greater is required
• Requires ½ Grade S only be used for overlays
• Allows reduced overlay depths if ½ is used

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Additional Requirements

• ½ Grade S can only be used if
• Ave. Rut 0.20 inches or less
• Ave Ride 80 in/mile or less
• An isolation lift is required
• Surfacing Design must approve

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Implementation

• Surfacing Design will review existing design
  projects and make recommendations
• Projects will not be changed from ¾ to ½ Grade
  S
• Change orders will be considered Should not be
  no cost

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½ Facts

• ½ Gr. S is more difficult to compact
• ½ Gr. S is more expensive

• ½ Gr. S is equal to or better than ¾
  structurally

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Ride Specification Revisions
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Meeting Agenda

• Introduction
• Project Background
• Draft Revised Ride Specification
• Discussion of Pay Adjustment Factors

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Project Purpose

• Review Current Specification
• Compare with Current Literature
• Compare with State-of-Practice
• End Products

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Why Is Pavement Roughness Important?

• Ride Quality
• Impacts on Vehicle Maintenance

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Why Is Pavement Roughness Important?

• User Cost
• WesTrack Experiment

Approx. 10 Drop in IRI
4.5 Increase in Fuel Efficiency Savings of
10,257 gal of fuel per 1,000,000 veh miles
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Project Background

• Montana Residents Survey in 1998
• Attention resources in the following order
• Winter maintenance
• Surface smoothness
• Highway striping, debris removal, highway
  signage, winter roadway information, roadway
  maintenance, rest stop maintenance
• Etc.

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Revised Documents

• Profiler Operations Manual (POM)
• Comprehensive
• MT-422 Document
• Summary of POM
• QC/QA Plan
• Emphasis on field activities
• Draft Revised Ride Specification

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Profiler Operations Manual (POM)

• Calibration of Equipment
• Full Calibration Check of Laser Sensors
• Calibration of Accelerometers
• Bounce Test Profiling System
• Calibration of DMI

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Full Calibration Check of Laser Sensors

• Calibrated and sealed by Manufacturer

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Courtesy Testing

• At least 7 calendar day notice to EPM
• MDT will provide once per project
• Not less than 2 and not more than 3 miles of
  continuous pavement
• Contractor interprets results

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Surface Smoothness

• All mainline travel lanes including climbing
  lanes, passing lanes and ramps that are 0.2 miles
  or longer
• Bridge decks included only if paved as part of
  project

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Surface Smoothness

• Not evaluated
• Climbing and passing lanes less than 0.2 miles
• Turning lanes
• Acceleration and deceleration lanes
• Shoulders and gore areas
• Road approaches

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Surface Smoothness

• Not evaluated
• Horizontal curves 900 feet or less in centerline
  radius
• Pavement within 50 feet of bridge decks (only for
  bridges not paved as part of project)
• Pavement within 50 feet of approach slabs and
  terminal paving points of project

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Profiling Test Section

• Procedures
• Minimum of Two Runs

Beginning of Project (BOP)
End of Project (EOP)
Exclude Area (e.g., Bridge) With F5 Key
Start of Data Collection With F3 Key
End of Data Collection With F3 Key
Approx. 500 ft.
Approx. 500 ft.
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Quality Control Report

• Acceptability
• For each interval, the average IRI for each run
  is within 5.7 of the mean IRI for both runs
• If a run has an interval that is outside the
  acceptable limit, additional runs (up to three)
  should be made on that lane

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Quality Control Report
Meets Criteria So Use Run 1for Roughness Report
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Surface Profile

• Correct surface profile defects that fail bump
  criteria
• 0.40 inches in a distance of 25 feet
• Correct surface profile defects
• Milling and filling
• Diamond grinding

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Bump Report

• Considered Other Methodologies
• Profilograph Simulation,
• Bumpfinder and Grinding Simulation
• Localized Roughness (TEX-1001-S) Method
• Current System is Satisfactory

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Bump Report

• Bump Report for only first error free profile run
  in each lane is presented to EPM
• Defect locations should be physically verified

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Expectations

• MDT profiles finished surface
• 2 times
• One run is the run
• Second run is for quality control
• After QC activities and acceptance
• Operator delivers IRI Report and Bump Report to
  EPM
• Potential defects will be physically examined

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File Naming Convention

• 7 Characters
• 1 to 4 is Control Number
• 5 to 6 is Direction
• 7 is Lane
• Example

1022NBT Control Number 1022, northbound
direction, travel lane
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File Directory

• Two Conventions
• By Control Number
• By Date

D\1022 D\15JUL05
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Current Ride Specification
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Data Set
75
100
90
Class IV Target
80
Class III Target
Post-Pave IRI (in/mi)
70
60
Class II Target
50
Class I Target
40
40
50
60
70
80
90
100
Post-Pave IRI (in/mi)
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Category 1

• Target IRI set at 50 to 55 in/mi
• Project with two or more opportunities to improve
  the ride
• Single lift overlays with pre-pave IRI lt 110
  in/mile
• Maximum post-pave IRI should not be greater than
  90 in/mi

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Category 2

• Target IRI set at 55 to 60 in/mi
• Single lift overlays with pre-pave IRI value ³
  110 in/mi and lt 190 in/mi
• Maximum post-pave IRI should not be greater than
  95 in/mi

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High Pre-Pave IRI Roadways

• Exception for roadways with pre-pave IRI gt190
  in/mi
• Treat as Category 1
• 2 or more opportunities
• Other
• Budget, functionality, etc.
• Specify a maximum post-pave IRI NOT be more than
  50 of pre-pave IRI

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Opportunities

• Placing a gravel base or surfacing course
• Placing plant mix bituminous base
• Placing cement treated base
• Placing pulverized plant mix surfacing
• Milling
• Cold recycling (milling and laydown)
• Each full 0.15 ft increment of new plant mix
  surfacing

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Data Set
81
100
90
Class IV Target
80
Class III Target
Post-Pave IRI (in/mi)
70
Category 2 Target
60
Class II Target
Category 1 Target
50
Class I Target
40
40
50
60
70
80
90
100
Post-Pave IRI (in/mi)
82
65
Avg Category 1
Avg Category 2
60
Category 2 Target
55
Category 1 Target
Post-Pave IRI (in/mi)
50
45
40
40
45
50
55
60
65
Post-Pave IRI (in/mi)
83
Current Pay Adjustment Factor
84
Pay Adjustment Factor Category 1
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Pay Adjustment Factor Category 2
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Testing Acceptance

• Prior to seal and cover
• Performed with 3 working days of completion
• Contractor must ensure entire finished lane width
  can be tested and not impeded
• Test results within 2 working days

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Economic Comparison

• Compared current classification pay versus
  category pay
• Evaluated a total of 53 lanes
• Category 1 would have 47 lanes
• Category 2 would have 6 lanes

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Total for Category 1
91
Total for Category 2
92
Total Difference
93
Incentive for Category 1
94
Incentive for Category 2
95
Incentive Difference
96
Disincentive for Category 1
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Disincentive Difference
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Economic Impact Example
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Economic Comparison

• Incentive
• Payment will be similar to current system
• Disincentive
• Penalty will be more rigorous than current system

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Why Is Pavement Roughness Important?

• Ride Quality
• Impacts on Vehicle Maintenance
• User Cost
• Montana Residents
• FHWA Performance Goals
• National Trends

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Concluding Remarks

• Held a seminar for contractors
• Complete Final Report
• Address Comments
• Finalize MDT Ride Specification Document
• First training session Spring 2006
• Implementation June 2006

102
Questions

• Draft Revised Ride Specification

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Compaction Issues 2005
104
Whats the problem?

• Extensive problems encountered during 2005
• Did not appear to be one specific problem
• Conditions varied between jobs

105
Glendive Area Projects
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Potential Contributing Factors

• Binder problems
• ½ PMS
• Aggregate Surface Treatment
• Aggregate Surfacing
• Weather
• Contractor Operations

107
Questions?

• Compaction Issues 2005

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Aggregate Surface Treatment

• Proposed Experimental Project

109
Whats wrong with MC-70

• High Volatile Organic Compounds or VOCs
• Past prime failures

110
Purpose of Surface Treatment

• Dust abatement
• Surface preservation
• Seal
• Plant mix compaction aid

111
Current Practice

• Magnesium Chloride

• SS-1 or CSS-1

112
Advantages

• Relatively inexpensive
• Effective for dust abatement
• Helps preserve the section in most cases
• Assists with compaction in most cases

113
Disadvantages

• Affinity for water
• Needs fines and PI in the gravel for optimum
  performance
• Corrosion concerns

114
New Specification

• Currently working on writing
• Intend to allow more flexibility
• Possibly allow alternate products

115
Experimental Project(s)

• Trying alternate emulsified asphalt products
• Pugmilling SS-1 into the top lift of aggregate
  surfacing
• Control sections

116
Objectives

• Try on 2 or 3 projects early in the season
• Evaluate the constructability immediately
• If successful, implement as soon as possible

117
Questions?

• Aggregate Surface Treatments