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Plant Mix Overview
MDT Training ConferenceBillings, Montana
March 1 & 2, 2006Presented By:
Matt Strizich and Danny Hood
Recent Plant Mix Use
0
5
10
15
20
25
30
35
40
Grade B Grade D Grade S
20022003200420052006
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
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Incentives
20052006
Ride Specification Incentives• 0.39% in 2002• 1.51% in 2003• 0.9% +/- from
2004-2006• Percentage of
total spent on PMS that year
00.050.1
0.150.2
0.250.3
0.350.4
0.450.5
Ride Spec
20022003200420052006
Compaction Statistics
-100
-50
0
50
100
150
200
250
300
350
2003 2004 2005 2006
Thousands
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
Quick Notes
• Volumetrics and the Ride Specification are not included on all projects
• All end-result specifications
Contractors are Earning it!
• MDT is paying 3-5% of PMS costs in incentives
• Plant production has been slowed
• Seeing quality compete with production
Purpose
• Present potential future changes
• Provide reasoning behind changes
• Share information from last year
• Provide the opportunity to ask questions
Topics
• Grade S & Grade D Commercial Specification Revisions
• New ½” Grade S Policy• Ride Specification Revisions• Compaction Issues in 2005• Aggregate Surface Treatment
Experiment
MDT Staff
• Construction Reviewers
• Project Staff• Internal Audit
Contractors
• Montana Contractors Association (MCA)
• Non-Uniformity Complaints
• Claims
Specification Change Process• All specification revisions go
through the Specification Section
• Dan Smith and Ryan Antonovich
• Defined process• Standards Committee coming
soon
Change Process
• Ensures thorough review
• Reviewed by MDT staff and contractors
Plant Mix Specifications
Grade S and Grade D Commercial
Grades of Plant Mix
• Grade S – Volumetrics– Non-
Volumetrics
• Grade D Commercial– Tested– Non-Tested
Why two versions?
• Contract administration• Quality of the same grades of
mix should be equal.• Testing and frequency of
testing varies
Grade S
• Completely revised mix
• Grade S has been successful
• Moved to gyratory compactors
• Bob Weber and Scott Barnes deserve the credit
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
Grade D Commercial
• Relatively new specification
• Always used on “smaller projects”
• Bill Fogarty leading the committee
Grade B
• Use for bike paths or other features not subject to heavy loading
• Consider using Grade D or S with chip seals instead
Grade C
• No longer needed
• Grade D Commercial should be used instead
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
Grade S Changes
• Changes are minimal
• Changes are the same for volumetrics and non-volumetrics versions
Mix Designs
• 50 Gyration mixes have been eliminated
• SHRP recommendation for low volume roads
• Created issues with meeting Hamburg testing requirements
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.
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.
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
Release Agents - Justification• Plant Mix
quality• Employee
safety• Environmental
concerns
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
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
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
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.
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.
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
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.
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.
“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
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.
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
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.
Contract Administration – Tied Projects
• Issue has been identified
• Materials working with construction to develop guidance
½” Grade S Policy
Why?
• Compaction Concerns
• Reduced lift thicknesses
• Lower overall cost
October 2003 Policy
• ½” Required for all lifts less than 60 mm
• Introduced in response to Grade S compaction concerns
• Followed SHRP recommendations
Revised Policy – April 2005
• Limited use of ½” Grade S to low volume roads
• Reduced the overall use.
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
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
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”
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
Ride Specification Revisions
Meeting Agenda
• Introduction
• Project Background
• Draft Revised Ride Specification
• Discussion of Pay Adjustment Factors
Project Purpose
• Review Current Specification
• Compare with Current Literature
• Compare with State-of-Practice
• End Products
Why Is Pavement Roughness Important?
• Ride Quality• Impacts on Vehicle
Maintenance
Why Is Pavement Roughness Important?
•User Cost
– WesTrack Experiment
4.5% Increase in Fuel Efficiency
Savings of 10,257 gal of fuel
per 1,000,000 veh miles
Approx. 10% Drop in IRI
$
Project Background• Montana Residents Survey in
1998– Attention & resources in the
following order: • Winter maintenance
• Surface smoothnessSurface smoothness• Highway striping, debris removal,
highway signage, winter roadway information, roadway maintenance, rest stop maintenance
• Etc.
Revised Documents
• Profiler Operations Manual (POM)– Comprehensive
• MT-422 Document– Summary of POM
• QC/QA Plan– Emphasis on field activities
• Draft Revised Ride Specification
Profiler Operations Manual (POM)
• Calibration of Equipment
1. Full Calibration Check of Laser Sensors
2. Calibration of Accelerometers
3. Bounce Test Profiling System
4. Calibration of DMI
Full Calibration Check of Laser Sensors
•Calibrated and sealed by Manufacturer
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
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
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
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
Profiling Test Section• Procedures• Minimum of Two Runs
Start of Data Collection
With F3 Key
End of Data CollectionWith F3 Key
Beginning of Project (BOP)
End of Project (EOP)Exclude
Area (e.g., Bridge)With F5 Key
Approx. 500 ft.Approx. 500 ft.
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
Quality Control Report
Interval Run 1 Run 2 MeanAvg
-5.7%Avg
+5.7%
Does Run 1 Meet
Criteria?
Does Run 2 Meet
Criteria?
1 67 67 67 63 71 okay okay
2 72 72 72 68 76 okay okay
3 68 67 68 64 71 okay okay
4 57 57 57 54 60 okay okay
5 67 66 67 63 70 okay okay
6 61 62 62 58 65 okay okay
7 59 60 60 56 63 okay okay
Meets Criteria So Use Run 1…for Roughness Report
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
Bump Report
• Considered Other Methodologies– Profilograph Simulation,
– Bumpfinder and Grinding Simulation
– Localized Roughness (TEX-1001-S) Method
• Current System is Satisfactory
Bump Report
• Bump Report for only first error free profile run in each lane is presented to EPM
• Defect locations should be physically verified
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 lane1022NBT: Control Number 1022, northbound direction, travel lane
File Directory
• Two Conventions– By Control Number– By Date
D:\1022
D:\15JUL05
D:\1022
D:\15JUL05
Current Ride SpecificationClas
s Target (in/mi)
Other Criteria
I 46-653 or more opportunities
Pre-Pave IRI < 140 in/mi2 Opportunities
Pre-Pave IRI <90 in/miSingle Lift Overlay
II 55-75
Pre-Pave IRI 140 in/mi2 Opportunities
Pre-Pave IRI >90 in/mi and <140 in/miSingle Opportunity
III 56-80
Pre-Pave IRI 140 in/mi and <190 in/miSingle Opportunity
IV 61-90Pre-Pave IRI >190 in/mi Single Opportunity
Data Set
Class Coun
t
Post-Pave IRI Avg (in/mi)
Min IRI (in/mi)
Maxi IRI
(in/mi)
Std Dev
(in/mi)
I 63 50 38 66 7
II 13 51 44 58 4
III 2 46 45 47 1
IV 2 61 59 63 3
40
50
60
70
80
90
100
40 50 60 70 80 90 100Post-Pave IRI (in/mi)
Post
-Pav
e IR
I (in
/mi)
Avg MDT Class I
Avg MDT Class II
Avg MDT Class III
Avg MDT Class IV
Class I Target
Class II Target
Class III Target
Class IV Target
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 < 110 in/mile
• Maximum post-pave IRI should not be greater than 90 in/mi
Category 2
• Target IRI set at 55 to 60 in/mi
• Single lift overlays with pre-pave IRI value 110 in/mi and < 190 in/mi
• Maximum post-pave IRI should not be greater than 95 in/mi
High Pre-Pave IRI Roadways
• Exception for roadways with pre-pave IRI >190 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
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
Data Set
Class Coun
t
Post-Pave IRI Avg (in/mi)
Min IRI (in/mi)
Maxi IRI
(in/mi)
Std Dev
(in/mi)
I 63 50 38 66 7
II 13 51 44 58 4
III 2 46 45 47 1
IV 2 61 59 63 3
Category
Count
Post-Pave IRI Avg (in/mi)
Min IRI (in/mi)
Maxi IRI
(in/mi)
Std Dev
(in/mi)
1 73 51 38 66 7
2 7 51 47 58 5
40
50
60
70
80
90
100
40 50 60 70 80 90 100Post-Pave IRI (in/mi)
Post
-Pav
e IR
I (in
/mi)
Class I Target
Class II Target
Class III Target
Class IV Target
Category 1 Target
Category 2 Target
Avg MDT Class I
Avg MDT Class II
Avg MDT Class III
Avg MDT Class IV
40
45
50
55
60
65
40 45 50 55 60 65Post-Pave IRI (in/mi)
Post
-Pav
e IR
I (in
/mi)
Avg Category 1
Avg Category 2
Category 1 Target
Category 2 Target
Current Pay Adjustment Factor
Class Actual IRI
(in/mi)Pay Factor
I
<40 1.25
40-45 1.10
46-65 1.00
>65 0.80
II
<45 1.25
45-55 1.10
56-75 1.00
>75 0.80
III
<56 1.10
56-80 1.00
>80 0.90
IV
<61 1.10
61-90 1.00
>90 0.90
Pay Adjustment Factor Category 1
IRI (in/mi) Pay Adjustment Factor
< 35 1.25
35 - 50 1.845 – 17/1000 * IRI
50 < IRI <55 1.00
55 - 75 1.825 – 3/200 * IRI
75 < IRI <90 0.70
> 90Corrective Action Required(Initially Assumed as a Zero
Pay)
Pay Adjustment Factor Category 2
IRI (in/mi) Pay Adjustment Factor
< 50 1.10
50 - 55 2.100 – 1/50 * IRI
55 < IRI <60 1.00
60 - 95 1.343 – 1/175 * IRI
> 95Corrective Action Required(Initially Assumed as a Zero
Pay)
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
IRI (in/mi)
Pay
Adj
ustm
ent F
acto
r
Category 1
Category 2
MDT Class I
MDT Class II
MDT Class III
MDT Class IV
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
1.30
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
IRI (in/mi)
Pay
Adj
ustm
ent F
acto
r
Category 1
Category 2
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
Economic Comparison
• Compared current classificationclassification pay versus categorycategory pay
• Evaluated a total of 53 lanes– Category 1 would have 47
lanes
– Category 2 would have 6 lanes
Total for Category 1
$(30,000)
$(20,000)
$(10,000)
$-
$10,000
$20,000
$30,000
$40,000
$50,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
Current
New Category 1
D
Total for Category 2
$(6,000)
$(4,000)
$(2,000)
$-
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
1 2 3 4 5 6
Current
New Category 2
D
Total Difference
CategoryCurren
t System
New System
D% of
Current System
1 $307,684
$179,083$(128,601
)58%
2 $43,120 $22,389 $(20,731) 52%
Incentive for Category 1
$(20,000)
$(10,000)
$-
$10,000
$20,000
$30,000
$40,000
$50,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
CurrentNew Category 1D
Incentive for Category 2
$(6,000)
$(4,000)
$(2,000)
$-
$2,000
$4,000
$6,000
$8,000
$10,000
$12,000
1 2 3 4 5 6
CurrentNew Category 2D
Incentive Difference
CategoryCurren
t System
New System
D% of
Current System
1 $362,072
$301,494 $(60,578) 83%
2 $43,120 $22,389 $(20,731) 52%
Disincentive for Category 1
$(25,000)
$(20,000)
$(15,000)
$(10,000)
$(5,000)
$-
$5,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
CurrentNew Category 1D
Disincentive Difference
CategoryCurren
t System
New System
D% of
Current System
1 $(54,388)
$(122,411)
$(68,022) 225%
2 - - - -
Economic Impact Example
Control Numbe
r
Direction
Current Class
Current Pay ($)
Category
New Pay ($)
Post-Pave IRI (in/mi)
2945
EB I $ 8,407 1 $
9,393 43
WB I $ 6,409 1$
6,527 45
4821
NB II $ 8,096 2$
4,226 47
SB II $ 7,569 2$
3,482 47
Economic Comparison
•Incentive–Payment will be similar to current system
•Disincentive–Penalty will be more rigorous than current system
Why Is Pavement Roughness Important?
• Ride Quality• Impacts on Vehicle
Maintenance• User Cost• Montana Residents • FHWA Performance Goals• National Trends
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
QuestionsQuestions
Draft Revised Ride SpecificationDraft Revised Ride Specification
Compaction Issues – 2005
What’s the problem?
• Extensive problems encountered during 2005
• Did not appear to be one specific problem
• Conditions varied between jobs
Glendive Area Projects
Potential Contributing Factors• Binder problems• ½” PMS• Aggregate Surface Treatment• Aggregate Surfacing• Weather• Contractor Operations
Questions?
Compaction Issues – 2005
Aggregate Surface Treatment
Proposed Experimental Project
What’s wrong with MC-70
• High Volatile Organic Compounds or VOC’s
• Past “prime” failures
Purpose of Surface Treatment • Dust abatement• Surface preservation • Seal• Plant mix compaction aid
Current Practice
• Magnesium Chloride
• SS-1 or CSS-1
Advantages
• Relatively inexpensive• Effective for dust abatement• Helps preserve the section in
most cases• Assists with compaction in
most cases
Disadvantages
• Affinity for water• Needs “fines” and PI in the
gravel for optimum performance
• Corrosion concerns
New Specification
• Currently working on writing
• Intend to allow more flexibility
• Possibly allow alternate products
Experimental Project(s)
• Trying alternate emulsified asphalt products
• Pugmilling SS-1 into the top lift of aggregate surfacing
• Control sections
Objectives
• Try on 2 or 3 projects early in the season
• Evaluate the constructability immediately
• If successful, implement as soon as possible
Questions?
Aggregate Surface Treatments