laydown & compaction
TRANSCRIPT
The California Asphalt Pavement Association
October 25-26, 20172017 Fall Conference; Doubletree Hotel, Sacramento , CA
Promoting
Learning
Advocating
Networking
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2013 Utah Asphalt Conference; Sandy UT - March 27-28, 2013
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We are ENGINEERS
HOW do we make it happen!!!
2013 Utah Asphalt Conference; Sandy UT - March 27-28, 2013
2013 Utah Asphalt Conference; Sandy UT - March 27-28, 2013
What is Compaction? Performance Requires Proper Compaction Keys to Compaction Quality Control Summary
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“to join or pack closelytogether; consolidate;condense.”
– dictionary.com
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1% change of in-place density = 10% change in performance life!!!
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Mix Characteristics
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Nominal maximum size: “one sieve size larger than the first sieve to retain more than 10 percent of the material” - NAPA
t/NMAS
3:1 minimum
4:1 optimal
5:1 very coarse mixes
6:1 adjust thickness or mix type
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Data: NCAT
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NCAT - Brown and Heitzman 2013
Permeability in a coarse dense-graded 12.5mm Superpave surface mix
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What happens when mix voids change?
Higher?
Lower?
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Temperatures
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Compact at the highest temperature possible!!
What is that Temperature?
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Does the mix have tender zones?
What temperature range should we avoid compactive effort?
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3 Inch Lift50°F Air &
Surface Temp300°F Mix
Delivery temp44 min to
complete compaction operations
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1” - Lift
50°F - Air &
Surface Temp
300°F - Mix
Delivery temp
7 minutes to
complete
compaction
operations
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Existing Pavement Structure
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If there is surface cracking or rutting due to plastic movement of the mix, the entire surface should be milled
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Laydown Process
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36Data: MNDOT
Rolling Operations
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What drum width is right for the project?
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Key considerations for optimizing roller operations: Frequency Amplitude Speed Passes
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Wid
th o
f m
at Pass1
Pass 2
Pass 3
Pass 4
This is a 5 pass pattern that
provides 2 complete coverages.
Conduct trial section to determine appropriate equipment setup and rolling pattern to achieve target densities.
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MIX PROD SCREED BREAK INTER FINISH
Trial 1 325F 290F 280F 250F 200F
Trial 2 290F 250F 240F 190F 135F
MIX AVG (%) BREAK INTER FINISH
Trial 1 93.2 4V 4V 2V
Trial 2 94.1 2V 4V 2S
Temperature
Density
Contractor QC Inspection
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Monitor Operations:
Temps
Density
Rolling pattern
Mix properties
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Intelligent Compaction (IC)
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“Intelligent compaction (IC) is an innovative pavement construction technology that equips conventional rollers with instrumentation that is used to monitor and control the material compaction process.”
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“…ensures that the target properties of the layer are more uniform and are more efficiently achieved.”
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GPS Positioning
Passes
Location
Temperature ICMV Real-Time Graphical
Interface Data Analysis
“…ensures that the target properties of the layer are more uniform and are more efficiently achieved.”
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“…ensures that the target properties of the layer are more uniform and are more efficiently achieved.”
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1. The primary conclusion that can be drawn from the FHWA/TPR study is that IC is very effective for achieving the target level of HMA compaction while at the same time increasing the uniformity of the material.
2. The IC roller demonstrations provided proof that IC rollers could track roller passes, monitor HMA surface temperature, and report an ICMV that the operator could use to better control the compaction process.
5. IC equipment can be used effectively to develop compaction curves and to determine the optimum number of roller passes.
6. The correlation studies show correlation between the ICMVs and in-situ measurements, including HMA density (from nuclear and non-nuclear density gauges) and certain deflection-based parameters i.e., normalized maximum deflection and layer modulus. However, there is considerable variability in the correlations.
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Rolling Towards Performance
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Establish the targets Identify the equipment
setup, the pattern, and the monitoring schedule.
Identify control and action limits
Identify actions to reestablish target
What contributes to success? Mix quality Temperatures
(ambient & mix Existing structure Equipment setup Rolling Pattern
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COMMUNICATION UNIFORMITY
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