the superpave gyratory compactor how do we use it. john dangelo office of pavement technology us...
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The Superpave Gyratory The Superpave Gyratory Compactor How do we use Compactor How do we use
it.it.
John D’AngeloJohn D’Angelo
Office of Pavement Technology US Office of Pavement Technology US Federal Highway AdministrationFederal Highway Administration
BackgroundBackground
• SHRP A-001 ContractSHRP A-001 Contract– Development of Superpave Mix Design Development of Superpave Mix Design
ProcedureProcedure•Gyratory Compactor ExperimentsGyratory Compactor Experiments
– Conducted at Asphalt InstituteConducted at Asphalt Institute
– Included rotational speed, NIncluded rotational speed, Ndesigndesign, sensitivity , sensitivity experimentsexperiments
– Comparison between prototype and production SGCComparison between prototype and production SGC Led to discovery of angle sensitivityLed to discovery of angle sensitivity Tolerance of Tolerance of ±0.02 degrees±0.02 degrees
Differences in SGCs –Differences in SGCs –NATC MixturesNATC Mixtures
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
1 2 3Compactor
Air
Vo
ids
, %
Prototype
Measurement of the Internal Measurement of the Internal Angle of GyrationAngle of Gyration
• Significant Differences in Air VoidsSignificant Differences in Air Voids– Difference in Design AC Could be as Difference in Design AC Could be as
Much as 0.8% Asphalt ContentMuch as 0.8% Asphalt Content
• Angle of GyrationAngle of Gyration– All Compactors set to 1.25° ExternallyAll Compactors set to 1.25° Externally– What is the Internal Angle of Gyration?What is the Internal Angle of Gyration?
•Frame compliance?Frame compliance?
4. APPARATUS4. APPARATUS
Superpave Gyratory CompactorSuperpave Gyratory Compactor – … – … The compactor shall tilt the specimen The compactor shall tilt the specimen molds at an molds at an externalexternal angle of angle of 1.25°1.25°++0.02° 0.02° oror an average internal an average internal angle of 1.16°angle of 1.16°+ + 0.02° in accordance 0.02° in accordance with AASHTO T312. The compactor with AASHTO T312. The compactor shallshall gyrate the specimens mold at a gyrate the specimens mold at a rate of 30.0 + 0.5 gyrations per rate of 30.0 + 0.5 gyrations per minute… minute…
4.1
Internal Angle of GyrationInternal Angle of Gyration
• Internal Angle of GyrationInternal Angle of Gyration– Development of the Dynamic Angle Development of the Dynamic Angle
Validator (DAV) or Angle Validation Kit Validator (DAV) or Angle Validation Kit (AVK)(AVK)•Wireless UnitWireless Unit
•Drop into mold either before or after adding Drop into mold either before or after adding mixmix
Dr. Kevin Hall, “Evaluating the Superpave Gyratory Compactor Internal Angle of Gyration Using Simulated Loading”, submitted to AAPT2005
Dynamic Angle ValidatorDynamic Angle Validator
DAV CalibrationDAV Calibration
AVG
T1.150
1.10
1.15
1.20
1.25
1.30
1.35
1.40
20
30
40
50
60
70
80
90
10
0
11
0
12
0
13
0
14
0
Specimen Height (mm)
Inte
rna
l An
gle
of G
yra
tion
(d
eg
ree
s)
Average Internal AngleTop Angle (individual AVK result)Top Angle (best fit)Bottom Angle (individual AVK result)Bottom Angle (best fit)target height (115 mm)angle at target height
After adjustment using the DAV Kit
Close Large Chart
Internal Angle of GyrationInternal Angle of Gyration
• DAVDAV– Validate Differences in SGCsValidate Differences in SGCs
•Demonstrated that internal angle of gyration Demonstrated that internal angle of gyration could be different even though external angle could be different even though external angle was the same.was the same.
– CalibrationCalibration•Potentially time-intensivePotentially time-intensive
– Up to 1 day for a calibrationUp to 1 day for a calibration
•Affected by mixture stiffness?Affected by mixture stiffness?– Requiring recalibration for different mix typesRequiring recalibration for different mix types
Forces Acting in a Mold During Forces Acting in a Mold During Gyratory CompactionGyratory Compaction
Mechanical Simulation of an Mechanical Simulation of an Asphalt Mixture – RAMAsphalt Mixture – RAM
RAM – Rapid Angle Measurement Device (Pine)
RAM OperationsRAM Operations
Increasing Ring Diameter =Increasing Mix Eccentricity
Mechanical Simulation of an Mechanical Simulation of an Asphalt Mixture – HMSAsphalt Mixture – HMS
HMS – Hot-Mix Simulator (TestQuip)
Purpose of ResearchPurpose of Research
• ObjectivesObjectives– Improve the determination and Improve the determination and
calibration of the dynamic internal angle calibration of the dynamic internal angle of gyration for the Superpave gyratory of gyration for the Superpave gyratory compactor using mechanical mixture compactor using mechanical mixture simulation devicessimulation devices•Reduce time for calibrationReduce time for calibration
• Improve reproducibility between different labsImprove reproducibility between different labs
•Recommend revisions to AASHTO T312Recommend revisions to AASHTO T312
Research Plan – Task 1Research Plan – Task 1
• Determine the Effect of Mix Determine the Effect of Mix Eccentricity on Internal Angle of Eccentricity on Internal Angle of GyrationGyration
SGC-A
SGC-B
Mix e
Internal Angle
Acceptable Range of Internal Angle
Internal Angle
Research Plan – Task 2Research Plan – Task 2
• Using a Wide Variety of Mixtures…Using a Wide Variety of Mixtures…– What is the relationship between What is the relationship between
mixture eccentricity and stiffness?mixture eccentricity and stiffness?– What is an “average” or representative What is an “average” or representative
mixture eccentricity?mixture eccentricity?– Is there a standard mixture eccentricity Is there a standard mixture eccentricity
that can be used to minimize variation that can be used to minimize variation in the percentage of air voids in in the percentage of air voids in specimens produced by different SGCs?specimens produced by different SGCs?
Research Plan – Task 3Research Plan – Task 3
• Using Mechanical Simulation Devices Using Mechanical Simulation Devices in the Calibration Processin the Calibration Process– IssuesIssues
•Necessity of heated molds?Necessity of heated molds?
Testing Testing AgencyAgency
Frame Stiffness (Deg / N-m)Frame Stiffness (Deg / N-m)
Superpave Gyratory Compactor (SGC) ModelSuperpave Gyratory Compactor (SGC) Model
PinePineAFG125xAFG125x
PinePineAFG1AFG1
PinePineAFGB1AFGB1
(Brovold)(Brovold)Troxler Troxler
41404140TroxlerTroxler
41414141 ServoPacServoPac
Univ. of ArkansasUniv. of Arkansas(Stiffness Study)(Stiffness Study) 0.000310.00031 0.000340.00034 0.000360.00036 0.001090.00109 0.000630.00063
Univ. of ArkansasUniv. of Arkansas(RAM ILS)(RAM ILS) 0.000460.00046 0.000250.00025 0.001390.00139 0.000580.00058
Univ. of ArkansasUniv. of Arkansas(RAM-DAV/HMS Study)(RAM-DAV/HMS Study) 0.000370.00037 0.000470.00047 0.000310.00031 0.001270.00127 0.000540.00054
Florida DOTFlorida DOT(used by permission)(used by permission) 0.000330.00033 0.000410.00041 0.001720.00172 0.000410.00041
InstroTekInstroTek(used by permission)(used by permission)
0.000470.00047 0.000500.00050 0.000550.00055 0.001760.00176 0.001800.00180
0.001360.00136 0.001220.00122
0.001320.00132
Mean ValueMean Value 0.000390.00039 0.000440.00044 0.000380.00038 0.001420.00142 0.000950.00095 0.000410.00041
Standard DeviationStandard Deviation 0.0000740.000074 0.0000850.000085 0.0001140.000114 0.0002420.000242 0.0005480.000548 N/AN/A
Coefficient ofCoefficient ofVariation (%)Variation (%) 19.019.0 19.519.5 30.330.3 17.117.1 57.557.5 N/AN/A
Frame Stiffness Measures – RAM only
Thanks!Thanks!