Determining Aggregate Determining Aggregate Characteristics of HMA: Characteristics of HMA:
3D Processing of X3D Processing of X--ray CT Images ray CT Images
M. Emin Kutay, Ph.D.M. Emin Kutay, Ph.D.Asphalt Mixture Scientist / Lab ManagerAsphalt Mixture Scientist / Lab ManagerTurnerTurner--Fairbank Highway Research CenterFairbank Highway Research Center
[email protected]@fhwa.dot.gov
Acknowledgements:Acknowledgements:Nelson Gibson, Ph.D.Nelson Gibson, Ph.D.Jack Youtcheff, Ph.D.Jack Youtcheff, Ph.D.Rick Meininger, P.E.Rick Meininger, P.E.Edith Arambula, Ph.D.Edith Arambula, Ph.D.
Effect of aggregate propertiesEffect of aggregate properties
•• Fine Fine graded HMA mixgraded HMA mix–– CoarseCoarse AggrAggr: Little or no contact points: Little or no contact points–– FineFine AggrAggr: Very important: Very important
•• Coarse Coarse graded HMA mixgraded HMA mix–– CoarseCoarse AggrAggr: Some contact points: Some contact points–– FineFine AggrAggr: Important: Important
•• SMA SMA MixMix–– CoarseCoarse AggrAggr: Many contact points: Many contact points–– FineFine AggrAggr: Less important: Less important
Steps of ImageSteps of Image--based Aggregate Extractionbased Aggregate Extraction
Varying aggregate type, Varying aggregate type, compaction characteristicscompaction characteristics
Specimen Prep.Specimen Prep.(Lab compacted / (Lab compacted /
field core)field core)
Measurement of 3D Measurement of 3D internal geometryinternal geometry XX--ray CT imagingray CT imaging
Rigorous image Rigorous image processing & analysisprocessing & analysis
Separation of aggregatesSeparation of aggregates
Individual aggregate props:Individual aggregate props:3D orientation, angularity, 3D orientation, angularity, Specific surface area Specific surface area ……etc.etc.
Calculation of contact Calculation of contact pointspoints
XX--ray Computed Tomography setupray Computed Tomography setup
X-Ray Source
Detector
Specimen
AlgorithmsCT# (in)
CT# (Out)
Vertical shift
Direct measurement of Direct measurement of aggregateaggregatecharacteristics: characteristics: 3D image3D image analysisanalysis
X-ray CT
Characteristics of Characteristics of aggregatesaggregatespackedpacked in an in an asphaltasphalt mixturemixture
–– 3D 3D Contact pointsContact points (or (or influence zone)influence zone)
–– 3D 3D OrientationOrientation–– SegregationSegregation: :
••Spatial distribution of Spatial distribution of different sizesdifferent sizes
–– 3D 3D AngularityAngularity, , sphericitysphericity, , specific specific surface areasurface area and and texturetexture
Aggregate contact pointsAggregate contact points•• Given : Given : ggradation and compaction radation and compaction
levellevel–– Variation of Variation of contact pointscontact points for for
different aggregates: different aggregates: rectangularrectangular, , flat , elongated and roundflat , elongated and round
•• Locking pointLocking point
•• Effect of number of Effect of number of contact pointscontact pointson HMA on HMA performanceperformance
•• Mix design Mix design consideringconsidering contact contact points points andand packingpacking
Challenge in Challenge in experimentationexperimentation: : separation of aggregatesseparation of aggregates
IdealIdeal RealReal
ThresholdingThresholding and labeling and labeling (2D description)(2D description)
Intensity Distribution
181
0 255
Grayscale imageGrayscale image ThresholdedThresholded binary imagebinary image
ThresholdingThresholding and labelingand labeling(2D description)(2D description)
Binary imageBinary image Labeled imageLabeled image
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Original Gaussian smoothed Hmax filtered
Watershed transformed imageInverted Watershed lines
Filtered watershed transformation
Original Gaussian smoothed Hmax filtered
Watershed transformed image
Watershed transformed image
Watershed transformed image
Not good Not good Good
ThresholdingThresholding and labelingand labeling
Intensity Distribution
176
0 255
12
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Image after watershedImage after watershed Labeled imageLabeled image
NoThresholdingThresholding &&labelinglabeling
1
2
3D 3D HmaxHmaxfilteringfiltering
3D Gaussian 3D Gaussian smoothingsmoothing
Original 3D imageOriginal 3D image
3D Watershed 3D Watershed surfaces (lines)surfaces (lines)
Separation of aggregates:Separation of aggregates:3D image processing steps3D image processing steps
ThresholdingThresholding IsuesIsues……Different intensitiesDifferent intensities
Dynamic Dynamic thresholdingthresholding in 2Din 2D
0 100 200 3000
100
200
300
400
500Original image Intensity histogram
peak
# of
pix
els
Grayscale intensity
Dynamic Dynamic thresholdingthresholding in 3Din 3D
0 100 200 3000
100
200
300
400
500
Intensity histogram
peak
# of
pix
els
Grayscale intensity
Calculation of aggregate properties
– 3D Contact points – 3D Orientation– 3D Volume,
Angularity, Specific surface area
– Segregation: • Spatial distribution
of different sizes
Calculation of contact points
Shortest distance between surface
voxels
Example calculationsExample calculations
0 1 2 3 40
20
40
60
80
100
Cum
ulat
ive
dist
ribut
ion
(%)
Specific Surface Area (1/mm)
AggregatesSphere equivalent
0 1 2 3 40
20
40
60
80
100
Specific Surface Area (1/ mm)
Cum
ulat
ive
dist
ribut
ion
(%)
AggregatesSphere Equivalent
N160
N35
N160
N35
Example calculationsExample calculations
0 10 20 300
20
40
60
80
100
EquivDiameter
Cum
ulat
ive
dist
ribut
ion
(%)
N35N160
N160
N35
XX--ray CT Image 3D Analysis Toolray CT Image 3D Analysis Tool
Thank You!Thank You!Try to catch the rotating snake with your eye!Try to catch the rotating snake with your eye!
The EndThe EndM. Emin Kutay, Ph.D.M. Emin Kutay, Ph.D.
Asphalt Mixture Scientist / Lab ManagerAsphalt Mixture Scientist / Lab ManagerTurnerTurner--Fairbank Highway Research CenterFairbank Highway Research Center
[email protected]@fhwa.dot.gov