Asphalt Pavement Compaction: What Can We Learn from the Particle Rotation?

Shihui ShenPenn State Altoona

October 28, 2019

1

Transportation Asset and Infrastructure Management Conference

Background2

Pavement compaction

Air void content

Air voidsize

Air void distribution

Smoothness Uniformity

Pavement performance and durability(resistance to cracking, rutting, and moisture damage)

• Compaction is one of the most critical steps in asphalt pavement construction that ultimately impacts pavement performance.

Background3

Pavement compaction

• Experience-based field compaction that leads to over/under compaction

Background4

Pavement compaction

Complex vehicle-surface interactions

• Intelligent Compaction—— Good improvement, accurate density control is still questionable

Hypothesis: particle movement, especially rotation, plays a significant role in the densification process of a particulate structure --- meso scale behavior

Objectives

• Understand asphalt pavement compaction mechanism from the

perspective of particle movement especially rotation

Correlate particle movement to different compaction methods;

Provide preliminary insight into the compaction mechanism;

and

Explore the correlation between the SGC and field compaction

at meso-scale.

5

Methodologies

• Using embedded sensors (SmartRock sensor) to capture the compaction (skeleton formation) characteristics of asphalt mixture in both field and lab

6

SmartRock Sensors

Methodologies7

Outside

3D – printedCan be defined to be similar to real stones

MaterialHigh-temperature resistant (140-170℃)High strengthGood compatibility and cohesion with asphalt

Reduced sizeLess than 1 inch each side

SmartRock Sensors

Methodologies8

Inside

Tri-axial gyroscope Tri-axial accelerometer Tri-axial magnetometer Temperature sensor Three directional stress cells

Long-life battery

6 months ~ 1 year

SmartRock Sensors

Methodologies9

SmartRock Sensors

Methodologies10

• SmartRock in Superpave gyratory compactor

Compaction characteristics in the lab11

Compaction characteristics in the lab

Particle follows a cyclic rotation pattern that repeats every 2 seconds that matches the SGC rotation speed of 30 rpm.

• Rotation plays a significant role for particle movement in a confined particulate structure.

A segment of rotation data output

12

Relative RotationThe difference between the peak and the valley values of the rotation angle for each cycle.

Compaction characteristics in the lab13

0 10 20 30 40 50 600

20

40

60

80

100

120

Perc

ent

Gyration Cycle

%Gmb %Relative rotation angle change_x %Relative rotation angle change_y

0 10 20 30 40 50 60 700

20

40

60

80

100

120

Perc

ent

Gyration Cycle

%Gmb %Relative rotation angle change_x %Relative rotation angle change_y

0 20 40 60 80 100 120 1400.0

0.5

1.0

1.5

2.0

2.5

Rel

ativ

e R

otat

ion(

°)

Gyration Cycle

x-direction y-direction z-direction—— Specimen Height

0

20

40

60

80

100

120

140

Spec

imen

Hei

ght(m

m)

0 20 40 60 80 100 120 1400

20

40

60

80

100

120

Perc

ent

Gyration Cycle

%Gmb %Relative rotation angle change_x %Relative rotation angle change_y

%𝐺 ,𝐺𝑖

𝐺ℎ

ℎ𝑖 100%

%Relative rotation, i𝑚𝑖𝑛𝑖𝑚𝑢𝑚 𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑟𝑜𝑡𝑎𝑡𝑖𝑜𝑛 𝑎𝑡 𝑐𝑦𝑐𝑙𝑒 𝑖

∗

*Wang X, Shen S, Huang H, et al. Characterization of particle movement in Superpave gyratory compactor at meso-scale using SmartRock sensors. Construction and Building Materials, 2018, 175: 206-214.

In SGC compaction, the relative rotation pattern of particles along x- and y- axis was directly related to material density change.

• Relationship between particle rotation and mixture density

Compaction characteristics in the lab14

*Wang X, Shen S, Huang H, et al. Characterization of particle movement in Superpave gyratory compactor at meso-scale using SmartRock sensors[J]. Construction and Building Materials, 2018, 175: 206-214.

• Compaction as a three-stage process

0 20 40 60 80 100 1201.5

2.0

2.5

Relative RotationRate Reduction Cycle

InitialCompactionStage Plateau StageTrasition Stage

Rel

ativ

e R

otat

ion

(°)

Gyration Cycle

Relative RotationStabilization Cycle

Stage I：Initial compaction stage(Particles had large relative rotation and also a sharp reduction, due to much compaction and height reduction.)

Stage II：Transition stage(Particle movement was restricted as represented by the reduced relative rotation rate.)

Stage III：Plateau stage(Particle rotation was much restricted by the compacted structure, except following the regular rotation of SGC.)

Compaction characteristics in the labAC relative rotation and specimen height change

• Generally, the relative rotation pattern of particles along x- and y- axis was directly related to material density change during the compaction process.

3 trials

15

0 10 20 30 40 50 60 70 800.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

Hei

ght (

mm

)

0 10 20 30 40 50 60 70 800.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

Hei

ght (

mm

)

0 10 20 30 40 50 60 70 800.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

Hei

ght (

mm

)

Compaction characteristics in the lab

Other mixture types: Relative rotation and height

PFC

SMA

0 20 40 60 80 1000.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

Hei

ght (

mm

)

0 20 40 60 80 1000.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

Hei

ght (

mm

)

0 20 40 60 80 1000.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

Hei

ght (

mm

)

16

0 50 100 150 200 2500.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

180

Hei

ght (

mm

)

-20 0 20 40 60 80 100 120 140 1600.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

180

Hei

ght (

mm

)

0 20 40 60 80 100 1200.0

0.5

1.0

1.5

2.0

2.5

3.0

Parti

cle

Rel

ativ

e R

otat

ion

(°)

Cycle

0

20

40

60

80

100

120

140

160

180

Hei

ght (

mm

)

Compaction characteristics in LabEffect of gradation on particle rotation and compaction

0 10 20 30 40 50 60 70 800

20

40

60

80

100

%Relative rotation %Gmb

Perc

ent

Gyration cycle0 20 40 60 80 100

0

10

20

30

40

50

60

70

80

90

100

%Relative rotation %Gmb

Perc

ent

Gyration cycle

0 50 100 150 200 2500

10

20

30

40

50

60

70

80

90

100

%Relative rotation %Gmb

Perc

ent

Gyration cycle

AC SMA

PFC

0 5 10 15 20

0

20

40

60

80

100

Pass

ing

perc

ent (

%)

Sieve size (mm)

GA SMA AC

Relative rotation change curve:Structural-skeleton-related- Dense structure: affected by both coarse and fine particles- Gap/open structure: affected by coarse-coarse

interaction

17

SmartRock in field asphalt pavement compaction

Compaction characteristics in field

Pavement Maintenance Project

Lane-widening Project

18

Particle rotation recorded by SmartRock in field asphalt layer compaction

Compaction characteristics in field19

0 500 1000 1500 2000 2500-8-6-4-202468

101214

Rot

atio

n an

gle

(°)

Time (s)

x-direction y-direction z-direction

Particle acceleration recorded by SmartRock in field asphalt layer compaction

Compaction characteristics in field20

0 500 1000 1500 2000 2500-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Acce

lera

tion(

m/s

2 )

Time (s)

x-direction y-direction z-direction

Compaction characteristics in field21

Particle’s reaction to different rollers in asphalt layer

Static rollerParticle translated in z-direction (vertically), however, only in 1~2 passes in the initial compaction stage when asphalt mixture was quite loose.

Pneumatic-tyred rollerParticle translated in x and y-directions, at the same time rotating in three directions.

Vibrating rollerParticle translated in z-direction (vertically) in the whole compaction process when vibrating roller was on.

Compaction characteristics in field22

0 10 20 30 40-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

x-Ac

cele

ratio

n (m

/s2 )

Time (s)

200s

0 10 20 30 40-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

x-Ac

cele

ratio

n (m

/s2 )

Time (s)

480s

0 10 20 30 40-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

x-Ac

cele

ratio

n (m

/s2 )

Time (s)

851s (Driving backward)

Driving backward

Particle x-direction acceleration to pneumatic-tyred roller

Particle movement characteristics in asphalt layer compaction

Compaction characteristics in field23

Particle z-direction rotation to pneumatic-tyred roller

-5 0 5 10 15 20 25 30 35 40

-4

-2

0

2

4

z-R

otat

ion

angl

e (°

)

Time (s)

200s

-5 0 5 10 15 20 25 30 35 40

-4

-2

0

2

4

z-R

otat

ion

angl

e (°

)

Time (s)

480s

-5 0 5 10 15 20 25 30 35 40

-4

-2

0

2

4

z-R

otat

ion

angl

e (°

)

Time (s)

851s (Driving backward)

Driving backward

Particle movement characteristics in asphalt layer compaction

24Compaction characteristics in field

Z-direction

X-direction

Y-direction

Four times of roller working forward and backward

Particle three-axial acceleration in base layer compaction (initial stage)

Comparison of particle acceleration in base layer during the initial and late stage

Compaction characteristics in field25

Initial stage

Late stage

Particle three-axial rotation in base layer compaction (initial stage)

Compaction characteristics in field26

Z-direction

X-direction

Y-direction

Time (s)

Rota

tion

(°)

• Comparison of particle rotation in base layer during the initial and late stage

Compaction characteristics in field27

Initial stage

Late stage

Rotation angle change

Almost no angle change

• Different particle acceleration mode in asphalt and base layer (initial stage)

Compaction characteristics in field28

Asphalt layer z-direction acceleration

Base layer z-direction acceleration

• Different particle rotation mode in asphalt and base layer (initial period)

Compaction characteristics in field29

Asphalt layer Base layer

-5 0 5 10 15 20 25 30 35 40

-4

-2

0

2

4

z-R

otat

ion

angl

e (

)

Time (s)

480s

Comparison between Lab and Field Compaction30

-5 0 5 10 15 20 25 30 35 40-1.5

-1.0

-0.5

0.0

0.5

1.0

y-R

otat

ion

angl

e (°

)

Time (s)

-1-0.5

00.5

11.5

2

0 1 2 3 4 5 6 7 8 9 10

Y-di

rect

ion

rota

tion

angl

e (°

)

Time (s)

-1

-0.5

0

0.5

1

1.5

2

1 2 3 4Time (s)

y‐rotation

 ang

le (°

)

Relationship between SGC and field compaction of asphalt mixture

Summary The SmartRock is capable of recording real-time particle translation and

rotation in the field and lab asphalt mixture compaction. Compared with the traditional sensors, the SmartRock has advantages in

pavement research : (1) it is wireless; (2) durable; and (3) it does not alter the motions of surrounding particles when embedded in asphalt mixture.

Particle reacted differently to different rollers, and the reaction can be explained by roller’s working mechanism.

Particle reacted different in different types of materials during compaction. Particle rotation characteristics is closely related to material density

change during compaction, and is affected by mixture gradation and skeleton.

The SGC compaction method could well simulate the kneading process produced by pneumatic-tyred roller.

31

Acknowledgements

Railroad Technology & Services (http://www.railtechs.com/) for technical support of SmartRock sensors and its application

Graduate and undergraduate students at Penn State University and visiting scholar from Tongji University in China for running experiments and data analysis

32

Thank you!

Any questions?33