Intelligent Compaction:Intelligent Compaction:Are We There Yet? Are We There Yet?

IHEEP Conference, Sept. 27 ~ Oct. 1, 2009 IHEEP Conference, Sept. 27 ~ Oct. 1, 2009 San Antonio, TexasSan Antonio, Texas

Jimmy Si, Ph.D., P.E.Jimmy Si, Ph.D., P.E.TxDOTTxDOT

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OutlineOutlineWhy need Intelligent Compaction (IC)?Why need Intelligent Compaction (IC)?What is it?What is it?How does it work?How does it work?What does it do?What does it do?National researchNational researchTxDOT experienceTxDOT experienceSummarySummary

33

Significance of Quality CompactionSignificance of Quality CompactionWeWe’’ve known it for a long timeve known it for a long time……

““The importance of compaction in highway The importance of compaction in highway construction has long been recognized. construction has long been recognized. Recent laboratory and field investigation Recent laboratory and field investigation have repeatedly emphasized the value of have repeatedly emphasized the value of thorough consolidation in both the base and thorough consolidation in both the base and surfacing courses.surfacing courses.””

Reference -- "Public Roads, May 1939,

authors J.T. Pauls and J.F. Goode"

4

Significance of Quality Compaction

0 5 10 15 20 25 30 35 40 45 50 55

E VIB

(MPa

)

0306090

120150180

0 5 10 15 20 25 30 35 40 45 50 55

E VIB

(MPa

)

0306090

120150180

a = 0.70mm

Distance (m)

0 5 10 15 20 25 30 35 40 45 50 55

E VIB

(MPa

)

0306090

120150180

a = 0.70 mm

a = 0.70 mm

Base Layer 2

Base Layer 1

Subgrade

3

2

1

Clay Subgrade – Subgrade (10‐12 inches)

Aggregate Base – Base Layer 2 (6 inches)

Aggregate Base – Base Layer 2 (6 inches)

1

2

3

EV

IB

SubsurfaceLayer (1) Final Layer (2)

~ 20

0 ft

~ 40 ft ~ 40 ft

Hard subsurface layer reflecting through surface compaction layer

Region of soft subsurface layer 

condition reflecting through surface compaction layer

Reflection of underlying non-uniformity to overlying layers

55

Significance of Quality CompactionSignificance of Quality Compaction

(from Thurner and Sandstrom, 1980)

Reflection of underlying non-uniformity to surface layers

The quality of asphalt can not make up for a poor subgrade or base.

6 in.

2 in.

66

Why Need Intelligent Compaction?Why Need Intelligent Compaction?How do we control or evaluate the quality of How do we control or evaluate the quality of compaction?compaction?–– Ordinary Compaction Ordinary Compaction -- Proof RollingProof Rolling–– Density Control Density Control –– Nuclear Gauge DensityNuclear Gauge Density

Is density the best way to characterize the quality of Is density the best way to characterize the quality of compaction?compaction?–– Do we use density in our pavement design?Do we use density in our pavement design?–– Density measurements Density measurements are spot check and layer specific, are spot check and layer specific,

and and may not be representative of entire section and full may not be representative of entire section and full depthdepth

–– How well does density correlate with stiffness/modulus of How well does density correlate with stiffness/modulus of the materials?the materials?

–– How sensitive does density response to compaction?How sensitive does density response to compaction?

77

Comparison of CMV and FWD/Dry DensityComparison of CMV and FWD/Dry Density

0 10 20 30 40 50

CM

V

0

20

40

60

80

060120180240300

Mapping Passa = 0.81 mm

Lane 2

Distance (m)

0 10 20 30 40 50

CM

V

0

20

40

60

80

060120180240300Mapping Pass

a = 1.00 mmLane 4

0 10 20 30 40 50

CM

V

0

20

40

60

80

060120180240300

Pass 12a = 0.80 mm

Lane 3

300‐mm FWD

0 10 20 30 40 50

CM

V

0

20

40

60

80

γ d (k

N/m

3 )

19

20

21

22

23

Mapping Passa = 0.79 mmLane 2

Distance (m)

0 10 20 30 40 50

CM

V

0

20

40

60

80

γ d (k

N/m

3 )

19

20

21

22

23

Mapping Passa = 1.07 mmLane 4

0 10 20 30 40 50

CM

V

0

20

40

60

80

γ d (k

N/m

3 )

19

20

21

22

23

Pass 12a = 1.01 mm

Lane 3

Dry Density

88

Correlation w/ InCorrelation w/ In--Situ TestingSitu TestingImpact ForceFrom Rollers 300 mm 

LWD/FWD200 mm 

LWDNuclear 

Density Gauge

DynamicCone Penetrometer

2.1 m

2.1 m

0.3 m 0.2 m 0.3 m

1.0 m

Influence depths are assumed ~ 1 x B (width)

Courtesy of Dr. David White

99

Why Need Intelligent Compaction?Why Need Intelligent Compaction?

How do we know the desired/target How do we know the desired/target density has been achieved?density has been achieved?–– ExperienceExperience–– Nuclear density gauge/sand coneNuclear density gauge/sand cone–– Density properties are not measured until Density properties are not measured until

after the compaction is completeafter the compaction is completeHow Can We Do Better?How Can We Do Better?–– Intelligent compaction technology appears to Intelligent compaction technology appears to

offer offer ““a better or smarter waya better or smarter way””

1010

What is Intelligent Compaction (IC)?What is Intelligent Compaction (IC)?Vibratory rollers with a feedback control measurement system– Measure material stiffness instead of density– Control system automatically changes

parameters (amplitude and frequency) based on measured material stiffness feedback

GPS-based documentation systems–– Continuous recording materialContinuous recording material’’s stiffnesss stiffness–– Continuous recording corresponding roller Continuous recording corresponding roller

locationlocation–– ColorColor--coded mapping of stiffnesscoded mapping of stiffness

1111

GPS Receiver

Display Panel

Accelerometer

How Does It Work?

1212

Amplitude & Frenquency Control

Hard Soil, well compacted; acting as an anvil

Soft Soil, poor compacted; acting as a SpringHigh Amplitude, Low Frequency, Penetrate DeeperHigh Amplitude, Low Frequency, Penetrate Deeper

Low Amplitude, High Frequency, Compact SurfaceLow Amplitude, High Frequency, Compact Surface

Courtesy of Ammann America

How Does It Work?

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Stiff

ness

GPSreference point

GPS – Satellite

Roller Stiffness

GPS-based Compaction Measurement

none10 MN/m

70 MN/m

140 MN/m

Courtesy of Ammann America

How Does It Work?

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National Research EffortsNational Research EffortsNCHRP 21NCHRP 21--0909

““Examining the Benefits and Adoptability of Intelligent Examining the Benefits and Adoptability of Intelligent Soil CompactionSoil Compaction””–– Report is under reviewReport is under review

Transportation Pooled Fund TPFTransportation Pooled Fund TPF--5(128)5(128)““Accelerated Implementation of Intelligent Compaction Accelerated Implementation of Intelligent Compaction Technology for Embankment Subgrade Soils, Aggregate Technology for Embankment Subgrade Soils, Aggregate Base and Asphalt Pavement MaterialBase and Asphalt Pavement Material””–– 12 states participated in this three12 states participated in this three--year pooled fund studyyear pooled fund study–– At least one demo project will be constructed in each At least one demo project will be constructed in each

participated state, either in soil/aggregate base or HMAparticipated state, either in soil/aggregate base or HMA

1515

MN

IA

KS

TXMS

IN

NY

PA

VAMD

ND

GA

WI

200820092010

Transportation Pooled Fund, TPF-5(128)12 States IC Demo Projects12 States IC Demo Projects

http://www.intelligentcompaction.com/

1616

Summary of Demo ProjectsSummary of Demo Projects

http://www.intelligentcompaction.com/

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TxDOT ExperienceTxDOT Experience

Fort Worth, Texas

Demo Project on FM156

1818

TxDOT ExperienceTxDOT ExperienceThree IC rollersThree IC rollers–– Single Single padfootpadfoot and smooth and smooth

drum steel wheel IC rollers drum steel wheel IC rollers from Case/Ammannfrom Case/Ammann

–– Single smooth drum steel Single smooth drum steel wheel IC roller from wheel IC roller from DynapacDynapac

Three types of materialsThree types of materials–– Untreated cohesive soil Untreated cohesive soil –– Lime treated soilLime treated soil–– Flexible limestone baseFlexible limestone base

Case/Ammann Single Drum IC RollerCase/Ammann Single Drum IC Roller

Dynapac Single Drum IC RollerDynapac Single Drum IC Roller

1919

TxDOT ExperienceTxDOT Experience

FWD

NDG

DSPA

LWD

DCP

PLT

2020

Untreated cohesive soil

Untreated cohesive soilUntreated cohesive soil

Untreated Subgrade Soil

2121

Flex Base (on both ends of the test bed) and Lime Flex Base (on both ends of the test bed) and Lime Stabilized SubgradeStabilized Subgrade

2222

Summary of TxDOT ExperienceBoth padfoot and smooth drum rollers work well for the quality compaction of the untreated and lime treated subgrade clay material with good repeatability.Both roller CMVs and in-situ point measurements captured the wide variation in stiffness of the compacted lime stabilized and flex base materials.The CMV measurements are influenced by the vibration amplitude and show that increasing amplitude generally causes an increase in CMV value on the material tested.

2323

Benefits of ICBenefits of ICIntelligent compaction rollers measure and Intelligent compaction rollers measure and record the quality of compaction during the record the quality of compaction during the compaction process (oncompaction process (on--thethe--fly)fly)–– Measure and record material stiffness values Measure and record material stiffness values

instead of densityinstead of density–– Integration of design with construction and Integration of design with construction and

pavement performance (density vs. pavement performance (density vs. modulus/stiffness)modulus/stiffness)

–– RealReal--time identify weak spots or nontime identify weak spots or non--compactable areascompactable areas

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Benefits of ICBenefits of IC100% coverage of compaction area for 100% coverage of compaction area for quality control quality control Improve Improve efficiencyefficiency of the compaction of the compaction processprocess–– Improve density uniformity of the pavement Improve density uniformity of the pavement

materialsmaterials–– Eliminate lost time and Eliminate lost time and the expense of having the expense of having

to rework areas where under or overto rework areas where under or over--compaction have occurredcompaction have occurred

–– Knowing when compaction is complete, taking Knowing when compaction is complete, taking the guess work out of compaction (less the guess work out of compaction (less operator accountability)operator accountability)

2525

Summary of BenefitsSummary of Benefits

Improve uniformity of density– better performanceImprove efficiency of compaction– cost savingsIncrease information of compaction– better QC/QA

2626

Research NeedsResearch NeedsDemonstrate that intelligent compaction leads to better compaction than conventional compaction by quantifying the differences between the two techniques.Study the depth of compaction that can be achieved by various rollers for various soils.Understand the interdependence between the modulus and water content.Develop a fast and simple field test to obtain the target modulus for IC roller calibration.Develop a fast and simple field test to measure the water content in real time.Develop standard specifications.

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What is Next for TxDOT?What is Next for TxDOT?Complete more pilot construction projects Complete more pilot construction projects using IC technology to determine:using IC technology to determine:–– Which test is used for calibration of IC rollersWhich test is used for calibration of IC rollers–– The benefits of using IC rollers over The benefits of using IC rollers over

conventional rollersconventional rollersDevelop a stateDevelop a state--wide ICwide IC--based construction based construction specification. specification. Conduct training workshops for Conduct training workshops for implementation of IC technology in districts.implementation of IC technology in districts.

2828

Questions?Questions?

Thank You