intelligent compaction: an overview overview... · intelligent compaction: an overview current...

INTELLIGENT COMPACTION:AN OVERVIEW

ByJean-Louis Briaud, PhD, P.E.

Professor and Holder of the Buchanan ChairDepartment of Civil Engineering

Texas A&M University

J-L Briaud, Texas A&M University

ACKNOWLEDGEMENTS

Chris Dumas, FHWA Hans Kloubert, BOMAG Roland Anderegg, AMMANN


1 MPa = 150 psi10 kN = 1 ton

25 mm = 1 inch


INTELLIGENT COMPACTION:AN OVERVIEW

Current practiceFuture practiceModulus and dry densityCompactions methodsIntelligent Compaction

PrincipleEquipment and instrumentationHow to get the stiffnessHow to get the modulusSpecs

Future needs


CURRENT PRACTICEBased on Density

• LAB: Proctor test to get dry densityvs. water content curve

• SPEC: x% of γd max within range of w opt

• FIELD: Compact and check that γd andw meet the specs


• LAB : Proctor Test



Water Content (%)

3 9 15 21

14

16

18

20

Dry

Density (

kN

/m3

)

!d max

w opt

S = 1S = 0.9

Water Content (%)

3 9 15 21

14

16

18

20

Dry

Density (

kN

/m3

)

!d max

w opt

S = 1S = 0.9

• SPECIFICATIONS.X % of γd max within range of w opt

• FIELD


Nuclear Density MeterFor γd and w


Dry Density:Advantages and Disadvantages

1. AdvantagesAccumulated knowledgeWell defined parameterIndication of solids per unit volume

2. DisadvantagesNot related to designNot very sensitiveNot easy to measure quickly in field


FUTURE PRACTICEBased on Modulus

• LAB: Modulus test to get modulus vs. water content curve

• SPEC: x% of E max

within range of w opt

• FIELD: Intelligent compaction and checkthat E max and w meet the specs


• SPECIFICATIONSX % of E max within range of w opt

• FIELD


Modulus MeterFor E and w

Intelligent Compaction

EIC



• LAB : Modulus Test


Water Content (%)6 10 14 18

Mod

ulus

(MPa

)

0

20

40

Sand

Clay

Emax

wopt

Modulus:Advantages and Disadvantages

1. AdvantagesDirectly related to designVery sensitive to water contentEasy to measure quickly in field

2. DisadvantagesMany influencing factorsNo lab test to get E vs. wNo target valuesNew concept


Which Modulus?

DEFINITIONInitialSecantTangentUnload-ResilientCyclicReload


Which Modulus?


Which Modulus?

STATE FACTORSDensityStructureWater contentStress historyCementation


Which Modulus?

LOADING FACTORSStress levelStrain levelStrain rateNumber of cyclesDrainage


Which Modulus?PLATE MODULUS in FIELD


BPT: Briaud Plate Test

Which Modulus?PLATE MODULUS in LAB


(E.CVEN#1)(08/02/2003)

0

50

100

150

200

250

0.00 0.02 0.04 0.06 0.08 0.10 0.12Displacement(mm)

Load

( N

)

EL=12.91 MPa

Er= 19.62 MPa

BPT: Briaud Plate Test

Range of Modulus

Steel: 200,000 MPaConcrete: 20,000 MPaWood, Plastic: 13,000 MPaRock: 2,000 to 30,000 MPaAsphalt: 150 to 25000 MPaSoil: 5 MPa to 1000 MPaMayonnaise: 0.5 MPa


NGES Silty Sand (Mold #5)

0

10

20

30

40

0 2 4 6 8 10 12 14

Water Content (%)

Mo

du

lus (

MP

a)

0

4

8

12

16

20

Dry

Un

it W

eig

ht

(kN

/m3)

Plate Reload Modulus (MPa)

Dry Unit Weight (kN/m^3)


Modulus measured with BPT: Briaud Plate Test

NGES Silty Sand (Mold #6)

0

10

20

30

40

0 2 4 6 8 10 12

Water Content (%)

Mo

du

lus

(M

Pa

)

0

4

8

12

16

20

Dry

Un

it W

eig

ht

(kN

/m3)





NGES Sand + Porcelain Clay (Mold #5)

0

10

20

30

40

0 2 4 6 8 10 12 14 16Water Content (%)

Mo

du

lus (

MP

a)

0

4

8

12

16

20

Dry

Un

it W

eig

ht

(kN

/m3)


Dry Unit Weight (kN/m^3))



NGES Sand + Porcelain Clay



0

20

40

60

0 2 4 6 8 10 12 14 16Water Content (%)

Mo

du

lus (

Mp

a)

0

4

8

12

16

20

Dry U

nit

Weig

ht

(kN

/m3)



0

20

40

60

0 2 4 6 8 10 12 14 16Water Content (%)

Mo

du

lus (

Mp

a)

0

4

8

12

16

20

Dry U

nit

Weig

ht

(kN

/m3)



• Only one of those threeis not enough

• Two of those three aresufficient

• All three would be nice


1. Density?2. Modulus?3. Water Content?

Three CompactionControl Methods

• Conventional Compaction• Continuous Control

Compaction• Intelligent Compaction


Conventional Compaction(static or vibratory smooth drum

or sheep-foot)


Continuous VibratoryCompaction Control

• Instrumented vibrating rollers• Measure roller accel. as a function of time• Calculate a soil stiffness or modulus• Modulus is compared to target value (specs)• The modulus value tells the operator if thespecified compaction level is reached


Intelligent Vibratory Compaction

• Instrumented vibrating rollers• Measure roller accel. as a function of time• Calculate a soil modulus• Intelligent roller modifies automaticallyand instantaneously settings (force, ampl.,freq.) to meet the target modulus


Recompaction of soft formation area with VARIOCONTROLautomatic mode, presetting ( target value ) EVIB = 80 MN/m²

Intelligent Compaction

Intelligent CompactionTests in the U.S.A.

4 2 -2

200

Soil Reaction Force (kN)

Fx max

-4

Fstat

x

Fx

1st Pass2nd Pass

3rd Pass

Drum Oscillation (mm)

Force-Displacement Curves


From BOMAG

From Acceleration to Stiffness

2 cos( ) ( )B d d u u f dF m x m r t m m g! " + # # + +&&

B B d B dF k x d x! + &

FB: soil-drum-interaction-force md: mass of the drum (kg)xd: vert. disp. of drum (m) : acceleration of drummf: mass of the frame (kg) mu: unbalanced mass (kg)ru: radial distance for mu Ω = g: acc. due to gravity (m/sec2) f: frequency of rotating shaft (Hz)

: velocity of drum kB: stiffness of soildB: damping coefficient (dB ~ 0.2)

dx&&

dx&&

2 f!

dx&

xw

FFlieh= mew2 cos(ö)

mR?g

mR?g

FB

xw


mR?g

mR?g

FB


mR?g

mR?g

FB

mw? g


Stiffness or Modulus?

K = F/x in MN/mE ~ σ/ε in MN/m2 or MPa

E = α F/BxK = F/x = EB/α


Stiffness or Modulus?

Stiffness depends on the size of theroller.

Modulus does not; it is a property ofthe soil only.

Use the modulus, not the stiffness


From Stiffness to Modulus(theoretical)

dx&&

( )( ) ( )

[ ]3

2

2

MN m

12 1 2.14 ln

2 1 16

B

f d

E Lk

L E

m m R g

!

!"

"

# #=

$ %& '# #( )# * # + # + ,( )* # # + # #+ ,- ./ 0


From Stiffness to Modulus(experimental)


From AMMANN

Soil Modulus for Intelligent Compaction

Soil: 5 MPa unacceptable200 MPa excellent


Soil layers Density Bearing capacity Eveness(Standard Proctor) (load bearing test, EV2) (4 m straight edge)

Laying and compaction specification for

road construction in Germany

Subbase 100 - 103 % * 100 - 150 MN/m?* 20 mm

Capping layer 100 - 103 % * 100 - 120 MN/m?* 40 mm

Formation 97 - 100 % * 45 - 80 MN/m?* 60 mm

* depending on road classification and road design

Specifications based on Modulus


From BOMAG

1. Reference modulus = plate test?

2. Develop simple lab modulus test

3. Study modulus vs water/asph. Content

4. Demonstrate that IC is better than CC

5. Calibrate rollers against plate modulus

6. Use same modulus test (lab and field)

FUTURE NEEDS


Example of same modulus testin lab and in field


BCD Test: Briaud Compaction Device

BCD on Proctor Mold BCD in the Field

7. Develop specs based on modulusfordiff. pavement cond.

8. Can the asphalt modulus be isolatedfrom the soil modulus

9. Use modulus control equipment

10. Demonstrate the IC equipment

11. First International Conference on Compaction

FUTURE NEEDS


INTELLIGENT COMPACTION: OVERVIEW AND RESEARCH NEEDS

Jean-Louis Briaud ([email protected]) and Jeongbok Seo

From BOMAG

From GEODYNAMIK

kB . . . . . . . . . . . . . . . . . . . . . . . . . . 70 M N/ mkB m ax. . . . . . . . . . . . . . . . . . 150 M N/ mkB m i n. . . . . . . . . . . . . . . . . . . 30 M N/ mΔ kB . . . . . . . . . . . . . . . . . . . . . . +10 M N/ mv. . . . . . . . . . . . . . . . . . . . . . . . . . . 3. 2 km / hL. . . . . . . . . . . . . . . . . . . . . . . . . . . 90 m

0 40 80 120 160k B

M N/ m0 m

25 m

50 m

75 m

Printer: - Single Device- Recording- Increase of Compaction

DATAS

ADSkB . . . . . . . . . . . . . . . . . . . . . . . . . . 70 M N/ mkB m ax. . . . . . . . . . . . . . . . . . 150 M N/ mkB m i n. . . . . . . . . . . . . . . . . . . 30 M N/ mΔ kB . . . . . . . . . . . . . . . . . . . . . . +10 M N/ mv. . . . . . . . . . . . . . . . . . . . . . . . . . . 3. 2 km / hL. . . . . . . . . . . . . . . . . . . . . . . . . . . 90 m

0 40 80 120 160k B

M N/ m0 m

25 m

50 m

75 m

kB . . . . . . . . . . . . . . . . . . . . . . . . . . 70 M N/ mkB m ax. . . . . . . . . . . . . . . . . . 150 M N/ mkB m i n. . . . . . . . . . . . . . . . . . . 30 M N/ mΔ kB . . . . . . . . . . . . . . . . . . . . . . +10 M N/ mv. . . . . . . . . . . . . . . . . . . . . . . . . . . 3. 2 km / hL. . . . . . . . . . . . . . . . . . . . . . . . . . . 90 m

0 40 80 120 160k B

M N/ m0 m

25 m

50 m

75 m

Printer: - Single Device- Recording- Increase of Compaction

DATAS

ADSADS

From AMMANN

December, 2003 Texas A&M University

THANK YOU

[email protected]


intelligent compaction: an overview overview... · intelligent compaction: an overview current...

Documents