ic tech brief soilsic v3b

7/28/2019 IC Tech Brief SoilsIC v3b

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Intelligent compaction (IC) is a construction method relatively newto the USA that uses modern vibratory rollers equipped IC compo-nents and technologies.

The IC technology and IC-related quality assurance (QA) specifications on earthwork has existed in Europe for more than 20 years. Under the on-going FHWA/TPFIC studies, various single drum IC rollers from manufacturers around the worldhave been demonstrated at full scale projects target-ing cohesive/incohesive soils, granular subbase, andstabilized base .

Components of soils and subbase IC include: single-drum IC rollers, roller measurement system, globalposition system (GPS) radio/receiver/base station,infrared temperature sensors, and integrated report-ing system. Therefore, a soils/subbase IC roller canadapt its behavior in response to varying situationsand requirements - being intelligent!

There are many benefits using soils/subbase ICrollers. To name a few: improved quality control (QC)of compaction, better correlate to compaction ofdeeper layer, monitor levels of compaction for 100%coverage area, and many more...

Introduction

Soils/Subbase IC Rollers in the US

There are at least 5 vendors around the world have been developing single-drumIC rollers. Currently, there are two various types of soils/subbase IC rollersavailable in the US that meet the above IC roller requirements: Bomag USA,Case/Ammann, Caterpillar, Dynapac, Sakai America, and Volvo. Most of theabove single-drum IC roller manufacturers offer smooth drum and padfoot mod-els.

Intelligent Compactionfor Soils and Subbase

Materials

The Transportation

Pooled Fund (TPF)

study, Accelerated

Implementation of In-

telligent Compaction

Technology for Em-

bankment Subgrade

Soils, Aggregate Base

and Asphalt Pavement

Material is being con-

ducted under TPF-5

(128). It is a three

year study beginning

September 2007 and

ending September

2010.

Visit the IC project

website for further de-

tails on IC technolo-

gies:

IntelligentCompaction.com

TechBrief

Bomag

IC System (courtesy of Bomag)

Top Three Factors for Soils/Subbase Compaction:

Moisture! Moisture! and Moisture!

Case/

AmmannCaterpillar Dynapac Sakai


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The basis of the Sakai IC system is the ICroller (equipped with CCV measurementsystem, temperature sensors, and GPS

radio/receiver) and a GPS with radio basestation. All measurements are consoli-dated to the CIS display. IC data canthen be transferred to PCs via USB portsfor further reporting/documentation andintegration with CAD systems.

The Sakai Compaction control value (CCV)is a unitless vibratory-based technologywhich makes use of an accelerometermounted to the roller drum to create arecord of machine-ground interaction. Itsvalue represents the stiffness of the compacted pavement layers underneath. Theconcept behind the CCV is that as the ground stiffness increases, the roller drumstarts to enter into a jumping motion which results in vibration accelerations atvarious frequency components. The current Sakai IC system does not yet consist ofauto-feedback.

Sakai Soil IC System

The Bomag IC system is called VarioControl ICsystem. The Bomag IC roller is equipped withtwo acceleration transducers, processor/controlunit, distance measurement, GPS ra-dio/antenna, Bomag Operation Panel (BOP),and onboard BCM 05 documentation system(BCM 05-Tablet-PC, BCM 05 mobile software).This system is capable of measuring compac-tion values that can be transferred to anothercomputer using USB memory sticks for furtheranalysis and reporting using the BCM05 officesoftware.

The Bomag IC measurement value is called Evib[MN/m2] or vibration modulus (more strictly,stiffness). The Evib values are computed based

on the compression paths of contact forces vs.drum displacement curves. The Evib valuesincrease with increasing pass number. Evib alsoresponds to changes of material density andasphalt mixture temperature (with droppingcompaction temperature, Evib of asphalt mix-tures becomes greater). The Bomag Evib valuescorrelate well with load bearing capacities(Ev1/Ev2) from the plate loading tests. Thefeedback control in the Bomag IC system iscalled VarioControl that enables the automatic adaption of the amplitude during thecompaction process.

Bomag Soil IC System

Page 2 INTELLIGENT COMPACTIONFOR SOILS AND SUBBASE MATERIALS

Sakai IC system

Bomag BCM05 System


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US DEPARTMENT OF TRANSPORTATION Page 3

The Case/Ammann IC system is called the ACE and feed-back drum system. The ACEplus system was formed by

combining the former Ammann Compaction Expert (ACE)measurement and control system with continuous com-paction control (CCC).

The roller-integrated stiffness (ks) measurement systemon the Case/Ammann IC rollers was introduced by Am-mann during late 1990s considering a lumped parametertwo-degree-of-freedom spring-mass-dashpot system.The spring-mass-dashpot model has been found effectivein representing the drum-ground interaction behavior.The drum inertia force and eccentric force time historiesare determined from drum acceleration and eccentric po-sition (neglecting frame inertia). The IC soil stiffness, ks,can be determined when there is no loss of contact be-tween drum and soil. It is closely related to the plate loading test results.

ACE is an electronic measuring and controlling system for vibratingrollers. It is an automatic close-loop control automatically adjustsroller vibratory amplitudes and frequencies to suit the characteristicof the compacted ground condition. The Case/Ammann ACE autofeedback system can adjust the roller vibratory frequency and am-plitude at each roller pass depending on the condition of the com-pacted ground condition thus, optimize the compaction with leastdesirable number of passes.

Case/Ammann Soil IC System

Caterpillar Soil IC System

The Caterpillar IC system include an accelerometer,slope sensor, controllers, communication data radio,Real-time Kinematic (RTK) GPS receiver, an off-boardGPS base station, and onboard report system. Theslope (angle) sensor measures the left/right tilt of thedrum to a range of 45. Collectively, the above com-ponents are integrated into so-called Caterpillar AccuG-rade system to provide accurate IC measurements dur-ing compaction.

The Caterpillar IC measurement values for indication oflevels of compaction include compaction meter values(CMV), resonance meter values (RMV), and machinedrive power (MDP).

The CMV was developed by Geodynamic in 1970s. CMV is defined as a scaled ratio of the second harmonic vs.the first harmonic of the drum vertical acceleration amplitudes basedon a spectral analysis. The scaling is made so that CMV values couldcover a range of 150. The CMV is reported as average values withintwo cycles of vibration or typically 0.5 seconds. The resulting CMV isa dimensionless, relative value requiring constant roller parameterssuch as drum diameter, linear load, frequency, amplitude, speed, andetc. Since the CMV is an integral with contribution from large depths(3 to 6 ft for Caterpillar IC rollers) with the highest weighting of thelayers closest to the surface, caution should be taken when compar-ing CMV to the top layer compaction level (often measured by otherin-situ devices such as nuclear gauges or LWD) only.

Compaction/SoilStiffness

Number of Passes/Time

CompactionDepth

CompactionDepth

GPS ReceiverRadio

Slope Sensor Accelerometer

Controllers

Display

F0,5F 2F fq

SA

F0,5F 2F fq

SA

8

F0,5F 2F

SA

fq

150

F0,5F 2F

SA

fq

150

F0,5F 2F

SA

fq

50

F0,5F 2F

SA

fq

50CMV

Soft material Hard materialSlightly harder

material


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The DCA system measures CMV as an indicator of com-paction quality. The CMV technology uses accelerometersto measure drum accelerations in response to soil behav-

ior during compaction operations (Figure 17). The ratiobetween the amplitude of the first harmonic and the am-plitude of the fundamental frequency provides an indica-tion of the soil compaction level. An increase in CMVvalue indicates increasing compaction.

CMV is a dimensionless parameter that depends on rollerdimensions (i.e., drum diameter, weight) and roller op-eration parameters (i.e., frequency, amplitude, andspeed). The machine used on this project reported ameasurement value approximately every 0.5 m at thedrum center along the direction of travel.

The machinealso reported abouncing value (BV) which provides an

indication of the drum behavior (e.g., con-tinuous contact, partial uplift, doublejump, rocking motion, and chaotic motion)and is calculated using Equation 3. Whenthe machine is operated in AFC mode, re-portedly the amplitude is reduced when BVapproaches 14 to prevent drum jumping.

Dynapac Soil IC System

For IC correlation analysis, in-situ tests are used to directly obtain the response ofthe compacted materials under various loading situations and drainage/moistureconditions. Recommended in-situ test devices for soils/subbase/stabilized IC are asfollowings (Dynamic Seismic Pavement Analyzer - DSPA - and Briaud CompactionDevice - BCD - are still being evaluated):

Light Weight Deflectometer (LWD)

Dynamic Cone Penetrometer (DCP)

Calibrated Nuclear Moisture-Density Gauge for soils and subbase (NG)

Falling Weight Deflectometer (FWD)

Static Plate Loading Test (PLT)

In-situ moisture testing is also recommended if available. Soil samples are oftentaken from the test sites to perform moisture measurement, Proctor tests, and etc.When a padfoot roller is used for compaction, the compacted mate-rials should be carefully excavated down to the bottom of the pad tocreate a level surface for in-situ testing.

In-situ Point Tests


LWD

DCP

NG

FWD

PLT

ISU geotechnical mobile lab

DSPA BCD

PLT


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The Global Positioning System (GPS) is a location system based on satellite signals

and their ground stations. Depending on the quality of the receiver, the environ-ment, the type of measurements made, and how the measurements are processed,the positioning accuracy of GPS can vary from a few meters to below 1 centimeter,permitting a wide range of positioning applications from vehicle navigation to stud-ies of the motion of the Earth's tectonic plates.

GPS is used in the IC system to record the coordinates of rollers at each pass.However, there are several external sources that may introduce errors into a GPSposition including: atmospheric conditions, ephemeris errors/clockdrift/measurement noise, selective availability, multipath, and etc.

The IC systems normally use differential correction GPS (or DGPS) to improve ac-curacies. Differential correction requires a second GPS receiver, a base station,collecting data at a stationary position on a precisely known point (e.g., a surveyedbenchmark). With the known physical location of the base station, a correctionfactor can be computed by comparing the known location with the GPS location

determined by using the satellites. Then, the correction factor can be applied tothe GPS data collected by a GPS receiver in the field.

Recommended GPS requirements for IC are as follows:

RTK-GPS (Real Time Kinematic-GPS) system (radio and receiver) on IC rollers.

System reports and records values in Northing and Easting and vertical positionin meters in UTM coordinates for the project site.

If an offset is necessary between GPS antenna and center of drum, the IC sys-tem settings and GPS measurements have to be validated onsite.

Current RTK-GPS system for IC may require a GPS base station, though stand-alone systems are evolving to obtain desirable accuracy.

The Universal Transverse Mercator Coordinate (UTM) system provides coordinates,northings and eastings, on a world wide flat grid for easy computation. Therefore,UTM is normally used in the IC data processing. The Universal Transverse MercatorCoordinate system divides the Earth into 60 zones, each being 6 degrees longitudewide, and extending from 80 degrees south latitude to 84 degrees north latitude.The polar regions are excluded. The first zone starts at the International Date Line(longitude 180 degrees) proceeding eastward. Cautions should be taken when thearea of interest extends from one zone to another.

Under this IC study, the UTM zones are restricted in the US from zone No. 10 tozone No. 19. It is recommended that all in-situ test locations are measured usingportable DGPS systems and reported with the same UTM zone as IC data.

Global Positioning System (GPS)

Displays measurements

and Guides the Operator

Accelerometer on drum

Measures soil stiffness as an

indication of Soil Compaction

GPS Base Station =

Centimeter accuracy

GPS Records & Maps

The Compaction Results


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Case/Ammann IC padfootroller measures soil stiffness ksvalues for multiple passes. It

identifies localized wet areawith moisture content of about27% that could be not com-pacted.

Compaction curve (i.e. com-paction values vs. rollerpasses) can be effectively

established using the Case/Ammann IC padfoot roller.The curve is consistent withback-calculated mechanisticsoil properties from in-situtests such as LWD and DCP.

Soft spots (i.e. hard-to-compacted) and undergroundstructures can easily located

by the Case/Ammann ICroller.

Contribution of truck traffic tocompaction on aggregate

base is identified by the Cat-erpillar smooth drum IC roller.

The Caterpillar smooth drumIC measurements of CMV and

MDP on granular subgradeare found to be comparable.

Compaction with the Bomagsmooth drum IC roller were

evaluated using manual/automodes and track/GPS modes.

TX IC Demonstration

NY IC Demonstration

Comparison between the Sa-kai padfoot and smooth drumIC measurements indicatesthat they results are consis-tentwhich is very encourag-ing.

Production compaction usingthe Caterpillar padfoot ICroller successfully track com-paction levels of various ma-terials such as fat clay andlean clay subgrade.

KS IC DemonstrationCompaction curve for cohesivesoils using the Sakai padfootIC roller was established thefirst time according to thepast published literature.


US 69, Pleasanton, KS

Cohesive SG, and Ag-gregate SB

FM 156, Fort Worth, TX

Cohesive SG, StabilizedSG, and Aggregate SB

Distance(m)

0

20

40

60

80

100

120

140

160

180

Pass1 2 3 4 5 6 7 8

Lane

1

234

5

Localized

Wet Area

Cohesive

Subgrade

Pass

0 2 4 6 8 10

AverageELWD-Z2(MPa)

6

9

12

15

18

0 2 4 6 8 10

Averagew(%)

5

10

15

20

25

30

35

Pass

0 2 4 6 8 1

AverageCBR(%)

3

6

9

12

15

18

0 2 4 6 8 10

AveragekSIPD(MN/m)

8

10

12

14

16

18

20

Std. Proctor wopt

= 17.8%

CBR (%)

0 10 2 0 3 0 4 0 5 0 6 0

Depth(mm)

0

200

400

600

800

Point 13

CBR (%)

0 10 20 30 4 0 5 0 6 0

Depth(mm)

0

200

400

600

800

Point 12

DCPrefusal(BoxCulvert)

CBR (%)

0 10 20 3 0 4 0 5 0 6 0

Depth(mm)

0

200

400

600

800

Point 5

CBR (%)

0 10 2 0 3 0 4 0 5 0 6 0

Depth(mm)

0

200

400

600

800

Point 1

Point1

Point5

Point12

Point13

w =29.5%

d =13.8kN/m3

ELWDZ2 =11.6MPa

ELWDZ2 =58.4MPa

EV1 = 96.9MPa

EV2 = 381.1MPa

EFWDD3 =145 MPa

EDSPA = 88 MPa

w =20.8%

d =16.0kN/m3

ELWDZ2 =61.1MPa

ELWDZ2 =47.5MPa

EV1 =42.1MPa

EV2 =121.1MPa

EFWDD3 =57 MPa

EDSPA =44MPa

Box Culvert

Pass

0 2 4 6 8 10 12 14

CCV

1

2

3

4

5

6

7

Pass

0 2 4 6 8 10 12 14

E

LWD-Z2(MPa)

0

10

20

30

40

50

60

Pass

0 2 4 6 8 10 12 14

d(kN/m3)

10

12

14

16

18

20

Pass

0 2 4 6 8 10 12 14

CBR(%)

0

5

10

15

20

Values corrected usingw% values after Pass 1

TB 4Lane 3:a= 2.19 mm, v = 6 km/h,f= 26 Hz (High amp setting)

MDPfor Pass Number1 2 3

Elevation(Pass #3)

Elev. (m)

>245.67245.67

245.06

244.45

243.84

243.23

242.62

9

8

7

6

5

4

3

2

1

280m

Pass Number1 2 3MDP80

>140

135

130

125

120

1150

US 219, Springville, NY

Non-cohesive SG, andAggregate SB

CMVPass 2

a =0.90mm

CMVPass 3

a =0.90mm

200m

MDP40

Pass1Static

MDP40

Pass 2a =0.90mm

MDP40

Pass 3

a =0.90mm

MDP40

>145

140

135

130

125

120

CMV

>100

80

60

40

20

0

In-SituTest

Locations

(1)

(2)

(3)

(4) (5)

(6)

(7)

(8)

(9)

(10)

MDP40

>140

130

120

110

100

90

0

76m

CMV

>100

80

60

40

20

0

Passes>9

8

7

6

5

4

3

2

1

MDP40

Final PassPassCount CMVFinal Pass

Trucktrafficcontributing to

compaction

Trucktrafficcontributing to

compaction

Map1Manual

a=0.70 mm

Map2Auto

amax

= 1.90mm

Map5Lane3Manual

a =0.70mm

Map 6Lane 3Manual

a= 1.10 mm

Lane1

2

3

4

5

Map3 Lane 3Manual

a =0.70mm

Map 4 Lane 3Manual

a=0.70 mm

TrackModeGPS Mode GPSMode


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The effects of curing vs. timefor stabilized granular sub-grade can be monitored with

the Case/Ammann smoothdrum IC roller.

The unstabilized granularsubgrade compactabilitywere evaluated with both the

Caterpillar and Case/Ammann smooth drum IC roll-ers with consistent results.

Effects of time delay for com-pacting stabilized base mate-rials are being investigated

with the prelim results indi-cates that the delay of com-paction may reduce the drydensity.

The relationship amonginfluence or measure-

ment depths of variousdevices would affecthow correlation testsshould be conducted andanalyzed/interpreted.

Investigation of the influencedepths of IC roller compaction

and measurements vs. other in-situ point tests (e.g. LWD,DCP, NG, and BCD) are be-ing investigated.

Stay tuned for more resultsfrom the IC research team.

MS IC Demonstration

Influence Depth of IC RMVs and In-situ Tests

Range of measurementvalues

Machine operations(amplitude, frequency,speed) and rollerjumping

Non-uniform drum/soilcontact

Limited number of in-situmeasurements for corre-lation

Uncertainty in spatialpairing of point measure-ments and RMVs

Not enough informationto interpret the results

Measurement errors as-

sociated with the RMVsand in-situ point testmeasurements

Factors Affecting IC RMVsThere are many factors af-fecting IC roller-integratedmeasurements (RMV). It iscrucial to future harmonizationof IC RMVs and IC-basedacceptance specification tounderstand these effects thor-oughly.

Heterogeneity in under-lying layer support con-ditions

Moisture content varia-tion

US 84, Wayne County, MS

Non-cohesive SG, Aggre-gate SB, STB

ks

Amp.( mm)

Freq.(Hz)

Amp. Freq.

ManualMode - TB4Shortlyafterstabilization

ks Amp. Freq.

AFC Mode - TB9

After 2-day cure

ks (MN/m)

304m

ks Amp. Freq.

ManualMode - TB9

After 2-day cure

Static pass after vibratorycompaction pass

109.5m

MDP40

>140

140130

120

110100

2020

15

105

2


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Contact Victor (Lee) Gallivan, P.E. [email protected] Office of Pavement Technology, 575 N. Pennsylvania St., Indianapolis, Indiana 46204, (317) 226-7493

George Chang, Ph.D., P.E. [email protected] Transtec Group, 6111 Balcones Drive, Austin TX 78731. (512) 451-6233 extension 227

Research This TechBrief was developed by Dr. George Chang and Qinwu Xu from the Transtec Group. The project team alsoincludes: Dr. Robert Otto Rasmussen and David Merritt of the Transtec Group, Larry Michael of LLM Asphalt Consulting, Dr. DavidWhite of Iowa State University, and Bob Horan of the Asphalt Institute.

Distribution This TechBrief is being distributed according to a standard distribution. Direct distribution is being made to FHWAsfield offices.

Availability This technical brief is freely available from the FHWA DTFH61-07-C-R0032 research project team Accelerated Im-plementation of Intelligent Compaction technology for Embankment Soils, Aggregate Base, and Asphalt Pavement Materials. Thegoal of this technical brief is to better inform the public about this study.

Key Words compaction, intelligent compaction, roller, soils, subgrade, aggregate, embankment, stabilized base, asphalt, HMA,pavement performance, quality control, quality assurance.

Notice This TechBrief is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of infor-mation exchange. The TechBrief does not establish policies or regulations, nor does it imply Federal Highway Administration(FHWA) endorsement of any products or the conclusions or recommendations presented here. The U.S. Government assumes noliability for the contents or their use.

Quality Assurance Statement FHWA provides high-quality information to serve Government, industry, and the public in a man-ner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility,and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure con-tinuous quality improvement.

Benefits of

Intelligent Compaction

Improve Densitybetter performance

Improve Efficiency

cost savings

Increase Information

better QC/QA

Validation of the IC Global Positioning Sys-

tem (GPS) setup prior to the compaction

operation using a survey grade GPS hand-

held unit is crucial to providing precise and

correct measurements.

To correlate in-situ tests with IC data prop-

erly, in-situ test locations must be estab-

lished using a hand-held GPS rover unit

that is tied into the project base station and

offers survey grade accuracy.

Use of IC RMVs can be as part of intelligent

QC/QA. Further study on linking IC RMVs to

mechanistic QA parameters in top 1~3 m

are strongly recommended.

Standardization is strongly recommended to

accelerate the implementation IC for State

agencies: a standard IC data storage for-

mat, an independent viewing/analysis soft-

ware tool, and detailed data collection plan

Recommendations

ic tech brief soilsic v3b

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