new light-weight device for measuring degree of compaction

New light-weight devicefor measuring degree of compactionand dynamic load bearing capacity

Zoltaacuten TOMPAI assistant lecturer

Department of Highway and Railway EngineeringBudapest University of Technology and Economics

Budapest ndash Hungary

lsquoLight-Weight Deflectometers ndash Experience and Best Practisersquo - Loughborough 18 April 2007

Zoltaacuten TOMPAI Department of Highway and Railway Engineering Budapest University of Technology Hungary 2

New light-weight device for measuring degree of compaction and dynamic load bearing capacity

Introduction

In-situ assessment of earthworks and subgrade materials in Hungary

1) Degree of compaction

ndash

ndash rarr modified Proctor-testndash In-situ testing rarr nuclear density test

Generally prescribed values 85 90 95 sometimes 97 ()

2) Bearing capacity

ndash (still exclusively) static plate load test (E2)

Generally prescribed values - 20-25 Nmm2 on subsoil- 55-60 Nmm2 under pavement structure

[]ρρT

maxd

drρ =

maxdρ



Introduction

Pavement design

bdquoCatalogue designrdquo

based on

- Type of subgrade material- Thickness of base course layer- Traffic data

(number of passing axle load)

Assuming that the required bearingcapacity of subgrade is reached



Development of a new light-weight device

BampC(bdquoBearing capacity and Compactionrdquo)

Developed by

ANDREAS Ltd(Hungary)

Mr ISTVAacuteN SUBERT

andreasandreashuwwwandreashu




Basic similaritiesbull Same applied dynamic load (707 kN)bull Same load pulse time (18plusmn2 ms)bull Calculation of bdquoclassicalrdquo dynamic

stiffness modulus(from the 4th 5th and 6th drops)

Basic differencesbull Plate diameter D = 163 mmbull Selectable Boussinesq plate coefficient

(p2 ndash rigid 2 ndash flexible)

bull Selectable Poissonrsquos ratio(03 ndash granular solis 04 ndash fine grained soils siltyfine sands 05 ndash clayey cohesive soils)

bull Calculation of bdquoterminal dynamicstiffness modulus (characteristic to thecompacted state of the layer) (from the last 3 drops of total 18 drops)

bull Calculation of relative and final degreeof compaction

copyZO

RN

LFWDBampC



Basic theoretical background

1 LFWD rarr Boussinesq plate coefficient set to 2 (flexible)rarr Poissonrsquos ratio set to 040 (bdquoaveragerdquo)

- Allows free selection of these parameters

2 Dynamic load of 707 kN + Load pulse time of 18plusmn2 ms + Plate diameterof D = 163 mm- Contact stress of 030-035 MPa- Calculation of dynamic stiffness modulus (Ed) close to the magnitude

of the static moduli

3 Calculation of bdquoRelative degree of compactionrdquo- 18 drops applied rarr calculation of bdquocompaction curvesrdquo- Applying same compaction work on site as the modified Proctor-test

(at a given moisture content)

bdquoRELATIVE DEGREE OF COMPACTIONrdquo (Tre )(ie generating a single point of the Proctor-curve on site)

Showing the actual compaction at the given field moisture content

(95 relative degree of compaction means that more rolling should be applied to reach100 compaction at the current moisture content)




4 - wopt ndash optimum moisture content rarr 100 degree of compaction- adjust the relative degree of compaction to the optimum

moisture content

- bdquoMOISTURE CORRECTION COEFFICIENTrdquo (Trw)(one point of the bdquonormalizedrdquo Proctor-curve)

Moisture Correction Coefficient Curve

- more Proctor points(min 7 or 8)

- curve fitting forapplicable equation

Mcc Earthwork fine sand M7 y = -00016x2 + 00292x + 08666R2 = 09586

080

085

090

095

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

w

Trw

lt=1

000

)001(ρρ

Tmaxd

idirw le=




5 Measurement of the moisture content of the layer on site(with conventional drying method or by a calibrated electronic device)- Calculation of the moisture correction coefficient

6 Calculation of the bdquoDYNAMIC DEGREE OF COMPACTIONrdquo (Trd)

Identical to the Degree of Compaction measured by conventionalmethods

(Mathematically proven + strong correlation found based on field measurements)

BasisProctor-method rarr volume of wet soil is constant (moisture content is changed)

darrBampC method rarr dry weight of soil is constant (moisture content is changed)

wopt rarr height of the compacted soil cylinder is the lowestthus the degree of compaction is the highest

difference in cylinder heights = diference is settlements on site (if the applied work is the same)

)T(TTT rρrerwrd =sdot=

Tre



Interpretation and applicability of results

BENEFITS

ndash Calculation of the bdquoterminal stiffness modulusrdquo (Edv) whichcharaterizes the layer after compaction(calculation of stiffness before and after compaction rarr correlation to staticmodulus E2 )

ndash Inmediate information on the effectiveness of the compaction(Can the layer be compacted more at the given moisture content)

ndash Moisture content of the layer + Proctor-curve of the materialrarr Can the prescribed degree of compaction be achieved

at all (need of dehydration or watering)

ndash Accuracy plusmn2-3 (nuclear method plusmn5-6 )

ndash bdquoTwo-in-onerdquo(measurement of bearing capacity and degree of compaction)

ndash No nuclear izotopes environmental friendlyndash Cheap and fastndash Easy to use




Correlation to static stiffness modulus

- M7 Highway ndash medium sand sandy gravel

for dynamic stiffness modulusE2 = 891Ed052 (r = 087)

for terminal dynamic stiffness modulus E2 = 647 Edv056 (r = 084)

or E2 asymp 076 divide 092 Edv (significant scatter)

- M6 Highway ndash furnace slag (recycled material few measurements)

E2 = 144Ed (r = 097)

- Road nr 4 near Albertirsa ndash silty sand chrushed stone stabilization

E2 = 112Ed (r = 065)

Hungarian experiences with LFWD E2 asymp 145 divide 202 EdM (r = 080-084)

Austrian experiences with LFWD E2 asymp 173 divide 202 EdM (r = 069-076)



Future prospects

ndash Possible application and introduction of the theory inbdquoContinous Compaction Controlrdquo

ndash Introduction of new parameters in quality control ofearthworks

ndash New classification for unbound granular materialsin Hungary

ndash Review of the required degree of compaction values(85 90 95 97 ) in Hungary

ZOLTAacuteN TOMPAIassistant lecturer

Budapest University of Technology and EconomicsDepartment of Highway and Railway Engineering

Hungary

Tel +36-1-463-2923Fax +36-1-463-3802

Mobile +36-30-3664-663E-mail tompaiuvtbmehu

THANK YOUFOR YOUR ATTENTION


New light-weight devicefor measuring degree of compactionand dynamic load bearing capacityZoltaacuten TOMPAI assistant lectur

Introduction

Introduction








Future prospects




Introduction

In-situ assessment of earthworks and subgrade materials in Hungary

1) Degree of compaction

ndash

ndash rarr modified Proctor-testndash In-situ testing rarr nuclear density test

Generally prescribed values 85 90 95 sometimes 97 ()

2) Bearing capacity

ndash (still exclusively) static plate load test (E2)

Generally prescribed values - 20-25 Nmm2 on subsoil- 55-60 Nmm2 under pavement structure

[]ρρT

maxd

drρ =

maxdρ



Introduction

Pavement design


based on








Developed by














copyZO

RN

LFWDBampC

















moisture content






080

085

090

095

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

w

Trw

lt=1

000

)001(ρρ

Tmaxd

idirw le=













Tre




BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects




Introduction

Pavement design


based on








Developed by














copyZO

RN

LFWDBampC

















moisture content






080

085

090

095

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

w

Trw

lt=1

000

)001(ρρ

Tmaxd

idirw le=













Tre




BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects






Developed by














copyZO

RN

LFWDBampC

















moisture content






080

085

090

095

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

w

Trw

lt=1

000

)001(ρρ

Tmaxd

idirw le=













Tre




BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects












copyZO

RN

LFWDBampC

















moisture content






080

085

090

095

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

w

Trw

lt=1

000

)001(ρρ

Tmaxd

idirw le=













Tre




BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects


















moisture content






080

085

090

095

100

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

w

Trw

lt=1

000

)001(ρρ

Tmaxd

idirw le=













Tre




BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects














Tre




BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects





BENEFITS

















E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects











E2 = 144Ed (r = 097)


E2 = 112Ed (r = 065)





Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects




Future prospects







Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects




Hungary

Tel +36-1-463-2923Fax +36-1-463-3802





Introduction

Introduction








Future prospects


new light-weight device for measuring degree of compaction

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