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COMPARISION OF DIFFERENT SOIL

COMPACTION TEST METHODS

Andrus Aavik, D.Sc. (Tech.)

Department of Transportation

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Introduction

Currently the quality control of embankment construction isdetermined by the Technological Requirements for Road Worksestablished with the Decree of the Ministry of Transportation andCommunication of the Republic of Estonia.

The Technological Requirements are not determining specific testmethods which can be used for determination of the soil compactioncoefficient.

The main objective of the research project was to compare differentsoil compaction test methods: core testing with the cutting ring and penetration with the

BELDORNII penetrometerwith determination of the compactioncoefficient and E-modulus and compaction factor determination with the

LOADMAN and INSPECTOR devices.

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What is compaction?

Compaction is the reduction in the void ratio on a soil bymechanical means (rolling or tamping) at constant moisture.

It is not possible to remove water from the voids by compaction, butthe addition of water to a slightly moist soil facilitates compaction byreducing surface tension.

There is an optimum moisture content which can be determined in

laboratory using the Proctor test and above which the addition ofwater causes an increase in voids.

Compactness of the embankment can be characterized with thecompaction coefficient (Kc) which is the ratio of actual dry density of the soil sample () and maximum dry density of the same soil at the optimum moisture

content (o) determined with the Proctor method:

Kc=/ o

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What is compaction?

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Soil Compaction Test Methods

There are 6 main on site compaction test methods: Core test using cutting ring; method is not suitable for coarse

grained soils; Sand replacement (sand cone test) method is precise and is

used for calibration of compaction meters with radioactiveisotope; inaccurate in porous soils;

Rubber balloon similar to the sand replacement test but

instead of sand the rubber balloon is used to fill the hollow in thecompacted layer; Nuclear gauge (compaction meter with radioactive isotope)

problems can occur when testing crushed stone and calcareousmaterials, needs to be calibrated;

Plate bearing test suitable for gravels and crushed stone;time-consuming; Penetrometer (dynamic or static) suitable for fine (sandy)

soils; fast results.

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Soil Compaction Requirements

Estonian Highway Design Norms are determining that the

compactness of the road embankment, characterized with the

compaction coefficient, has to fulfill the following requirements:

Comments:

Hp thickness of the pavement structure, m.

Subgrade of the embankment in low fill, in 0-profile or in cut has to be compacteduntil the compaction coefficient values presented in the first row of the table.

Wet zone type description is provided in the Highway Design Norms

Minimum values of the compactioncoefficient Kcfor different pavement typesLayer of the embankment orwet zone type

Depth h from thepavement surface,

mPermanentpavement

Light or transientpavement

Active zoneh< Hp+ 0,5

Hp+ 0,5 h < 1,5

1,000,98

0,980,95

Wet zone type I h1,5 0,95 0,95

Wet zone type II and III h1,5 0,98 0,95

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Scope of the Research

Current research covers experimental determination of the changeof granular sandy soils (4 types) density during compaction.

Measurements were performed with INSPECTOR and LOADMANdevices and recording the measured E-modulus values.Based on those compaction factors (T) were calculated.

Parallel to the INSPECTOR and LOADMAN measurements theBELDORNII penetrometer and core testing (with cutting ring) wereused for determination of the compaction coefficients (Kc) of samesoils at the same stage of compaction.

The main objective of the research project was to find thecorrelation between the compaction coefficients (Kc) andcompaction factors (T).

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Main Results of the Research (1)

Compaction coefficient values (Kc) determined with the core testand penetrometer test are almost equal (Fig.).

The compaction coefficient determined with the core test is about

1,2 % higher than the compaction coefficient determined with the

penetrometer.

y = 1,012x

R2= 0,5622

y = 0,9484x + 0,0602

R2= 0,5647

0

0,2

0,4

0,6

0,8

1

1,2

0,82 0,84 0,86 0,88 0,9 0,92 0,94 0,96 0,98 1 1,02

Com paction coefficient determ ined w ith penetrom eter

Com

pactioncoefficientdetermined

withcoretest

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Main Results of the Research (3)

Relationship between the compaction factor values (T) of sandy soilcalculated based on the INSPECTOR and LOADMANmeasurement data and the compaction coefficient values (Kc):

Using INSPECTOR:Kc = -0,1264*TI+1,1449,

where: Kc - compaction coefficient;

TI - compaction factor determined on bases ofINSPECTOR measurement data.

Using LOADMAN:Kc= -0,1537*TL+1,1712,

where: Kc - compaction coefficient;TL - compaction factor determined on bases of

LOADMAN measurement data.

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Main Results of the Research (4)

The value of the compaction factor (T) equal to 2 which is takenover from Finnish requirements and indicating that the layer of a

sandy soil has reached the required density, is not correct: using LOADMAN the compaction factor value 2 equals to the

compaction coefficient value 0,86 and

using INSPECTOR the compaction factor value 2 equals to thecompaction coefficient value 0,89.

Both compaction coefficient values are not satisfying the minimumrequired compaction coefficient value of embankment equal to 0,95.

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THANK YOU FOR YOUR ATTENTION!