Mérnökgeológia-Kőzetmechanika 2015 (Szerk: Török Á., Görög P. & Vásárhelyi B.)

oldalak: 379 – 394

CWA15846:2008 módosítási javaslat és főbb háttértanulmányai

CWA15846:2008 Modification Draft and Main Background Studies

István Subert MSc Civil Engineer, MSc Economic Engineer, CEO Andreas Ltd, Hungary e-mail: andreas@andreas.hu

ÖSSZEFOGLALÁS: CWA15846:2008 (dinamikus tömörség- és teherbírás mérés) javasolt

módosítása héttér vizsgálatokat igényelt az elmúlt nyolc év mérési tapasztalatainak figyelembe

vételével. Az Európai egyetemeken végzett mérési verifikációkat és szakértői véleményeket

megvizsgáltuk - bevonva azokat, illetve háttérelemzések eredményei alapján kiegészítő javaslatokat

dolgoztuk ki a dinamikus tömörségmérés vizsgálati szabványához. Ily módon lehetővé vált a

módosítás tervezet elkészítése a felmerült kérdések elemzése a beérkezett észrevételek

feldolgozásával. A fontos talaj-jellemzők meghatározására kifejlesztett első szabályozást CWA15846-

WS33 munkabizottság készítette el 2006-ban az Andreas előkészítésében. Az alkalmazott tárcsa alatti

terhelés 0.35MPa jelentősen eltér a korábban alkalmazottaktól (pl német mérési mód TP BF-StB Part

B8.3) így nem csak a dinamikus modulus, hanem a dinamikus tömörségi fok meghatározására is

alkalmas a tárcsa elmozdítása nélkül végrehatott 10-18 ejtéssel. Meghatározható egy süllyedési-

alakváltozási görbe az LFW terhelési módszert alkalmazva, így a vizsgálat egy helyszíni Porctor-

tömöríthetőségi vizsgálatot szimulál. Jelen cikkben összefoglaltuk mindezen mérési- tapasztalatokat és

a háttérvizsgátokat és javaslatokat a CWA15846:2008 véglegesítéséhez, egy EN szabvány eléréséhez. Kulcsszavak: Dinamikus tömörség- és teherbírás mérés, SP-LFWD kistárcsás könnyűejtősúlyos mérőeszköz, tömörség és teherbírás mérés egy méréssel, CWA15846, környezetbarát mérőeszköz laboroknak, kivitelezői önellenőrzés.

ABSTRACT: The modification draft of the CWA15846:2008 (dynamic compactness- and bearing

capacity measuring method) needed background investigations, which based on the test experiences

gained in last eight years. The verifications of the test – made by European Universities and foreign

experts in this theme - also needs deep investigations, to solve or to involve the addition of this

dynamic compactness test standard. On this way we can finished and working our suggestion for the

CWA modification draft, with analyzing the questions and incoming comments.

The theory determines this important soil parameters developed and prepared in the first regulation

CWA15846-WS33 in 2006, prepared by Andreas. The applied loading under the disc is 0.35 MPa is

very different from the earlier (e.g.TP BF-StB Part B8.3 German test method), thus suitable measuring

not only the Ed module but the dynamic compactness-degree also, calculated from the deformation-

settlement curve, gained from 10-18 drops of weight without moving the plate. On this way can be

determined the settlement curve - using the LFW loading system - so this test simulating on-site

compatibility Proctor test. In this article we summarized all the test experiences and background

investigations results, finalization the CWA15846 to reach an EN Standard from this. keywords: Dynamic compactness-test, isotope-free SP-LFWD small plate light falling weight compactness measurement device, compactness- and bearing capacity measuring with one test, environmental friendly equipment for laboratory, CWA15846, environmental laboratory test, Contractor’s self-checking.

1. INTRODUCTION

The most important quality parameters of the building of earthworks, of building materials of railway,

roadway, base of industrial buildings, waterway embankment structures is the compactness-rate and

bearing capacity, which can be measuring by CWA15846:2008 in one test. All European regulations

treat the limiting values necessary for avoiding the settlement after compacting, reduction of the water

penetration, near the necessary bearing. The compactness degree traditionally is a quotient of the dry

bulk density and the dry reference density, expressed in percentage. Totally new direction and method

can be considered in the CWA 15846 Standard SP-LFWD (Small-Plate Light Falling Weight

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380

Deflectometer) equipment, with the analysis of the compaction curve taking shape in the course of the

drops. The widespread nuclear (isotope) density test measurement method is cannot applicable in the

future. Not an environment friendly and not a SMEs-friendly test method. The CWA15846:2008

Measuring method for Dynamic Compactness & Bearing Capacity with SP-LFWD (Small - plate

Light Falling Weight Deflectometer test gives the only solution. Near the qualification tests, the self-

control concept of the ISO is important also, the contractors have not had any opportunity until now

for self-checking. Only the laboratory was able to qualify their earthwork - ex post and not during the

construction. The quality of earthwork is feasible with avoid the settlement. Immediate, in-situ

monitoring (e.g. the limy-mix stabilization work) is possible using BC2 device solely, applying this

Standard test.

2. TRADITIOLAL TEST METHODS IN EUROPE

There are traditional compactness on-site test all over the world, which based on the ratio of dry field

density and reference (e.g. modified Proctor) maximum dry density.

2.1. Nuclear Density Test

One of the most widespread measurement procedures (ASTM D6938), a detector observes the

gamma-radiation; and the number of the impulsions counted under the measurement time is

proportional to the wet density of the soil. Plane probe and pin probe measurements happened as well.

For the determination of the compactness degree is needed also the value of the water content and the

reference density, to which the field dry density is compared. In Europe characteristically according to

the EN 13286-2 modified- (on German areas still the simplified-) Proctor dry density in use. The

examination time is 15-25 minutes and it is necessary to make three different directions and average it.

Two laboratory technicians is the staff requirement. The measurement accuracy is high +/-5-6 Trd%

2.2. Sand-Cone method

The principle of the measurement (ASTMD4914) is that the soil sample taken out with the chisel, a

spoon, is substituted for sand, to define the volume. Onto the surface they put the circle disk slot

scheme, it is taken out carefully through its slot then, and wet mass and water content are measured.

Filled up with dry sand, can be calculated the volume. From the received field density it is - taking the

reference density into consideration - the compactness-rate. The examination time of the sand filling

method is more than 30 minutes on site; one laboratory technician is sufficient.

Picture 1. Isotopic compactness test Picture 2. Sand-Cone test

2.3. Tube sampling

This method is a well-known old measurement, but its accuracy according to certain estimations is

similar to the isotopic measurement. The mass of the substance staying in the cylinder, the value of the

water content are needed for the determination of the field density, and then the relation of the dry

field density calculated in this manner and the ratio with the reference density gives the compactness

degree. We are aware of a comparative measurement on a flying ash filling on the motorway M35 in

Hungary. The density-corrected values of the B&C measurement were some percentages lower, than

the tube sampling results (see later).

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2.4. Portancemetre-method

This is a French instrument for continuous measuring of the load bearing capacity of the earthwork

towed with a vehicle. The entire measurement can be commanded from the driver's cabin, where the

data collecting and processing system receives placed. The wheel with a vibratory load, the perceptive

framework of this are hanged on the frame of the trailer. The measurement velocity is 1m/sec. The

great advantage of the examination is that it is continuous, in 30 minutes 1.800 metres are measurable

on the site. A laboratory technician and a leader are sufficient for the measurement. As a parallel

examination they measure backwards and forwards on a trace beside each other.

Picture 3. BP-LFWD and SP-LFWD test Picture 4. Portancemetre test method

2.5. SP-LFWD dynamic compactness measuring method: CWA15846:2008

This is a 2nd

generation test using light falling weight loading system, near p=0.35Mpa under plate

press, D=163mm diameter of the rigid plate, named small-disk. It generates a compaction curve, in

that manner, that we drop the falling weight from 10 to 18 times from a given altitude with a 10kg

weight using even a stabile flexible behaviour artificial gum or steel-disc damper. From the series of

the fall amplitudes defined the compaction curve and from the weighted settlement differences gives

the on-site relative compactness degree, beside the given field water content (TrE%).

The dynamic compactness-rate (Trd%) is the multiplication of this on-site relative compactness

degree (TrE%) and the moister correction coefficient (Trw). The moister correction coefficient taking

the effect of the moistness into consideration characterizes the proctor-compactness of the soil

depending on the field water content (Trw<=1,00). The +/-1TrE% measurement accuracy of the quick

test enables the correction of the efficiency of the quality control, the fair quality attestation. The

measurement is very quick (one minute), needs only one technician, and forms an average with a

parallel test measurement. The method is independent of the density (only depending on rate of

densities) ; therefore it is suitable for the measurement of any type of laying materials, even of the very

low density flying ash, or of the inhomogeneous density blast furnace slag, suitable for test of limy

(calcareous) stabilisations, which unable to test with isotopic method. Furthermore the B&C near the

dynamic compactness-degree at the same time determines also the dynamic load bearing capacity

modulus Ed (MPa) of the soil. A parallel test is applied – as the CWA15846 standard required.

2.6. Continuous Compaction Control (CCC) – Large surface compactness test method

For compactness and load bearing capacity measurement of large surface compactions, which

developed by Prof Brandl, Prof Kopf and Prof Adam for the qualification of large surface earthworks.

Comprehensive comparative test series involving also the nuclear (isotope) density tests, that they

performed already in the 1970s showed, that nuclear method has several weak points. Therefore, this

method was hardly used any more in Austria (from about 1980 on). The German-LFWD (TP BF-StB

Part B8.3) dynamic load plate test has proved very well, also for the calibration of CCC. This roller-

integrated method has been obligatory in Austria for all earthworks (e.g. roads and highways,

railways, dams and dykes, waste deposits, soil exchange, etc.) since about 15 years. With the

accelerometer fixed on the roller from the changes of the measured amplitudes can be determine the

Evib modulus and the Omega index-number. The measurement gives a three dimension table result,

which identifies with colour codes the for the compactness typical measurement results. It was related

to the compactness degree already in an experiential way.

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382

We have to remark that the studies of the Geotechnical Faculty of the Technical University Slovenia

manifested an outstandingly good correlation (R2=0,92) between the CWA15846 draft B&C dynamic

bearing capacity (Ed) and the value of the CCC Evib also.

Picture 5. CCC - Large surface compactness test (Evib and Omega)

2.7. Compactness - determined from static bearing modulus ratio E2v / E1v

The Plate Load test bearing capacity can be examined according to the static plate examination

traditional (used also in Hungary) near D=300mm (e.g. ASTM D1194) or D=600mm French standard

(NF P 94-117-1). The ratio of two E module (second / first uploading) shows the compactness-

coefficient known as a related parameter with the compactness. The uploading sections and the

valuation of the standard measuring methods differ in some points from the one accustomed in

Hungary MSZ 2509-3 (CEN ISO/TS 22476-13). One examination time is 25-35 minutes on the site,

one technician is sufficient for the measurement. For the loading a counterweight (e.g. roller) is

necessary. Parallel examination is not applied.

2.8. BP-LFWD Light Falling Weight Devices

The application of dynamic load measurement methods has spread all over the world very quickly.

The method does not require any counterweight, and the measurement is much quicker in comparison

to the earlier static method. It has enabled a measurement of the same modelling impact as the

effective dynamic traffic loading, on the one hand, and the application of a more accurate and reliable

(e.g. more just and economical) qualification mode, on the other hand. Furthermore, it has increased

the efficiency and the reliability of the quality control of pavements, earthworks and other granular

substance layers. (Dynatest, KUAB, German LFWD, HMP, Loadman)

As it is known, from the measurement result of the D=300mm disk diameter Big-Plate Light Falling

Weight Device the s/v (deflection/velocity) quotient somehow represents the compactibility also. The

appliance of the LFWD type devices (Zorn, HMP) is widespread in Europe for the determination the

load bearing capacity, at which from a given height drop a 10kg mass body. This creates only pdin=0,1

MPa press under the plate (TPBF-StB8.3, RVS 08.03.04), near using c=2 Boussinesq plate-multiplier

(flexible) and 0.5 (clay) Poisson-ratio (from this C=22,5) and Evd = 22,5/s (N/mm2). The average

settlement amplitude (s) must be determined of the second series (from 4-5-6 drops).

In the extension of the CCC method Professor Bradl-Kopf-Adam suggested to use this method as a

very informative, pre-calculated calibrated test.

The examination time is 2-4 minutes on site; one laboratory technician is sufficient for the

measurement. Parallel examination is not applied.

2.9. GeoGauge method – for determine the variability stiffness

For load bearing capacity feature’s determination suitable applied the GeoGauge electromechanical

method (ASTMD 6758 – 02). The instrument recommended for the measurement of granular materials

without cohesion, and for the analysis of slightly muddy and clayey substances, that are not exposed to

the change of the moisture content. The main disadvantage of the method is that vibratory load of the

workplace (running roller) can disturb the measurement result very easily. According to our

knowledge the compactness cannot be characterised, but from the load bearing capacity it is possible

to deduce the suitability based on the test compaction. The examination time is 10-15 minutes per site,

one laboratory technician is sufficient for the measurement. A parallel examination is not applied.

CWA 15846:2008

383

Picture 6. Static PLT test D=600mm, Picture 7. Humboldt H-4140 Geogauge device

On the invitation of the Geotechnical Faculty of the Technical University of Portugal Professor

Correia, on a test section - beside this above mentioned tests – Andreas Ltd may have been also tested

with the CWA15846 Dynamic Compactness and Bearing Capacity Test device in Evora (Portugal) -

with many thanks on this way also.

3. THE BASIC THEORY OF DYMANIC COMPACTNESS-RATE

TrE% - on site relative compactness rate (near natural field-water content)

This is the measured test value using the CWA15846 SP-LFWD device, which represents the roller

work effectiveness, independently from the optimum water content, near the given field-water

(1)

where comes from the modified Proctor test regression, and 1,25 is the rate of

Picture 8. Introduction the dynamic compactness measurement’s theory

CWA 15846 requires control the value from the Proctor laboratory test results. If the value and

difference higher than the given limit, the measured real value must use in the calculation. (There

wasn’t such as cases in our practice). The chosen value is *.

Trw%=0,97%

Proctor TrE%=100%

Trd%= TrE%*Trw=96,0x0,97=93,4%

B&C measurement TrE%=96,0%

wopt=Trw%=1,00

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Moister Correction Coefficient (Trw)

To get the Compactness-rate one can transform the TrE% in-site relative compactness to the optimum

water content. To do this, one can use the normalized Proctor-curve, the dry density near the given

water content divided by the maximum dry density. This can define easily from the Proctor test.

Dynamic Compactness Rate (CWA15846:2008 SP-LFWD)

Multiplying the TrE% in-site relative compactness rate (near natural field-water content) and the

to transform on optimum water content.

and (2)

4. STUDIES ABOUT CORRECTIONS

4.1. Dynamic modulus correction due to Law of Impulse

All of measured dynamic modulus should be corrected depending on soil density. Correction must be

done for Ed only, it has smaller effect on TrE%. Correction must only be done in case fly-ash, slag or

other high-density materials:

Ed KORR = Ed *K where K= 1.766/ (dmax*1/(1+wopt)) (3)

All dynamic (falling weight) measurements use the act of impulse in order to create a loading on the

surface of the earthwork. The links and the weights thereof are known. The purpose of this essay is to

make statements as regards possible consequences of the density variation of soil, by looking at and

analysing these links, and by revealing the potential correlations thereof. Only the CWA15846 SP-

LFWD is, that applies an alternative Poisson’s ratio (=0.3-0.4-0.5 or others), which is closer to the

measured type of material, as well as with an optional plate multiplier (c=2 or /2) (because of that:

C= is not constant):

a

din

ds

rpcE

)1( 2 (4)

4.1.1. Impulse transmitted to the soil, or a granular layer

The final side of the impulse is the soil layer which compacts by the impulse transmitted by the plate;

it moves downwards. The soil, depending on its flexibility, generates a recoil motion towards the plate

which is reduced by the energy put on the deformation. One part of the energy will be consumed by

the remaining deformation, and this is the reason why the recoil motion can never reach the typical

value of the infinite rigid modulus, e.g. h=v2/2g. The difference in height, measured in comparison to

this, is at the same time proportional to the absorbed energy, and the latter is proportional to the

deflection (settlement) under the plate.

Deformation under the plate results in volume contraction and the increase of density. The subplate

area and the effective depth are constant, the thusly determined volume can be considered as standard.

The soil density to be observed by the act of impulse can be easily calculated by the measurement

theory of CWA15846. The density is directly proportional to compactness (the smaller the

compactness is, the smaller the density will be), and it is directly proportional to water content (the

lower the humidity is, the lower the density will be).

It follows from this that the soil density under the plate at the time of the measurement is:

100

%1

100

%Pr

wTrEn (5)

where: w% water content during measurement

ρPr the highest dry density according to the Proctor-test, Section 7.4 of EN13282-2

%rET the on-site relative compactness of the tested layer at a given water content

Since the subsoil can be of different types and the water content may differ, too, values of the recoiling

- and of the deformation measured under the plate - will also depend thereon. Accordingly, the

measured deflection amplitude will include the impact thereof.

The principle question is whether this measured value has to reach the qualifying limit values of

bearing capacity and compactness, or the measured value has to be fulfilled “irrespective of the

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385

material”. Obviously that a given general qualifying limit values, not handle them depending on the

material.

4.1.2. Correction of the Ed dynamic modulus

Calculation of the dynamic modulus (formula 4) occurs on the basis of the measurement of the “s”

deflection amplitude. If the density of the measured material changes, then so does the deflection

amplitude, and accordingly, the dynamic modulus, changes too. This means that the dynamic modulus

is proportional to density, which, at the same time, depends on the compactness and the density

furthermore the water content of soil.

Correction factors calculated in Table Nr. 1-2. shows, that the measurement result Ed=40 MPa

looks as follows for materials included in the examination the series, by order, includes fly-ash, fine

sand, silty sand and gravel, after corrections due to compactness and water content.

Table Nr. 1. Standard qualifying dynamic modulus of tested materials in case of a basis of Ed=40 MPa

We calculated the relative ratios from the measured values. We indicate this as a typical range for

actually tested cases (which is valid for materials with a variation of both extreme and non-extreme

densities) in Table Nr. 2.

Table Nr. 2. Typical relative variation of the extreme values of tested materials

for all the four tested materials Average 100%

Min 74%

Max 148%

Standard deviation 21%

for reference base and silty sand Average 100%

Min 86%

Max 116%

Standard deviation 8%

By summarizing the analysis on dynamic modulus, it can be stated that by examining materials of

extreme densities (that are used in the construction practice), the correction factor of the dynamic

modulus will modify the modulus value measurably, and the correction factor will have a value

between 1.69 and 0.84 (!). Correction cannot even be avoided in case of a smaller density variation

and an allowable range of water content, which shows a relative variation of -14% to +16% in a

compactness range of 85-100%, and accordingly, in the whole measurement practice. Based on the

above mentioned every measured dynamic modulus would be corrected in every case in order to

enable a correlation thereof with the limit values, because the variation might be considerable. The

correction thereof is usually calculated as follows:

%

100

1

1

22

11

rEE Tw

w

(6)

If we want to determine dynamic bearing capacity exactly, then conclusions and correlations can not

be considered acceptable without correction.

It’s only natural that statements made here are to be adapted to all dynamic deflectometers, such as the

big-plate LFWD and FWD-s (Dynatest, KUAB...). By the correction there of (by introducing the term

’qualifying dynamic modulus’) significant progress can be made by the review of correlations.

Accordingly, it can be stated that the exact value of the dynamic modulus cannot be determined

without the knowledge of soil density (compactness rate, water content and dry Proctor-density).

Edmin qualifying, standard value: Ed measured = 40MPa* correction factor Substance

65.9 67.5 64.4 62.3 63.8 60.8 59.0 60.4 57.6 56.0 57.4 54.7 Fly-ash

47.1 48.4 45.8 44.4 45.7 43.2 42.1 43.3 41.0 40.0 41.2 38.9 Sa, Basis

43.5 44.7 42.4 41.1 42.2 40.0 38.9 40.0 37.9 37.0 38.0 36.0 saSi

40.8 42.0 39.7 38.6 39.7 37.5 36.5 37.6 35.5 34.7 35.7 33.7 Gr

wopt% -3% +3% wopt% -3% +3% wopt% -3% +3% wopt% -3% +3% w (m%)

TrE%=85 TrE%=90 TrE%=95 TrE%=100 TrE%

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4.1.3. Correction of the dynamic compactness rate

Based on the previous train of thought, the measured deflection amplitude can also be corrected due to

the variation of the values of water content and density. Since in the calculation of the relative

compactness rate we take the deflection amplitude differences into account, their effects have to be

different as well. The situation is different in case of a correction due to the variation of water content,

because there will be only a small change in the value of Trw around wopt.

We performed analysis of the dynamic compactness rate for materials which had been selected

for the present test. These are presented in Table Nr. 6. Here, the multiplier can be transposed before

Dm in the formula.

mrE DT 100% and rwrErd

TTT %% (7)

From the chosen materials we selected data series for examination. Here we examined how the

calculated on-site relative compactness rate will change by a chosen continued proportion, e.g.

0.85–0.9–0.95–1.0–1.05–1.1–1.15, beside a correction factor that reckons with the impact of water

content and density (Formula 8). Based on the above mentioned, the density and water content

correction will be as follows:

22

11

1

1

w

w

(8)

Table Nr. 3 - Sensitivity of TrE% to the correction of density

TrE%

56th

measurement

62nd

measurement Variation

56th

measurement

62nd

measurement

0.85 95.8 92.0 90.3 -0.15 0.70 1.40 1.70

0.90 95.6 91.6 89.7 -0.10 0.50 1.00 1.10

0.95 95.3 91.1 89.2 -0.05 0.20 0.50 0.60

1.00 95.1 90.6 88.6 0.00 0.00 0.00 0.00

1.05 94.8 90.2 88.0 0.05 -0.30 -0.40 -0.60

1.10 94.6 89.7 87.4 0.10 -0.50 -0.90 -1.20

1.15 94.3 89.2 86.9 0.15 -0.80 -1.40 -1.70

Table Nr.3 presents the examination of elasticity of 25 measurement data series. Results were

processed in such a way that density corrections were also considered by the determination of

deflection amplitudes, the on-site relative compactness rate was recalculated, and the variation thereof

was determined. For all corrections we calculated the average of the values of the on-site relative

compactness rates of 25 measurements, and we took out the 56th and the 62

nd measurement, where the

on-site relative compactness rate turned to be the lowest, and accordingly, the most sensitive.

To take an example, the TrE% average of 25 measurements changed from 95.1% to 95.8% at a

density correction factor of 0.85. Since compactness rates must be rounded to whole numbers, it is to

be stated that variation of the dynamic compactness rate in case of traditional materials moves around

1% because of the correction of density, which is not significant.

Figure 1. Dependence of the TrE% relative dynamic compactness rate on the correction of density

Figure (1) shows the impact of the correction of density on the average as well as the on-site relative

compactness rates of the 56th and 62nd recorded measurements. These are linear, but the slope there

of is different. By analysing the correlation between the slope (m) and the on-site relative compactness

rate we arrived at the following result:

m = 0.986·TrE% – 98.7 (R2=1) (9)

According to the above mentioned, in case of traditional materials, density will have only a marginal

impact on the relative compactness rate, but in case that high accuracy is requested, it can be

CWA 15846:2008

387

calculated easily. In fact, it has significance during the use of fly-ash in the construction industry,

because the density thereof is very low. Figure Nr. 2. Dependence of the slope of correlation on TrE%

It follows from this that, according to the examination of the impulse, the impact on the dynamic

compactness rate is irrelevant. This means that, in case of generally used materials, density has no

significant impact on the compactness rate. In case that fly-ash is used, the measured on-site relative

compactness rate has to be corrected, too, but the impact thereof is not so significant, either, that it

could not be neglected for safety.

4.2. Controlling the sufficient compacting work

CWA 15846 modification draft determines the layer thickness limits, to ensure the accuracy of the

dynamic compactness test. Lot of cases may be the layer ticker, or must to know if the compactness

work was enough or not. Perform a new compactness test, without moving the plate. If the result TrE%

is smaller than 98%, correction needed, This value decreases the Trw value.

(10)

TrwCorr = Trw * CWC; and Trd% = TrE% * TrwCorr (11)

In this way the dynamic compactness rate measuring can be considered as an independent test from

the layer thickness.

4.3. IDP Correction: Investigation of effective depth - using the Boussinesq-theory

IDP= Impact Depth Multiplier, to considering the layer thickness.

Example: (12)

, in case of different E soil-modulus also. Proctor value depending on layer thickness. No need thickness correction between 22-28cm layer

thickness if we accept accurate range. No need thickness correction

between 20-31cm layer thickness if we accept range of accuracy.

Table Nr. 4 – IDP Correction factor depending on layer thickness

cm

+2% 1,25 20 0,474

+1% 1,14 22 0,431

0% 1,0 25 0,380

-1% 0,89 28 0,340

-2% 0,81 31 0,308

To choose the layer thickness 25,0cm, we select IDP=1,25 which makes ±2% in TrE%, in case of 25cm

layer thickness. Thickness correction need in all, other cases. LTC=Layer Thickness Correction.

LTC is: where

where: h is the layer thickness in cm (13)

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Figure Nr. 3. Value depending on layer thickness

4.4. Conversion of compactness-rate between simplified, and modified Proctor-test

The maximum dry density has to be known, as it is specified in the standard No. EN 13286-2 and

carried out the modified Proctor test. The reference density can be determined by dynamic methods

specified in standards EN 13286-3 Vibrocompression, EN 13286-4 Vibrating hammer, and EN 13286-

5 Vibrating table, but these require the determination of requirements (limit values).

As a conclusion from the above mentioned facts, CWA15846 is only one method, that gives the result

of compactness rate without reference density, namely the dynamic compactness test, rather it uses the

relationship between settlement and compactness degree, which derived from the theory of modified

Proctor test. Figure 4.: Test results of simplified and modified Proctor-test

The given soil from gravel layer material, is tested carried out both type of Proctor (modified and

simplified) during the suitability test series. We determine the general characteristics and the moisture

correction coefficients for both types. In figures and formulas we mark the simplified Proctor type

results with lower index „s”, while „m” is used in the modified case.

The multiplier can be calculated as the ratio of maximum dry densities of two Proctor tests:

md

sd

max

max

(14)

Compactness-rate complies with simplified Proctor test: In this case, the compactness-rate calculated

by the simplified Proctor test is the following:

%0.102%2.96943.0/1/1% mrdsrd TT (15)

The optimum water content of the simplified Proctor is wopt-s = 13.5%. The natural water content is the

same as previous wt = 9.6, this now means Trw-s = 0.948 moisture correction coefficient.

CWA 15846:2008

389

It is well-known, that the simplified Proctor 100% compactness-rate corresponds only 94.3%, in the

scale of the modified proctor test, that is why, if we have larger then 94.3% compactness-rate, then it

exceeds the 100% compactness-rate in terms of simplified Proctor compactness-rate.

We developed the method, which is capable to measure the on site relative compactness-rate by

CWA15846 SP-LFWD. This conversion is always made so, that we chose values of Trd-m%, wopt-m and

convert them to values of Trd-s%, wopt-s, the on site relative TrE-s% compactness is calculated with the

Trw-s moisture correction coefficient.

Figure 5: Conversion calculation between modified and simplified Proctor test results

5. CWA 15846:2008 MODIFICATION DRAFT

We performed in the last period with the measurements and we analyzed them, which need to clarify

the processing, and prepare the final modifications. In particular, the following questions we have

clarified:

- We worked out a regulation of the inspections which must apply on all trial section

- Refine of the value of linear coefficient based on 411pcs Proctor-test series, modification

from 0,365 to 0,380

- Change the tolerance also of value from +/-0.025 to +/-0.020

- Relationship of and the layer thickness (accuracy between 22-28cm+/-1Trd%, and between

20--31cm +/-2Trd%)

- Controlling the test device compactness work and correction opportunity

- Investigation of the effect of high or law bulk density materials on test results using impulse low

- Calculation of the deformation index modification from n=18 to n=17

- Calculation opportunity of dynamic bedding coefficient in case of BC

- Calculation opportunity of CBR% value from dynamic measuring results of BC (Subert)

- Usage of Proctor-curve 6-th degree polynomial regression at Trw

- Conversion opportunity of the dynamic compactness rate from modified Proctor to simplified

one

- Taking into consideration of the depth effect on value, near D163 SP-plate and the modified

Proctor test mould geometry, using Boussinesq-stress and strain distribution (1,25·)

- Comparing the sand-cone test to BC Trd% compactness results from independent measurement

- Analysis the deviation of isotopic- and dynamic test theoretically and on real 26pc trial sections

- Controlling the Proctor-work calculations based on EN 13286-2, regarding the fact that the

mould area four times of rammer area, which is the standard ignore

=1,82/1,93=0,943

1/=1,060

Trd-m=*Trd-s

Trd-s=1/*Trd-m

87,6%

92,9%

97,5%

103,4%

Subert

390

Investigation of the suggested modification shows at Trd90% only -2,5Trd%, but significant in the low

measurement range.

6. RESULTS OF RELATIOSHIP INVESTIGATIONS

6.1. Investigation of E2v – Ed relationship (figure 6.) Based on Hungarian motorways M43, M7, M6 trial sections database, we analyzed the relationships.

We involved 58 trial sections, with all of 763 measured data point.

The investigation shows that the static modulus E2v Ed or E2v=1,0*Ed R2=0,8, so the approximately

the same value like the SP-LFWD’s Ed value. The regression degree is rather good, which means that

CWA15846:2015 may be a useful device in civil engineering practice.

Tests carried out MSZ2509-3 by D=300mm static plate test and BC-1 Dynamic Compactness- and

Bearing Capacity device. The considered tolerance of static plate test is ±5MPa, CWA 15846 Ed value

±2,6MPa.

Figure 6. Relationship between dynamic Ed and static E2v

6.2. Investigation of Isotopic Tr% and Trd% Dynamic compactness-rate relationship

Based on Hungarian motorways M43, M7, M6 trial sections database, we analyzed the relationships.

We involved 32 trial sections, with all of 501 measured data point (figure 7.) The investigation shows that Trd% dynamic Compactness-rate equal to the other, density-ratio

systems. (R2=0.7)

The regression degree is rather good. This means that BC is a useful device in civil engineering

practice. Tests carried out by MC-3 Nuclear density measure device and type BC-1 Dynamic

Compactness- and Bearing Capacity device. The considered tolerance in case of isotopic test is

±3Tr% and CWA 15846:2015 ±1 TrE%.

CWA 15846:2008

391

Figure 7. Relationship between dynamic Compactness-rate and Nuclear Density test

6.3. Sand Cone test Compaction-rate – Dynamic Compaction-rate Comparative test

The investigation shows that Sand Cone test Compaction-rate – Dynamic Compaction-rate

Relationship is very tight. We’ve got the measure data from RAMKHAMHAENG University,

Bangkok Thailand Department of Civil Engineering (Comparison of B&C LFWD and sand filling

method –Ramkhamhaeng University, Thailand Ms.Panarat-Mr Korrakoch Taweesin: Calibration

Certificate B&C, Gabor Enterprise CO Ltd. 2007). One place, 30pcs test results:

Figure 8. Relationship between dynamic Compactness-rate and Sand-Cone test

AASHTO T-191 Sand Cone test comparing to the CWA 15864 dynamic compaction rate (Bangkok-

Thailand) N=30 pcs, carried out on the same place. The deviation of Sand Cone test results is 1.40,

average 95,9%, The deviation of CWA15846 Dynamic Compactness test results is 1.13 (better),

average 95,9% (equal), the gray line is the CWA15846 modification result.

6.4. Investigation of compactibility measure work –Proctor Test

Standard EN 13286-2 point 7.4 has been recommended the modified Proctor test. It is important in EN

13286-2 to highlight the calculation method of the amount of the executed work, which is in our

opinion faulty, as well as the inaccuracies of the indicated data (which is supposed to be suitable for

reference and comparison).

Subert

392

Main point of the error: The area of the rammer differs from the area of the mould; but at the same

time, the calculation supposes the ramming of the whole surface for all drops (instead of one quarter!).

The height of the attachment placed on the mould is regulated only approximately (>50 mm), but

during the calculation of the executed work neither its height, nor its volume is taken into

consideration. In our opinion, at the execution of work projected on the volume not the remaining

roller volume, but the volume of the heightened roller at the time of the compaction (i.e. the

parameters of the roller without removing the attachment) should be taken into consideration.

6.5. The air content and the saturation level belonging to the optimal water content We found the relationship between the air content and the saturation belonging to the optimal water

content for 8 different materials. These relationships are linear. By the processing of the very different

materials and all our 566 pcs Proctor results we fixed the relationship between the air content and the

saturation belonging to the optimal water content, which is the following:

aSr 03.01 (16)

where:

a the air content,

Sr the relevant saturation.

It is typical to have fare lower pores than 12 volume% at the optimal water content (at the highest dry density).

Figure 9. General relationships between the air content and the saturation belonging to wopt

The relationship between air content and saturation belonging to the optimum water

content

y = -0.03x + 1

R2 = 0.92

0.40

0.60

0.80

1.00

0 2 4 6 8 10 12 14 16 18 20 22 24

air content

satu

ration

all samples Grail dolomite Linear (all samples)

Figure 10. Frequency distribution of the air content belonging to the optimal water content

Distribution of air content belonging to the optimum water content

0

10

20

30

40

50

60

70

80

90

0 -

1

1 -

2

2 -

3

3 -

4

4 -

5

5 -

6

6 -

7

7 -

8

8 -

9

9 -

10

10 -

11

11 -

12

12 -

13

13 -

14

14 -

15

15 -

16

16 -

17

17 -

18

18 -

19

19 -

20

20 -

21

21 -

22

22 -

23

23 -

24

24 -

25

The distribution of the available Proctor-test results is lognormal (figure 10). The air content defined

at wopt is very frequently, typically in range 1-6 volume% Using the relationship of the regression-

analysis is the saturation correctly between S=0.88 – 0.94, which accords to the experiences and is

practically determinant for the adaptation of the dynamic compactness measurement.

CWA 15846:2008

393

6.6. Analysis of isotopic and the dynamic compactness rate’s deviation

The traditional way of compactness test is wet density measurement, where the calculated the dry

density value and compared to the laboratory reference dray density, expressed as a percentage. Since

wet density and water content are both measured on site, there are a total of three measuring

accuracies that cumulate in the compactness rate: the measuring accuracy of Proctor-test, the on site

water content and the wet density.

We calculated the measurement accuracy with a reliability of 90%, by the Student’s

distribution used for small-sample statistical analysis (for both density and water content), with the

following formula. The expected value (M), the measurement range and the accuracy are as follows:

n

tS , the expected value M = X ± (17)

positive and negative range from the expected value, the accuracy range of measurement

S standard deviation of the measurement fundamental set

n 3, isotopic measurement is averaged from partial results measured from three different directions, in

accordance with regulation ÚT 2-3.103 but n=2 and = (n-1) = 1 degree, Student 6.314 at ÚT2-2.124

t 2.92 at a Student’s coefficient = (n-1) = 2 degree of freedom and = 0.1 significance level

X average value of measured test results

6.7. Comparison of standard deviation, range and test accuracy

Results on the measurement accuracy, that we’ve got from the range, calculated on the basis of the

standard deviations, on the M7 motorway we did a total of 19 pcs trial-sections by the method

described above, are presented in Table 5. The two different types of compactness measurement were

analysed the same way during the analysis of the year 2008 trial-sections, which aimed at the

determination of the standard deviation of the isotopic test, as well as of the standard deviation, the

range and the accuracy of the dynamic compactness rate measured by the CWA15846. We went on by

using different materials for test compactions on the motorway M6 between Dunaújváros and Paks

(section 76+200 – 109+700 km). So far a total of seven test trial sections have been carried out, the

results thereof are summarized in Table 6.

Table Nr. 5. Results of compactness measurements at 19pcs trial-section of M7 highway

19 trial sections M7

isotopic test N=21pcs/hole

dynamic test N=9pcs/1m2

ACCURACY [compactness rate, ± %]

without effect of dmax with accuracy of

dmax

Type of compactness measurement

isotopic dynamic isotopic dynamic

Expected value range (p=90%, Student ) 5,3% 1,2% 6,5% 2,0%

The average accuracy of the isotopic measurements at the M7 highway (half of the range determined

by standard deviation) was ±6,5Tr%. In case of the dynamic compactness measurement it was much

lower: ±2,0Trd%. The average accuracy of isotopic measurements at the M6 highway (under

construction) was ±8,8Tr% from a sample (which contained also blast furnace slag aggregate with

inhomogeneous density), while in case of the dynamic compactness measurement it was much more

favourable ±2.5Trd%.

It can be stated on the basis of the processing of available data that the CWA15846 dynamic

compactness rate seems to be more accurate and to have a smaller range than the isotopic method of

measurement.

Table Nr. 6. Results of compactness measurements at the trial-sections of M6 motorway

7 trial sections M6

isotopic test N=21pcs/hole

dynamic test N=9pcs/1m2

+/- ACCURACY [compactness rate %]

without the effect of dmax with accuracy of dmax

Type of compactness measurement

isotopic dynamic isotopic dynamic

Expected value range

(p=90%Student ) 7.7% 1.3% 8.8% 2.5%

Subert

394

Literature

CWA15846:2008 Measuring method for Dynamic Compactness & Bearing Capacity with SP-LFWD

(Small - plate Light Falling Weight Deflectometer)

EN 13286-2 “Unbound and hydraulically bound mixtures 2.Test methods for the determination of the

laboratory reference density and water content. Proctor compaction”

CEN ISO/TS 22476-13 Geotechnical investigation and testing – Field testing,

Part 13 Plate Loading Test

MSZ 2509-3:1989 Útpályaszerkezetek teherbíró képességének vizsgálata. Tárcsás vizsgálat.

MSZ 15320 Földművek tömörségének meghatározása radioizotópos módszerrel

ÚT 2-2.124 Dinamikus tömörség és teherbírás mérés kistárcsás könnyűejtősúlyos berendezéssel.

ÚT 2-3.103 Radiometriás tömörségmérés. Földművek, kötőanyag nélküli alaprétegek hidraulikus

kötőanyagú útalapok térfogatsűrűségének és víztartalmának meghatározása

Dr Kézdy Á. Talajmechanika I. 1972. Tankönyvkiadó p.74-94, 388-403.

Dr Kézdy Á. Talajmechanika II. 1975. Tankönyvkiadó p.153-163, 175-196.

D.Adam, F.Kopf (2004) Operational devices for compaction optimization and quality control

(Continuous Compaction Control & Light Falling Weight Device). Proceedings of the International

Seminar on Geotechnics in Pavement and Railway Design and Construction, Rotterdam.

Brandl, H. and Adam, D. (2004) Basics and Application of the Dynamic Load Plate Test in Form of the

Light Falling Weight Device. A.W. Skempton Memorial Conference. Proc. of Imperial College,

London.

Anna Petkovsek (2008) Report on usage of Andreas dynamic load bearing capacit ity of Ljubljana

Katedra za mehaniko tal z laboratorijem. Univerza v Ljubljani Faculteta za gradbenistvo in

geodezijo. Report p.:10

Ms. Panarat (2007): Comparison of B&C LFWD and sand filling method Ramkhamhaeng University,

Thailand. Calibration Report

Dr Boromisza Tibor (2005) Megjegyzések Subert István: A dinamikus tömörség- és teherbírás mérés

újabb paraméterei és modulusok átszámíthatósági kérdései c.cikkéhez. Közúti és mélyépítési Szemle

55.évf 2.szám. p.:35-36.

Subert (2006) Method for measuring Compactness-rate with New Dynamic LFWD. XIIIth Danube-

European Conference on Geotechnical Engineering Ljubljana, Slovenia 2006, V.2. p:125-130.

Subert (2006) CWA15846-WS33 Measuring method for Dynamic Compactness & Bearing Capacity

with SP-LFWD (Small - plate Light Falling Weight Deflectometer) Draft. p.26

Subert (2014) Isotope-free Compaction-rate & Bearing Capacity Measure on Lime Stabilization – Self

control. Article and Presentation. Carmeuse Conference. 09 sept 2014 Vecsés, Hungary p.:10

Subert (2014) Izotópmentes tömörség- és teherbírás mérése – Önellenőrzés. 2014EPB Konferencia

Gyergyószentmiklós, Románia, p:14, á 6.

Subert (2012) Önellenőrzés a földműépítésben. Innotéka június p:35

Subert (2010) Földmű süllyedések elkerülése garanciával - A B&C dinamikus tömörség- és

teherbírásmérő berendezés egy új lehetőség. Gazdasági tükörkép magazin, nov p:57

Subert-T.Q.Phong (2009) Az izotópos és a dinamikus tömörség szórásának vizsgálata. Transport

Science Bulletin / Közlekedéstudományi szemle apr p:23-27.

Subert (2009) A tömörségi fok átszámítása az egyszerűsített és módosított Proctor vizsgálatok között”.

Transport Science Bulletin / Közlekedéstudományi szemle jun-2009 p:23-28.

Subert-T.Q.Phong (2007) Proctor-vizsgálat új értelmezési lehetőségei. Revue of Roads and Civil

Engineering / Közúti és mélyépítési szemle, ISSN 1419-0702 , 57. évf. 12. sz. p.7-12.

Fáy M., Király Á., Subert I. (2006) Közúti forgalom igénybevételének modellezése új, dinamikus

tömörség- és teherbírásméréssel. Urban Transport / Városi közlekedés, 46. évf. 5. sz. 274-278. old

Fáy M., Király Á., Subert I. (2006) Egy földmű-tömörségi anomália feltárása és megoldása. Revue of

Roads and Civil Engineering /Közúti és mélyépítési szemle, 56. évf. 9-10. p.: 19-23.

Subert I.(2005): „A dinamikus tömörség- és teherbírásmérés újabb paraméterei és a modulusok

átszámíthatósági kérdései” Közúti és mélyépítési szemle 55. évf. 1. sz. p.28-32.

Subert I. (2004) B&C dinamikus tömörségmérés Mélyépítés 2004 október–december p. 38–39

Subert I. (2004) Új, környezetkímélő, gazdaságos mérőeszközök a közlekedésépítésben /New,

environmental-friendly, economical measuring instruments in traffic building / Geotechnika

Konferencia Ráckeve október 26–27.

Subert (2003) Dinamikus tömörség- és teherbírás-mérés könnyű-ejtősúlyos berendezéssel. Közúti és

mélyépítési szemle 53. évf. N°5. p: 184-191.