BITUMINOUS BINDERS RESULTS OF DANISH ROUND ROBINS FOR CEN TEST METHODS FROM

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BITUMINOUS BINDERS

RESULTS OF DANISH ROUND ROBINS

FOR CEN TEST METHODS FROM 2000 - 2009

DANISH ROAD INSTITUTE

R E P O R T 176 - 2 0 0 9

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176 - 2009

BITUMINOUS BINDERS - RESULTS OF DANISH ROUND ROBINS FOR CEN TEST METHODS FROM 2000 - 2009 REPORT DATED: COPYRIGHT: AUTHORS: PUBLISHED BY: LAYOUT: ISBN ELECTRONIC: PHOTO: November 2009

Road Directorate, Danish Road Institute Svenning Olm

978-87-92094-55-1 Erik Nielsen, Pelle P

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CONTENTS

PREFACE

The purpose of this report is to document the Danish road sector's effort on quality assurance with focus on Proficiency Testing Schemes and Round Robins (interlaboratory comparisons) on test method precision with respect to European test methods under CEN TC336 "Bituminous binders" in the period 2000-2009.

The annual Round Robins (which also include methods from TC154 "Agggates" and TC227 "Road materials") have been documented in internal re-ports in Danish which only have been distributed among the participants of the Round Robins. In addition the mathematical interpretation has followed a long establish practise on reporting mean value and standard deviation in a way that not fully comply with the ISO standard DS/ISO 5725-2 Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method.

Primarily as an input to newly established Task Group 9 "Precision" under CEN TC336 WG1 "Paving Grade Bitumen" the huge amount of data complied in these annual Round Robins have been re-examined in accordance with DS/ISO 5725-2 and documented in English with an international bibliographic reference in order to contribute to the Pan-European effort to improve our common test methods.

I acknowledge the help and contribution from my colleagues Erik Olesen and Jørn Raaberg for their comments and suggestions on this report.

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FORORD

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FORORD

Rapportens formål er at dokumentere den danske vejsektors indsats på kvali-tets-området med ringprøvningsaktiviteter på de europæiske prøvningsstan-darder indenfor CEN TC336 "Bituminous binders" i perioden 2000-2009. Mere specifikt skal rapporten bruges som dansk input (arbejdspapir) i Task Group 9 om præcision af prøvningsmetoder, som er nedsat under CEN TC336 WG1 "Vejbitumener". Rapporten dokumenterer en dansk indsats på måske flere mandårs arbejde indenfor kvalitet og præcision af prøvningsme-toder. Ringprøvningsaktiviteter er generelt ofte meget omfattende i deres da-ta-grundlag, og derfor sker det i mange tilfælde, at veludførte ringprøvninger ikke dokumenteres på en måde, så internationale forskere kan finde de grundlæggende henvisninger til diverse arbejder af denne karakter. Et delfor-mål for rapporten er også at råde bod på dette forhold for det danske arbejde med de europæiske prøvningsmetoder for bituminøse bindemidler.

Jeg takker endvidere Erik Olesen og Jørn Raaberg for deres faglige kommen-tarer og korrekturlæsning af rapporten.

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RESUME

Danish Road Institute under the Danish Road Directorate has since 1994 or-ganised annual Proficiency Testing Schemes among interested parties in the Danish Road sector. For test methods concerning asphalt materials and bitu-minous binders the set has actually been in the format of Round Robins (inter-laboratory comparison) with the possibility of evaluation the precision of the test methods, but the interpretation of data which was documented in internal reports (in Danish) among the participants has been focused on the Profi-ciency part of the exercise.

On some occasions the (now former) Danish mirror committee on bituminous binders, S 293, under the Danish CEN member, Dansk Standard, has organ-ised some Round Robins on test methods which were not part of the annual Round Robin. These Round Robins have primarily been for the internal work within the mirror committee to gain information and facilitate the introduction of test methods in Denmark.

In general the documentation of Round Robins often tends to be used inter-nally among the participants and not made available for a more international forum a lot of valuable information gather dust in archives. This has also to some extent been the case in Denmark. The participants have come from nearly all the laboratories in Denmark from aggregate and bitumen suppliers over contractors and third parties like consultancy laboratories and of course Danish Road Institute itself. These Round Robins are documented annually in reports for the participants but a retrospective overview of this huge effort since its start in 1994 has been documented externally with focus on profi-ciency testing in Report 172 of the Danish Road Institute. In Denmark an addi-tional point for the annual Round Robins has been that – even though the data were collected – the material was analysed with the main focus on profi-ciency testing (possible deviations between laboratories) and not from the view angle of test methods’ precision.

Under CEN TC336 "Bituminous Binders" Working Group1 "Paving Grade Bi-tumen" established in 2008 TG 9 "Task Group on Precision of European Test Methods". This report documents - as a Danish contribution to this group - the results of the annual Round Robins performed in Denmark during the period 2000 - 2009.

Since 2000 the Round Robins have involved the European test methods com-ing from CEN. To benefit the objective of TG9 where the focus is on the preci-sion (repeatability and reproducibility) of the concerned test methods the re-sults for bituminous binders on the European test methods have been ana-lysed once more. This time the detailed analysis have been done in accor-dance with ISO standard DS/ISO 5725-2 Accuracy (trueness and precision)

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RESUME

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of measurement methods and results - Part 2: Basic method for the determi-nation of repeatability and reproducibility of a standard measurement method. This report documents the annual precision statements that can be extracted from the data set. In order to fulfil its objective certain additional information is given from the annual analysis to render a thorough evaluation of the base for the statements possible with respect to type of sample, number of participants and identified outliers and/or stragglers.

As the report is intended for readers familiar with the CEN test methods the language is "CEN English" which has influence on notation of numbers (e.g. the unit of penetration is "0,1 x mm" in stead of "0.1 x mm").

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SAMMENFATNING

Vejteknisk Institut under Vejdirektoratet har siden 1994 stået for en årlig prøvning blandt interesserede parter i den danske vejsektor. De dele af ring-prøvningsaktiviteterne, som har omhandlet asfaltmaterialer og bituminøse bindemidler, har faktisk fulgt formatet for en ringprøvning (d.v.s. sammenlig-ning mellem laboratorier med mulighed for at vurderer præcisionen af de ud-førte metoder), men tolkningen af data i de interne rapporter til deltagerne har været fokuseret på præstationsprøvning for de involverede parter.

Ved visse lejligheder har det nu nedlagte Standardiseringsudvalg, S 293, un-der Dansk Standard for bituminøse bindemidler koordineret ringprøvninger for prøvningsmetoder, som ikke var del af de årlige aktiviteter. Disse ringprøvnin-ger har for det meste været til internt brug i udvalget for at indhente informati-on om og lette introduktiinformati-onen af europæiske CEN metoder i Danmark. Generelt har dokumentation af ringprøvninger ofte en tendens til at blive brugt internt mellem deltagerne og ikke blive offentliggjort i et mere internationalt forum, hvilket kan medføre, at værdifuld information samler støv i arkiverne. Det har også til en vis grad været situationen i Danmark. Deltagerne i ring-prøvningerne har kommet fra næsten alle producentlaboratorier for sten og bitumen over entreprenørlaboratorier samt 3. parts-laboratorier som konsu-lentfirmaer og naturligvis Vejteknisk Institut selv. De årlige ringprøvninger er dokumenteret årligt i interne notater til deltagerne, men der er for nyligt lavet et retrospektivt overblik af den store indsats fra dens start i 1994 og til 2009 med fokus på præstationsprøvning i rapport nr. 172 fra Vejteknisk Institut. I Danmark har en yderligere begrænsning i anvendelse af de årlige interne no-tater i forhold til anvendeligheden for præcision af prøvningsmetoderne været, at selvom data har været indsamlet, har den talmæssige behandling fokuseret på præstationsprøvning (sammenligning af laboratorier) og ikke også fra synsvinklen af metodenøjagtighed.

Under CEN TC336 "Bituminøse bindemidler" nedsatte Working Group 1 "Vej-bitumener" i 2008 en Task Group 9 "Task Group om præcision af europæiske prøvningsmetoder". Denne rapport skal – som et dansk bidrag til dette arbej-de – dokumentere resultaterne af arbej-de årlige ringprøvninger, arbej-der er udført i pe-rioden 2000-2009.

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SAMMENFATNING

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Siden 2000 har de årlige ringprøvninger involveret de nye europæiske prøv-ningsmetoder fra CEN. Til støtte for formålet med TG9, hvor fokus er på præ-cision (repeterbarhed og reproducerbarhed) af den pågældende prøvnings-metode, så er datamaterialet for de udførte, europæiske prøvningsmetoder analyseret igen med udgangspunkt i den internationale ISO standard DS/ISO 5725-2 Nøjagtighed (korrekthed og præcision) af målemetoder og resultater – Del 2: Grundlæggende metode til bestemmelse af repeterbarhed og reprodu-cerbarhed for en standardiseret målemetode.

Rapporten dokumenter de årlige præcisions-bestemmelser (repeterbarhed og reproducerbarhed), som kan udtrækkes af data-materialet. For at opfylde sit formål som støtte til TG9 er der yderligere information angivet for at give vur-deringsgrundlag for validiteten af resultaterne. Det drejer sig om type af prø-ve, antal deltagere og antallet af identificerede "afvigere" eller "strejfere". Da rapporten i hovedsagen henvender sig til læsere af europæiske CEN standarder, er rapporten skrevet på "CEN engelsk", hvilket betyder, at dansk tal-notation følges (f.eks. er enheden for penetration "0,1 x mm" og ikke "0.1 x mm").

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BACKGROUND

Under CEN TC336 "Bituminous Binders" Working Group1 "Paving Grade Bi-tumen" established in 2008 TG 9 "Task Group on Precision of European Test Methods". This report documents - as a Danish contribution to this group - the results of the annual Round Robins performed in Denmark during the period 2000 - 2009.

The Round Robins which function as Proficiency Testing Schemes for the laboratories in the Danish road sector have been coordinated by Danish Road Institute. The participants come from nearly all the laboratories in Denmark from aggregate and bitumen suppliers over contractors and third parties like consultancy laboratories and of course Danish Road Institute itself. These Round Robins are documented annually in reports for the participants and a retrospective overview of this huge effort since its start in 1994 has been documented with focus on proficiency testing in Report 172 of the Danish Road Institute.

The set-up of the Round Robins on bituminous binders and asphalt materials has been performed in a way that the results also can be used for estimation of accuracy (trueness and precision) of the involved test methods even though the data are not normally analysed for this objective.

The former Danish mirror committee for CEN TC336, S-293, under Dansk Standard (Danish Standards) has in the same period organised Round Rob-ins on special issues. The results from these activities will also be reported or mentioned in this document.

Since 2000 the Round Robins have involved the European test methods com-ing from CEN. To benefit the objective of TG9 where the focus is on the preci-sion (repeatability and reproducibility) of the concerned test methods the re-sults for bituminous binders on the European test methods have been ana-lysed once more. This time the detailed analysis have been done in accor-dance with ISO standard DS/ISO 5725-2 Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determina-tion of repeatability and reproducibility of a standard measurement method. TG9 has as an initial task started a collection of available information on na-tional precision studies in order to "harvest" work already performed to identify the test methods where recent or well funded accuracy statements either are scarce or do not exist. When TG9 has an overview of the present situation suggestions for Round Robins to fill out the gaps can be put forward and fi-nance sought for a focused Pan-European exercise to the benefit of the common European market with respect for trade relations on these products and information exchange.

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BACKGROUND

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This report documents the annual precision statements that can be extracted from the data set. In order to fulfil its objective certain additional information is given from the annual analysis to render a thorough evaluation of the base for the statements possible with respect to type of sample, number of participants and identified outliers and/or stragglers.

As the report is intended for readers familiar with the CEN test methods the language is "CEN English" which has influence on notation of numbers (e.g. the unit of penetration is "0,1 x mm" in stead of "0.1 x mm").

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TEST METHODS

1. TEST METHODS

The test methods with their associated conditions and/or type of samples are mentioned in Table 1 and 2. Some of the test methods have been subjected to Systematic Review and revision. This has only meant slight alterations and no dramatic changes in the test methods. In some cases updated information on precision has been introduced which will be reflected in the reference val-ues in the tables in qval-uestion. In any given year of the period 2000-2009 the valid Danish version from Dansk Standard (DS/EN xxxxx) has been used in the Round Robin.

Table 1. Test methods in Round Robins organised by Danish Road Institute.

Test method reference

Description (including selection of condi-tions)

Type of sample

EN 1426 Penetration @ 25 °C Normal paving grade bitumens & polymer modified binders EN 1426 Penetration @ 15 °C Normal paving grade bitumens EN 1427 Softening point ring & ball (in water) Normal paving grade bitumens &

polymer modified binders EN 1427 Softening point ring & ball (in glycerol) Polymer modified binders EN 12596 Dynamic viscosity @ 60 °C Normal paving grade bitumens EN 12595 Kinematic viscosity @ 135 °C Normal paving grade bitumens EN 13398 Elastic recovery @ 10 °C Polymer modified binders EN 12607-1 RTFOT Change in mass Normal paving grade bitumens &

polymer modified binders EN 1426 Retained penetration (after RTFOT) Normal paving grade bitumens &

polymer modified binders EN 1427 Increase in softening point ring & ball (after

RTFOT)

Normal paving grade bitumens & polymer modified binders

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TEST METHODS

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Table 2. Test methods in Round Robins organised by S 293.

Test method reference

Description (including selection of condi-tion)

Type of sample

EN 1427 Softening point ring & ball (in glycerol) Polymer modified binders EN 12596 Dynamic viscosity @ 60 °C Normal paving grade bitumens &

polymer modified binder prEN 13302 1) Dynamic viscosity @ 60 °C (for comparison

with EN 12596)

Normal paving grade bitumens & polymer modified binder

EN 12595 Kinematic viscosity @ 135 °C Normal paving grade bitumens & polymer modified binder

prEN 13302 1) Dynamic viscosity @ 135 °C (for comparison with EN 12595)

Normal paving grade bitumens & polymer modified binder

EN 13589 & EN 13705

Force ductility @ 5, 10 and 15 °C together with

Deformation Energy

Polymer modified binders

1)

At the time of the Round Robin the test methods only existed as prEN. The results of the Round Robins will be presented in tables in Annex A in the same order as stated in Table 1. The analysis will be documented in a similar manner for all the test methods which consists of a table with detailed infor-mation for each analysis of estiinfor-mation of precision (repeatability, r, and repro-ducibility, R). In the discussion part of the report the precision data will be il-lustrated as a function of the value of measurement to indicate whether or not there might be a dependency of the precision of the test method with the ob-tained level of the measurand. The columns of the table are

1. year of the performed Round Robin (e.g. 2001/2002 means winter period)

2. grade designation (either in accordance with old national specification or the product standards EN 12591 or EN 14023)

3. Sample No. (for identification in the Round Robins)

4. Global mean value estimated after removal of outliers and stragglers (if any)

5. The total number of participating laboratories and the number of repetitions. The number of repetitions are stated in accordance with the requirements of ISO 5725-2 which means that if all laboratories but one of a Round Robin perform three repetitions and the remain-ing one only two repetitions the whole data set is analysed with less statistical "precision" or lower statistical impact. Since 2004/2005 one of the participants has persistently delivered results from two repeti-tions and only in the cases where this laboratory has been removed

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TEST METHODS

from the population due to being identified as a outlier or straggler the number of repetitions has been raised to three used by the other laboratories.

6. The number of outliers and the number of stragglers discarded by Cochran's and Grubbs' test

7. The obtained repeatability, r, of the Round Robin of the remaining laboratories

8. The obtained reproducibility, R, of the Round Robin of the remaining laboratories

9. The repeatability, r, stated of the test method (for some methods a function of the obtained value)

10. The reproducibility, R, stated of the test method (for some methods a function of the obtained value)

Table 3. Danish Road Institute Round Robins on bituminous binders.

Penetration

@ 25 °C

Penetration

@ 15 °C

Softening poin

t ring & ball

Dynamic visc o s ity @ 60 °C Kinematic visc osity @ 135 °C Elastic recov e ry @ 10 °C

RTFOT Change in mass

Retained Pen

e

tration @ 25

°C

Increase in So

ftening point ring & ball

PMB - T r&b b e low 80 °C PMB - Tr&b a bove 80 °C PMB - high Tr &b - S 293 Year EN 1426 EN 1426 EN 1427 _{EN 12596} _{EN 12595} _{EN 13398} _EN 12607-1 EN 1426 EN 1427 2000 2001/2002 2002/2003 2003/2004 2004/2005 2005/2006 2006/2007 2007/2008 2008/2009 Performed Not performed

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TEST METHODS

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Table 4. S 293 - mirror committee for bituminous binders - Round Robins on special issues.

Initial Round

Robin

Softening poin

t ring & ball

PMB

- high Tr&b - S 293

Polymer dispe

rsion - used for

trouble shooting Dynamic visc o s ity @ 60 °C Dynamic visc o s ity @ 60 °C Kinematic visc osity @ 135 °C Kinematic visc osity @ 135 °C Force Ductility & Deformatio n Energy @ 5, 1 0 & 15 °C Bitumen emulsions Year _Several methods EN 1427 _{EN 13632} _{EN 12596}

prEN 13302 EN 12595 prEN 13302 prEN 13589 prEN 13703 Several methods

2000 2001/2002 1) 2002/2003 2003/2004 2004/2005 2005/2006 2) 2006/2007 2007/2008 2008/2009

Performed Not performed

1)

Data report (without conclusion) exists in Danish for the results from 5 laboratories with 4 samples and 5 repetitions at 5, 10 and 15 °C.

2)

Too few of the participating laboratories responded with test results for a thorough analysis. A report in Danish exists.

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DISCUSSION AND COMMENTS

2. DISCUSSION AND COMMENTS

On the following pages comments and visual extracts of the tables in the an-nex will show

1. whether or not it is likely that the precision estimation has a depend-ency of the measurand and

2. if the determined precision in general seems to be in agreement with the precision stated in the test method.

2.1Penetration @ 25 °C

Figure 1 shows the result of the precision estimated for penetration @ 25 °C for all the samples. It is evident that the regression lines for repeatability (r, dark blue line) and reproducibility (R, red line) are strongly influenced by the single sample of a grade 330/430.

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Figure 2. Penetration @ 25 °C (r & R as function of global mean).

This sample is outside the range of the CEN method but can be determined in accordance with the national penetration method preceding the European test method it would have been possible to measure this soft grade as the valid range went up to approx. 500 x 0,1 mm. In Figure 2 all normal paving grades (excluding the 330/430 grade) are extracted from Table 5 and there is no de-pendency on the precision of the measurand. The regression line for repeat-ability is at or below the value stated in the test method, but the regression line for the reproducibility exceeds the value of the test method as several es-timations of R are higher than the value in the test method.

The results for the polymer modified samples are extracted in Figure 3. Again the regression lines are influenced by a single sample but in this case its ex-clusion will not alter the fact that there is no dependence on the precision es-timation from the measurand in the range of the samples tested. The repeat-ability is within the precision of the test method but for the polymer modified samples around 60 x 0,1 mm many of the Round Robins have found higher values than stated in the test method.

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Figure 3. Penetration @ 25 °C (r & R as function of global mean for polymer modified samples).

2.2Penetration @ 15 °C

Through the period 2000 - 2009 only five samples have been measured at 15 °C. Apart from the reproducibility of the 330/430 grade tested in 2005/2006 (value = 138,9 x 0,1 mm) the estimated precision values shown in Figure 4 are more or less in accordance with the method and show no dependency of the measurand.

2.3Softening point ring & ball

The results for softening point ring & ball (Tr&b) for all normal paving grade bitumens depicted in Figure 5 show no dependency of the measurand and that the levels of repeatability and reproducibility are similar to the value stated in the test method.

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Figure 4. Penetration @ 15 °C (r & R as function of global mean).

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The results for polymer modified bitumens has to be extracted from Table 7 in two different figures due to the different measuring conditions. For a softening point ring & ball below 80 °C the test is performed with water as heating me-dium in the beaker while above 80 °C glycerol is used. Figure 6 contains an extract of the low polymer modified bitumens which have softening points ring & ball below 80 °C. There is no dependence of the measurand on the preci-sion data. If the sample with softening point ring & ball of 45,5 °C is excluded the remaining range of measurand is too small for any analysis of depend-ency of the measurand. The repeatability is almost in accordance with the test method's value for r, but some of the found values for reproducibility exceed the method's value for R.

The precision data for high polymer modified bitumens with softening points ring & ball above 80 °C are extracted from Table 7 to Figure 7. The range of the measurand is not large but a slight dependence of the measurand can be seen for the repeatability as well as for the reproducibility. However, the latter reveals a large scatter around the regression line which – in addition to sev-eral large values for R – means that these high polymer modified bitumens potentially can be difficult to agree upon between supplier and customer. One of the possible causes for the large deviation between laboratories is sample preparation which is of immense importance for this kind of binder.

Figure 6. Softening point ring & ball - polymer modified bitumens with Tr&b below 80 °C (r & R as function of global mean).

2.4Dynamic viscosity @ 60 °C

There is too few samples for an analysis of the dependency of the measurand (Figure 8) and the sample of polymer modified bitumen (viscosity = 777,5 Pa·s) shows very poor reproducibility.

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2.5Kinematic viscosity @ 135 °C

Again too few samples for an analysis of dependency of measurand but Figure 9 shows that the level of repeatability is almost in accordance with the test method's value, but for reproducibility the estimated values for the soft grade and the polymer modified grade are higher than expected from the test method values.

Figure 7. Softening point ring & ball - polymer modified bitumens with Tr&b above 80 °C (r & R as function of global mean).

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Figure 9. Kinematic viscosity @ 135 °C (r & R as function of global mean).

2.6Elastic recovery @ 10 °C

The precision of DS/EN 13398 is presently unknown at 10 °C but test method contains a precision statement valid for 25 °C with repeatability and repro-ducibility as 4 % and 7 % respectively. For the polymer modified bitumens having an Elastic recovery above 70 % the stated precision could also be valid at 10 °C, but Figure 10 shows that soft polymer modified bitumen (90/150-45; ER = 63,4 %) and the relative soft normal paving grade (160/220; ER = 11,0 %) have repeatability acceptable to the test method but reproduci-bility in the range of 12-14 %. If this is due to the nature of the binder (rela-tively soft) or an impact of the test temperature on precision is unknown. In case of the low value of elastic recovery the relative uncertainty in determina-tion of small recoveries is bound to go up but the scope of the test method is not limited to polymer modified bitumens with high elastic recoveries.

2.7RTFOT Change in mass

The results of repeatability of change in mass after RTFOT hardening shown in Figure 11 are excellent compared with the precision statement in DS/EN 12607-1. The number of participating laboratories may be small (typical 5 laboratories) but the highest estimated value for repeatability is 0,041 % abs. compared to the test method's value of 0,15 (more than three times higher). The reproducibility in the test method is stated as 0,20 % abs. but the regres-sion line of reproducibility in Figure 11 indicates strongly that the reproducibil-ity is a function of the measurand in the range from -0,35 % to +0,05 %.

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The 15 samples cover normal paving grades bitumens from 40/60 to 330/430 and different polymer modified bitumens like low modified 50/70-53 and high modified 40/100-75.

It is a recommendation to CEN TC336 WG1 TG9 to verify this observation and if verified introduce this dependency of the measurand on the reproduci-bility of change in mass at the next revision of EN 12607-1.

Figure 10. Elastic recovery @ 10 °C (r & R as function of global mean).

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2.8Retained penetration (after RTFOT)

Figure 12 shows the results of 15 estimation of precision which indicates that the present precision statement in the test method ( r = 7 % abs. and R = 10 % abs.) is difficult to achieve. This is not linked to the type of binder (polymer modified or not) even though the three samples with retained penetration above 70 % are polymer modified. The conditioning method EN 12607-1 men-tions that the precision stated is only indicative with respect to modified and oxidised bitumens but one sample of polymer modified bitumen is fulfilling the precision in the standard. The three samples with retained penetration above 70 % cover both high and low polymer content.

The overall result is that CEN TC336 WG1 TG9 ought to strengthen the documentation with respect to whether or not the levels for repeatability and reproducibility of retained penetration need to be corrected to higher values.

Figure 12. Retained penetration after RTFOT (r & R as function of global mean).

2.9Increase in softening point ring & ball (after RTFOT) As indicated in the discussion on RTFOT change in mass there is a limited number of potential participants possible for conditioning/hardening of bitumi-nous binders and the associated tests on the laboratory aged binder. Five Rolling Thin Film Ovens exist in Denmark and they all participate in the Round Robins, but the small number has to be kept in mind when the results are in-terpreted. Figure 13 shows that two distinct groups of samples exist. Three high content polymer modified bitumen containing SBS (Styrene-Butadiene-Styrene) exhibit a negative increase in softening point ring & ball after RTFOT (range roughly from -2,5 °C down to - 5 °C) while the normal paving grades and low content polymer modified bitumens occupy a range from +3,5 °C up to +6 °C.

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Because of the two distinct groups of samples the overall regression lines for repeatability and reproducibility have no physical meaning. If the three sam-ples with negative increase are removed from the population of results the remaining samples will show no dependency of the measurand. The precision statement in DS/EN 12607-1 concerning increase in softening point ring & ball is only valid for normal paving grades and indicative for other samples. Never-theless it can be seen that several of the results exceed the stated precision in the test method for repeatability and reproducibility (1,5 °C and 2,5 °C re-spectively).

Figure 13. Increase in softening point ring & ball after RTFOT (r & R as function of global mean).

The estimated precision for increase in softening point ring & ball has three major elements of uncertainty:

¾ The precision of the softening point ring & ball of the original bitumen

¾ The influence of the conditioning/hardening procedure and

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This combined influence on the overall determined value is seen as the rea-son for a peculiarity. Out of the 15 samples four samples show estimated pre-cision data where the repeatability is higher than the reproducibility. Of course the effect is boarder line, but it could be interpreted in the following manner: In stead of doing the repetition of the test in your own laboratory you will get less deviation if you let the sample be re-tested at another laboratory! There is no indication that this peculiarity is linked to the nature of the sample as the four samples are:

¾ Two normal paving grades (40/60 and 330/430)

¾ One low content polymer modified bitumen (50/70-53) and

¾ One high content polymer modified bitumen (40/100-75).

As indicated earlier one of the laboratories has persistently only delivered two test results instead of the normal three results. In this situation it would have been interesting to have a stronger statistical evaluation of the variation within the laboratories because it could perhaps improve the analysis and help to verify whether or not it is an artefact or a not unusual occurrence.

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CONCLUSIONS AND RECOMMENDATIONS

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CONCLUSIONS AND

RECOMMENDATIONS

This report documents the results of the Round Robins on European test methods for bituminous binders performed in Denmark in the period from 2000 to 2009. The Round Robins have been coordinated annually by Danish Road Institute or on special occasions by the Danish TC336 mirror committee, S-293.

The Round Robins have - as a Danish contribution to the work of T9 "Task Group on Precision of European Test Methods" under CEN TC336 "Bitumi-nous Binders" Working Group1 "Paving Grade Bitumen" - been analysed in detail in accordance with ISO standard DS/ISO 5725-2 Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard meas-urement method. This gives the possibility to establish the precision (repeat-ability and reproducibility) of the concerned European test methods for bitumi-nous binders.

The report gives the following recommendations to TG9 to indicate possible areas for improvement or need for further detailed studies for optimising the precision statement of the test methods from TC336 WG1:

¾ EN 1427 Softening point ring & ball for high content poly-mer modified bitumens

The precision data indicate that the test method (and probably also sample preparation EN 12594) for polymer modified bitu-mens with softening points ring & ball above 80 °C need to be improved.

¾ EN 13398 Elastic recovery @ 10 °C

There is no precision statement in the test method for 10 °C, and the present report indicates that the reproducibility can possibly be a function of the measurand.

¾ EN 12607-1 RTFOT Change in mass

The regression line of the estimated precision on reproducibility indicates strongly that the reproducibility is a function of the measurand in the range from -0,35 % to +0,05 %. This point needs to be examined further. If verified the reproducibility of the test method can be changed to be a function of the measurand at the next revision of EN 12607-1.

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CONCLUSIONS AND RECOMMENDATIONS

¾ Retained Penetration (after RTFOT)

The overall result is that CEN TC336 WG1 TG9 ought to strengthen the documentation with respect to whether or not the levels for repeatability and reproducibility of retained penetration need to be corrected to higher values.

¾ Increase in softening point ring & Ball (after RTFOT)

The report indicates that the present level of precision found for normal paving grades needs to be corrected to higher values. Especially the behaviour of certain high content SBS polymer modified bitumens (negative increase) need to be addressed. Again this may also involve improvements in EN 12594 Sample Preparation.

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ANNEX A TABLES OF THE ESTIMATED PRECISION

Annex A Tables of the estimated precision

Table 5. Penetration @ 25 °C - DS/EN 1426.

Unit : %

Unit : 0,1 x mm

DRI Round Robin Standard

Year grade Sample No. Global No. Labs / Stragglers/ Repeatability Reproducibility Repeatability Reproducibility

mean No. Samples Outliers r R r R

2000 B60 540 56,5 5 / 3 0 / 0 4,3 10,7 4 6 2000 50/70-53 542 63,1 5 / 3 0 / 0 3,7 9,9 5 10 2001/2002 40/60 550 51,2 9 / 3 1 / 1 3,9 7,6 4 6 2001/2002 50/70-53 552 58,5 10 / 3 0 / 1 3,7 6,9 5 10 2002/2003 40/60 559 50,0 9 / 3 2 / 1 3,8 9,7 4 6 2002/2003 50/70-53 561 60,9 12 / 3 0 / 0 6,0 20,5 5 10 2003/2004 40/60 568 48,1 11 / 3 1 / 1 3,3 18,4 4 6 2003/2004 160/220 569 193,1 9 / 3 2 / 2 2,3 3,7 4 6 2003/2004 50/70-53 570 59,2 10 / 3 1 / 2 3,3 13,9 5 10 2004/2005 40/60 577 50,0 11 / 2 0 / 1 3,0 14,2 4 6 2004/2005 160/220 578 157,0 10 / 3 2 / 0 2,3 10,2 4 6 2004/2005 50/100-75 579 61,1 11 / 2 0 / 1 6,2 13,8 5 10 2005/2006 330/430 583 388,9 7 / 2 0 / 0 16,4 19,5 2005/2006 40/60 584 50,6 12 / 2 1 / 1 4,8 11,3 4 6 2005/2006 40/100-75 585 60,3 12 / 2 0 / 2 4,0 10,3 5 10 2006/2007 50/70-53 589 60,9 10 / 2 1 / 1 5,0 13,0 5 10 2006/2007 40/60 590 52,5 11 / 2 0 / 2 3,8 13,2 4 6 2006/2007 160/220 591 168,5 12 / 2 0 / 1 3,7 12,6 4 6 2007/2008 35/50 595 31,3 12 / 2 1 / 1 1,6 9,5 2 3 2007/2008 40/60 596 49,7 14 / 2 0 / 0 3,6 9,4 2 3 2007/2008 160/220 597 171,1 14 / 2 0 / 0 5,1 10,0 4 6 2007/2008 40/100-75 598 66,0 13 / 2 0 / 1 6,7 13,8 5 10 2008/2009 40/60 602 48,7 13 / 2 1 / 0 2,4 5,0 2 3 2008/2009 90/150-45 604 107,0 13 / 2 1 / 0 3,1 7,0 5 10 ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N 30

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Table 6. Penetration @ 15 °C - DS/EN 1426.

Unit : %

2000 B500 541 138,8 5 / 3 0 / 0 3,2 9,3 5 8 2001/2002 330/430 551 126,3 8 / 3 0 / 2 3,2 8,3 5 8 2002/2003 330/430 560 147,1 10 / 3 1 / 1 3,3 8,7 5 8 2005/2006 330/430 583 138,9 11 / 3 0 / 1 6,0 25,0 5 8 2008/2009 330/430 603 131,4 12 / 2 0 / 1 4,9 10,2 5 8 ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N

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Table 7. Softening point ring & ball - DS/EN 1427.

Unit : °C

2000 B60 540 50,8 6 / 3 0 / 0 0,7 1,8 1 2 2000 B500 541 29,9 6 / 3 0 / 0 1,0 1,9 1 2 2000 50/70-53 542 55,5 6 / 3 0 / 0 5,9 5,9 1,5 3,5 2000 B60 546 50,4 6 / 3 0 / 0 0,8 2,5 1 2 2001/2002 40/60 550 49,7 10 / 3 1 / 0 0,8 2,2 1 2 2001/2002 330/430 551 30,6 10 / 3 0 / 0 1,3 2,9 1 2 2001/2002 50/70-53 552 56,8 7 / 3 1 / 3 1,4 1,3 1,5 3,5 2001/2002 50/100-75 elastomer 97,0 13 / 3 3 3,3 10,2 ? ? 2001/2002 Tr&b > 90 °C PMB 95,7 13 / 3 3 1,0 2,9 ? ? 2002/2003 40/60 559 50,1 8 / 3 3 / 1 0,5 1,5 1 2 2002/2003 330/430 560 29,6 10 / 3 2 /0 1,0 2,6 1 2 2002/2003 50/70-53 561 56,2 10 / 3 0 / 2 2,1 7,7 1,5 3,5 2002/2003 50/100-75 A 91,4 20 / 3 0 / 0 2,4 4,6 ? ? 2002/2003 50/70-75 C 94,6 15 / 3 5 2,3 7,7 ? ? 2002/2003 50/100-75 D 93,6 20 / 3 0 / 0 2,2 5,9 ? ? 2003/2004 40/60 568 51,0 13 / 3 0 / 0 0,8 2,5 1 2 2003/2004 160/220 569 37,3 12 / 3 1 / 0 0,6 1,8 1 2 2003/2004 50/70-53 570 56,2 13 / 3 0 / 0 2,6 5,3 1,5 3,5 2004/2005 40/60 577 50,5 11 / 2 0 / 1 1,2 2,6 1 2 2004/2005 160/220 578 39,6 11 /2 1 / 0 0,8 2,7 1 2 2004/2005 50/100-75 579 88,5 11 / 3 1 / 0 4,1 14,9 2,2 6,3 2005/2006 330/430 583 30,6 14 / 2 0 / 0 1,8 3,3 1 2 2005/2006 40/60 584 50,2 14 / 2 0 / 0 1,7 2,8 1 2 2005/2006 40/100-75 585 89,4 12 / 2 0 / 1 4,4 9,4 2,2 6,3

S 293 Round Robin Bath liquid = glycerol

32 _ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N

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Softening point ring & ball - DS/EN 1427 (Continued)

Unit : °C

2006/2007 50/70-53 589 58,5 10 / 2 0 / 2 1,0 2,9 1,5 3,5 2006/2007 40/60 590 50,5 12 / 2 1 / 0 0,9 2,0 1 2 2006/2007 160/220 591 38,4 13 / 2 0 / 0 1,3 2,7 1 2 2007/2008 35/50 595 55,5 11 / 2 2 / 1 0,6 1,5 1 2 2007/2008 40/60 596 50,1 14 / 2 0 / 0 1,6 1,9 1 2 2007/2008 160/220 597 38,4 14 / 2 0 / 0 1,8 3,2 1 2 2007/2008 40/100-75 598 87,9 13 / 2 0 / 1 4,0 12,4 2,2 6,3 2008/2009 40/60 602 50,7 14 / 2 0 / 0 1,1 1,8 1 2 2008/2009 330/430 603 30,3 11 / 2 2 / 0 0,4 1,4 1 2 2008/2009 90/150-45 604 45,5 12 / 2 1 / 2 1,1 2,6 1,5 3,5

S 293 Round Robin Bath liquid = glycerol

ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N

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Table 8. Dynamic viscosity @ 60 °C - predominantly DS/EN 12596.

Unit : %

2000 B60 540 447,1 5 / 3 1 / 0 7,2 10,1 6 10 < 2000 Pa s

2000 B500 541 22,4 6 / 3 0 / 0 3,7 22,5 6 10 < 2000 Pa s

2000 50/70-53 542 777,5 6 / 2 0 / 0 8,8 54,7 6 10 < 2000 Pa s

Some data reported as dynamic viscosity was not based on EN 12596 but on some rotational viscometer equipment.

Table 9. Kinematic viscosity @ 135 °C - predominantly DS/EN 12595.

Unit : %

Year grade

Sample

No. Global No. Labs / Stragglers/ Repeatability Reproducibility Repeatability Reproducibility

2000 B60 540 559,5 5 / 3 0 / 0 1,7 6,6 4 6 < 600 mm2/s

2000 B500 541 124,7 6 / 3 0 / 0 4,6 12,7 4 6 < 600 mm2/s

2000 50/70-53 542 967,5 5 / 3 0 / 0 2,0 11,2 4 9 > 600 mm2/s

Some data reported as kinematic viscosity was not based on EN 12595 but on some rotational viscometer equipment.

ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N 34

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Table 10. Elastic recovery @ 10 °C - DS/EN 13398.

Unit : % (abs)

2004/2005 160/220 578 11,0 5 / 2 0 / 0 4,1 12,4 4 7 2004/2005 50/100-75 579 86,6 5 / 2 0 / 0 2,2 3,7 4 7 2005/2006 40/100-75 585 85,1 6 / 2 0 / 0 3,0 3,9 4 7 2006/2007 50/70-53 589 73,1 7 /2 0 / 0 2,1 4,7 4 7 2007/2008 40/100-75 598 84,6 7 / 2 0 / 0 1,6 6,2 4 7 2008/2009 90/150-45 604 63,4 7 / 2 0 / 0 3,7 13,9 4 7

Precision data valid for 25 °C

ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N

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Table 11. RTFOT change in mass - DS/EN 12607-1.

Unit : % (abs)

2001/2002 40/60 550 -0,0600 4 / 3 0 / 0 0,028 0,125 0,15 0,2 2001/2002 330/430 551 -0,3400 4 / 3 0 / 0 0,028 0,296 0,15 0,2 2001/2002 50/70-53 552 -0,0700 4 / 3 0 / 0 0,028 0,111 0,15 0,2 2004/2005 40/60 577 0,0093 5 / 2 0 / 0 0,031 0,098 0,15 0,20 2004/2005 160/220 578 -0,1024 5 / 2 0 / 0 0,041 0,259 0,15 0,20 2004/2005 50/100-75 579 0,0207 5 / 2 0 / 0 0,035 0,085 0,15 0,20 2005/2006 330/430 583 -0,3192 5 / 2 0 / 0 0,035 0,489 0,15 0,20 2005/2006 40/60 584 0,0068 5 / 2 0 / 0 0,023 0,086 0,15 0,20 2005/2006 40/100-75 585 -0,0387 5 / 2 0 / 0 0,019 0,128 0,15 0,20 2006/2007 50/70-53 589 -0,0831 5 / 2 0 / 0 0,040 0,172 0,15 0,20 2006/2007 40/60 590 0,0488 5 / 2 0 / 0 0,036 0,052 0,15 0,20 2006/2007 160/220 591 -0,1703 5 / 2 0 / 0 0,013 0,282 0,15 0,20 2007/2008 40/60 596 -0,007 5 / 2 0 / 0 0,027 0,113 0,15 0,20 2007/2008 40/100-75 598 0,036 5 / 2 0 / 0 0,034 0,044 0,15 0,20 2008/2009 40/60 602 -0,049 5 / 2 0 / 0 0,025 0,152 0,15 0,20 ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N 36

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Table 12. Retained penetration (after RTFOT DS/EN 12607-1).

Unit : % (abs)

2001/2002 40/60 550 67,1 4 / 3 0 / 0 3,9 4,7 7 10 2001/2002 330/430 551 69,2 4 / 3 0 / 0 3,2 8,8 ? ? 2001/2002 50/70-53 552 74,9 4 / 3 0 / 0 17,3 18,9 7 10 2004/2005 40/60 577 64,6 5 / 2 0 / 0 8,5 10,0 7 10 2004/2005 160/220 578 63,1 5 / 2 0 / 0 8,4 10,8 7 10 2004/2005 50/100-75 579 79,0 5 / 2 0 / 0 9,5 31,2 7 10 2005/2006 330/430 583 63,8 5 / 2 0 / 0 6,6 13,5 7 10 2005/2006 40/60 584 63,1 5 / 2 0 / 0 4,5 11,5 7 10 2005/2006 40/100-75 585 75,0 5 / 2 0 / 0 6,9 14,9 7 10 2006/2007 50/70-53 589 65,5 5 / 2 0 / 0 7,4 9,9 7 10 2006/2007 40/60 590 66,0 5 / 2 0 / 0 5,7 8,2 7 10 2006/2007 160/220 591 64,0 5 / 2 0 / 0 3,6 6,5 7 10 2007/2008 40/60 596 66,1 5 / 2 0 / 0 3,0 8,2 7 10 2007/2008 40/100-75 598 68,3 5 / 2 0 / 0 9,8 14,7 7 10 2008/2009 40/60 602 67,0 5 / 2 0 / 0 5,2 11,7 7 10 @ 15 °C ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N

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Table 13. Increase in softening point ring & ball (after RTFOT DS/EN 12607-1).

Unit : °C

2001/2002 40/60 550 5,2 4 / 3 0 / 0 1,0 1,6 1,5 2,5 2001/2002 330/430 551 4,3 4 / 3 0 / 0 1,2 1,4 1,5 2,5 2001/2002 50/70-53 552 4,3 4 / 3 0 / 0 1,5 1,4 1,5 2,5 2004/2005 40/60 577 5,4 5 / 2 0 / 0 1,6 1,8 1,5 2,5 2004/2005 160/220 578 4,9 5 / 2 0 / 0 1,8 2,7 1,5 2,5 2004/2005 50/100-75 579 -4,1 5 / 2 0 / 0 6,0 8,7 1,5 2,5 2005/2006 330/430 583 4,8 5 / 2 0 / 0 2,7 2,3 1,5 2,5 2005/2006 40/60 584 5,9 5 / 2 0 / 0 2,8 3,4 1,5 2,5 2005/2006 40/100-75 585 -4,7 5 / 2 0 / 0 5,9 8,5 1,5 2,5 2006/2007 50/70-53 589 3,5 5 / 2 0 / 0 2,0 2,3 1,5 2,5 2006/2007 40/60 590 4,9 5 / 2 0 / 0 2,4 3,0 1,5 2,5 2006/2007 160/220 591 4,6 5 / 2 0 / 0 1,5 3,5 1,5 2,5 2007/2008 40/60 596 5,3 5 / 2 0 / 0 3,4 3,2 1,5 2,5 2007/2008 40/100-75 598 -2,5 5 / 2 0 / 0 6,5 6,1 1,5 2,5 2008/2009 40/60 602 5,2 5 / 2 0 / 0 0,7 1,1 1,5 2,5 ANNEX A TABLE S O F T H E E S TIMAT E D PREC ISIO N 38

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ANNEX B REFERENCES

Annex B

References

DS/ISO 5725-1

Accuracy (trueness and precision) of measurement methods and results - Part 1: General principles and definitions.

DS/ISO 5725-2

Accuracy (trueness and precision) of measurement methods and results - Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method.

DS/ISO 5725-5

Accuracy (trueness and precision) of measurement methods and results - Part 5: Alternative methods for the determination of the precision of a stan-dard measurement method.

DS/ISO 13528

Statistical methods for use in proficiency testing by interlaboratory compari-sons

DS/ISO/ TR 22971

Accuracy (trueness and precision) of measurement methods and results – Practical guidance for the use of ISO 5725-2:1994 in designing, implementing and statistically analysing interlaboratory repeatability and reproducibility re-sults.

Erik Nielsen:

Vejteknisk Instituts ringprøvning – Asfalt

Undersøgelse af udvikling i spredning i perioden 1994-2008/2009

(English: Danish Road Institute - Round Robins on bituminous materials - A study of the trend in standard deviation in the period from 1994 - 2008/2009.) Report 172, Danish Road Directorate. 2009

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Rapport / Report

Nr. No.

Titel/Title Forfatter/ Au thor

159 DRI – DWW Thin Layer Project – Final report Hans Bendtsen Erik Nielsen 160 Thin Asphalt Layers for Highways

– Optimised for low tyre / road noise

Bent Andersen Hans Bendtsen 161 Road Surfacings – Noise reduction time history Jørgen Kragh 162 Optimized thin layers for urban roads

– Paper for Acoustics ’08 in Paris

Bent Andersen Hans Bendtsen 163 Råstofforsyning i Danmark Caroline Hejlesen Michael Larsen 164 Livscyklusvurdering af vejbefæstelser

– Projekt Bording – Funder MV

Knud A. Pihl Jørn Raaberg Helle Blæsbjerg Michael Quist Morten Bendsen Harpa Birgisdóttir 165 Two-layer porous asphalt – lifecycle

- The Øster Søgade experiment

Lars Ellebjerg Hans Bendtsen Jørgen Kragh 166 ISAP Symposium Zürich - 2008

Asphalt Pavements & Environment

Erik Nielsen Erik Olesen 167 Urban Thin Quiet SMA Pavements

Paper TRB in Washington 2009

Hans Bendtsen 168 Øster Søgade

8 år med 2-lag drænasfalt

Jørn Raaberg Annette Neidel 169 Temperature influence on road traffic noise

Californian OBSI measurement study

Hans Bendtsen Qing Lu Erwin Kohler 170 ABM type c til broer

Indstampningstemperaturens indflydelse på

materialeparametre ved Marshall-fremstilling og -prøvning.

Erik Nielsen 171 Acoustic aging of asphalt pavements

A Californian / Danish comparison

Hans Bendtsen Qing Lu Erwin Kohler 172 Vejteknisk Instituts ringprøvning – Asfalt

Undersøgelse af udvikling i spredning i perioden 1994-2008/2009

Erik Nielsen 173 Highway noise abatement

Planning tools and Danish examples

Hans Bendtsen 174 Noise Barrier Design

Danish and some European Examples

Hans Bendtsen 175 Paper Temperature influence on noise measurements

EURONOISE 2009 - Edinburgh

Hans Bendtsen Qing Lu Erwin Kohler Bruce Rymer 176 Bituminous binders – results of Danish Round Robins for

CEN test methods from 2000 - 2009

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COPENHAGEN

Niels Juels Gade 13 P.O. Box 9018

DK-1022 Copenhagen K Phone +45 7244 3333

HEDEHUSENE

Danish Road Institute Guldalderen 12 DK-2640 Hedehusene Phone +45 7244 7000

SKANDERBORG

Thomas Helsteds Vej 11 P.O. Box 529

DK-8660 Skanderborg Phone +45 7244 2200 [email protected]