RILEM - INTERLABORATORY TESTS ON PERFORMANCE PREDICTION OF PAVEMENT

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1 Performance Testing and Evaluation of Bituminous Materials 39 RILEM - INTERLBORTORY TESTS ON PERFORMNCE PREDICTION OF PVEMENT Herald Piber 1), Manfred N. Partl 2) 1) mt der Kärntner Landesregierung, Bautechnik, Klagenfurt, ustria, 2) Switzerland. EMP, Dübendorf, bstract First conclusive results of an ongoing international RILEM test programme are presented where performance predictions of different laboratories based on their own test methods and models are compared. Slabs and technical data of two motorway test sections were provided to 16 laboratories participating on a voluntary basis. This paper focuses on rutting, fatigue, thermal cracking and surface distress predictions for a period of 10 years. It was found that the predicted rut depths varied over a wide range. Compared to rutting, the fatigue predictions were in better agreement. However, the conclusion that fatigue models are more accurate could not be drawn. For both rutting and fatigue prediction, none of the laboratories followed a procedure and methodology which was directly comparable. This made clear that further exchange and co-ordination of research efforts is extremely necessary. 1 Introduction The former RILEM TC 152 PMB (Performance of Bituminous Materials) initiated 1997 this test program. These Interlaboratory tests was focused on the assessment and performance evaluation of a given mix design and not on the evaluation of the optimal mix design procedure. Newly laid asphalt courses were tested and their future performance predicted. The prediction deals especially with the main damages, as permanent deformation, cracking and surface defects. The actual behaviour is monitored and documented simultaneously over a period of about ten years. The test program consist two parts. 1. Laboratory part: Laboratory tests on field samples and prediction of long term pavement performance. 2. Section operator part: Long term pavement performance of the test sections and comparison of the results. The aim of these Interlaboratory tests is to check the validity of the performance prediction s statements obtained by the different laboratories with respect to pavement performance in practice. Various laboratory tests and the prediction models are on trial.

2 40 6th RILEM Symposium PTEBM'03, Zurich, Test sections It was the aim to consider extreme climatic condition in Europe and nevertheless to restrain on a small number of test sections. Finally it was decided to choose two road sections - one in a warm weather region and one in a cold climate region. 2.1 Basic data of test sections Mindelo WWRIPPPE This section is located in Portugal Province Porto on the motorway IC 1 Valença / Lisboa, Sublanço Perafita/Mindelo. The sea level is 35 m and represent the warm weather region. The pavement which was constructed in the years 1996 and WW- 40 mm P 16 - porous asphalt (1997) WW-BC2 110 mm C 22 - asphalt concrete (1996) WW-BC1 110 mm C 32 - asphalt concrete (1996) 200 mm unbound material(1996) 300 mm unbound material (1996) cutting (1996) The bearing capacity of the unbounded courses and the subsoil was tested with a Falling Weight Deflectometer and the values were given. The average annual daily traffic volume was 9405 vehicles and the DHTV was 971 lorries per day and both directions in The traffic forecast was + 4 % p.a. The weather data were also available. The mean value of average maximum air temperature of the hottest 7 day period according SHRP is 30,0 2,5 C and the mean value of annual minimum air temperature is 0,4 2,0 C. 2.2 Basic data of test sections Villach CCRIPPPE The section which are representing the cold climate region is located in ustria Province Carinthia on the motorway 10 Salzburg Villach. The sea level is about 500 m. The pavement was constructed in two steps between 1987 and CC- 35 mm SM 11 - stone mastic asphalt (1997) CC-BC4 80 mm BT I 22 HS - bituminous road base (1997) CC-BC3 80 mm BT I 22 HS - bituminous road base (1997) CC-BC2 65 mm BTS I 22 - bituminous road base (1988) CC-BC1 65 mm BTS I 22 - bituminous road base (1988) 200 mm unbound material(1988) 300 mm unbound material (1988) embankment (1987) The bearing capacity of the road base, sub base and sub grade was tested during the construction with a loading plate and the results were available. The traffic census counted vehicles and lorries per day and both directions in The traffic forecast was + 3 % p.a. The mean value of average maximum air temperature of the hottest 7 day period according SHRP is 30,7 1,8 C and the mean value of annual minimum air temperature is -19,3 3,7 C. 2.3 Sampling From a test area of 2,5 x 3,3 m slabs of 250 x 550 mm were taken in 1997 (Mindelo) and May 1998 (Villach), clearly marked and thoroughly packed in wooden boxes. The thickness was equivalent to the asphalt pavement. The boxes were sent to the laboratories. 2.4 Test program The types of test depended on the pavement performance prediction model chosen by each of the participating laboratories. It was to use several alternative pavement performance prediction

3 Performance Testing and Evaluation of Bituminous Materials 41 models. The final result for four possible main damages had to be indicated in accordance with the following classification scale. The prediction time period was 10 years (2008). Table 1: Prediction table No Type of damage Dimension Class of distress B C D 1 Rutting 1) mm < < < Single cracks (thermal cracking) m/100 m < Net cracks (fatigue cracking) % of 100 m² < < < surface defects 2) % of 100 m² < 2 2 1) Rutting in surface course and deformation of each asphalt course, (max. depth and change of thickness) 2) Loss of material and/or ravelling 3 Interlaboratory test reports Reports of the following 13 laboratories and reporters were delivered. Some reports were very detailed and contained valuable additional information on aspects such as traffic, temperature models, test procedures and distress models. This exceeds the original goal of the test programme and allows further evaluation and intensified discussions of the data in the future. : H. Piber, Bautechnik, Klagenfurt B: L. Francken, D. Leonard,. Vanelstraete, BRRC, Brussels CH: M.N. Partl, EMP, Dübendorf CZ: J. Kudrna, Technical University of Brno D1: K.W. Damm, asphalt Labor, Wahlstedt D2: Ch. Recknagel, E.J. Vater, BM, Berlin DK: C. Bredahl Nielsen, Danish Road Institute, Roskilde E: J.M. Baena Rangel, CEDEX, Madrid I:. Montepara, University of Parma P: J.M.B. Sousa, Consulpav, Porto Salvo S: S. Said, H. Jansson, VTI, Linköping S: F.J. Jooste, BMJ Verhaeghe, M. Vlok, Transportek CSIR, Pretoria US1: D. Hung, C.L. Monismith, University of California, Berkeley ll laboratories based their prediction on mechanical tests on the materials in the original state, i.e. as delivered.. Some participants carried out conventional asphalt tests. Hence, additional information on binder properties, volumetric characteristics of the asphalt courses and mixtures is also available. 4 Laboratory tests 4.1 Preparation of samples Only one participant considered the long term ageing effect. In this case, samples were stored in a climatic test chamber according to the SHRP geing Methods

4 42 6th RILEM Symposium PTEBM'03, Zurich, Physical properties of the asphalt courses Partly physical properties as maximum density, bulk density, air void and compaction degree were determined. 4.3 Composition of the asphalt mixture The binder content and the particle size distribution were determined too. 4.4 Binder properties Some laboratories carried out on recovered binder conventional tests as needle penetration, softening point ring and ball, breaking point Fraaß, viscosity, ductility and creep stiffness. 4.5 Mechanical Tests In this Interlaboratory Test Program various mechanical tests were carried out. The laboratories used national standards, regulations or their own procedure. Following mechanical tests were carried out during this Interlaboratory test program: Particle loss of specimen, Static Compression Test (S-CO), Cyclic Compression Test (C-CO), Two Points Bending Beam (2PB), Three Points Bending Beam (3PB), Four Point Bending Beam (4PB), Wheel Tracking Test (WT), Indirect tensile test (IT), Simple Shear Test (SH), low temperature cracking and water sensitivity 5 Rutting prediction 5.1 Selection of representative layers for testing ll laboratories used a sample of the top layer of the base course for rutting prediction (BC4 in case of CCRIPPPE and BC2 in case of WWRIPPPE). It was surprising that the surface course was not taken into account by some laboratories. In case of CCRIPPPE, only one participant and in case of WWRIPPPE, only three participants determined and used the material properties of all asphalt courses. From Table 2 follows that one laboratory used two different tests. It can be seen that the laboratories tested the layers either individually or in a combined way. Note, that test CH and S were partly performed with different course combinations. Table 2: Courses and Number of Tests Used for Rutting Prediction. Test-N DK S E P US1 B CH CS D1 S D2 Test section: CCRIPPPE - Villach BC4 BC3 BC2 BC1 Test section: WWRIPPPE - Mindelo BC2 BC1 5.2 Type of test Table 3 contains information on how the different test methods were conducted.

5 Performance Testing and Evaluation of Bituminous Materials 43 Table 3 :For the prediction of rutting different types of test were used. Mechanical test: Laboratory: Static Compression Test S-CO-CY 1 Cyclic Compression Test C-CO-CY DK, S, 2 Cyclic Compression Test C-CO-PL S 1 Wheel Tracking Test WT-PL B, CH, CS, D1, DK 5 Cyclic Indirect Tensile Test C-IT-CY D2 1 Simple Shear Test SH-CY P, US1, 2 CY = cylindrical specimen PL = plate specimen The test methods can be attributed to six classes. Most laboratories preferred compression and wheel tracking tests and used load controlled procedures. Test temperatures for the materials of the two sections were equal with the exception of the shear test. This demonstrates that the input results for the models depend not only on the test procedure but also significantly on the individual interpretation of the data initially provided to the participants. Note, that Cyclic Indirect Tensile Test was carried out on horizontally cored test specimens using double haversine cycles. Generally, input results for the models are deformations. 5.3 Rutting results and predictions On principle, the laboratories used four different methods to assess the test results: 1. Simple comparison of test results with requirements from national standards. 2. Comparison of the design traffic load and the traffic load calculated from test results based on an acceptable rut depth of 12,5 mm. 3. Comparison of the design traffic load and the traffic load calculated from test results based on an acceptable strain on the top of the subgrade. 4. Calculation of the rut depth based on experimental data without comparison to any requirement. In the first method, the test conditions and requirements are fixed in a regulation or national standard, taking into consideration the regional weather and traffic conditions. Hence, the assessment from this method is restricted to this specific situation. The results are shown in Table 4. ccording to the laboratories CS and D1 the surface course of the WWRIPPPE section does not fulfil the requirements. Table 4. Results of the First Method Measured Value (mm) Type of Criteria CCRIPPPE WWRIPPPE Test BC 4 BC 2 Permanent deformation at 1,09 0,83 3,77 0, cycles required < 1,8 CS WT-PL Deformation increase between 0,29 0,15 1,57 0, and cycles required < 0,32 Permanent deformation at 1,82 3,17 9,38 8,00 D1 WT-PL cycles required < 4,5 The results for the second method are shown in Table 5. The tests are based on a SHRP procedure where the test temperature has to be calculated from weather data. It is interesting to note, that laboratory P has chosen the test temperature for the CCRIPPPE section higher than for the

6 44 6th RILEM Symposium PTEBM'03, Zurich, 2003 WWRIPPPE section, whereas laboratory US1 has chosen the temperatures in a reversed way. The number of load cycles to obtain an acceptable strain in the shear test are converted into 130 kn or 80 kn ESLs which are equivalent to a rut depth of 12,5 mm. ccording to Table 5 the WWRIPPPE section fails laboratory P whereas the CCRIPPPE section fails at laboratory US1. Table 5. Results of the Second Method Type of Number of ESLs Criteria ESLs Test CCRIPPPE WWRIPPPE Calculated , P SH-CY Shear strain 130 kn cceptable > 7, > 5, US1 SH-CY Shear strain 80 kn Calculated 3, , cceptable > 10, > 6, The third method is quite similar. Therefore laboratory P could also be applied in this case. The experimentally determined complex modulus is used to calculate the strain on the top of subgrade with an elastic multi-layer response model. The number of load cycles to obtain an acceptable strain on top of the subgrade is converted into 130 kn ESLs and compared to the acceptable design traffic load. From Table 6 follows that both sections passed this design criteria. Note, however, the laboratories E and P found out that the acceptable number of 130 kn ESLs was different by a factor of three. Table 6. Results of the Third Method Type Number of 130 kn ESLs of Test Property ESLs Calculation CCRIPPPE WWRIPPPE Model E C-CO- Complex Calculated 50, , Shell/BISR CY modulus cceptable > 2, > 1, Calculated Shell/BISR P 4PB- Complex Calculated sphalt PR modulus Institute cceptable > 7, > 5, s far as the fourth method is concerned, six laboratories using different test methods tried to determine the rut depth curve exactly. The climatic and traffic conditions were considered either in the definition of the test conditions or in the prediction model. The different procedures are listed in Table 7, 8 and 9. The results are compared in Figure 1. Generally, the different procedures predict larger permanent deformations for the CCRIPPPE than for the WWRIPPPE section. However, the values of the CCRIPPPE section are more scattered. Most curves show a successive decrease of the rutting rate except for laboratory which led to an almost linear rutting characteristic.

7 Performance Testing and Evaluation of Bituminous Materials 45 Table 7. Results of the Fourth Method DK S B CH D2 Type of Test Property S-CO- CY WT- PL C-CO- PR WT- PL WT- PL C-IT- CY Energy based deformation modulus at 50 C Permanent deformation at 20, 25, 40 and 50 C Deformation rate at 30, 40 and 50 C Permanent deformation at 35 and 45 C Secant modulus at 38 and 60 C Permanent deformation at 25, 34, 40and 44 C Climatic and Traffic Conditions 100 kn ESLs at days with air temperatures > 25 C are considered in the evaluation. 100 kn ESLs at days with air temperatures > 25 C are considered in the evaluation. Tyre load changes at different periods of temperature considered in the evaluation 100 kn ESLs at different periods of temperature considered in the evaluation 100 kn ESLs at days with air temperatures > 25 C are considered in the evaluation. xle load changes at different periods of temperature considered in the test and evaluation Calculation Method Empirical formula developed by laboratory compares test and field data Formula based on power function Formula developed by laboratory Formula developed by laboratory Rut calculation with BISR Formula developed by laboratory The laboratories used for the calculation traffic and climatic data. Details on the energy based deformation modulus resulting from test 1 are reported by Herbst [1997]. In Table 8 the laboratories, DK, CH and D2 calculated rutting for the time with air temperatures of more than 25 C or 20 C. The other laboratories B and S considered the whole year. The results are shown in figure 1. In Table 9 the laboratories, DK, and CH calculated rutting for the time with air temperatures of more than 25 C or 20 C. The other laboratories B and S considered the whole year. The results are shown in figure 2.

8 46 6th RILEM Symposium PTEBM'03, Zurich, 2003 Table 8: CCRIPPPE Villach: Evaluation of the traffic and climatic data for rutting prediction 100 kn ESLs /day ir Number of 100 kn ESLS for 10 temperature days years 970 > DK 1393 > B CH 1393 > Lorries / day temperature ,5 D , S Single axles / day 15 mm Tyre loads for 10 years Rut depth (mm) Year DK S B CH D2 Figure 1: Calculated Rutting for CCRIPPPE section

9 Performance Testing and Evaluation of Bituminous Materials 47 Table 9: WWRIPPPE Mindelo: Evaluation of the traffic and climatic data for rutting prediction 100 kn ESLs /day ir Number of 100 kn ESLS for 10 temperature days years 642 > DK 971 > B CH 1167 > S Single axles / day 40 mm Tyre loads for 10 years Rut depth (mm) Year DK S B CH Figure 2. Calculated Rutting for WWRIPPPE section In Table 10, a summary of the classification of all rutting test and prediction results is presented. The result surprises: In spite of considerable world wide long term efforts to improve the accuracy of rutting prediction, the only general agreement from this Interlaboratory test programme is that rutting will probably not exceed 20 mm in both sections. The predictions based on the wheel tracking test are extremely unfavourable for the WWRIPPPE section, whereas the prediction with the compression test 5 leads to a completely reverse conclusion.

10 48 6th RILEM Symposium PTEBM'03, Zurich, 2003 Table 10. Classification of Rutting Test and Prediction Results for 10 Years Rut Depth 1) (mm) CCRIPPPE Villach WWRIPPPE Mindelo <5 5 -< <20 20 <5 5 -< <20 20 B CS D1 E S CH DK P D2 S US1 E P S S B DK US1 Total: ) Rutting in surface course and deformation of each asphalt course (max. depth and change of thickness) 6 Tests for fatigue prediction 6.1 Selection of representative layers for testing s shown in Table 11, the majority of laboratories used specimens from the lowest layer of the base course (BC1) for fatigue prediction. In three cases (CCRIPPPE) and two cases (WWRIPPPE) all layers were tested. For test I a combination of layers was investigated. CH CS D1 Table 11. Courses Used for Fatigue Tests. Test N I B CZ E P S US1 S CCRIPPPE Villach BC4 BC3 BC2 BC1 WWRIPPPE Mindelo BC2 BC1 6.2 Type of test Table 12 contains information on how the different test methods were conducted. Similar to rutting, the test methods can be attributed to six classes. Most laboratories preferred bending beam tests and used deformation or strain controlled methods. With the exception of two tests, fatigue test temperatures for the materials of the two sections were equal. The input results for the models were generally complex modulus and fatigue curves.

11 Performance Testing and Evaluation of Bituminous Materials 49 Table 12: For the prediction of fatigue or net cracking different types of test were used. Mechanical test: Laboratory: Static Compression Test S-CO-CY 1 Cyclic Compression Test C-CO-CY I 1 Two Point Bending Beam Test 2PB-TR B, CZ, 2 Three Point Bending Beam Test 3PB-PR E 1 Four Point Bending Beam Test 4PB-PR P, S, US1 3 Indirect Tensile Test IT-CY S 1 CY = cylindrical specimen PR = prismatic specimen 6.3 Fatigue and prediction model On principle, all laboratories followed the same procedure. The modulus of the bituminous courses and layers were determined by different test methods and the modulus of subgrade and subsoil estimated. Strain and stresses were calculated by means of elastic multi-layer models and converted to ESLs which were compared to the acceptable design traffic loads. Where the participating laboratories did not provide an estimate on the remaining life after 10 years, this value was calculated during the general evaluation of the different test reports using the following equation: N RL 1 n where RL denotes the remaining life after 10 years in percent; n stands for the calculated ESLs from the test results and N is the design traffic load in ESLs. The results are presented in Table 14. With the exception of laboratory S the CCRIPPPE section is predicted to last much longer than the WWRIPPPE section. For the CCRIPPPE section the remaining life after 10 years is generally expected to be more than 80 %. For the WWRIPPPE section no agreement is observed. In this case, the estimation of the remaining life ranges from 0 to 84 %. Table 13. Fatigue Test, Characteristics and Calculation Model and Result Type of Test Characteristic Calculation Model Result S-CO-CY Energy based modulus, Jones stress R I C-CO-CY Complex modulus BISR R B 2PB-TR Stiffness modulus PMIN, BISR a CZ 2PB-TR Stiffness modulus BISR R E C-CO-CY Dynamic modulus BISR 3PB-PR Fatigue curve R 4PB-PR Stiffness modulus BISR R P sphalt Institute R Fatigue curve R S 4PB-PR Stiffness modulus PROPD Fatigue curve b US1 4PB-PR Stiffness modulus ELSYM5 R S C-IT-CY Fatigue curve Resilient modulus Fatigue curve VGDIM95, CHEVRON R

12 50 6th RILEM Symposium PTEBM'03, Zurich, 2003 R Remaining Life after 10 years a expected cracked area was provided (CCRIPPPE = 0,0 % and WWRIPPPE = 0,6 %) b engineering judgement was provided Table 14 : Standard xle Load, Design Load and expected EWSL s in Millions and Remaining Life after 10 Years. CCRIPPPE WWRIPPPE Standard Design Expected Design Expected xle: R R Load ESL s Load ESL s 100 kn 4,4 44,3 0,90 2,9 6,2 0,52 I 120 kn 3,4 780,0 1,00 CZ 100 kn 8,1 164,9 0,95 3,8 3,9 0,03 E 130 kn 2,3 37,8 0,94 2,0 1,4-0,42 51,0 0,86 30,1 0,82 P 130 kn 7,0 8,2 0,15 5,4 5,9 0,09 243,1 0,97 6,7 0,19 US1 80 kn 10, ,0 1,00 6,8 41,2 0,83 S 100 kn 6,6 14,5 0,55 2,9 9,1 0,68 The comparison of the design load expressed in 100 kn ESL s (Table 15) shows a wide range. The values reach from 4,1 Mio to 19,8 Mio for the CCRIPPPE section and from 2,8 Mio to 15,4 Mio for the WWRIPPPE section. The ration is about 1 to 5. Table 15: Comparison of the Design Load for a Standard xle Load of 100 kn Standard xle: CCRIPPPE Mio - ESL s Standard xle 100 kn Standard xle WWRIPPPE Mio - ESL s 100 kn 100 kn 4,4 4,4 2,9 2,9 B 100 kn 6,3 6,3 4,5 4,5 I 120 kn 3,4 7,1 - - CZ 100 kn 8,1 8,1 3,8 3,8 E 130 kn 2,3 6,7 2,0 5,6 P 130 kn 7,0 19,9 5,4 15,4 US1 80 kn 10,0 4,1 6,8 2,8 S 100 kn 6,6 6,6 2,9 2,9 Fatigue life prediction by all laboratories in terms of net cracking is summarised in the classification Table number 16. Whereas the laboratories reached a good agreement for the CCRIPPPE section, the results for the WWRIPPPE section were different in two cases. s compared to rutting, the fatigue prediction was generally in better agreement. However, it has to be kept in mind that the prediction period of 10 years was about half of the real design period of the motorways. Therefore it can not be concluded from these results that the fatigue models are more accurate than the permanent deformation models.

13 Performance Testing and Evaluation of Bituminous Materials 51 Table 16: Classification of Fatigue Test and Prediction Results for 10 Years Net Cracking (% of 100 m²) CCRIPPPE Villach WWRIPPPE Mindelo <5 5 -< <20 20 <5 5 -< <20 20 B CZ E B CZ P US1 E Lab I P S S US1 S S Total: Tests for thermal and surface cracking prediction 7.1 Selection of representative layers for testing s shown in Table 17, the laboratories used specimen from the top layers of the pavement. Table 17. Courses used for Surface Cracking. Test N CZ D1 S CCRIPPPE Villach BC4 BC3 BC2 BC1 WWRIPPPE Mindelo BC2 BC1 7.2 Type of test The Table 18 contains information on how the different test methods were conducted. Table 18: For the prediction of thermal and surface cracking different types of test were used. Mechanical test: Laboratory: Static Compression Test S-CO-CY 1 Indirect Tensile Creep Test ITCT-PR CZ, 1 ssessment of the binder properties - D1 1 Indirect Tensile Test IT-CY S Surface cracking and prediction model The laboratories followed different procedures. Laboratory determined the critical temperature with help of the temperature modulus curve. The laboratories CZ and S carried out tensile tests and laboratory D1 assessed the behaviour according the binder properties.

14 52 6th RILEM Symposium PTEBM'03, Zurich, 2003 Table 19: Critical Temperatures of Surface courses. Type of Test Critical or Breaking Temperature CCRIPPPE WWRIPPPE S-CO-CY - 22 C - 29 C CZ ITCT-PR - 24,2 C - 17,1 C 1) S IT-CY + 24,8 C - 1) Determined on BC2 The result for the CCRIPPPE section is in a small range. The prediction of all laboratories for the thermal or surface cracking behaviour is summarised Table 20. Table 20: Surface or Thermal Cracking and Prediction Results for 10 Years Single cracks (Thermal cracking) (m/100 m) CCRIPPPE Villach WWRIPPPE Mindelo <4 4 <4 4 CZ CZ D1 D1 S Total: Tests and surface defects prediction Only two laboratories dealt with surface defects. Laboratory carried out a test according EN and laboratory CZ used the volumetric values for an assessment. The prediction is shown in Table 21. Table 21: Surface Defects and Prediction Results for 10 Years Surface defects 2) (% of 100 m²) CCRIPPPE Villach WWRIPPPE Mindelo <2 2 <2 2 CZ Total: ) Loss of material and/or ravelling 9 Tests for thermal and surface cracking prediction 9.1 Selection of representative layers for testing s shown in Table 22, the laboratories used specimen from the top layers of the pavement.

15 Performance Testing and Evaluation of Bituminous Materials 53 Table 22. Courses Used for Surface Cracking. Test N CZ D1 S CCRIPPPE Villach BC4 BC3 BC2 BC1 WWRIPPPE Mindelo BC2 BC1 9.2 Type of test The Table 23 contains information on how the different test methods were conducted. Table 23: For the prediction of thermal and surface cracking different types of test were used. Mechanical test: Laboratory: Static Compression Test S-CO-CY 1 Indirect Tensile Creep Test ITCT-PR CZ, 1 ssessment of the binder properties - D1 1 Indirect Tensile Test IT-CY S Surface cracking and prediction model The laboratories followed different procedures. Laboratory determined the critical temperature with help of the temperature modulus curve. The laboratories CZ and S carried out tensile tests and laboratory D1 assessed the behaviour according the binder properties. Table 24: Critical Temperatures of Surface courses. Type of Test Critical or Breaking Temperature CCRIPPPE WWRIPPPE S-CO-CY - 22 C - 29 C CZ ITCT-PR - 24,2 C - 17,1 C 1) S IT-CY + 24,8 C - 1) Determined on BC2 The result for the CCRIPPPE section is in a small range. The prediction of all laboratories for the thermal or surface cracking behaviour is summarised Table 25. Table 25: Surface or Thermal Cracking and Prediction Results for 10 Years Single cracks (Thermal cracking) (m/100 m) CCRIPPPE Villach WWRIPPPE Mindelo <4 4 <4 4 CZ CZ D1 D1 S Total:

16 54 6th RILEM Symposium PTEBM'03, Zurich, Tests and surface defects prediction Only two laboratories dealt with surface defects. Laboratory carried out a test according EN and laboratory CZ used the volumetric values for an assessment. The prediction is shown in Table 26. Table 26: Surface Defects and Prediction Results for 10 Years Surface defects 2) (% of 100 m²) CCRIPPPE Villach WWRIPPPE Mindelo <2 2 <2 2 CZ Total: ) Loss of material and/or ravelling 11 Conclusion From the first results of this ongoing RILEM interlaboratory test programme the following conclusions can be drawn. Note, that the conclusions deal only with the pavement performance prediction by the laboratories. comparison with the in field behaviour of the two sections is not possible yet. None of the laboratories followed a procedure and methodology which was directly comparable to one of the others. The rut depths predicted by different laboratories using their own test methods and prediction models varied over a wide range. In those cases where the curve of rut depth development was determined exactly, generally the larger permanent deformations were predicted for the CCRIPPPE than for the WWRIPPPE section. The values of the CCRIPPPE section were more scattered. Some laboratories compared their rutting results with requirements which are fixed in regulations or national standards and came partly to contradicting conclusions. Hence, in some cases, the CCRIPPPE section and in other cases, the WWRIPPPE section did not pass the requirements. It was generally agreed, that rutting will probably not exceed 20 mm in both sections. s compared to the other methods, the predictions based on the wheel tracking test were extremely unfavourable for the WWRIPPPE section. Compared to rutting, the fatigue predictions were in better agreement. However due to the fact that the prediction period was only about half of the design period, it can not be concluded that the fatigue models are more accurate than the permanent deformation models. With one exception the remaining life after 10 years of the CCRIPPPE section is predicted to be higher. For the WWRIPPPE section the prediction showed less agreement. Fatigue life prediction by all laboratories in terms of net cracking confirmed this finding. In summary, the findings clearly demonstrate that further exchange and co-ordination of research efforts is extremely necessary. 12 cknowledgement The authors would like to express their thanks to all participating laboratories and to the two section operators for their contributions provided on a completely voluntary basis. Many thanks

17 Performance Testing and Evaluation of Bituminous Materials 55 also to the members of the RILEM TC 182-PEB and in particular of its TG 4 Pavement Performance Prediction & Evaluation for their input and comments. 13 References 1. Francken, L, 1998, Bituminous, Binders and Mixtures, State of the rt and Interlaboratory Tests on Mechanical Behaviour and Mix Design, Report 17, E&FN Spon, ISBN , RILEM TC 152 PBM 2. RILEM TC 152 PBM. Report: Part I, Pavement Performance Prediction and Evaluation (PPPE) Interlaboratory tests, unpublished, RILEM TC 182 PEB, Report: Part II, Test Report of participating Laboratories, mt der Kärntner Landesregierung, 17 BT Bautechnik, Informationsdienst Nr.: 28, Klagenfurt, Partl, M.N.; Piber, H.: RILEM Interlaboratory tests on performance prediction of pavements, Ninth International Conference on sphalt Pavements, Conference proceedings, Copenhagen, RILEM TC 182 PEB, Report: Part III, Laboratory Tests, Results and Evaluation, mt der Kärntner Landesregierung, 17 BT Bautechnik, Informationsdienst Nr.: 287, Klagenfurt, 2002