Zpráva - ANG - Textilní zkušební ústav
Transkript
Zpráva - ANG - Textilní zkušební ústav
Textile Testing Institute Notified body No. 1021 Václavská 6, 658 41 Brno, Czech Republic REPORT Evaluation of interlaboratory test results in the field of geotextiles and geomembranes (geosynthetics) according to EN 12224 – Determination of the resistance to weathering further to EN 12226 – General tests for evaluation following durability testing used for conformity evaluation of constructional products according to NV No. 190/2002 Sb. (corresponding to Building Directive 89/106 EEC) Prepared by: Ing. Markéta Ondráčková Approved by: RNDr. Pavel Malčík Brno, November 16, 2007 Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 1 ze 1 Contents Contents...................................................................................................................................... 2 1. Introduction ............................................................................................................................ 2 2. Time schedule ........................................................................................................................ 3 3. Preparation of test specimens ................................................................................................. 3 4. Results and evaluation............................................................................................................ 3 4.1Technical parameters of equipments used ........................................................................ 3 4.2Test evaluation .................................................................................................................. 5 4.2.1Detailed examination of consistency and outlaying values ....................................... 7 4.2.2Summary of results expressed in the z-score graphic form ..................................... 11 4.2.3Summary of results................................................................................................... 13 5. Conclusion............................................................................................................................ 16 Annex – Testing of homogeneity ............................................................................................. 17 Homogeneity test of sample A ............................................................................................. 17 Homogeneity test of sample B ............................................................................................. 18 1. Introduction More than 60 laboratories had been addressed and 6 laboratories actually participated. These include testing laboratories functioning within the frame of the European Notified Bodies. The following list of the trial participants is arranged in the alphabetical order and any potential relation to the laboratory code number is a coincidence only. Institution name Address WWW AITEX - Instituto Tecnológico Textil Plaza Emilio Sala, 1 03801 Alcoy - Spain PASEO 22 DE JULIO, 218 TERRASSA (BARCELONA) 08221 Spain www.aitex.es Arsenal, Objekt 213 www.ofi.at LEITAT TECHNOLOGICAL CENTRE ÖFI TECHNOLOGIE & INNOVATION GMBH 1030 Wien Austria SP Sveriges Tekniska Forskningsinstitut AB Box 857501 15 BORAS Sweden TZU – Textile Testing Institute Václavská 6 Accredited Testing Laboratory 658 41 Brno Czech Republic Technical and Testing Institute of Structural Laboratory in Tatranská Štrba Materials, N. O. Štefánikova 24 059 41 Tatranská Štrba Slovakia Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz www.leitat.com www.sp.se www.tzu.cz www.tsus.sk Stránka 2 ze 2 2. Time schedule The offers for participation were sent out during May 2007. The samples were prepared during June 2007. In this period, also homogeneity of the samples was verified. The samples were sent out on July 2, 2007. In most cases, the measurements were carried out according to our instructions as early as feasible after receiving the samples, namely between July 10 and October 30, 2007. The results were received from four laboratories by the date stated, i.e. September 28, 2007. However, two laboratories sent the results as late as the end of October. This Report was completed on November 16, 2007 3. Preparation of test specimens Two test fabrics ready for the interlaboratory comparison were prepared at the Textile Testing Institute, Brno. The first sample labelled by capital “A” was non-woven polypropylene textile fabric and sample labelled by capital “B” was woven polyester textile fabric. From each of the materials were prepared specimens for homogeneity tests and also specimens for each participating laboratory. Their sizes were selected so that enough material was available for testing. Homogeneity of both materials was tested using original samples. (Annex – Testing of homogeneity) 4. Results and evaluation Individual testing laboratories were allotted identification numbers according to the sequence in obtaining reply to participate in the test trial. Each of the participating laboratories can find its own number in the “Certificate on participation in the comparative tests”. 4.1 Technical parameters of equipments used Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 3 ze 3 Table No.1 – Determination of resistance to weathering according to EN 12224 Lab Type of Age of light Type of equipment used Radiation intensity code UV lamp source Filters used 1 not available UVA 340 200 h 0.68 W/m2/340 nm none 2 UV 2000 UVA 340 - 0.76 W/m2/340 nm none 3 QUV Accelerated Weathering Tester Model QUV / spray – with Solar Eye UVA 340 Irradiance Control - 0.68 W/m2/340 nm none 4 Weathering tester - Model QUV/spray UVA 340 14334 h 0.68 W/m2/340 nm none 5 not available UVA 340 - 0.95 W/m2/340 nm none 6 Atlas UV 2000 UVA 340 1883 h 0.68 W/m2/340 nm none Table No. 2 - Tensile properties according to EN 12226 Lab Type of equipment used Conditioning code 24 h 1 not available relative humidity 62,3 %, temperature 20 °C 24 h 2 not available relative humidity 50±4 %, temperature 22±2 °C 3 FPZ 10/1 WPM Leipzig, Germany 4 ZWICK 1454 (CRE) ZDM 30 5 ZWICK 1474 6 not available 24 h relative humidity 50 %, temperature 23 °C 24 h relative humidity 65±4 %, temperature 20±2 °C 72 h relative humidity 50 %, temperature 23°C 48 h relative humidity 52 %, temperature 23 °C Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Exposition time 426 h (71 cycles) not available Testing conditions 5 h dry phase 1 h spraying 5 h dry phase 1 h spraying Energy of irradiation 1042 kJ/m2 (340 nm) 426 h (71 cycles) 5 h dry phase 1 h spraying 50 MJ/m2 426 h (71 cycles) 426 h (71 cycles) 426 h (71 cycles) 5 h dry phase 1 h spraying 5 h dry phase 1h spraying 5 h dry phase 1 h spraying 50 MJ/m2 50 MJ/m2 51,15 MJ/m2 50 MJ/m2 Strength range Gauge length Rate of head traverse 5000 N Length – 200 mm 100 mm/min 100000 N Width – 50 mm 100 mm/min 0-400 N 0-2000 N 0-4000 N 0-5000 N 0-300kN Length– 200 mm Width – 50 mm 100 mm/min Length – 200 mm Width – 50 mm 100 mm/min 100000 N Length – 200 mm 100 mm/min 2500 N Width – 50 mm 100 mm/min Stránka 4 ze 4 4.2 Test evaluation The average values for both test specimens from all participants was selected after statistical processing and after excluding the outlying values (these being denoted by “**”). It should be remarked that original data provided by the participants were used, i.e. no effort to round them up has been made. After irradiation Sample A Original Table No. 3 – Measured values from all participants for sample A Lab code 1 2 Strength Strength Direction SD SD (N) (N) longitudinal 368,5 34,5 371,47 40,19 transverse 1384,5 30,5 1324,21 77,05 Elongation Elongation Direction SD SD (%) (%) 129,99 8,76 longitudinal 138,4 7,5 transverse 62,7 3,0 63,60 2,28 Strength Strength Direction SD SD (N) (N) longitudinal 370,5* 15,0 59,13 23,93 transverse 1546,0** 27,5 88,91 12,46 Elongation Elongation Direction SD SD (%) (%) longitudinal 117,1 2,7 83,58 12,40 transverse 60,0 1,5 28,09 1,89 Percenlongitudinal 100,5 15,92 tage of residual transverse 111,5 6,72 strength Percenlongitudinal 84,5 64,30 tage of residual transverse 95,5 44,17 elongation * - distant values ** - outlying values SD – standard deviation Textilní zkušební ústav, Václavská 6, 658 41 Brno 3 Strength (N) 388 1310 Elongation (%) 120,0 63,5 Strength (N) 3,4 90 Elongation (%) 31,5 28,5 11,5 3,1 4 Strength (N) 359,18 1382,46 Elongation (%) 118,9 59,03 Strength (N) 33,47 132,64 Elongation (%) 58,44 21,87 0,9 - 9,3 - 22,1 - 70,5 - 6,9 - 9,6 - 11,2 - 74,7 - 26,3 - 49,2 - 64,5 - 35,0 - 45,1 - 37,1 - 40,8 - 48,6 - www.tzu.cz SD 11,7 81,4 SD 5,4 1,2 SD 2,5 27,4 SD Stránka 5 ze 5 11,0 2,40 5 Strength (N) 308 1158* Elongation (%) 141 61 Strength (N) 68 130 Elongation (%) 91 24,9 16,9 0,6 6 Strength (N) 403 1387 Elongation (%) 206* 107** Strength (N) 119 351 Elongation (%) 134* 554 SD 26,13 51,08 SD 8,8 1,09 SD 6,7 19,30 SD SD 6 18 SD 2,8 SD 6 20 SD SD 15 34 SD 5 13 SD 16 97 SD 8 - Percentage longitudinal of residual transverse elongation * - distant values ** - outlying values SD – standard deviation 3 Strength (N) 3200 2200 Elongation (%) 8,5 9,0 Strength (N) 2100 1000 Elongation (%) 7,4 9,0 0,2 1,7 4 Strength (N) 6197,72 4059,43 Elongation (%) 11,79 11,95 Strength (N) 2665,12 1660,79 Elongation (%) 6,63 7,51 66,0 - 43,0 - 53,9 - 46,3 - 40,9 - 33,7 - SD 49,7 138,3 SD 0,2 0,3 SD 189,2 58,9 SD 5 SD 222,37 120,28 SD 0,19 0,91 SD 47,67 53,25 SD 0,25 0,64 Sample was not tested After irradiation Sample B Original Table No. 4 – Measured values from all participants for sample B Lab code 1 2 Strength Strength Direction SD SD (N) (N) longitudinal 5601,0 5259,55 191,90 transverse 3619 3632,87 99,19 Elongation Elongation Direction SD SD (%) (%) 12,00 0,20 longitudinal 12,5 transverse 13,0 12,81 0,52 Strength Strength Direction SD SD (N) (N) longitudinal 5588,0 2947,58 168,64 transverse 3609,0* 1646,64 57,02 Elongation Elongation Direction SD SD (%) (%) 8,07 0,19 longitudinal 13,0 9,04 0,48 transverse 13,0 Percentage longitudinal 99,5 56,04 of residual transverse 99,5 45,33 strength 6 Strength (N) 988 984 Elongation (%) 28,7* 9,0 Strength (N) 1521 1316 Elongation (%) 9,3 8,9 SD 50 22 SD 6,7 0,4 SD 110 55 SD 0,3 0,3 104,0 - 67,25 - 86,1 - 56,2 - 67,6 - 100,0 - 70,56 - 99,0 - 62,8 - 1,1 - It is evident from Tables No. 3 and 4 that the results (percentage of residual strength and elongation) provided by the relevant participants differ principally. This observation also refers to the original (unexposed) samples! Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 6 ze 6 4.2.1 Detailed examination of consistency and outlaying values To obtain consistency of the results, Mandel´s statistics h (interlaboratory statistics of consistency) was used. Depicted horizontal lines correspond to the relevant values of Mandel´s indicators on the levels of statistical significance of 1 and 5 %, respectively. Chart No. 1 Mandel´s statistics of interlaboratory consistency h – for original sample A – grouped according to the laboratories Mandel´s statistics h sample A – original strength – longitudinal direction strength – transverse direction elongation – longitudinal direction elongation – transverse direction 2,50 2,00 1,50 1,00 0,50 0,00 -0,50 -1,00 1 2 3 4 5 6 -1,50 -2,00 -2,50 Chart No. 2 Mandel´s statistics of interlaboratory consistency h - for sample A after irradiation – grouped according to the laboratories Mandel´s statistics h sample A – after irradiation strength – longitudinal direction strength – transverse direction elongation – longitudinal direction elongation – transverse direction 2,50 2,00 1,50 1,00 0,50 0,00 -0,50 -1,00 1 2 3 4 5 6 -1,50 -2,00 -2,50 Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 7 ze 7 Chart No. 3 Mandel´s statistics of interlaboratory consistency h – for original sample B – grouped according to the laboratories Mandel´s statistics h sample B – original strength – longitudinal direction strength – transverse direction elongation – longitudinal direction elongation – transverse direction 2,00 1,50 1,00 0,50 0,00 -0,50 1 2 3 4 5 6 -1,00 -1,50 -2,00 Chart No. 4 Mandel´s statistics of interlaboratory consistency h – for sample B after irradiation – grouped according to the laboratories Mandel´s statistics h sample B –after irradiation strength – longitudinal direction strength – transverse direction elongation – longitudinal direction elongation – transverse direction 2,00 1,50 1,00 0,50 0,00 -0,50 1 2 3 4 5 6 -1,00 -1,50 -2,00 It follows from Chart No. 1 that laboratories 5 and 6 reported different results as compared to other participants. It is evident from Chart No. 2 that the participating laboratories obtained different results of strength and elongation after irradiation. Large differences were observed particularly in laboratories No. 1 and 6. It can be deduced from Chart No.3 that laboratory No. 6 obtained different results as compared to other laboratories. Laboratory No.5 did not test sample B. Chart No. 4 reveals different results after irradiation for sample B in laboratory No.1. Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 8 ze 8 It was decided that all results would be included into overall assessment providing that they would be subjected to Grubbs´ test related to outlying values. Table No. 5 Values of Grubbs´ test for mean values of strength STRENGTH SAMPLE A SAMPLE B Direction One small One large One small One large 1,793 1,126 1,521 0,909 longitudinal Original 1,889* 0,711 1,495 0,906 transverse After 0,789 1,955* 0,922 1,676 longitudinal irradia0,523 2,011** 0,828 1,724* transverse tion Distant value (5 %) 1,887 1,715 Outlying value (1 %) 1,973 1,764 Table No. 6 Values of Grubbs´ test for mean values of elongation ELONGATION SAMPLE A SAMPLE B Direction One small One large One small One large 0,723 1,959* 0,776 1,754* longitudinal Original 2,032** 1,074 0,922 0,565 transverse After 1,711 0,951 0,899 1,646 longitudinal irradia 0,635 1,935* 0,960 1,701 transverse tion Distant value (5 %) 1,887 1,715 Outlying value (1 %) 1,973 1,764 Test type Grubb´s test statistics Grubb´s critical values Test type Grubb´s test statistics Grubb´s critical values The Grubbs´ statistics G determines whether or nor it is possible to consider the mean value of the determination as a) correct b) distant (if G is higher or equal to 5 % of critical value); it is denoted as “*” in Tables No 2, 3 and 6 c) outlying (if G is higher or equal to 1 % of critical value); it is denoted as “**” in Tables No 2, 3 and 6 The Grubbs´ test found the results of results of laboratory 1 for strength of sample A and laboratory 6 for elongation of sample B as outlying. Therefore, the pairs of the lowest and highest mean values were not tested any further. The results of these laboratories were excluded form calculation of total mean value for particular properties. Therefore, the following statistical analysis includes five laboratories only. The concluding overview of results is offered by z-score, which was calculated from all measured values according to the equation: x−X z= σ where: x – mean value of determination for the particular laboratory X – mean value of all determinations of the particular samples σ − mean value of standard deviation for particular samples Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 9 ze 9 It was most important for graphical expression of results employing z-score to select the most suitable way of calculation of standard deviation of values obtained for particular samples. As the most trustworthy value of deviation was selected the value obtained from results of the particular participants; i.e. from the measured values after excluding outlying results for sample A. There were no outlying values for sample B; therefore, all results obtained were used for the calculation. The following table shows a summary of standard deviations and mean values and presents the resulting values employed for statistical processing (denoted by bold letters). Table No. 7 Values of standard deviation employed for calculation of z-score STRENGTH Parameter Overall mean value RSD** SD Mean a.e.o.v.* RSD a.e.o.v. SD a.e.o.v..* Sample A SAMPLE B original after irradiation original after irradiation A – long. A – trans. A – long. A – trans. B – long. B – trans. B – long. B – trans. 366,4 1324,4 108,9 389,8 4249,3 2899,1 108,9 389,8 8,9 32,6 6,7 88,1 122,8 133,8 147,5 574,9 50,4 2143,7 44,2 1280,6 122,8 133,8 147,5 574,9 365,9 1312,3 56,6 158,5 - - - - 9,9 7,1 76,0 69,2 - - - - 36,4 92,8 43,0 109,6 - - - - ELONGATION Parameter Sample A Sample B original after irradiation original after irradiation A – long. A - trans A – long. A – trans. B – long. B – trans. B – long. B – trans. Total 142,4 69,5 79,7 49,6 14,7 11,2 8,9 9,5 mean * RSD** 22,8 26,6 51,9 88,0 54,3 18,0 28,2 21,7 SD* 32,5 18,5 41,3 43,6 8,0 2,0 2,5 2,1 Mean value 129,7 62,0 71,8 32,7 a.e.o.v..* RSD 7,9 3,1 57,0 47,4 a.e.o.v... SD 10,2 1,9 40,9 15,5 a.e.o.v..* a.e.o.v.. – after exclusion of outlying values * - values used for statistical processing ** - selected standard deviation expressed in percentage from mean of results obtained by the participants of the test SD = n∑ x 2 − ( ∑ x) 2 n(n − 1) Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 10 ze 10 4.2.2 Summary of results expressed in the z-score graphic form Table No. 8 Values of z-score of particular laboratories for samples A and B STRENGTH Sample A Sample B Laboratory original after irradiation original after irradiation z A long. z A trans. z A long. z A trans. z B long. z B trans. z B long. z B trans. 0,1 0,8 7,3 12,7 0,6 0,6 1,7 1,7 1 0,2 0,1 0,1 -0,6 0,5 0,6 0,0 -0,2 2 0,6 0,0 -1,2 -0,6 -0,5 -0,5 -0,6 -0,8 3 -0,2 0,8 -0,5 -0,2 0,9 0,9 -0,2 -0,2 4 -1,6 -1,7 0,3 -0,3 5 1,0 0,8 1,5 1,8 -1,5 -1,5 -0,9 -0,5 6 ELONGATION Sample A Sample B Laboratory original after irradiation original after irradiation z A long. z A trans. z A long. z A trans. z B long. z B trans. z B long. z B trans. 0,9 0,4 1,1 1,8 -0,3 0,9 1,6 1,7 1 0,0 0,8 0,3 -0,3 -0,3 0,8 -0,3 -0,2 2 -1,0 0,8 -1,5 -0,3 -0,8 -1,1 -0,6 -0,2 3 -1,1 -1,6 -0,3 -0,7 -0,4 0,4 -0,9 -1,0 4 1,1 -0,5 0,5 -0,5 5 7,5 23,7 1,2 6,5 1,8 -1,1 0,2 -0,3 6 z A, B – obtained z-score values for particular participants z<±2 acceptable result ± 2 < z < ± 3 cautionary borderline z>±3 unacceptable result Chart No. 5a,b,c,d - z-score values of strength for sample A from particular laboratories Sam ple A, original strength – transverse direction Sample A, original strength – longitudinal direction 2,0 1,5 2,0 1,0 z - score 1,0 0,5 0,0 -0,5 -1,0 -1,5 -2,0 5 4 1 2 3 6 z - score 1,5 0,5 0,0 -0,5 5 3 2 4 1 6 -1,0 -1,5 -2,0 Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 11 ze 11 Sam ple A, after irradiation strength – longitudinal direction Sam ple A, after irradiation strength – transverse direction 12,0 10,0 7,0 z - score 6,0 z - score 5,0 4,0 3,0 2,0 6,0 4,0 2,0 1,0 0,0 -1,0 8,0 3 5 2 4 6 0,0 1 5 3 2 -2,0 -2,0 4 1 6 Chart No. 6a,b,c,d - z-score values of elongation for sample A from particular laboratories Sam ple A, original elongation – transverse direction Sam ple A, original elongation – longitudinal direction 2,0 1,5 7,5 1,0 6,5 z - score 5,5 z - score 4,5 3,5 2,5 1,5 0,0 -0,5 5 4 1 3 2 6 -1,0 0,5 -0,5 -1,5 0,5 4 2 3 1 5 -1,5 6 -2,0 -2,5 Sam ple A, after irradiation elongation – transverse direction Sample A, after irradiation elongation – longitudinal direction 7,0 6,0 2,0 5,0 z - score 1,0 0,5 0,0 -0,5 3 2 4 1 5 6 z - score 1,5 4,0 3,0 2,0 1,0 -1,0 0,0 -1,5 -1,0 -2,0 -2,0 4 5 1 3 2 6 Chart No. 7a,b,c,d - z-score values of strength for sample B from particular laboratories Sample B, original strength – longitudinal direction Sam ple B, original strength – transverse direction 2,0 1,5 2,5 1,0 1,5 0,5 z - score 1,0 0,5 0,0 -0,5 -1,0 6 3 2 1 4 z - score 2,0 0,0 -0,5 6 3 1 2 4 -1,0 -1,5 -1,5 -2,0 -2,5 -2,0 -2,5 Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 12 ze 12 Sam ple B, after irradiation strength – transverse direction Sample B, after irradiation strength – longitudinal direction 2,5 2,0 2,5 1,5 2,0 z - score 1,0 0,5 0,0 6 -0,5 3 4 2 1 z - score 1,0 1,5 0,5 0,0 3 -0,5 6 2 4 1 -1,0 -1,0 -1,5 -1,5 -2,0 -2,0 -2,5 -2,5 Chart No. 8a,b,c,d - z-score values of elongation for sample B from particular laboratories Sam ple B, original elongation – transverse direction Sam ple B, original elongation – longitudinal direction 2,0 1,5 2,0 1,0 z - score 1,0 0,5 0,0 -0,5 3 4 2 1 6 z - score 1,5 0,5 0,0 3 -0,5 6 2 4 1 -1,0 -1,0 -1,5 -1,5 -2,0 -2,0 Sam ple B, after irradiation elongation – transverse direction Sam ple B, after irradiation elongation – longitudinal direction 2,0 1,5 2,0 1 z - score 1,0 6 0,5 0,0 -0,5 4 3 z - score 1,0 1,5 0,5 -0,5 2 1 0,0 4 6 3 2 -1,0 -1,0 -1,5 -1,5 -2,0 -2,0 4.2.3 Summary of results The following characteristics summarise z-score values and provide information on how a particular laboratory – in general terms - coped with other laboratories concerning all measurements. ∑z RSZ = m SSZ = ∑ z 2 where RSZ is relative sum of z-score for sample A (B) SSZ is sum of z-score squares for sample A (B) Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 13 ze 13 m is number of z-score values for each sample Table No. 9 Values of relative sum of z-score and sum of z- score squares from particular laboratories for samples A and B Sample A Sample B Laboratory RSZ SSZ RSZ SSZ 8,8 219,4 3,0 12,9 1 0,2 1,3 0,3 1,5 2 -1,1 6,2 -1,8 3,8 3 -1,4 5,1 -0,1 3,7 4 -1,0 7,4 5 15,5 667,8 -1,4 10,1 6 Chart No. 9 Relative sum of z-score for sample A RSZ 16,0 11,0 6,0 1,0 4 3 5 2 1 6 5 1 6 -4,0 Chart No. 10 Sum of z- score squares for sample A SSZ 250,0 200,0 150,0 100,0 50,0 2 4 3 0,0 Chart 10 of square values of z-score reveals again statistically significant deviation of results from two laboratories. Critical value of distribution χ2(α=0,05) = 12,59 for the six participating Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 14 ze 14 laboratories. This graphical expression allows at the same time to compare mutually particular laboratories from the point of view of measurement at all levels. Hence, the sequence of numbers in the chart corresponds with the overall success of the laboratory in the test. Chart No. 11 Relative sum of z-score for sample B RSZ 4,0 3,0 2,0 1,0 0,0 3 6 4 2 1 6 1 -1,0 -2,0 -3,0 -4,0 Chart No. 12 Sum of z- score squares for sample B SSZ 14,0 12,0 10,0 8,0 6,0 4,0 2,0 2 4 3 0,0 Chart 12 of square values of z-score reveals an apparent deviation of results from laboratory No. 1. Critical value of distribution χ2(α=0,05) = 11,07 for five participating laboratories. Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 15 ze 15 5. Conclusion The aim of this interlaboratory comparison was to provide to the participating laboratories carrying out tests on the resistance to weathering an overview of their results within the frame of the whole EU. The offers were sent out to a majority of notified bodies involved in conformity evaluation of geotextiles. The interlaboratory comparison was attended by six laboratories from five EU members. The samples sent out: A – needled non-woven textile fabric (100 % polypropylene) B – woven textile fabric (100 % polyester) The results have revealed that the participant reached very differing values for both samples being tested. This refers particularly to the samples AFTER EXPOSURE, but also to the original material – sample B. These results are very alarming. It means that the same material would be assessed as satisfactory by some laboratories, while it would be rated as unsatisfactory in other laboratories, considering the requirements of harmonised standards. The round robin test should be repeated as soon as possible and the results obtained should be reported to the working group for geotextiles SG 11. The successful participants will be provided with “Certificate on participation in interlaboratory comparison”. This report is also available in electronic form. The organisers wish to thank to all the participants and they look forward to a further collaboration. Team of the TZÚ´s (TTI´s) accredited testing laboratory Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 16 ze 16 Annex – Testing of homogeneity The homogeneity testing of the samples was carried out before the interlaboratory comparison. Homogeneity of both samples was tested independently. The materials were cut to obtain particular samples. Using the random number generator (Microsoft Excel) program, ten samples were randomly chosen from each of the materials. Each of the original samples were subjected to determination of strength only. The values obtained were processed statistically using Grubbs´ test and no outlying and distant values were found. Thus, it can be concluded that the original samples were homogeneous. Homogeneity test of sample A Original sample A Measurement Direction: longitudinal Direction: transverse Strength Elongation Strangth Elongation 1 306,0 132,8 1453,5 62,0 2 316,5 132,9 1429,5 69,9 3 344,0 136,8 1448,3 67,6 4 400,5 148,0 1539,1 67,2 5 291,7 134,0 1358,9 63,4 6 366,5 140,8 1370,8 61,3 7 342,9 138,4 1374,6 67,5 8 284,3 130,2 1500,3 63,2 9 372,7 132,2 1285,5 60,9 10 356,6 129,9 1444,6 60,8 Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 17 ze 17 Mean value 338,2 135,6 1416,8 64,7 Standard deviation 37,8 5,6 77,8 3,4 STRENGTH Direction x longitudinal Original transverse Distant value (5 %) ELONGATION One small One large One small One large 1,43 1,65 1,02 2,22 1,69 1,57 1,11 1,54 Outlying value (1 %) 2,290 2,290 2,482 2,482 Test type Grubb´s test statistics Grubb´s critical values Homogeneity test of sample B Original sample B Measurement Direction: longitudinal Direction: transverse Strength Elongation Strength Elongation 1 5939,8 11,4 4141,5 12,6 2 6043,0 11,6 4141,5 11,0 3 6104,2 11,6 4007,7 11,4 4 5959,9 11,3 4141,5 13,0 5 6135,6 11,6 4007,7 12,7 6 6104,2 11,6 3935,1 11,3 7 6073,6 11,5 3903,7 12,4 8 6155,8 11,6 4152,0 12,4 9 5959,9 11,6 4027,6 11,2 10 5887,4 11,3 3811,0 12,1 Mean value Standard deviation 6036,3 11,5 4014,2 11,9 93,1 0,1 118,0 0,7 STRENGTH Direction x One small One large ELONGATION One small Textilní zkušební ústav, Václavská 6, 658 41 Brno One large www.tzu.cz Test type Stránka 18 ze 18 longitudinal Original transverse Distant value (5 %) Outlying value (1 %) 1,60 1,28 1,86 0,94 1,72 1,17 1,29 1,43 2,290 2,290 2,482 2,482 Grubb´s test statistics Grubb´s critical values References: 1 - Thompson M., Wood R.: International Harmonized protocol for Proficiency testing of (chemical) Analytical Laboratories, Journal of AOAC, Vol.76, No. 4, 1993, 926-940; 2 - RNDr. František Jaroš: Pravděpodobnost a statistika (druhé vydání), Ed. VŠCHT Praha, 1998 (in Czech) 3 - ISO 5725-2 Accuracy (trueness and precision) of measurement method and results – Part 2: Basic method for determination of repeatability and reproducibility of a standard measurement method 4 – Doc. RNDr. Jiří Anděl CSc.: Matematická statistika (in Czech) Textilní zkušební ústav, Václavská 6, 658 41 Brno www.tzu.cz Stránka 19 ze 19