1、DRAFT FOR DEVELOPMENTDD CEN/TS 15325:2008Bitumen and bituminous binders Determination of Zero-Shear Viscosity (ZSV) using a Shear Stress Rheometer in creep modeICS 91.100.50g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g5
2、1g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58DD CEN/TS 15325:2008This Draft for Development was published under the authority of the Standards Policy and Strategy Committee on 31 March 2008 BSI 2008ISBN 978 0 580 55733 0National forewordThis Draft for Development is the U
3、K implementation of CEN/TS 15325:2008.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications and is of a provisional nature. It should be applied on this provisional basis, so that information and experience of its practica
4、l application can be obtained.Comments arising from the use of this Draft for Development are requested so that UK experience can be reported to the European organization responsible for its conversion to a European standard. A review of this publication will be initiated not later than three years
5、after its publication by the European organization so that a decision can be taken on its status. Notification of the start of the review period will be made in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period, the respons
6、ible BSI Committee will decide whether to support the conversion into a European Standard, to extend the life of the Technical Specification or to withdraw it. Comments should be sent to the Secretary of the responsible BSI Technical Committee at British Standards House, 389 Chiswick High Road, Lond
7、on W4 4AL.The UK participation in its preparation was entrusted by Technical Committee B/510, Road materials, to Subcommittee B/510/19, Bitumen and related products.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to
8、include all the necessary provisions of a contract. Users are responsible for its correct application.Amendments/corrigenda issued since publicationDate CommentsTECHNICAL SPECIFICATIONSPCIFICATION TECHNIQUETECHNISCHE SPEZIFIKATIONCEN/TS 15325January 2008ICS 91.100.50English VersionBitumen and bitumi
9、nous binders - Determination of Zero-ShearViscosity (ZSV) using a Shear Stress Rheometer in creep modeBitumes et liants bitumineux - Dtermination de la viscosit taux de cisaillement nul (ZSV) utilisant un rhomtre contrainte de cisaillement en mode de fluageBitumen und bitumenhaltige Bindemittel - Be
10、stimmung derNull-Scherviskositt (ZSV) mit Hilfe einesSchubspannungs-Rheometers im KriechmodusThis Technical Specification (CEN/TS) was approved by CEN on 23 March 2007 for provisional application.The period of validity of this CEN/TS is limited initially to three years. After two years the members o
11、f CEN will be requested to submit theircomments, particularly on the question whether the CEN/TS can be converted into a European Standard.CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS availablepromptly at national level in an a
12、ppropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)until the final decision about the possible conversion of the CEN/TS into an EN is reached.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic
13、, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALI
14、SATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2008 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TS 15325:2008: E2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and
15、 definitions .4 4 Apparatus .5 5 Specimen preparation .6 6 Test execution7 7 Expression of results 9 8 Precision.9 9 Test report 10 Annex A (informative) Temperature verification procedure .15 Bibliography 16 CEN/TS 15325:20083 Foreword This document (CEN/TS 15325:2008) has been prepared by Technica
16、l Committee CEN/TC 336 “Bituminous binders”, the secretariat of which is held by AFNOR. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights
17、. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
18、Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. CEN/TS 15325:20084 1 Scope This European standard describes the determination of Zero Shear Viscosity (ZSV), o, for bitumens and bitumin
19、ous binders, preferably using test temperature domains in which 100 Pa.s three times the size of the largest polymeric inclusions (usually, d 1 mm). CEN/TS 15325:20086 NOTE The selection of system geometry may affect the accuracy of results. The manufacturer may have determined the operational limit
20、s and this information may be available but, if not, it can be determined by running a test specimen over a range of test temperatures using all the test geometries likely to be used in practice. 4.5 Zero-gap setting Carefully prepare the rheometer plates to receive the test specimen by cleaning wit
21、h a suitable solvent and soft cleaning cloth or paper. Do not use metal or any other materials, which may damage the surfaces of the plates, and take care not to bend the shaft of the upper plate. Set the geometry temperature to the required test temperature and wait for thermal equilibrium (10 min
22、to 30 min). Apply the manufacturers procedure to reset the gap between the plates prior to loading the test specimen, with both plates at nominally the same temperature. 5 Specimen preparation 5.1 Test specimen preparation Prepare the binder in accordance with EN 12594. Two methods can be used: spec
23、imen preparation in a mould followed by attachment to a test plate (preferred method); loading directly into the plate gap. In the latter case, pour sufficient binder from the vial onto the test geometry for there to be an excess appropriate to the measuring geometry chosen (proceed to sub-clause 5.
24、2). If using moulds, pour sufficient binder from the vial into the mould. To avoid successive sample heating, several specimens should be prepared at this stage. Discard any binder remaining in the vial. Store the covered moulds or sheet material at ambient temperature before testing. Any specimen n
25、ot tested within 7 days shall be discarded. To minimise the effect of sample preparation, it is advised to pour the specimens 24 h before measuring. Before testing, if necessary, place the specimens in a refrigerator (approximately 5 C) to allow them to stiffen for proper, deformation-free release f
26、rom the moulds. To avoid physical hardening, it is recommended not to leave the specimens in the cool chamber for longer than the time needed to obtain proper stiffness. The recommended time is approximately 10 min and shall not exceed 30 min. Release the samples from the moulds. Wipe away any relea
27、se agent that may have been used. Attach the specimens to the clean, dry test plate. 5.2 Setting the gap and trimming the sample After the specimen has been placed on one of the test plates as described above, bring the test specimen to the selected gap setting plus 0,05 mm. Trim any excess binder w
28、ith a knife or spatula. The tool may be heated on a hot plate or with a flame. After trimming, raise or lower the opposing plate to the set testing gap ( 0,01 mm). Do not trim at this stage. If the CEN/TS 15325:20087 test specimen does not cover the whole measuring plate (indicated by a slight bulgi
29、ng at the periphery of the test specimen), remove it and re-prepare the rheometer plates, and prepare a fresh test specimen. 6 Test execution 6.1 General The experiment is conducted in two steps. Step 1 is an optional stress sweep performed in conditions close to steady-state to gain some knowledge
30、on the binder. In case of unknown binders, this step will shed some light on the non-Newtonian character of the binder and allow the proper stress selection for Step 2. In case of bitumen quality control (with a well-known binder), this step may be skipped. In Step 2, the Zero Shear Viscosity value
31、is determined at a given temperature and at a single (low) stress value. In no case, should Step 1 replace Step 2 in the determination of the ZSV because it is possible that not enough time has been spent in Step 1 to reach a steady state flow. 6.2 Step 1: stress sweep The following sequence is appl
32、ied to the same sample, without interruption between the consecutive creep tests: Table 1 Sequence applied with the same sample Stress, Pa Time, min t Accumulated time, min. t Viscosity, Pa.s 10 20 50 100 200 500 1000 100 50 20 10 5 2 1 100 150 170 180 185 187 188 Computed during last 20 min Compute
33、d during last 10 min Computed during last 4 min Computed during last 2 min Computed during last 1 min Computed during last 24 s Computed during last 12 s NOTE The choice of these seven creep times has been selected to minimise the duration of the stress sweep. It is based on experience but does not
34、guarantee a steady state flow. In other words, it is not certain that the measured properties are steady state viscosities (SSV). The obtained flow curve may thus only be an approximation of the real one. The computed viscosity values can be plotted versus stress as shown for example in Figure 1 to
35、Figure 3. Figure 1 shows the flow curve of conventional 10/20 bitumen. The viscosity is almost independent of the applied shear stress. The binder presents a Newtonian character. Figure 2 shows the flow curve of slightly modified bitumen ( 4 % of elastomer). The binder presents a higher non-Newtonia
36、n character when the viscosity plateaus at stresses below 50 Pa. Figure 3 shows the flow curve of heavily modified bitumen ( 7 % of polymer). The binder presents a non-Newtonian character and even the existence of the Newtonian plateau is not clear. CEN/TS 15325:20088 6.3 Step 2: creep test at a giv
37、en stress level The critical point here is to select the right stress level for the creep test. This is generally below 5 000 Pa for conventional, oxidised and special bitumens, and between 10 Pa and 50 Pa for non-fluxed polymer-modified bitumens. To remain within the linear viscoelastic range of th
38、e specimen, the stress must be kept sufficiently low. Especially for very viscous binders, the stress selection depends on the shear rate experienced by the sample. The shear rate, noted d/dt, is defined as follows: =dtd(1) If the strain rate is too low, the equipment limits can be reached and measu
39、rements become inaccurate. Check whether the operational limits of your rheometer have not been exceeded. If the strain rate is too high, the conditions of “zero shear” are not achieved and the integrity of the sample can be threatened. The data shown on Figure 1, Figure 2 and Figure 3 have also bee
40、n presented (Figure 4) in a plot of viscosity versus shear rate. It can be seen that when the viscosity becomes large, the shear rate drops to very low values (of the order of 10-5s-1in the case of the highly modified bitumen). In the case of a non modified binder, the flow curve is likely to be New
41、tonian as in Figure 1. Here, the ZSV may be measured at any stress between 10 Pa and 100 Pa. The advised (reference) stress level is 50 Pa. In the case of a polymer modified binder, the selection of the right shear stress may be delicate: stress value should be chosen within the Newtonian plateau; s
42、hear rate should preferably be above 10-4s-1(see Figure 4). For heavily modified binders, it may be impossible to obey the combination of these two constraints. In the particular example of Figure 3, the Newtonian plateau is not clearly visible even at stresses as low as 10 Pa where the shear rate g
43、ets close to 10-5s-1. Instead of decreasing the stress level more and more (with the risk of increasing scatter), the reference stress of 50 Pa may be selected but it must be mentioned that the measurement was not performed in the Newtonian plateau. An alternative is to increase the temperature to r
44、educe the non-Newtonian character of the binder. It must be noted that the reference temperature, T for the ZSV method is 60 C and that it is necessary to compare different binders at the same temperature. The creep times have been chosen at 1 h and 4 h for respectively non-modified and polymer modi
45、fied binders. These creep times are generally sufficiently long to guarantee a steady state flow. If after the recommended creep time, the instantaneous viscosity still increases by more than 5 % in 15 min, the creep time may be extended to a maximum of 8 h. Table 2 Recommended values of the test co
46、nditions Type of binder Stress , Pa Time t, h Temperature T, C Non modified Polymer modified 50 10 to 50 1 4 60 60 Perform the creep test with the selected parameters (, t, T). CEN/TS 15325:20089 Compute the average viscosity over the last 15 min. This is obtained by dividing the change in time (t)
47、by the change in compliance (J) over the last 15 min (900 s) of the test. This can be expressed in mathematical terms as follows: ()endbeforeendiJJJt=min15900 (2) Repeat the measurement (each time with a new sample). Perform a third measurement (with a new sample) if the difference between the first
48、 two results exceeds 5 % of their average value. 7 Expression of results The ZSV value is the average of the two (or three) individual values determined in Step 2. Express the ZSV value to three significant figures. 8 Precision Precision was determined in a Round Robin exercise including nine labora
49、tories. Five binders were tested: bitumens A and B are conventional grades. PMB 1 and 2 are lightly modified binders. PMB 3 is a highly modified binder ( 7% of polymer). The creep tests were repeated two or three times as requested in Section 6.3. The standard deviations for repeatability and reproducibility as well as the coefficient of variation (defined as the standard deviation divided by the average value of the population) of the ZSV values were measured. In the statistics in Table 2 below, all data were taken into account, as t
