DIN EN 12697-45-2012 Bituminous mixtures - Test methods for hot mix asphalt - Part 45 Saturation Ageing Tensile Stiffness (SATS) conditioning test German version EN 12697-45 2012《沥.pdf

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1、-XO7UDQVODWLRQE,16SUDFKHQGLHQVW(QJOLVKSULFHJURXS1RSDUWRIWKLVWUDQVODWLRQPDEHUHSURGXFHGZLWKRXWSULRUSHUPLVVLRQRI,1HXWVFKHV,QVWLWXWIU1RUPXQJH9%HUOLQ%HXWK9HUODJ*PE+%HUOLQ*HUPDQKDVWKHHFOXVLYHULJKWRIVDOHIRU*HUPDQ6WDQGDUGV ,11RUPHQ , b) maintaining the temperature at all points within the vessel at the agei

2、ng temperature 0,5 C. SAFETY PRECAUTIONS The pressure ageing vessel operates at high temperatures and high pressures. All safety guidelines issued by equipment manufacturers shall be adhered to. 5.2.4 Pressure controlling devices 5.2.4.1 Pressure release valve, which prevents pressure in the vessel

3、from exceeding 2,5 MPa during the ageing procedure. 5.2.4.2 Pressure regulator, capable of controlling the pressure within the vessel to 0,1 MPa and with a capacity sufficient to reduce the pressure from the source of compressed air so that the pressure within the vessel is maintained at the operati

4、ng pressure of (2,1 0,1) MPa. 5.2.4.3 Slow release bleed valve, which allows the pressure in the vessel at the completion of the test to be reduced from the 2,1 MPa operating pressure, to atmospheric pressure within 20 min to 30 min. 5.2.4.4 Pressure gauge, capable of measuring the pressure within t

5、he vessel to within 0,3 MPa during the test. The pressure gauge shall be calibrated to an accuracy of 0,1 MPa at appropriate intervals. 5.2.4.5 Porous disc, 5 mm thick by 100 mm diameter, with a permeability substantially greater than that of the asphalt and the capability withstand the maximum vert

6、ical pressure likely to be imposed. The discs shall be checked before each use to ensure that they are not clogged by particles. They shall be boiled for at least 10 min in distilled water before use and kept immersed in de-aerated water until required. 5.2.5 Thermometer, accurate to 0,1 C, for meas

7、uring the temperature inside the pressure vessel. NOTE A resistance thermal detector (RTD) has been found to be suitable. 5.2.6 Temperature recording device, data acquisition system capable of recording the temperature throughout the test to 0,1 C. NOTE The current method of monitoring temperature i

8、s via a computerised log of time and temperature. It is assumed the temperature recorded is that which is to be found within every point within the ageing vessel. DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 9 Dimensions in millimetres Key 1 pressure regulator 2 compressed air cylinder 3 pressure ve

9、ssel Figure 1 Schematic diagram and dimensions of typical pressure vessel 5.2.7 Specimen tray, having the form and dimensions specified in Figure 2, to accommodate five test specimens for a full test. The tray shall sit in the pressure vessel on top of a porous disc, as shown in Figure 3. NOTE 1 The

10、 form and dimensions of the pressure vessel and specimen tray shown in Figures 1 and 2 have been found to be practicable in the SATS test when used with different aggregate types. Other forms of pressure vessel and specimen tray may also be suitable, but have not yet been specifically investigated.

11、However, early work carried out in a standard binder pressure ageing vessel in EN 14769 yielded similar results to those generated using the apparatus described in this European Standard. NOTE 2 The fifth sample is placed so that, unlike the other samples, it is submerged during the test. As such, i

12、t is not included in the averaging to produce the overall result. However, the ratio for this sample can be used to provide additional information on the properties of the mixture. DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 10 Dimensions in millimetres Key 1 8 mm diameter stainless steel pillars 2

13、 5 mm diameter holes, evenly spaced (6 6 = 36 holes) 3 100 mm to 105 mm square by 2 mm thick stainless steel plate aenlarged sectional view Figure 2 Schematic diagram and dimensions of typical specimen tray NOTE If the specimens have a diameter greater than 100 mm, then the dimensions of the square

14、plate should also be at least equal to diameter of the specimens in order to avoid any overhang. DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 11 Dimensions in millimetres Key 1 to 5 asphalt specimens 6 pressure vessel 7 specimen tray 8 partially filled with water to (5 5) mm above the 5thtray 9 poro

15、us disk Figure 3 Schematic diagram of the specimen configuration in the pressure vessel 5.3 Comparative test Steel load frame and associated equipment in accordance with EN 12697-26:2012, Annex C. NOTE If the comparative test is not the IT-CY stiffness test, other equipment may be required. 6 Solven

16、t and other materials 6.1 Distilled water (or water of equivalent purity), freshly de-aired and cooled. 6.2 Self-adhesive aluminium foil capable of adhering to and covering the specimen with an impervious coating. 6.3 Absorbent paper towelling. 7 Sample preparation 7.1 Test specimens shall be cylind

17、ers of (100 5) mm diameter and (60 5) mm thickness. Specimens shall be cored from a slab manufactured using a laboratory roller compactor in accordance with EN 12697-33. The specimens shall be compacted to have to an air voids content of (8 2) %. DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 12 Alter

18、natively, samples may be taken from the site or manufactured using an impact compactor in accordance with EN 12697-30 or using a gyratory compactor in accordance with EN 12697-31. NOTE 1 However, it can be difficult to achieve homogenous distribution of air voids and the samples should be cored, eve

19、n from a cylindrical specimen, in order to have cut faces. The method of compaction should then be included in the test report. NOTE 2 The lower limit on the air voids content is set in order to have a reasonable probability that the air voids will be interconnected so that the pressure in the condi

20、tioning phase will apply throughout the specimen. Having set one limit, the upper limit is imposed to ensure comparable samples. NOTE 3 If specimens are manufactured to the correct dimension by gyratory or impact compactor without cut faces, this fact should be clearly included in the test report. 7

21、.2 The slab shall be approximately 100 mm thick and shall be produced using the recipe for the bituminous mixture to be tested. NOTE The binder grade, but not the binder source, has been found to be a significant parameter. The control on the grade is imposed to ensure comparable results between dif

22、ferent aggregate skeletons. If the test is used for a mixture with a binder other than 10/20 paving grade, a standard 10/20 paving grade binder to EN 13924 should be substituted. 7.3 The cores shall be cut from the slabs and sawn to the correct length, removing approximately equal amounts from each

23、end of the core (see Figure 4). Five specimens with similar densities shall be used for a full test. NOTE 1 It can be useful to prepare more than five specimens because some of them may have to be rejected after the air voids content (see 8.3) saturation (see 8.7) determinations. NOTE 2 The SATS tes

24、t involves specimens cored from a slab manufactured using a laboratory roller compactor. Specimens for testing may also be cored from an in-service pavement in accordance with EN 12697-27, but research data on the performance of such specimens in the SATS test is currently unavailable. Dimensions in

25、 millimetres Key 1 sections of core to be discarded from sample 2 section of core forming the sample Figure 4 Schematic diagram of the specimen cut from core 8 Conditioning procedure 8.1 The maximum density of the bituminous mixture under test shall be determined in accordance with EN 12697-5:2009,

26、Procedure A. DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 13 8.2 The bulk density of each compacted specimen shall be determined in accordance with EN 12697-6:2012, Procedure C. Remove any sealing material after the test. NOTE Wax is not considered entirely suitable as the sealing material for Proce

27、dure C because it is practically impossible to remove from the specimens that will be subjected to subsequent mechanical testing. Self-adhesive aluminium foil, as defined in 6.2, has been successfully used in a number of laboratories for over 10 years, and is easy to remove. However, for laboratory

28、prepared specimens with a rough surface texture, the foil may cause observation of texture voids as internal specimen voids, which may cause an under-estimation of the specimen density and an over-estimation of the air voids level of the specimen. Yet the risk of this inaccuracy of estimation is con

29、sidered to be relatively small in the case of SATS test specimens, which are normally cored from a laboratory manufactured slab and then trimmed (sawn) to the specified thickness. 8.3 The air voids content of each specimen shall be calculated in accordance with EN 12697-8. Any specimen whose calcula

30、ted air voids are outside the range (8 2) % shall be rejected and replaced with further samples of suitable void content. 8.4 The IT-CY stiffness test (or another comparative test) is undertaken on the unconditioned (initial) specimens and the results designated CTRU. NOTE If an alternative comparat

31、ive test is used that is destructive, such as the indirect tensile strength test, an extra set of samples is needed for the unconditioned results. 8.5 Determine the dry mass of each specimen using the balance and designate this as Md. 8.6 The specimens shall be partially saturated by placing them in

32、 the vacuum desiccator and covering them with distilled water at (20 1) C. After sealing the apparatus, a vacuum shall be applied so that a residual pressure of between 40 kPa and 70 kPa is reached in the vacuum desiccator within 60 s. The residual pressure of between 40 kPa and 70 kPa shall be main

33、tained for (30 2) min. 8.7 Remove each specimen from the vacuum desiccator and remove any water on its surface using the absorbent paper towelling. Determine its wet mass and designate this as Mw. The proportion saturation (S) shall be determined in accordance with 10.2. Any specimens whose calculat

34、ed saturation is 80 % shall be rejected and replaced with a core with a saturation of less than 80 %. 8.8 Partly fill the pressure vessel with water. The water level shall be between the 4thand 5thspecimen after loading the samples, as shown in Figure 3. Only freshly distilled water shall be used (i

35、.e. do not re-use water). The vessel and water shall be controlled to the target temperature of 85 C for at least 2 h before the conditioning procedure commences. NOTE Preheating to a lower temperature, such as 75 C, has proven to be suitable for preventing overheating due to the pressure build-up.

36、8.9 The specimens shall be placed into the vessel, using the specimen tray. The specimen tray shall be centrally placed in the chamber of the vessel so that the specimen trays are as close to horizontal as practicable. The cover shall be closed and the pressure gradually increased from atmospheric p

37、ressure to 2,1 MPa and the temperature raised to 85 C over a period of 20 min. The conditioning procedure shall then be performed at (2,1 0,1) MPa pressure and at a temperature of (85 1) C for (65 1) h. 8.10 After the test period of 65 h has elapsed, adjust the target temperature to 30 C. Leave the

38、vessel for approximately a further 24 h to cool to the adjusted temperature of 30 C. Do not release the pressure. NOTE The 24 h cooling period is applied to minimise pressure-related damage during the depressurising process. It has been found that the reduced target temperature (30 C) can be achieve

39、d well within 24 h using the apparatus described in this test method. The pressure needs to be carefully maintained during this cooling process because the reducing temperature will reduce the vessel pressure accordingly. This maintenance can be achieved by careful adjustment of the pressure input c

40、ontrolling valve to just below the target pressure (2,1 MPa); any gradual loss of pressure will then be automatically compensated for by the gradual input of pressure from the compressed air cylinder. DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 14 8.11 When the pressure vessel display temperature h

41、as reduced to 30 C (i.e. after the 24 h cooling period), the heater shall be turned off and the pressure shall be slowly released from the vessel. The pressure release mechanism shall be adjusted so that the pressure returns to atmospheric pressure over a period of 20 min to 30 min (linear reduction

42、). The cover shall then be opened and all the specimens extracted, on the tray, from the vessel. NOTE A slow release of pressure is required at the end of the SATS conditioning procedure in order to minimise damage to the specimens as a result of sudden changes. 8.12 Each specimen shall be surface d

43、ried using the absorbent paper towelling, and its wet mass measured within 3 min of removing the specimens from the pressure vessel. Designate this mass as Mw2. The saturation after the conditioning procedure (Sa) shall be calculated in accordance with 10.3. NOTE 3 min has been found to be a practic

44、al time period to complete the surface drying and weighing of all five specimens after removal from the pressure vessel. Any reduction in this time period (below 3 min) should help to improve the precision of the test. 8.13 The specimens shall be observed for any visual cracks and unusual appearance

45、s (e.g. colour of binder or aggregates). Record any comments as appropriate. 8.14 The comparative tests shall be undertaken on the conditioned (final) specimens within 8 h after turning off the heater on the pressure vessel and the results designated CTRC. 9 Comparative test procedure 9.1 The compar

46、ative test shall be the IT-CY stiffness modulus at (20 0,5) C in accordance with EN 12697-26:2012, Annex C, except that the sample size shall be 100 mm diameter for all grain sizes. 9.2 Alternatively, other tests can be used as the comparative test, provided the test method is included in the test r

47、eport. 10 Calculation 10.1 Bulk density and air voids content 10.1.1 Calculate the bulk density of each specimen in accordance with EN 12697-6:2012, Procedure C. The specimen bulk density shall be expressed in megagrams per cubic metre (Mg/m3) to 0,001 Mg/m3. 10.1.2 The air voids content of each spe

48、cimen shall be calculated in accordance with EN 12697-8. The calculated air voids shall be expressed in per cent (%) to 0,1 %. 10.2 Saturation before conditioning 10.2.1 Calculate the saturation before conditioning as follows: =uuuGGMMMS11100 (1) where S is the proportion saturation before conditioning, in percent (%); Mdis the mass of dry specimen, in grams (g); DIN EN 12697-45:2012-07 EN 12697-45:2012 (E) 15 Mwis the mass of wet spe