untitled BRITISH STANDARD BS EN 13588 2008 BS 2000 522 2008 Bitumen and bituminous binders — Determination of cohesion of bituminous binders with pendulum test ICS 75 140; 91 100 50; 93 080 20 �������[.]
BRITISH STANDARD Bitumen and bituminous binders — Determination of cohesion of bituminous binders with pendulum test ICS 75.140; 91.100.50; 93.080.20 12&23 0,2 ml) As quickly as possible, place the cube on the support with the serrations facing each other and the ridges on the cube parallel to the edge of the support, which will be parallel to the plane of movement of the pendulum when the assembly is inserted in the clamping device of the tester Apply pressure to the cube and support so that excess binder is squeezed out and the ridges of the cube are in contact with the support NOTE Some binders show elastic behaviour which can lead to stress being retained in the binder film and poor repeatability between tests In extreme cases the cube may lift from the support before testing commences To avoid this problem the cube, support and sample should be pre-heated to a higher temperature A mass of approximately 500 g may be put on top of the cube 7.3.3 Repeat 8.3.2 for each test assembly 7.3.4 Remove the excess binder from the cube faces of the test assemblies by scraping with a knife blade (6.5), which may be heated If necessary, clean the cube face which will be struck by the pendulum using absorbent paper with a little solvent Ensure that the solvent does not contaminate the exposed edge of the film of binder 7.4 Storage of the assemblies Place the set of test assemblies in a thermostatically controlled enclosure maintained at the required test temperature for 90 to h if a liquid bath is used, or h to 15 h if an air bath is used 7.5 Adjustment of the pendulum Place the cohesion tester on a rigid, stable support and ensure that it is level Check that the impact edge of the pendulum is undamaged and straight Set the pendulum hanging freely in the down position and ensure that the scale reading is (0 ± 0,5)° by adjusting the scale dial, if necessary Adjust the position of the clamping device so that a test assembly is held in a position such that the impact edge of the pendulum is parallel to the bottom edge of the cube and just in contact with the cube over its full length, at a height of (2,0 ± 0,2) mm above the top of the serrations of the cube support (see Annex B) Set the pendulum in the “up” position Set the pointer in contact with the pendulum in this “up” position Release the pendulum repeatedly with no test assembly in position until the swing-through angle of the pendulum o o is constant to ± 0,5 and a minimum of 155,0 for six successive swings is achieved If necessary, adjust the friction device of the pointer to achieve this BS EN 13588:2008 EN 13588:2008 (E) In the “up” position, the pendulum and pointer are at an angle of (4,0± 1,0)° with the vertical, and no impulse is required for release The pointer retaining system is sensitive to temperature variation and the room ambient temperature shall be in the range 18 °C to 28 °C during preparation of the apparatus and for subsequent testing In such case the energy dissipated in friction during a pendulum swing without a test specimen should be considered negligible compared to the energy absorbed by breaking a binder during a test 7.6 Selection of test temperatures Select three temperatures at 10 °C intervals according to the observed room temperature consistency of the binder, e.g 10 °C, 20 °C and 30 °C for fluxed bitumens, 30 °C, 40 °C and 50 °C for stabilised pure or modified bitumens Then select additional test temperatures so that at least: a) one result is less than 0,4 J/cm² at both the low and high temperature ends of the curve or the determined ° cohesion value at (- 10 C) and (+ 80 °C), if a value of 0,4 J/cm² has not been achieved; b) three results are within °C of the temperature of maximum cohesion c) At least one further result shall be between the peak and between 40 % and 60 % of the peak value, on both low and high temperature sides of the curve Then the temperatures, at which cohesion energy is 0,5J/cm2, shall be chosen on both low and high temperature sides of the curve Or if previous temperature cannot be reached, one further result shall be determined, on both low and high temperature sides of the curve, at a temperature of half the difference between the peak value and the minimum cohesion value determined in a) NOTE If a binder has been already tested, larger or smaller intervals than 10 °C can be used and another range of temperatures selected according to the intention of the test 7.7 Measurement Set the pendulum in the ”up” position, and reset the pointer in contact with the pendulum Open the door of the protective cage Transfer a test assembly from the temperature-controlled environment to the clamping device of the tester taking care to ensure that the assembly is moved without disturbance of the cube relative to the support Close the door of the protective cage and release the pendulum Ensure that the time taken to perform the above procedure since the transfer is less than 20 s and that all tests at one temperature are performed within a 10 period Record the swing-through angle α indicated by the pointer to the nearest 0,5° Remove the detached cube and the cube support from the protective cage and examine the faces in contact with binder for evidence of adhesion failure If an area of bare metal greater than mm is visible on either cube or support, discard the results and repeat the test Examine the impact edge of the pendulum If any binder is adhering, remove it using absorbent paper with a small quantity of solvent Reset the pendulum in the “up” position and reset the pointer in contact with the pendulum Replace the cube support with another, clean, support and place the cube just tested on this support with its clean face downwards Release the pendulum and record the swing-through angle α ’1 indicated by the pointer to the nearest half-degree Repeat the measurements for the other test pieces and note the angles α, α ’2,…………… α 6, α ’6 10 BS EN 13588:2008 EN 13588:2008 (E) 7.8 Special precautions The cohesion value is the difference between the two measurements with and without binder Ensure that these measurements are consecutive and are as close together as possible, i.e not more than apart, in order to achieve optimum test accuracy At temperatures close to maximum cohesion, the break of the binder on impact can occasionally result in binder remaining on the support If the pendulum contacts this residual binder the swing-through angle will be reduced It is important to detect this phenomenon to avoid the risk of errors If this occurs a repeat test should be carried out at an alternative temperature The pointer is in a plane parallel to the dial, approximately five millimetres from the dial Take pointer readings at a constant distance from the dial, approximately 500 mm, with ambient lighting, avoiding projected shadows and taking care to avoid parallax errors Expression of results Express the values for pendulum swing-through angles α (with binder) and α ’ (no binder) expressed in ° (degree), and record these on the work sheet (see Annex A) E, energy absorbed by the impact, expressed in joules, is calculated from Equation (1): E = mgr (1 + cos α ) (1) No correction is made for the 4° initial angle of the pendulum E ', energy absorbed in breaking the binder, expressed in joules, is calculated using Equation (2): E ' = mgr (1 + cos α ') (2) and cohesion is expressed in J/cm by means of Equation (3): C = ( E − E ' ) / s = mgr (cos α − cos α' )/s (3) where s is the breaking area (see definition in Clause 4) According to the dimensions of the cube (Figure 3), and more precisely to the area in contact with the binder, s is equal to cm NOTE g is the acceleration due to gravity, i.e g = 9,81 m/s Each angle α and α ’ is converted to an energy value, E and E ’, expressed in joule The mean value of (E - E ’) for four or six releases, is determined for a given test temperature The test piece section is cm² and the cohesion value is expressed in J/cm Plot the results from tests over a range of temperatures on a graph having linear axes for temperature and cohesion Plot a smooth curve through the point and determine the maximum value of cohesion (Cm) and the corresponding temperature (Tm) NOTE It is convenient to construct a table giving equivalent values of α and E for a specific instrument rather than perform the calculation each time Precision The following precision data are the best currently estimated and are proposed until results of further round robin tests are available 11 BS EN 13588:2008 EN 13588:2008 (E) 9.1 Pure bitumen The repeatability between two successive results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, in the long run, in the normal and correct operation of the test method, would not differ by more than 0,06 J/cm² The reproducibility between two single results and independent results obtained by different operators working in different laboratories on identical test material, in the long run, in the normal and correct operation of the test method, would not differ more than 0,18 J/cm² 9.2 Polymer modified bitumen The repeatability between two successive results, obtained by the same operator with the same apparatus under constant operating conditions on identical test material, in the long run, in the normal and correct operation of the test method, would not differ by more than 0,10 J/cm The reproducibility between two single and independent results obtained by different operators working in different laboratories on identical test material, in the long run, in the normal and correct operation of the test method, would not differ by more than 0,36 J/cm 10 Test report The test report shall contain at least the following information: a) type and complete identification of the sample under test; b) reference to this European Standard; c) ambient room temperature during testing; d) maximum cohesion and its temperature and the work sheet as shown in Annex A (see Clause 8); e) any deviation, by agreement or otherwise, from the procedure specified; f) statement affirming that the thermal history of the sample is available from the laboratory g) mass of the pendulum h) date of the test 12 BS EN 13588:2008 EN 1358:2008 (E) Dimensions in millimetres Unless otherwise is indicated, tolerances are ± mm Radius at point of impact: (500 ± 1) mm Figure — Ram pendulum 13 BS EN 13588:2008 EN 13588:2008 (E) Dimensions in millimetres Unless otherwise indicated, tolerances are ± 0,1 mm and ± 0,5° for the angles Figure — Cube for sample 14 BS EN 13588:2008 EN 13588:2008 (E) Dimensions in millimetres Unless otherwise indicated, tolerances are ± mm Figure — Cube support Tolerances are ± 0,1 mm and ± 0,5° for the angles Figure — Typical construction of the cube and cube support 15 BS EN 13588:2008 EN 13588:2008 (E) Annex A (informative) Work sheet Nature, type of binder: TEMPERATURE (°C) TEMPERATURE (°C) Date: With binder No binder With binder Room ambient temperature: α α‘ E E’ E-E’ α E No binder α‘ E’ E-E’ Remarks: Name of person responsible for the test: Signature of person responsible for the test: MEAN ENERGY (J) MEAN ENERGY (J) 2 COHESION (J/cm ) COHESION (J/cm ) TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) TEST With binder No binder With binder With binder N° α α‘ E E’ E-E’ α E No binder α‘ E’ E-E’ α E No binder α‘ E’ E-E’ MEAN ENERGY (J) MEAN ENERGY (J) MEAN ENERGY (J) 2 COHESION (J/cm ) COHESION (J/cm ) COHESION (J/cm ) TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) TEST With binder No binder With binder With binder N° α α‘ E E’ E-E’ α E No binder α‘ E’ E-E’ α E No binder α‘ MEAN ENERGY (J) 16 MEAN ENERGY (J) MEAN ENERGY (J) COHESION (J/cm ) COHESION (J/cm ) COHESION (J/cm ) TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) E’ E-E’ BS EN 13588:2008 EN 13588:2008 (E) Annex B (normative) Drawing details Dimensions in millimetres Key α Initial position Limit of swing after impact Reference angle "zero" Swept angle after impact (with binder) Line of impact with cube Support (see Figure 4) Top of the serrations of the cube support Bottom of the pendulum Figure B.1 — Principle of the pendulum 17 BS EN 13588:2008 EN 13588:2008 (E) Bibliography [1] EN 1427, Bitumen and bituminous binders – Determination of the softening point – Ring and Ball method [2] EN 12597, Bitumen and bituminous binders – Terminology 18