EN 13632:2010 – Bitumen and bituminous binders – Visualisation of polymer dispersion in polymer modified bitumen
5 Preparation of test samples
Take the sample in accordance with EN 58. Prepare it in accordance with EN 12594. Homogenise the sample by gentle hand stirring for at least 1 min and not more than 5 min. Pour the material into the aluminium basin placed in a sand bath (4.7) preheated to the same temperature as the sample during homogenising.
The sand bath is an evaporating basin (4.5) containing sand (4.6). The aluminium basin (4.4) shall be totally surrounded by the sand and there shall be 20 mm of sand between the bottom of aluminium basin and the evaporating basin. The sample is cooled to ambient temperature by switching off the heating of the sand bath. After cooling to ambient temperature, cool the sample to – 20 °C or lower if the sample needs to become brittle. Using a freezer (4.2), a cooling time of 3 h minimum is required; using solid carbon dioxide (4.2) in a dewar, 10 min is sufficient. NOTE The cooling procedure can be essential for the morphology. By cooling in the sand bath, a steady cooling rate is assured. 6 Procedure Prepare small pieces of the frozen material by breaking or cutting with appropriate sharp tool (4.3).
This preparation shall be done rapidly to avoid warming the sample. Inspect the freshly broken or cut surface within 1 h.
The inspection can be done through a protecting glass or directly on the surface. Using a protecting glass turn the freshly broken surface towards a microscope cover glass and arrange for the freshly broken or cut surfaces to stick to this without disturbing the surface by moving. Turn the cover glass over and place it on the hole of the rigid support such that a perfectly horizontal and flat surface is observed through the glass. Select the magnification according to the particle size and distribution; magnifications of 25 to 500 are suitable. Analyse each polymer modified bitumen on a minimum of 3 independently prepared surfaces scanning the entire surface before collecting the typical picture. Provide a reference scale with the picture.
NOTE The picture can be obtained and stored by photographic or electronic systems.
7 Expression of results
Express the binder morphology either as a picture, a picture number (according to Annex A) or a combination of the characterisation letters shown in Annex A. Intermediate numbers are not allowed. If no fluorescent emission can be detected and the sample appears all black, note this as O. NOTE Numbers are used as a simple tool for comparing pictures and neither assessing the quality, nor the performance of the binder.
EN 13632:2010 – Bitumen and bituminous binders – Visualisation of polymer dispersion in polymer modified bitumen