🛣️ Determination of the Fraass breaking point of bitumen and bituminous binders — (410 ± 10) mg of binder is spread in an even layer on a spring steel plaque (41 × 20 × 0.15 mm), after 30–240 minutes the plaque is cooled in the apparatus at a rate of 1 °C/min and flexed at every degree by bringing the clamps 3.5 mm closer; the result is the temperature at which the first crack of the layer appears, PN-EN 12593

Construction PN-EN 12593

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN 12593:2015-08 (Polish version), first sentence (our translation): “This European Standard describes a method for determining the Fraass breaking point, which allows the brittleness of bitumen and bituminous binders at low temperatures to be measured”; the field then repeats the safety warning. We read the text of the standard in the sample of SIST EN 12593:2015 (the text of EN 12593:2015 without changes) from the title page through the contents, foreword and Clauses 1–6 up to and including 7.2.1 of Clause 7. Outside the sample remain 7.2.2 (fully automatic apparatus), 7.3 (determination of the breaking point and the scheme of Figure 7), Clauses 8–10 (expression of results, precision, test report), Figures 1–7 and Annexes A–B (thermometer characteristics, examples).

ACCORDING TO THE TEXT OF EN 12593:2015 (Clauses 1–7.2.1). The standard was prepared by CEN/TC 336 “Bituminous binders” (secretariat AFNOR); it superseded EN 12593:2007. Three main changes according to the foreword: the standard was changed because of the reference to mercury thermometers — mainly the text of 5.3.3, and Annex A became informative; application by press was removed from the sample preparation, and the maximum time for preparing a plaque — 10 min — was moved from a note into the text of the requirements; the explanations of the determination of the breaking point (former 7.3 and 7.4) were edited into the present 7.3 with a scheme in the new Figure 7. Scope (1): method for determining the Fraass breaking point, which measures the brittleness of bitumen and bituminous binders at low temperatures. References (2): EN 58 (sampling), EN 1425 (perceptible properties), EN 1427 (softening point by the ring and ball method), EN 12594 (preparation of test samples). Definition (3.1): Fraass breaking point — temperature in degrees Celsius at which a binder layer of specified and uniform thickness cracks under specified loading conditions. Principle (4): a sample of the binder is applied in an even layer to a metal plaque, which is cooled at a constant rate and repeatedly flexed until the layer cracks; the temperature of the first crack is the result. Apparatus (5): hardened spring steel plaques (41.00 ± 0.05) mm × (20.0 ± 0.2) mm × (0.15 ± 0.02) mm, flat and protected against corrosion — bent or corroded ones are discarded; magnetic block with a smooth surface for 1–3 plaques with a cover; metal base with two zones — heated with control and water-cooled — levelled with a spirit level; Fraass apparatus: flexing device with two tubes (play not greater than 1 mm) of a material with low expansion (linear coefficient < 40 × 10−6 1/K) and poor thermal conductivity (< 0.3 W/K · m), the plaque held in two steel clamps, the thermometer placed so that the connector does not shield its sensor; eleven turns of the crank reduce the initial clamp distance of (40.0 ± 0.1) mm by (3.5 ± 0.1) mm; a semi-automatic apparatus (e.g. cam disc with motor) and a fully automatic one are permitted if the conditions of the standard are maintained; cooling device — inner and outer test tube and a glass cylinder with desiccant, cooling with solid carbon dioxide, alternatively a transparent Dewar vessel with an internal diameter of (75 ± 5) mm with liquid (e.g. ethanol, 1-propanol, 2-propanol); temperature measuring device: range at least from −40 °C to 40 °C, reading to 0.5 °C or better, accuracy 0.5 °C or better, response time comparable to the former reference thermometer (Annex A), regularly calibrated; platinum sensors were found suitable; because the temperature falls during reading, corrections shall be determined in advance and applied to the readings; tongs for inserting the plaques with a stop (ends of the arms not wider than 8 mm, not closer than 35 mm); balance accurate to ± 5 mg; calibration or checking of all equipment at least once a year, and a recommended monthly check of the temperature measuring device, cooling rate and flexing detection. Sample (6): sampling according to EN 58, preparation according to EN 12594, sample homogeneous and free of contamination (EN 1425); three plaques degreased (e.g. with acetone, cyclohexane or methylene chloride), dried and weighed to the nearest 0.01 g; layers of uniform thickness are essential for repeatability and reproducibility; the layer is applied to the convex side of the plaque (the plaque itself bends to that side); at least 3 plaques in case the expected result does not prove correct. Application (6.3) for binders with a softening point (EN 1427) up to 100 °C — by hand: (410 ± 10) mg of binder per plaque, magnetic block on the heated base at a temperature not higher than the softening point plus 80 °C, and for polymer modified bitumens (EN 14023) — 180–200 °C regardless of the softening point, in any case not higher than 200 °C; when the binder flows, spread it evenly (a heated thin blade may help), wait 1–2 min, remove bubbles by lightly sweeping with a flame without local overheating; move the block to the cooled side, cover against dust; the whole preparation time of a plaque shall not exceed 10 min; the plaques lie horizontally until they reach ambient temperature. Test conditions (7.1): the plaque is tested 30–240 min after application, starting at least 15 °C above the expected breaking point; cooling 1 °C/min, flexing at every degree from 8–12 °C above the expected result. Measurement (7.2.1): the plaque is inserted with the tongs so gently that the layer does not crack — if it cracks, the next one is taken; thermometer sensor centrally behind the plaque; the first 3 min serve to establish the cooling rate, then the temperature falls by 1 °C every (60 ± 5) s, and no deviation may exceed ± 5 s and it shall not be averaged during the test; the space between the test tubes is filled to at least 100 mm with liquid at the plaque temperature, and the temperature decrease is achieved by adding small portions of solid carbon dioxide.

STATUS (catalogue cards as of 03.10.2026). The card of PN-EN 12593:2015-08 (Polish version, published 06-02-2017, 20 pages, price group K) has no “Withdrawn” header: Chemistry Sector, KT 222/PK 2 Bitumen, ICS 75.140, 91.100.50, “Introduces: EN 12593:2015 [IDT]”, “Supersedes: PN-EN 12593:2009 — Polish version”. The English version PN-EN 12593:2015-08 (published 21-08-2015, 19 pages) also has no “Withdrawn” header and has the additional element PN-EN 12593:2015-08/Ap1:2017-01 (we did not read the corrigendum). The PKN search (query “PN-EN 12593”, 03.10.2026) also shows the earlier editions 2002, 2004, 2007 and 2009. In the iTeh catalogue (read 03.10.2026) SIST EN 12593:2015 has the status “Published”.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read 03.10.2026). The number 12593 appears in 7 records at 6 laboratories: AB 422, AB 474, AB 484, AB 1484, AB 1486, AB 1529 — everywhere as “PN-EN 12593:2015-08”. In the current scopes on the PCA website (read 03.10.2026, issues from 15.01.2026 to 09.09.2026) five laboratories give the same notation; for AB 474 the PCA page does not provide a scope document — here we rely only on the database copy. The “Laboratories” tab (“PN-EN 12593”) shows the same 6 laboratories; checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (PCA items). Bitumen and bituminous binders (AB 1484, AB 1486, AB 1529), paving and modified bitumens and torch-on roofing felts (AB 422), paving and industrial bitumens and bituminous products as “other petroleum products” (AB 474, AB 484). Item “Breaking point”, Fraass method. Ranges: from 5 to −38 °C (AB 422), from 0 to −30 °C and from −23 to −8 °C (AB 484, two items), from −25 to +10 °C (AB 474, according to the copy); AB 1484, AB 1486 and AB 1529 give no range. The lower limit of AB 422 (−38 °C) lies close to the lower limit of the required range of the temperature measuring device (at least from −40 °C).

WHERE A SEEMINGLY CORRECT RESULT IS EASY. At plaque preparation: uniform layer thickness is according to the standard essential for repeatability and reproducibility, and the layer is applied to the convex side (6.2); a base hotter than the softening point + 80 °C (for modified bitumens — above 200 °C), preparation longer than 10 min and remaining bubbles are deviations from 6.3 that the result does not show. At timing: a plaque tested earlier than 30 min or later than 240 min after application does not meet 7.1. At cooling: the rate of 1 °C every (60 ± 5) s is a test condition — no deviation may exceed ± 5 s and it shall not be averaged (7.2.1). At temperature measurement: reading at a falling temperature requires corrections determined in advance; an electronic device must have a response time comparable to the former reference thermometer (5.3.3). At insertion: a layer cracked when the plaque is inserted is not a result — the next plaque is taken (7.2.1). At the start: flexing must begin 8–12 °C above the expected result, and the standard requires at least 3 plaques to be prepared in case the prediction does not prove correct (6.2, 7.1).

WHAT WE DO NOT GIVE. We did not read 7.2.2 and 7.3, Clauses 8–10, the figures and annexes, so we do not give how the result is established from several plaques (scheme of Figure 7), rounding, precision or test report requirements; we also do not give the application method for binders with a softening point above 100 °C, because the description ends with the manual case. We do not know the content of the corrigendum Ap1:2017-01. We do not give breaking point requirements for individual bitumens, because we did not read the product standards for this entry.

Method principle

A thin, uniform binder layer on an elastic steel plaque is flexed at every degree under constant cooling of 1 °C per minute; as long as the binder is sufficiently plastic it follows the deformation of the plaque, and when it becomes brittle — it cracks. The temperature of the first crack of the layer under these fixed loading conditions is the Fraass breaking point.

Applications

• Bitumen and bituminous binders — brittleness at low temperatures (Clause 1)
• Polymer modified bitumens (EN 14023) — with a separate base temperature condition of 180–200 °C during application (6.3)
• Paving and industrial bitumens, torch-on roofing felts, bituminous products — in the accreditation scopes of 6 laboratories at PCA

Key parameters

Standard

Standard number

PN-EN 12593:2015-08

Title (PL)

Asfalty i lepiszcza asfaltowe — Oznaczanie temperatury łamliwości Fraassa

Title (EN)

Bitumen and bituminous binders — Determination of the Fraass breaking point

Step-by-step procedure

1. Plaques

   Degrease three plaques, dry, weigh to the nearest 0.01 g; identify the convex side. PN-EN 12593:2015-08 current (PKN catalogue card as of 03.10.2026).

2. Application of the binder

   (410 ± 10) mg per plaque, block on the heated base (≤ softening point + 80 °C; modified bitumens 180–200 °C), spread evenly, remove bubbles, move to the cooled side; altogether ≤ 10 min.

3. Waiting

   Plaques horizontal under cover until ambient temperature; test 30–240 min after application.

4. Cooling and flexing

   Plaque in the clamps, sensor behind the plaque; start ≥ 15 °C above the expected result; 1 °C/min (60 ± 5 s per degree); flexing every 1 °C from 8–12 °C above.

5. Result

   Temperature of the first crack of the layer; establishing the result from several plaques (7.3) outside the sample read.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Use of the standard may involve hazardous materials, equipment and operations — safety practices are established by the user (warning in Clause 1)
• Solid carbon dioxide and cooling liquid below −30 °C — insulating gloves, eye protection; alcohols are flammable
• Hot binder (up to 200 °C) and a flame for removing bubbles — risk of burns and ignition

Frequently asked questions