EN 12697-49:2022

SLOVENSKI STANDARD
01-april-2022
Nadomešča:
SIST EN 12697-49:2014
Bitumenske zmesi - Preskusne metode - 49. del: Ugotavljanje tornih sposobnosti
po poliranju
Bituminous mixtures - Test methods - Part 49: Determination of friction after polishing
Asphalt - Prüfverfahren - Teil 49: Messung der Griffigkeit nach dem Polieren
Mélanges bitumineux - Méthodes d’essai - Partie 49 : Détermination du frottement après
polissage
Ta slovenski standard je istoveten z: EN 12697-49:2022
ICS:
93.080.20 Materiali za gradnjo cest Road construction materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 12697-49
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2022
EUROPÄISCHE NORM
ICS 93.080.20 Supersedes EN 12697-49:2014
English Version
Bituminous mixtures - Test methods - Part 49:
Determination of friction after polishing
Mélanges bitumineux - Méthodes d'essai - Partie 49 : Asphalt - Prüfverfahren - Teil 49: Messung der
Détermination du frottement après polissage Griffigkeit nach dem Polieren
This European Standard was approved by CEN on 15 November 2021.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
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Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
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Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12697-49:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 4
Introduction . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, symbols and abbreviated terms . 8
3.1 Terms and definitions . 8
3.2 Symbols and abbreviated terms . 8
4 Principle . 9
5 Equipment . 9
5.1 Test device . 9
5.2 Control plate for comparative measurements . 15
5.3 Sand-blasting-equipment . 15
6 Other materials . 15
6.1 Quartz powder . 15
6.2 Water quartz powder mixture . 15
6.3 Corundum . 15
7 Test method . 16
7.1 Preparation of the specimens . 16
7.2 Polishing procedure . 16
7.3 Friction measurement . 17
8 Calculation and expression of the results . 18
8.1 Friction result μ on a single specimen . 18
FAP
8.2 Determination of FAP . 19
9 Test report . 19
10 Precision . 19
Annex A (informative) Example of polishing head and friction unit . 20
Annex B (informative) Results obtained from the curve FAP against passes . 21
B.1 General . 21
B.2 Results obtained from the curve FAP against passes . 21
Annex C (informative) National experiences . 22
C.1 General . 22
C.2 National experiences . 22
Bibliography . 29
European foreword
This document (EN 12697-49:2022) has been prepared by Technical Committee CEN/TC 227 “Road
materials”, the secretariat of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2022, and conflicting national standards shall
be withdrawn at the latest by August 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12697-49:2014.
The main changes compared to the previous edition are listed below:
— The title no longer refers to hot mix asphalt;
— [Introduction] added, giving the general context of the test method and the need to improve it;
— [1] Possibility of following Friction After Polishing (FAP) evolution as a function of the number of
polishing passes. NOTE deleted since the Wehner and Schulze method is now mentioned in the
Introduction;
— [2] and [5.1.4.5] Change of normative reference to ISO 48-4 for the determination of Shore
hardness;
— [3.1.1] Rewording of the definition of pass, and information given as a Note to entry;
— [3.1.2] Definition of FAP added;
— [3.2] Title completed;
— [3.2] Introduction of the symbol µ, and rewording of μ and μ definition;
ref FAP
— [3.2] Deletion of the symbol Ø;
— [5.1.1] Addition of reference to Annex A;
— [5.1.1] Completed with obligation to work in specified temperature and humidity room conditions;
— [5.1.2.3] Requirements for H modified (value and tolerance);
— [5.1.2.3] Figure 2 corrected (D and D );
1 2
— [5.1.2.3] Introduction of additional requirements for polishing rollers storage;
— [5.1.2.3] Modification of requirement for the number of conditioning passes;
— [5.1.2.5] Addition of a clause about the washing device;
— [5.1.4] Rewording of title;
— [5.1.4.2] Rewording of title, and deletion of the requirement for inertia moment;
— [5.1.4.3] Modification the title. And “moment” replaced by “torque” in all the document;
— [5.1.4.3] Modification of the tolerance for torque measurement;
— [5.1.4.5] Modification of the criteria for resilience of sliding blocks. Deletion of Table 1 and following
paragraph. Following tables renumbered accordingly;
— [5.1.4.5] Figure 4 corrected since it was mirror inverted. Correction of the rotation radius value;
— [5.2] Rewording of title, definition of μ value transferred to 3.2;
ref
— [5.3] Additional requirements for sand-blasting equipment;
— [6.1] Additional recommendations for quartz powder;
— [6.2] Additional requirements for water/quartz-powder mixture;
— [6.3] Addition of a footnote about the supplier of corundum;
— [7.1.1] Addition of a new sub-heading “7.1.1 General”. Following subclauses renumbered
accordingly;
— [7.1.1] Achievement – or not – of sandblasting according to the test and/or product context;
— [7.1.2] Rewriting of sandblasting procedure, and change of storage position;
— [7.1.3] Modification of thickness requirement and change of storage position;
— [7.1.4] New clause added for the conditioning of specimens;
— [7.2] Polishing procedure completed for conditioning, water/quartz-powder mixture, washing;
— [7.2] Clause now subdivided in tree sub clauses;
— [7.2.3] Clarification of the number of passes for “other applications”;
— [7.2.3] Requirement for the consistency of torque value imported from 5.1.2.3;
— [7.3.1] Obligation of pre-test check for each specimen;
— [7.3.2] Additional dispositions about water introduction, torque values recording and control plate
test;
— [8.1] Title modified and Clause totally rewritten for more clarity and consistency;
— [8.1] Formula (1) modified;
— [8.2] Formula (2) moved to 8.1 Formula (3);
— [8.2] Rewording of the criterion for validating the test, and possibility of a curve FAP against passes;
— [9] Information to be reported simplified. Added references to Clauses 8.1 and 8.2 for the
calculation;
— [10] Update of the precision values;
— [Annex A] In Figure A.1, correction of the key line 4;
— [Annex B] New informative annex added to provide results from the curve FAP against passes;
— [Annex C] New informative annex added to provide information about national experiences;
— [Bibliography] Updated.
A list of all parts in the EN 12697 series can be found on the CEN website.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Introduction
Regarding skid resistance of road surfaces, the test of the polished stone value, PSV according to
EN 1097-8 has long been a reference [1]. It characterizes a curved specimen of a coarse aggregate, but
cannot alone predict the adhesion of a bituminous mixture once it is in place. A second limit is that it
characterizes one surface state of the coarse aggregate, but does not provide any information about its
speed of evolution under a polishing action.
In the 1960s Pr B. Wehner and K.-H. Schulze developed testing devices, able to polish and characterize
the skid resistance of a flat specimen, of coarse aggregate, sand, or bituminous mixture, and to follow
its evolution as a function of the number of polishing passes [2]. After different developments of the so-
called “Wehner and Schulze apparatus”, this test method, applied to bituminous mixtures, became in
2014 the European Standard EN 12697-49, Bituminous mixtures - Test methods for hot mix asphalt - Part
49: Determination of friction after polishing. It characterizes one surface state of a bituminous mixture
after a fixed number of polishing passes.
The use of this standard in different European countries (see Annex C) in recent years, in contexts of
tenders and/or research, brought to light the need to improve it in both metrological and operating
aspects. It is the subject of this document, which should accordingly lead to improve the reproducibility
of the test.
1 Scope
This document specifies a method to determine the friction at 60 km/h after polishing during a fixed
number of passes on surfaces of bituminous mixtures samples, or to follow its evolution as a function
of the number of polishing passes.
The samples used are either produced in a laboratory or are cores taken from the site.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 12697-27, Bituminous mixtures - Test methods - Part 27: Sampling
EN 12697-33, Bituminous mixtures - Test method - Part 33: Specimen prepared by roller compactor
ISO 4662, Rubber, vulcanized or thermoplastic — Determination of rebound resilience
ISO 48-4, Rubber, vulcanized or thermoplastic — Determination of hardness — Part 4: Indentation
hardness by durometer method (Shore hardness)
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• ISO Online browsing platform: available at https://www.iso.org/obp
• IEC Electropedia: available at https://www.electropedia.org/
3.1.1
pass
passage of a single roller of the polishing head on one given point of the sample surface
Note 1 to entry: A complete revolution of the rotating polishing head is equivalent to three roller passes on one
given point of the sample surface.
3.1.2
FAP
average of two or more single results μ
FAP
3.2 Symbols and abbreviated terms
μ friction coefficient
μ friction coefficient at 60 km/h
m
μ
mean value of the control plate before and after the friction measurement
km
μ
moving average of the last 50 friction measurements on the control plate
ref
μ
single result of friction measurement on a single specimen

FAP
FAP Friction After Polishing
4 Principle
The sample is polished and the friction force is determined. The device comprises a polishing unit and
a unit for measuring the friction. The polishing unit, which is continuously supplied with a mixture of
water and quartz powder, contains three polishing rollers that can be lowered in order to move across
the test surface at a predefined vertical force.
In the measuring unit, a rotating measuring head is lowered onto the test surface while water is being
added. The measuring head is fitted with three sliding blocks. The torque generated by the contact
between the sliding blocks and the test surface is continuously measured and recorded until the
measuring head comes to a standstill. The Friction After Polishing, FAP, is subsequently calculated from
the torque measured at 60 km/h.
5 Equipment
5.1 Test device
5.1.1 General
The test device consists of a unit to polish the sample, a specimen clamping system and a unit for
determining its friction coefficient. (See an example of polishing head and friction unit in Annex A,
Figure A.1.) The test device shall be operated in a room with ambient temperature of (20 ± 5) °C.
5.1.2 Polishing unit
5.1.2.1 General
The polishing unit includes a polishing head with polishing rollers and a water-quartz powder mixture
projection system.
5.1.2.2 Polishing head
A polishing head equipped with three polishing rollers as indicated on Figure 1, able to be lowered onto
the test surface with loading force calibrated in static of (392 ± 3) N. The polishing head shall move on
the surface of the specimen during the polishing procedure and rotate at a rotation speed of (500 ± 5)
r/min.
Dimensions in millimetres
Key
1 polishing roller
2 water quartz powder projection device
Figure 1 — Polishing head (view from below)
5.1.2.3 Polishing rollers
The rollers, as shown in Figure 2, consist of a circular, cone-shaped metal carrier housing covered with
a layer of rubber with a Shore hardness of (65 ± 3) Shore A at a temperature of (23 ± 2) °C, according to
ISO 48-4.
The polishing rollers shall have the following initial dimensions:
— diameter D : (36 ± 1) mm and D : (80 ± 1) mm;
1 2
— height H: (57,5 ± 0,5) mm;
— thickness of the rubber layer: (8,5 ± 0,5) mm.
Eight equally spaced profile grooves, as shown in Figure 2, are cut into the rubber layer with the
following initial groove dimensions:
— depth: (4,5 ± 0,5) mm;
— width: (3,5 ± 0,5) mm.
Any new polishing rollers not used shall be packed in film and stored, until the first use, in a dark and
dry place at a temperature of 4 °C to 10 °C for less than two years after the date of the manufacture.
When new polishing rollers have been fitted, they shall be conditioned using an (old) test sample subject
to between 475 000 and 525 000 passes of the rollers in the polishing unit with water/quartz powder
mixture according to 6.2. Record the date of first use of each polishing roller.
Once the polishing rollers are used they shall be protected from UV-light when they are not operating
in a test. If the polishing rollers are not used, for a period not longer than two months, they shall be
dismantled and stored as new polishing rollers.
The three roller linings shall be replaced at the same time when at least one of the following conditions
occurs:
— when they are worn;
— when they feel sticky;
— when they show strong signs of rubber wear;
— when dark traces of wear appear on the test surfaces;
— at the latest after around 2 × 10 passes per roller;
— at latest 2 years after their first use.
Dimensions in millimetres
a)
b)
Figure 2 — Polishing rollers — Cross and longitudinal section, 3D view
5.1.2.4 Water-quartz-powder mixture projection device
The water-quartz-powder mixture projection device consists of:
a) A bin with a stirrer to keep the water-quartz-mixture homogenous;
b) A pump with a capacity of (5,0 ± 0,5) l/min to bring the water-quartz-powder mixture through the
centre of the polishing head to the surface of the specimen while the polishing action is going on.
The diameter of the gun shall be (8,5 ± 0,5) mm.
5.1.2.5 Washing device
A washing device shall enable the sample to be cleaned from the polishing media, with clear water, over
the specified duration. It shall also allow the dirty washing water to be removed from the machine.
5.1.3 Specimen clamping system
At the bottom-plate a clamp which provides a proper fixation of the specimen with a diameter of at least
225 mm or parallelepiped samples with at least the following dimensions: 320 mm × 260 mm and a
thickness of not more than 50 mm.
5.1.4 Measuring unit
5.1.4.1 General
The measuring unit includes a declutching rotating head with three sliding blocks spaced at angles of
(120 ± 5)°.
5.1.4.2 Measuring head
A rotating head equipped with three sliding blocks as indicated on Figure 3, able to reach at least a
rotation speed of 50 r/s and to apply a vertical static force of (253 ± 3) N.
Dimensions in millimetres
Figure 3 — Measuring head (view from below)
5.1.4.3 Torque measuring system
The unit shall be equipped with a system able to measure the torque to ± 0,25 N·m during the braking
procedure.
5.1.4.4 Rotation speed measurement system
The rotating head shall be equipped with a system able to measure the speed of rotation to ± 2 r/s
during the braking procedure.
5.1.4.5 Sliding blocks
The new sliding blocks consist of a ring segment-shaped metal carrier with a clamping device to which
a rubber lining with a thickness of (5 ± 1) mm has been applied.
The characteristics of a new sliding block are as follows:
— width (14,5 ± 0,1) mm;
— average length (30 ± 1) mm of the flat surface in contact with the test specimen, measured as
average of L , L as indicated Figure 4;
1 2
— the radius of curvature: R (7,5 ± 0,5) mm as shown in Figure 4;
— shore hardness (65 ± 3), Shore A at a temperature of (23 ± 2) °C according to ISO 48-4;
— resilience (%) of the slider rubber (67 to 74) at a temperature of (23 ± 2) °C according to ISO 4662.
Any new sliding blocks and any sheet rubber not used shall be packed in film and stored, until the first
use, in a dark and dry place at a temperature of 4 °C to 10 °C for less than two years after the date of the
manufacture.
New sliding blocks shall be conditioned using an already polished asphalt sample by carrying out a
minimum number of 5 measurements. Before each measurement, the sliding blocks shall be
conditioned to room temperature. Record the date of first use of each sliding block.
Once the sliding blocks are used they shall be protected from UV-light when they are not operating in a
test. If the sliding blocks are not used, for a period not longer than two months, they shall be dismantled
and stored as new sliding blocks.
If a sliding block is in use one year after the date of first use withdraw it from use. The sliding blocks
shall be replaced all three at the same time.
Dimensions in millimetres
Key
1 rubber lining
2 metallic base
3 contact surface for measuring the average length
Figure 4 — Shape of the rubber, sliding block (plan view and cross section)
5.1.4.6 Water projection system
The friction measuring unit shall be equipped with a system able to spray water on the specimen with
a flow volume of (20 ± 2) l/min when the measuring head is at the braking stage.
5.2 Control plate for comparative measurements
Control plate with a textured surface (ornamental wire glass 521 mm to 7 mm) with a friction μ .
ref
5.3 Sand-blasting-equipment
A sand blasting equipment for the preparation of the samples, fitted with a plate turning at
(24 ± 2) r/min, with a round nozzle of (6,3 ± 0,3) mm diameter, able to blast corundum 0,5/1 mm with
a compressed air at a pressure of (6,0 ± 0,3) bar.
The distance between the nozzle and the specimen shall be (70 ± 5) mm and the angle between the
compressed air direction and the surface of the specimen shall be approximately 75°.
6 Other materials
6.1 Quartz powder
Quartz-powder less than 0,063 mm type “Millisil W6” from Quarzwerke Frechen . The quartz powder
should respect the following grading values.
Total passing:
— at 2 mm: 100 %
— at 0,125 mm: 96 %
— at 0,063 mm: 72 %
6.2 Water quartz powder mixture
At the beginning of the test, the water-quartz-powder mixture consists of a mixture of quartz powder
consistent with 6.1 and water, at a mixing ratio of (60 ± 2) g quartz powder per litre of water. No
addition is carried out during the test.
6.3 Corundum
The sieve size of corundum shall be 0,5/1 mm, complying with the grading specified in Table 1.
Table 1 — Grading requirements for corundum
Sieve size Total passing
mm %
2,00 100
1,00 90 to 100
0,710 30 to 40
0,500 0 to 15
0,250 0 to 5
"Millisil W6" is the tradename of a product supplied by Quarzwerke Frechen. The quartz powder "Millisil W6"
supplied by Quarzwerke Frechen is suitable for the test. This information is given for the convenience of users of
this European Standard and does not constitute an endorsement by CEN of the product named. Equivalent
products may be used if they can be shown to lead to the same results. Address of the company: Quarzwerke
Frechen, Hauptverwaltung Kaskadenweg 40, 50226 Frechen, Germany.
The corundum supplied by Baustoff-Prüfsystem Wennigsen GmbH – Werner-von-Siemens-Str. 1, D-30974
Wennigsen – Germany is an example of a suitable corundum for the test. Equivalent products may be used if they
can be shown to lead to the same results.
7 Test method
7.1 Preparation of the specimens
7.1.1 General
Depending on the test and/or product context, a sandblast may be carried out before the test. The
achievement – or not – of sandblasting shall be mentioned in the test report.
7.1.2 Specimens prepared in the laboratory
Asphalt test specimens, produced in a laboratory, shall be prepared using a roller compactor in
accordance with EN 12697-33. The test specimens may either be used as plates or as a base for drill
cores with a diameter ∅ of about 225 mm or parallelepiped specimens with the following approximate
dimensions:
320 mm × 260 mm and a thickness of not more than 50 mm.
Before sandblasting the specimens shall be stored on a plane support at a temperature of (5 ± 3) °C
during at least 120 min with the surface for testing downwards.
The surface of the specimens shall be dried by blowing air over them.
On each sample, sandblast evenly the circular area of approximately 40 mm wide where the friction
measurements are carried out. Sandblast is carried out during (120 ± 5) s with new corundum powder,
in accordance to requirements of 5.3. Remove all remaining particles by blowing air. Store the
specimens at room-temperature on a plane rigid support with the surface for testing downwards under
conditions defined in 7.1.4.
7.1.3 Specimens taken from the site
Drill cores shall be removed according to EN 12697-27. The diameter of the drill cores shall be at least
225 mm and compatible with the clamping device. When drilling and removing the drill cores from the
drill hole, care shall be taken that the surface and especially the edges are not damaged, as any chipping
can adversely affect the results. Damaged areas shall not be part of tested areas.
The test specimen should have a thickness of not more than 50 mm to enable it to be mounted properly
in the clamping device. The lower part of the drill core that is too high shall be sawn off and discarded.
Drill cores taken from roads that have not been subject to traffic for extended periods usually require
preliminary treatment by sand-blasting according to 7.1.2.
Store the specimen at room-temperature with the surface for testing on a plane rigid support with the
surface for testing downwards under conditions defined in 7.1.4.
7.1.4 Conditioning of specimens
For at least 120 min before the beginning of the test, and during the test, each specimen shall be kept at
a temperature between 15 °C and 25 °C.
7.2 Polishing procedure
7.2.1 General
The water/quartz powder mixture is prepared for each specimen with new components.
Before testing each sample, the polishing head with the polishing rollers and the clamping device shall
be carefully cleaned to remove any quartz powder that may adhere to them.
7.2.2 Pre-test check of the polishing unit
The roller bearings shall be checked for free movement and replaced when movement becomes difficult
or when there is friction in the bearings.
The polishing rollers shall be checked for possible damage according to 5.1.2.3.
7.2.3 Polishing process
The test specimen is horizontally fastened in the clamping device of the polishing unit.
The polishing head is lowered to the surface of the specimen with a static load of (392 ± 3) N. Make the
water-quartz-powder mixture projection device work. The temperature of the water/quartz powder
mixture shall be between 15 °C and 25 °C during the polishing process.
The polishing action is carried out with a velocity of (500 ± 5) r/min.
Stop the polishing action after 90 000 passes without intermediate stop. Wash the sample surface for
(180 ± 5) s, with a recommended flow of clear water of (5 ± 1) l/min to remove the polishing media.
Then carry out the procedure described in 7.3.2.
For other applications, the polishing procedure may be stopped:
— test without sandblasting: at 1 000, 2 000, 3 000, 4 000, 5 000, 6 000, 7 000, 8 000, 10 000, 15 000,
20 000, 50 000, 90 000, 180 000 and 270 000 passes;
— test with sandblasting: at 4 500, 7 500, 15 000, 22 500, 30 000, 45 000, 90 000, 135 000, 180 000,
225 000 and 270 000 passes.
These values can be adapted according to the tested product and its behaviour during the test. This shall
be mentioned in the test report.
After each stop wash the sample surface for (180 ± 5) s, with a recommended flow of clear water of
(5 ±
...