EN 12697-48:2021

Bituminous mixtures - Test methods - Part 48: Interlayer Bonding

This document specifies test methods for determining the bond strength between an asphalt layer and other newly constructed construction layers or existing substrates in road or airfield pavements. The tests can also be applied on laboratory prepared interlayers.
The normative tests described in this document are:
—   Torque Bond Test (TBT), generally applicable to any layer thicknesses;
—   Shear Bond Test (SBT), generally applicable to layer thicknesses > 15 mm;
—   Tensile Adhesion Test (TAT), generally applicable to layer thicknesses ≤ 15 mm.
NOTE   Further non normative test methods are described in informative annexes:
—   Annex A (informative) - Compressed Shear Bond Test (CSBT);
—   Annex B (informative) - Alternative Shear Bond Test (ASBT);
—   Annex C (informative) - Layer Adhesion Measuring Instrument (LAMI).

Asphalt - Prüfverfahren - Teil 48: Schichtenverbund

Dieses Dokument legt Prüfverfahren für die Bestimmung der Haftfestigkeit zwischen einer Asphaltschicht und anderen, neu aufgetragenen Schichten der Fahrbahnbefestigung oder vorhandenen Untergründen von Straßen oder Flugplätzen fest. Die Prüfungen können auch auf im Labor hergestellte Zwischenschichten angewendet werden.
In diesem Dokument werden die folgenden normativen Prüfungen beschrieben:
- Prüfung der Haftfestigkeit unter Drehmoment (TBT, en: Torque Bond Test), allgemein anwendbar bei jeder Schichtdicke;
- Scherhaftfestigkeitsprüfung (SBT, en: Shear Bond Test), allgemein anwendbar bei Schichtdicken > 15 mm;
- Haftzugfestigkeitsprüfung (TAT, en: Tensile Adhesion Test), allgemein anwendbar bei Schichtdicken ≤ 15 mm.
ANMERKUNG   Weitere nicht normative Prüfverfahren werden in informativen Anhängen beschrieben:
- Anhang A (informativ) – Scherhaftfestigkeitsprüfung unter Druckbelastung (CSBT, en: Compressed Shear Bond Test);
- Anhang B (informativ) – alternative Scherhaftfestigkeitsprüfung (ASBT, en: Alternative Shear Bond Test);
- Anhang C (informativ) – Schichthaftungsmessinstrument (LAMI, en: Layer Adhesion Measuring Instrument).

Mélanges bitumineux - Méthodes d’essai - Partie 48 : Collage entre couches

Le présent document spécifie les méthodes d'essai pour la détermination de la résistance du collage entre une couche d’enrobé et d’autres couches récemment construites ou de supports existants dans des chaussées routières ou aéronautiques. L’essai peut également être appliqué à des bicouches confectionnés en laboratoire.
Les essais normatifs décrits dans le présent document sont :
—   Essai de collage en torsion (TBT), applicable généralement quelle que soit l’épaisseur des couches ;
—   Essai de collage en cisaillement (SBT), applicable généralement aux couches d’épaisseurs > 15 mm ;
—   Essai de collage en traction (TAT), applicable généralement aux couches d’épaisseurs ≤ 15 mm ;
NOTE    D’autres méthodes d'essai non normatives sont décrites dans les annexes informatives :
—   Annexe A (informative) - Essai de collage en compression cisaillement (CSBT)
—   Annexe B (informative) - Essai alternatif de collage en cisaillement (ASBT)
—   Annexe C (informative) - Instrument de mesure du collage entre couches (LAMI)

Bitumenske zmesi - Preskusne metode - 48. del: Zlepljenost plasti

Ta evropski standard določa preskusne metode za določanje sprijemne trdnosti med plastjo asfalta in drugimi novozgrajenimi plastmi gradbenega materiala oziroma obstoječimi podlagami v cestah ali letaliških stezah. Preskus je mogoče uporabiti tudi za laboratorijsko pripravljene vmesne plasti. Dodatne informativne preskusne metode so določene za vrednotenje kompleksne sprijemne togosti med plastmi materiala za gradnjo cest.
V tem standardu so opisani naslednji preskusi:
– preskus torzijske sprijemnosti (TBT), ki se na splošno uporablja za vse debeline plasti;
– preskus strižne sprijemnosti (SBT), ki se na splošno uporablja za debeline plasti ≥ 15 mm;
– preskus natezne sprijemnosti (TAT), ki se na splošno uporablja za debeline plasti < 15 mm.
OPOMBA 1: Dodatne preskusne metode, ki niso normativne, so opisane v informativnih dodatkih:
– dodatek A (informativni): preskus strižne sprijemnosti pod pritiskom (CSBT);
– dodatek B (informativni): preskus strižne sprijemnosti pod cikličnim pritiskom (CCSBT);
– dodatek C (informativni): preskus alternativne strižne sprijemnosti (ASBT);
– dodatek D (informativni): Instrument za merjenje sprijemnosti plasti (LAMI).

General Information

• Status: Published
• Publication Date: 27-Feb-2022
• Withdrawal Date: 30-May-2022
• ICS: 93.080.20 - Road construction materials
• Technical Committee: CEN/TC 227 - Road materials
• Drafting Committee: CEN/TC 227/WG 1 - Bituminous mixtures
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 10-Nov-2021
• Due Date: 08-Nov-2021
• Completion Date: 10-Nov-2021
• Ref Project: SIST EN 12697-48:2022 - Bituminous mixtures - Test methods - Part 48: Interlayer Bonding

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 12697-48:2022
01-januar-2022
Bitumenske zmesi - Preskusne metode - 48. del: Zlepljenost plasti
Bituminous mixtures - Test methods - Part 48: Interlayer Bonding
Asphalt - Prüfverfahren - Teil 48: Schichtenverbund
Mélanges bitumineux - Méthodes d'essai - Partie 48: Lien de couches
Ta slovenski standard je istoveten z: EN 12697-48:2021
ICS:
93.080.20 Materiali za gradnjo cest Road construction materials
SIST EN 12697-48:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 12697-48:2022
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SIST EN 12697-48:2022
EN 12697-48
EUROPEAN STANDARD
NORME EUROPÉENNE
November 2021
EUROPÄISCHE NORM
ICS 93.080.20
English Version
Bituminous mixtures - Test methods - Part 48: Interlayer
Bonding

Mélanges bitumineux - Méthodes d'essai - Partie 48: Asphalt - Prüfverfahren - Teil 48: Schichtenverbund

Lien de couches
This European Standard was approved by CEN on 16 August 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

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

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,

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

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

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12697-48:2021 E

worldwide for CEN national Members.
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SIST EN 12697-48:2022
EN 12697-48:2021 (E)
Contents Page

European foreword ............................................................................................................................................. 3

1 Scope .......................................................................................................................................................... 4

2 Normative references .......................................................................................................................... 4

3 Terms and definitions ......................................................................................................................... 4

4 Principle ................................................................................................................................................... 5

4.1 General ...................................................................................................................................................... 5

4.2 Torque Bond Test (TBT) ..................................................................................................................... 5

4.3 Shear Bond Test (SBT)......................................................................................................................... 6

4.4 Tensile Adhesion Test (TAT) ............................................................................................................ 6

5 Specimens ................................................................................................................................................ 6

6 Torque Bond Test (TBT) ..................................................................................................................... 7

6.1 Apparatus ................................................................................................................................................. 7

6.2 Materials ................................................................................................................................................... 7

6.3 Site test method ..................................................................................................................................... 7

6.4 Laboratory test method ...................................................................................................................... 8

6.5 Calculation of Torque Bond Strength and expression of results ......................................... 9

6.6 Visual assessment of the mode of failure ..................................................................................... 9

6.7 Test report .............................................................................................................................................10

6.8 Precision .................................................................................................................................................10

7 Shear Bond Test (SBT).......................................................................................................................11

7.1 Apparatus ...............................................................................................................................................11

7.2 Specimens ..............................................................................................................................................12

7.3 Test procedure .....................................................................................................................................13

7.4 Calculation and Expression of Results .........................................................................................14

7.5 Test report .............................................................................................................................................16

7.6 Precision .................................................................................................................................................16

8 Tensile Adhesion Test (TAT) ..........................................................................................................17

8.1 Apparatus ...............................................................................................................................................17

8.2 Materials .................................................................................................................................................18

8.3 Specimen ................................................................................................................................................18

8.4 Test procedure .....................................................................................................................................19

8.5 Calculation and expression of results ..........................................................................................20

8.6 Test report .............................................................................................................................................20

8.7 Precision .................................................................................................................................................21

Annex A (informative) Compressed Shear Bond Test (CSBT) ..........................................................22

Annex B (informative) Alternative Shear Bond Test (ASBT) ............................................................31

Annex C (informative) Layer Adhesion Measuring Instrument (LAMI) .......................................34

Bibliography ........................................................................................................................................................45

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SIST EN 12697-48:2022
EN 12697-48:2021 (E)
European foreword

This document (EN 12697-48:2021) 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 May 2022, and conflicting national standards shall be

withdrawn at the latest by May 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.

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.
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SIST EN 12697-48:2022
EN 12697-48:2021 (E)
1 Scope

This document specifies test methods for determining the bond strength between an asphalt layer and

other newly constructed construction layers or existing substrates in road or airfield pavements. The

tests can also be applied on laboratory prepared interlayers.
The normative tests described in this document are:
— Torque Bond Test (TBT), generally applicable to any layer thicknesses;
— Shear Bond Test (SBT), generally applicable to layer thicknesses > 15 mm;

— Tensile Adhesion Test (TAT), generally applicable to layer thicknesses ≤ 15 mm.

NOTE Further non normative test methods are described in informative annexes:
— Annex A (informative) - Compressed Shear Bond Test (CSBT);
— Annex B (informative) - Alternative Shear Bond Test (ASBT);
— Annex C (informative) - Layer Adhesion Measuring Instrument (LAMI).
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 12697-29, Bituminous mixtures — Test methods — Part 29: Determination of the dimensions of a

bituminous specimen

EN 12697-33, Bituminous mixtures — Test methods — Part 33: Specimen prepared by roller compactor

3 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:

• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
peak shear stress of the interface
SBT,max

maximum value of shear stress [MPa] determined as the maximum force F divided by the initial cross

sectional area A, of a specimen when tested as described in this document
3.2
displacement at peak shear stress
SBT,max

displacement at the maximum value of shear stress of a specimen when tested as described in this

document
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EN 12697-48:2021 (E)
3.3
shear stiffness modulus
SBT,max

slope of the shear stress versus displacement - graph determined from the linear part of the graph

3.4
effective cross sectional area
value of the effective contact area between the two layers of the specimen

Note 1 to entry: This area can be expressed as a function of the relative displacement of the two portions of the

specimen as shown in Figure A.3.
3.5
dilatancy

ratio between the difference of the last two current recorded values of the vertical and the horizontal

displacement [d = (η - η )/(δ - δ )] of a specimen when tested as described in Annex A

i i-1 i i-1
3.6
normal stress

ratio between the normal load and the effective cross sectional area of a specimen when tested as

described in Annex A
3.7
critical condition

shearing of the interface in residual (pure friction) condition at constant volume of a specimen when

tested as described in Annex A
4 Principle
4.1 General

The described test methods simulate different loading conditions and are applicable on different bonds

between road construction layers. The methods give different results because they measure different

failure modes.
4.2 Torque Bond Test (TBT)
The torque bond test assesses the resistance to horizontal shear stress:

• The torque bond test is suitable for testing the bond strength between road layers in laboratory and

in situ;

• The torque bond test assesses the resistance to the stresses generated primarily by traffic

accelerating or braking, but also by different thermal movements when the layers are of different

materials;
• The torque bond test can be carried out immediately after laying;

• The torque bond test can be applied to assess the interlayer bond quality of bond coats or tack coats.

When the thickness of the top layer above the interlayer assessed is less than 15 mm, the torque bond

test can be applied for evaluating the durability of the top layer.
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EN 12697-48:2021 (E)

The torque bond test is carried out either in situ or in the laboratory using cores. A circular steel plate is

glued to the top road surface in situ or on top of a core in a laboratory. A rotational horizontal force is

applied to the steel plate and the torque moment is measured. For a top layer with a thickness < 15 mm,

the steel plate is glued on top of the surface or – for the laboratory test method – a core that is larger than

the plate diameter. For a top layer with a thickness ≥ 15 mm, a cylindrical groove of the same dimension

as the plate is cut through the upper layer down into the bottom layer.
4.3 Shear Bond Test (SBT)

The shear bond test assesses the resistance to horizontal shear stresses in the interlayer of two road

construction layers.

• The shear bond test assesses the resistance to the stresses generated primarily by traffic accelerating

or braking, but also by different thermal movements when the layers are of different materials;

• The shear bond test can be applied to assess the interlayer bond quality of bond coats or tack coats;

• The shear bond test is suitable to evaluate the shear bond strength of construction layers with a

thickness > 15 mm.

Cylindrical test specimens are subjected to direct shear loading at controlled temperature with constant

shear rate. The development of shear deformation and force is recorded and the maximum recorded

shear stress is determined as shear strength (in MPa) at the interface between layers. The thickness of

the layer above the interlayer of interest shall be ≥ 20 mm. The core shall have a (remaining) thickness

of at least 70 mm below the interface. For thinner layers than 20 mm, a grooved metal plate extension

can be affixed to the specimen to minimize bulging in the top layer.
4.4 Tensile Adhesion Test (TAT)

The tensile adhesion test assesses the tensile bond strength between two road construction layers.

• The test method is generally applicable for thin surface layers (thickness ≤ 15 mm);

• The tensile adhesion test can be applied to assess the interlayer bond quality of bond coats or tack

coats as well as the internal cohesion of the two road construction layers.

The tensile adhesion test determines the adhesion between a surface layer and the bottom layer,

perpendicular to the plane of the specimen. A test-plunger is glued on the incised and ground surface of

the top layer and is pulled off with a suitable tension testing device at constant test temperature and

strain rate. The maximum force related to the tension area is the adhesive tension strength in MPa.

NOTE Also the cohesion failure of the surface layer might determine the test result when the test is applied on

thicker layers.
5 Specimens

The test methods to assess the interlayer bonding are either conducted on site or on specimens cored

from the pavement. The interlayer bonding conditions change after laying with time, temperature and

traffic loading. Therefore, the time span between laying and testing for site tests or coring of laboratory

specimens shall be considered. The time span shall be reported in the test report.

The cores shall be stored fully supported. The support on which the cores rest shall be flat and clean.

Cores shall not be stacked on top of each other. Cores shall be stored at a temperature between 15 °C and

25 °C for a maximum duration of 1 week. If a longer duration of storing is necessary, the storing

temperature shall be between 0 °C and 5 °C.
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EN 12697-48:2021 (E)
6 Torque Bond Test (TBT)
6.1 Apparatus

6.1.1 Core cutting apparatus, suitable for cutting nominally 100 mm or 200 mm diameter cores in

bituminous and hydraulically bound materials with minimum vibration, preferably using air cooling.

6.1.2 Torque meter, fitted with a reading gauge that indicates the maximum torque obtained. The

device shall be calibrated over a range of 0 Nm to 400 Nm. The torque moment shall be measured to the

nearest 10 Nm. The device shall be fitted with socket-fitting allowing steel plates to be fitted and removed.

6.1.3 Metal Plate of mild steel having a diameter of (95 ± 5) mm and a thickness of (14 ± 2) mm. The

plate shall incorporate a fitting enabling it to be coupled to the torque meter.
NOTE Fittings of 12,7 mm and 19,05 mm have been found to be suitable.

6.1.4 Thermometer, readable to 0,1 °C and with a maximum permissible error of 0,5 °C.

6.1.5 Steel Ruler readable to 1 mm.
6.1.6 Callipers for measurement of core diameters.
6.1.7 Watch or Timer, readable and with a maximum permissible error of 1 s.

6.1.8 Mould for confining laboratory test specimens (e.g. a mould for casting concrete test cubes).

6.1.9 Spirit Level for checking laboratory test specimens.
6.1.10 Water bath of suitable size for temperature conditioning of the specimen.
6.1.11 Oven or refrigerated incubator (optional).
6.2 Materials

6.2.1 Adhesive (a stiff adhesive, such as rapid setting epoxy resin, with sufficient strength to avoid

failure within the adhesive or at the adhesive/road surface interface).

6.2.2 Mounting material (for laboratory tests), e.g. rapid hardening mortar, concrete or grout.

6.3 Site test method
6.3.1 General

For each test location, 6 torque bond tests are conducted to evaluate one result. The test locations shall

be located within 2 m of each other at least 100 mm apart. Another number of test locations may be

chosen, e.g. in order to reduce the damage to the pavement. The number shall be reported.

6.3.2 For top layer thickness ≥ 15 mm, a 100 mm diameter groove shall be cored to a depth of

(20 ± 5) mm below the interface to be tested. The cores shall not be removed. Where the layer thickness

of the layer above the interlayer bond of interest is less than 15 mm, no coring is needed.

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EN 12697-48:2021 (E)

6.3.3 Measure and record the core diameter at two locations approximately 90° apart using callipers

and record the mean value, D, to the nearest 1 mm.

In the case that no groove is cored into the surface, the diameter D equals the diameter of the steel plate

glued on top of the surface.

6.3.4 Ensure that all debris is removed from the rebate formed by the core barrel. Clean and dry the

surface to be tested.

6.3.5 Use the adhesive to glue the metal plate to the surface of the core or the surface layer if not cored,

taking care to ensure that the plate is parallel to the surface.

6.3.6 When the bonding agent has developed sufficient strength, (i.e. failure shall not occur within the

adhesive), fit the torque meter to the metal plate, using adapters and extension rods as appropriate.

6.3.7 Record the pavement surface temperature in the vicinity of the test location.

6.3.8 Apply torque to the core at a steady rate so that the torque wrench sweeps an angle of 90° within

(30 ± 15) s. Care shall be taken to ensure that the torque is applied parallel to the core surface

(within ± 10°). Torque is applied to the plate until failure of the bond occurs or a torque of 400 Nm is

exceeded. In later case, 6.3.9 to 6.3.11 are not applied.

6.3.9 Record the value of torque at failure, M, in Nm. Measure and record the bond interface

temperature immediately after failure. Any interface that comes apart during preparation shall be

deemed to have a bond strength of 0 Nm. Examine the core and substrate and record the condition of the

bond interface (e.g. smooth, planar, rough or irregular) and record the mode of failure according the

classification in 6.6. Record the substrate type (e.g. asphalt or hydraulically bound surface).

6.3.10 Measure and record the depth of the failed interface from the pavement surface to the nearest

1 mm.
6.3.11 Calculate the bond strength in accordance with 6.5.
6.4 Laboratory test method

6.4.1 Specimens shall be cored from an in-service pavement or from a slab compacted in laboratory in

accordance to EN 12697-33 with a laboratory manufactured bonding layer.

Cut six cores to a minimum depth of 80 mm below the interface being tested or down to the bottom of

the asphalt layers. Extract the core taking care not to damage the surface of the core or the bond interface.

For top layer thickness ≥ 15 mm, the cores shall have a diameter of (100 ± 2) mm. For top layer

thickness < 15 mm, the cores shall have a diameter of (200 ± 2) mm. Another number of test specimens

may be chosen, e.g. in order to reduce the damage to the pavement. The number shall be reported.

If laboratory tests are to be compared to site test results, similar duration between laying of the layer on

top of the bonding layer shall be applied.

NOTE The duration between laying and compaction, coring and testing influences the test results.

6.4.2 Trim the core to a length suitable for mounting if appropriate.
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6.4.3 Place the core in the mould, using mortar or grout as a bedding layer if appropriate, so that the

upper layer and the bond interface to be tested is (20 ± 10) mm above the rim of the mould. Fill the mould

with the mortar/grout and trim flush with the mould rim, ensuring that the core is perpendicular to and

the upper surface parallel with the mould surface. Check using the spirit level.

6.4.4 Glue the metal plate to the core surface using the adhesive and allow to set.

6.4.5 Condition the mounted cores by storing at a temperature of (20 ± 2) °C for a minimum of 4 h

before testing. Record the times and temperatures employed.
The standard test temperature is (20 ± 2) °C.
Other test temperatures may be applied for other purposes.

NOTE Example of other purpose can be when data obtained from site tests carried out at a temperature other

than (20±2) °C is subject to comparison.

6.4.6 Test the core at a temperature of (20 ± 2) °C. If other temperatures are used, the test shall be

completed within five minutes of removal from the conditioning environment.

6.4.7 Fix or clamp the mould containing the mounted core to a suitably rigid surface. Carry out the test

as described in 6.3.8.

6.4.8 Examine the core and record all the relevant information as described in 6.6 and 6.7.

6.5 Calculation of Torque Bond Strength and expression of results

6.5.1 Calculate the torque bond strength τ for each specimen using the following formula:

TBT,max
16××M 10
τ = (1)
TBT,max
π×D
where
τ inter-layer torque shear bond strength, in kilopascals (kPa),
TBT,max
M peak value of applied shearing torque, in newton metres (Nm),
D diameter of core, in millimetres (mm).

6.5.2 Calculate the arithmetic mean of the torque bond strength measured on the six specimens /

locations.
6.6 Visual assessment of the mode of failure

In case of failure of the interface, the visual assessment of the failed surface shall be determined according

to the following classification:
a) within the surface layer (cohesion failure),
b) partly at the interface, partly in the surfacing layer (mixed failure),
c) at the interface (adhesion failure),
d) partly in the bottom layer, partly at the interface (mixed failure),
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EN 12697-48:2021 (E)
e) in the bottom layer (cohesion failure),
f) partly or completely in the adhesive.

If a mixed failure is observed, the proportions of the failure modes shall be estimated with a maximum

permissible error of 10 %.
In the case, that the interface did not fail, “no failure” shall be recorded.
6.7 Test report
The test report shall include the following information:
a) name of organization carrying out the test;
b) reference to this document;
c) method of test used (in situ, laboratory) and if cored or not;
d) description of materials (system and substrate);
e) date of test;

f) number of tests conducted per location or number of tested laboratory specimens;

g) peak torque at failure (Nm) for individual cores;
h) inter-layer torque bond strength τ (kPa), (individual and mean values);
TBT
i) time to failure (seconds);
j) diameter of cores (mm) if appropriate;
k) depths of Bond interface (mm);
l) temperature of the pavement surface or the specimen (°C);
m) conditioning details (duration and temperature);
n) site or laboratory test;
o) identification of site or scheme;
p) specimen or location number;
q) age of the tested interface at the time of test;
r) mode of failure.
6.8 Precision
The precision for this test method has not been determined.
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EN 12697-48:2021 (E)
7 Shear Bond Test (SBT)
7.1 Apparatus

7.1.1 Shear test apparatus, as shown in Figure 1, composed of a base body (A) on which are fixed the

sample support (B) and the lower shear ring (C). The upper shear ring (D) is attached to the upper body

(E), which is movable vertically along the guiding bars (F).
A gap width ≤ 5 mm is recommended.
NOTE The gap width between shear rings influences the test results.
Dimensions in millimetres
Key
A base body
B sample support
C lower shear ring
D upper shear ring
E upper body
F guiding bar
1 range max. ± 20 mm
Figure 1—Schematic diagram of the Shear Bond Test apparatus

7.1.2 Loading frame capable of achieving a constant vertical displacement rate of (50,0 ± 2) mm per

minute up to a displacement of at least 7 mm and a maximum load of at least 35 kN.

7.1.3 Data logging system to record load and displacement during the test.

7.1.4 Metal plate extension as shown in Figure 2, composed of aluminium or other metal.

7.1.5 Adhesive (a stiff adhesive, such as rapid setting epoxy resin, with sufficient strength to avoid

failure within the adhesive or at the adhesive/thin surfacing interface).
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Dimensions in millimetres
Key
1 dimension to suit diameter of specimen
Figure 2 — Schematic diagram of the metal plate extension (example)
7.2 Specimens
7.2.1 At least two specimens shall be cored from the pavement to be tested.

7.2.2 Specimens shall be cores of (150 ± 2) mm or (100 ± 2) mm diameter. The minimum thickness of

the layers above the interface to be tested shall be 20 mm and below the interface 70 mm respectively.

Specimens shall be cored from an in-service pavement according EN 12697-27 or from a slab

manufactured using a laboratory roller compactor in accordance with EN 12697-33.

For top and/or bottom layer thickness below the requirement, a metal plate extension can be glued to

the specimen.

For layers with maximum aggregate size > 14 mm, specimens with diameter 150 mm is recommended.

NOTE The specimen diameter influences the test results.

7.2.3 Cores shall have constant diameters throughout their length and smooth lateral surfaces to allow

adequate placement in the apparatus. The interface between layers shall be perpendicular to the core’s

longitudinal axis. The maximum acceptable deviation from the standard plane shall be 5 mm (see

Figure 3).

If cores taken from in-service-pavements are tested, the direction of traffic shall be marked to the cores.

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Figure 3 — Maximum acceptable deviation from the standard plane
7.3 Test procedure

7.3.1 The diameter and thickness of the specimen shall be determined according to EN 12697-29 to the

nearest 0,1 mm. Further the core diame
...

SLOVENSKI STANDARD
oSIST prEN 12697-48:2020
01-januar-2020
Bitumenske zmesi - Preskusne metode - 48. del: Zlepljenost plasti
Bituminous mixtures - Test methods - Part 48: Interlayer Bonding
Asphalt - Prüfverfahren - Teil 48: Schichtenverbund
Mélanges bitumineux - Méthodes d'essai - Partie 48: Lien de couches
Ta slovenski standard je istoveten z: prEN 12697-48
ICS:
93.080.20 Materiali za gradnjo cest Road construction materials
oSIST prEN 12697-48:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN 12697-48:2020
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oSIST prEN 12697-48:2020
DRAFT
EUROPEAN STANDARD
prEN 12697-48
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2019
ICS 93.080.20
English Version
Bituminous mixtures - Test methods - Part 48: Interlayer
Bonding

Mélanges bitumineux - Méthodes d'essai - Partie 48: Asphalt - Prüfverfahren - Teil 48: Schichtenverbund

Lien de couches

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 227.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC

Management 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,

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

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without

notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12697-48:2019 E

worldwide for CEN national Members.
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Contents Page

European Foreword ...................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and Definitions ................................................................................................................................... 5

4 Principle ............................................................................................................................................................. 6

4.1 General ................................................................................................................................................................ 6

4.2 Torque Bond Test (TBT) ............................................................................................................................... 6

4.3 Shear Bond Test (SBT)................................................................................................................................... 7

4.4 Tensile Adhesion Test (TAT) ...................................................................................................................... 7

5 Specimens .......................................................................................................................................................... 7

6 Torque Bond Test (TBT) ............................................................................................................................... 8

6.1 Apparatus ........................................................................................................................................................... 8

6.2 Materials ............................................................................................................................................................. 8

6.3 Site test method ............................................................................................................................................... 8

6.4 Laboratory test method ................................................................................................................................ 9

6.5 Calculation of Torque Bond Strength and expression of results ................................................ 10

6.6 Visual assessment of the mode of failure ............................................................................................ 10

6.7 Test report ...................................................................................................................................................... 11

6.8 Precision .......................................................................................................................................................... 11

7 Shear Bond Test (SBT)................................................................................................................................ 11

7.1 Apparatus ........................................................................................................................................................ 11

7.2 Specimens ....................................................................................................................................................... 13

7.3 Test Procedure .............................................................................................................................................. 14

7.4 Calculation and Expression of Results .................................................................................................. 15

7.5 Test Report ..................................................................................................................................................... 17

7.6 Precision .......................................................................................................................................................... 18

8 Tensile Adhesion Test (TAT) ................................................................................................................... 19

8.1 Apparatus ........................................................................................................................................................ 19

8.2 Specimen ......................................................................................................................................................... 20

8.3 Test procedure .............................................................................................................................................. 21

8.4 Calculation and expression of results ................................................................................................... 22

8.5 Test report ...................................................................................................................................................... 22

8.6 Precision .......................................................................................................................................................... 23

Annex A (informative) Compressed Shear Bond Test (CSBT) ................................................................... 24

A.1 Principle .......................................................................................................................................................... 24

A.2 Apparatus ........................................................................................................................................................ 24

A.3 Sample Preparation..................................................................................................................................... 26

A.4 Test Procedure .............................................................................................................................................. 26

A.5 Calculation and expression of results ................................................................................................... 27

A.6 Test Report ..................................................................................................................................................... 28

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A.7 Precision .......................................................................................................................................................... 29

A.7.1 Repeatability .................................................................................................................................................. 29

A.7.2 Reproducibility .............................................................................................................................................. 29

Annex B (informative) Cyclic Compressed Shear Bond Test (CCSBT) .................................................... 33

B.1 Principle ........................................................................................................................................................... 33

B.2 Apparatus ........................................................................................................................................................ 33

B.3 Sample preparation ..................................................................................................................................... 37

B.4 Test procedure .............................................................................................................................................. 37

B.5 Results .............................................................................................................................................................. 38

B.6 Test Report...................................................................................................................................................... 38

B.7 Precision .......................................................................................................................................................... 39

Annex C (informative) Alternative Shear Bond Test (ASBT) ..................................................................... 40

C.1 Principle ........................................................................................................................................................... 40

C.2 Objective and scope ..................................................................................................................................... 40

C.3 Alternative shear test apparatus ............................................................................................................ 40

C.4 Calculation and expression of results ................................................................................................... 42

Annex D (informative) Layer Adhesion Measuring Instrument (LAMI) ................................................ 43

D.1 Principle ........................................................................................................................................................... 43

D.2 Apparatus ........................................................................................................................................................ 43

D.3 Test Procedure .............................................................................................................................................. 47

D.4 Visual assessment of the mode of failure ............................................................................................. 49

D.5 Calculation and Expression of Results .................................................................................................. 49

D.6 Calibration of the LAMI ............................................................................................................................... 50

D.7 Test Report...................................................................................................................................................... 52

D.8 Precision .......................................................................................................................................................... 52

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European foreword

This document (prEN 12697-48:2019) has been prepared by Technical Committee CEN/TC 227 “Road

materials”, the secretariat of which is held by BSI.
This document is currently submitted to the CEN Enquiry.
A list of all parts in the EN 12697 series can be found on the CEN website.
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1 Scope

This document specifies test methods for determining the bond strength between an asphalt layer and

other newly constructed construction layers or existing substrates in road or airfield pavements. The

tests can also be applied on laboratory prepared interlayers.
The normative tests described in this document are:
— Torque Bond Test (TBT), generally applicable to any layer thicknesses;
— Shear Bond Test (SBT), generally applicable to layer thicknesses ≥ 15 mm;

— Tensile Adhesion Test (TAT), generally applicable to layer thicknesses < 15 mm;

NOTE 1 Further non normative test methods are described in informative annexes:
— Annex A (informative) - Compressed shear bond test (CSBT)
— Annex B (informative) - Cyclic compressed shear bond test (CCSBT)
— Annex C (informative) - Alternative Shear bond test (ASBT)
— Annex D (informative) - Layer Adhesion Measuring Instrument (LAMI)
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 12697-29, Bituminous mixtures — Test methods for hot mix asphalt — Part 29: Determination of the

dimensions of a bituminous specimen

EN 12697-33, Bituminous mixtures — Test methods for hot mix asphalt — Part 33: Specimen prepared by

roller compactor
3 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:

• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
peak shear stress of the interface
τSBT,max

maximum value of shear stress [MPa], determined as the maximum force F divided by the initial cross

sectional area A, of a specimen when tested as described in this document
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3.2
displacement at peak shear stress
δSBT,max

displacement at the maximum value of shear stress, of a specimen when tested as described in this

document
3.3
shear stiffness modulus
kSBT,max

slope of the shear stress versus displacement - graph, determined from the linear part of the graph

3.4
effective cross sectional area
value of the effective contact area between the two layers of the specimen

Note 1 to entry: This area can be express as a function of the relative displacement of the two portions of the

specimen as shown in Figure A.3.
3.5
dilatancy

ratio between the difference of the last two current recorded values of the vertical and the horizontal

displacement [d = (η - η )/(δ - δ )], of a specimen when tested as described in Annex A

i i-1 i i-1
3.9
normal stress

ratio between the normal load and the effective cross sectional area, of a specimen when tested as

described in Annex A
3.10
critical condition

shearing of the interface in residual (pure friction) condition at constant volume, of a specimen when

tested as described in Annex A
4 Principle
4.1 General

The described test methods simulate different loading conditions and are applicable on different bonds

between road construction layers. The methods give different results because they measure different

failure modes.
4.2 Torque Bond Test (TBT)
The torque bond test assesses the resistance to horizontal shear stress:

• The torque bond test is suitable for testing the bond strength between road layers in laboratory and

in situ;

• The torque bond test assesses the resistance to the stresses generated primarily by traffic

accelerating or braking, but also by different thermal movements when the layers are of different

materials;
• The torque bond test can be carried out immediately after laying;

• The torque bond test can be applied to assess the capability of bond coats or tack coats.

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When the thickness of the top layer above the interlayer assessed is less than 15 mm, the torque bond

test can be applied for evaluating the durability of the top layer.

The torque bond test is carried out either in situ or in the laboratory using cores. A circular steel plate is

glued to the top road surface in situ or on top of a core in a laboratory. A rotational horizontal force is

applied to the steel plate and the torque moment is measured. For a top layer with a thickness < 15 mm,

the steel plate is glued on top of the surface or a – for the laboratory test method – a core that is larger

than the plate diameter. For a top layer with a thickness ≥ 15 mm, a cylindrical groove of the same

dimension as the plate is cut through the upper layer down into the bottom layer.

4.3 Shear Bond Test (SBT)

The shear bond test assesses the resistance to horizontal shear stresses in the interlayer of two road

construction layers.

• The shear bond test assesses the resistance to the stresses generated primarily by traffic

accelerating or braking, but also by different thermal movements when the layers are of different

materials.

• The shear bond test can be applied to assess the capability of bond coats or tack coats.

• The shear bond test is suitable to evaluate the shear bond strength of construction layers with a

thickness ≥ 15 mm.

Cylindrical test specimens are subjected to direct shear loading at controlled temperature with constant

shear rate. The development of shear deformation and force is recorded and the maximum recorded

shear stress is determined as shear strength (in MPa) at the interface between layers. The thickness of

the layer above the interlayer of interest shall be ≥ 20 mm. The core shall have a (remaining) thickness

of at least 70 mm below the interface. For thinner layers than 20 mm, a grooved metal plate extension

can be affixed to the specimen to minimize bulging in the top layer.
4.4 Tensile Adhesion Test (TAT)

The tensile adhesion test assesses the tensile bond strength between two road construction layers.

• The test method is applicable for thin surface layers;

• The tensile adhesion test can be applied to assess the capability of bond coats or tack coats as well

as the internal cohesion of the two road construction layers.

The tensile adhesion test determines the adhesion between a surface layer and the bottom layer,

perpendicular to the plane of the specimen. A test-plunger is glued on the incised and ground surface of

the top layer and is pulled off with a suitable tension testing device at constant test temperature and

strain rate. The maximum force related to the tension area is the adhesive tension strength in MPa.

5 Specimens

The test methods to assess the interlayer bonding are either conducted on site or on specimens cored

from the pavement. The interlayer bonding conditions changes after laying with time, temperature and

traffic loading. Therefore, the time span between laying and testing for site tests or coring of laboratory

specimens shall be considered. The time span shall be reported in the test report.

The cores shall be stored fully supported. The support on which the cores rest shall be flat and clean.

Cores shall not be stacked on top of each other. Cores shall be stored in a dry room at a temperature

between 15 °C and 25 °C.
The relative humidity in the storage room should not exceed 80 %.
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6 Torque Bond Test (TBT)
6.1 Apparatus

6.1.1 Core cutting apparatus, suitable for cutting nominally 100 mm or 200 mm diameter cores in

bituminous and hydraulically bound materials with minimum vibration, preferably using air cooling.

6.1.2 Torque meter, fitted with a reading gauge that indicates the maximum torque obtained. The

device shall be calibrated over a range of 0 Nm to 400 Nm. The torque moment shall be measured to the

nearest 10 Nm. The device shall be fitted with socket-fitting allowing steel plates to be fitted and

removed.

6.1.3 Metal Plate of mild steel having a diameter of (95 ± 5) mm and a thickness of (14 ± 2) mm. The

plate shall incorporate a fitting enabling it to be coupled to the torque meter.
NOTE Fittings of 12,7 mm and 19,05 mm have been found to be suitable.
6.1.4 Thermometer, readable to 0,1°C and accurate to 0,5°C.
6.1.5 Steel Ruler readable to 1 mm.
6.1.6 Callipers for measurement of core diameters.
6.1.7 Watch or Timer readable and accurate to 1 s.

6.1.8 Mould for confining laboratory test specimens, (e.g. a concrete cube mould).

6.1.9 Spirit Level for checking laboratory test specimens.
6.1.10 Water bath of suitable size for temperature conditioning of the specimen.
6.1.11 Oven or refrigerated incubator (optional).
6.2 Materials

6.2.1 Adhesive (a stiff adhesive, such as rapid setting epoxy resin, with sufficient strength to avoid

failure within the adhesive or at the adhesive/road surface interface).

6.2.2 Mounting material (for laboratory tests), e.g. rapid hardening mortar, concrete or grout.

6.3 Site test method
6.3.1 General

For each test location, 6 torque bond tests are conducted to evaluate one result. The test locations shall

be located within 2 m of each other at least 100 mm apart. Another number of test locations may be

chosen, e.g. in order to reduce the damage to the pavement. The number shall be reported.

6.3.2 For top layer thickness ≥ 15 mm, a 100 mm diameter groove shall be cored to a depth of

20 ± 5 mm below the interface to be tested. The cores shall not be removed. Where the layer thickness

of the layer above the interlayer bond of interest is less than 15 mm, no coring is needed.

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6.3.3 Measure and record the core diameter at two locations approximately 90° apart using callipers

and record the mean value, D, to an accuracy of 1 mm.

In the case that no groove is cored into the surface, the diameter D equals the diameter of the steel plate

glued on top of the surface.

6.3.4 Ensure that all debris is removed from the rebate formed by the core barrel. Clean and dry the

surface to be tested.

6.3.5 Use the adhesive to glue the metal plate to the surface of the core or the surface layer if not

cored, taking care to ensure that the plate is parallel to the surface.

6.3.6 When the bonding agent has developed sufficient strength, (i.e. failure shall not occur within the

adhesive), fit the torque meter to the metal plate, using adapters and extension rods as appropriate.

6.3.7 Record the pavement surface temperature in the vicinity of the test location.

6.3.8 Apply torque to the core at a steady rate so that the torque wrench sweeps an angle of 90°

within (30 ± 15) s. Care shall be taken to ensure that the torque is applied parallel to the core surface

(within ± 10°). Torque is applied to the plate until failure of the bond occurs or a torque of 400 Nm is

exceeded. In later case, 6.3.9 to 6.3.11 are not applied.

6.3.9 Record the value of torque at failure, M, in Nm. Measure and record the bond interface

temperature immediately after failure. Any interface that comes apart during preparation shall be

deemed to have a bond strength of 0 Nm. Examine the core and substrate and record the condition of

the bond interface (e.g. smooth, planar, rough or irregular) and record the mode of failure according the

classification in 6.6. Record the substrate type (e.g. asphalt or hydraulically bound surface).

6.3.10 Measure and record the depth of the failed interface from the pavement surface to an accuracy

of 1mm.
6.3.11 Calculate the bond strength in accordance with 6.5.
6.4 Laboratory test method

6.4.1 Specimens shall be cored from an in-service pavement or from a slab compacted in laboratory in

accordance to EN 12697-33 with a laboratory manufactured bonding layer.

Cut six cores to a minimum depth of 80 mm below the interface being tested or down to the bottom of

the asphalt layers. Extract the core taking care not to damage the surface of the core or the bond

interface. For top layer thickness ≥ 15 mm, the cores shall have a diameter of 100 ± 2 mm. For top layer

thickness < 15 mm, the cores shall have a diameter of 200 ± 2 mm. Another number of test specimens

may be chosen, e.g. in order to reduce the damage to the pavement. The number shall be reported.

If laboratory tests are to be compared to site test results, similar duration between laying of the layer on

top of the bonding layer shall be applied.

NOTE The duration between laying and compaction, coring and testing influences the test results.

If immediate testing is not possible, the cores shall be stored at a temperature between 0 °C and 5 °C

until testing.
6.4.2 Trim the core to a length suitable for mounting if appropriate.
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6.4.3 Place the core in the mould, using mortar or grout as a bedding layer if appropriate, so that the

upper layer and the bond interface to be tested is (20 ± 10) mm above the rim of the mould. Fill the

mould with the mortar/grout and trim flush with the mould rim, ensuring that the core is perpendicular

to, and the upper surface parallel with, the mould surface. Check using the spirit level.

6.4.4 Glue the metal plate to the core surface using the adhesive and allow to set.

6.4.5 Condition the mounted cores by storing at a temperature of (20 ± 2) °C for a minimum of 4 h

before testing. Record the times and temperatures employed.
The standard test temperature is (20 ± 2) °C.
Other test temperatures may be applied for other purposes.

NOTE Example of other purpose can be when data obtained from site tests carried out at a temperature other

than (20±2) °C is subject to comparison.

6.4.6 Test the core at a temperature of (20 ± 2) °C. If other temperatures are used the test shall be

completed within 5 min of removal from the conditioning environment.

6.4.7 Fix or clamp the mould containing the mounted core to a suitably rigid surface. Carry out the

test as described in 6.3.8.

6.4.8 Examine the core and record all the relevant information as described in 6.6 and 6.7.

6.5 Calculation of Torque Bond Strength and expression of results

6.5.1 Calculate the torque bond strength τ for each specimen using the following formula:

TBT
12××M 10
τ = (1)
TBT
π× D
where
τ inter-layer torque shear bond strength in kilopascal (kPa)
TBT
M peak value of applied shearing torque in Newton meter (Nm),
D diameter of core in millimetres (mm)

6.5.2 Calculate the arithmetic mean of the torque bond strength measured on the six specimens /

locations.
6.6 Visual assessment of the mode of failure

In case of failure of the interface, the visual assessment of the failed surface shall be determined

according to the following classification:
a) Within the surface layer (cohesion failure),
b) partly at the interface, partly in the surfacing layer (mixed failure),
c) at the interface (adhesion failure),
d) partly in the bottom layer, partly at the interface (mixed failure),
e) in the bottom layer (cohesion failure),
f) partly or completely in the adhesive.
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If a mixed failure is observed, the proportions of the failure modes shall be estimated with an accuracy

of 10 %.
In the case, that the interface did no
...