EN 12697-48:2021
(Main)Bituminous mixtures - Test methods - Part 48: Interlayer Bonding
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
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
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
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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.
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
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.
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
τ
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
δ
SBT,max
displacement at the maximum value of shear stress of a specimen when tested as described in this
document
3.3
shear stiffness modulus
k
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.
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.
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.
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.
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),
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.
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).
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.
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 diameter at the interface is measured.
The tested interlayer shall be marked.
In case of the application of metal plate extension, the grooved surface shall be glued to the surface of the
specimen. The metal plate diameter shall be slightly higher than the diameter of the specimen (≤ 2 mm).
The shear ring shall form a loose fit around the metal plate extension.
7.3.2 The specimen shall be placed into a temperature cabinet at controlled conditioning temperature
of 20 °C ± 1 °C for a minimum of 4 h.
NOTE Other test temperatures or conditioning procedures can be applied but will influence the test result.
7.3.3 The appropriate shear rings, to form a loose fit around the specimen, shall be selected and
attached to the test frame. The shear rings shall have the same or slightly higher (≤ 2 mm) radius as the
tested specimen.
7.3.4 The specimen shall be placed into the test apparatus and the interface aligned, between the upper
and lower shear rings.
If direction of traffic is marked on the specimen, the shear load shall be applied in parallel to the direction
of traffic.
If metal plate extension is applied, the grooves shall be perpendicular to the direction of applied shear
force.
7.3.5 Tighten the sample support.
7.3.6 If the test frame is not already fixed to the loading frame, the test apparatus shall be placed into
the loading frame and adjusted until the upper shear ring nearly touches the specimen.
7.3.7 Start the data logging system (to record load and displacement) and commence shear loading.
The loading rate shall be (50 ± 2) mm per minute.
NOTE Other loading rates or modes (e.g. force-control) can be applied but will affect the test result.
7.3.8 Stop the shear loading when the test frame reaches its limit or when the shear force decreases
down to a shear force of 70 % of the maximum shear force recorded. The length of time between removal
of the specimen from the temperature controlled conditioning environment and completion of testing
shall not exceed 15 min.
7.3.9 Record the load F to the nearest 0,1 kN and the displacement δ to the nearest 0,1 mm during the
test.
7.3.10 The specimen shall be observed (especially the interface) for any visual cracks and unusual
appearance (i.e. crushed aggregates on edges), which could indicate misalignment of the specimen in the
shear plane. Record any comments as necessary.
NOTE 1 Suitable observations for reporting are:
• total separation of top and bottom layer,
• obvious slipping displacement of the top layer,
• obvious deformation of the top layer,
• cracking of aggregates in the interlayer zone.
NOTE 2 It can occur that the interface will not fail completely and the two layers are still fixed to each other. This
is a typical test result even in the case where a maximum shear force is clearly visible in the graph.
7.4 Calculation and Expression of Results
7.4.1 Plot the recorded shear force F versus the displacement δ (an example is shown in Figure 4).
7.4.2 Determine the following parameters from the graph:
a) F is the peak shear force of the interface, kN, expressed to the nearest 0,1;
SBT,max
'
b) F is the slope of the linear part of the force-displacement graph.
SBT
c) δ is the displacement at peak shear stress as measured between the displacement at maximum
SBT,max
shear stress and the intersection of the linear Force-slope F' with the displacement-axis, mm,
SBT
expressed to the nearest 0,1;
7.4.3 Calculate the maximum shear stress as follows:
F
SBT,max
τ ⋅ 1 000
SBT,max
(2)
D
π⋅
where
τ is the maximum shear stress of the interface in (MPa), expressed to the nearest
SBT,max
0,01 MPa;
F is maximum vertical shear force (in kN);
SBT,max
D is the initial diameter of specimen in the interlayer (in mm).
=
7.4.4 Calculate the shear stiffness modulus as follows:
'
F
SBT
k =
SBT,max
(3)
D
π⋅
where
k is the shear stiffness modulus of the interface in (MPa/mm), expressed to the
SBT,max
nearest 0,1 MPa/mm;
F’ is the slope of the linear part of the force-deflection graph (in kN/mm);
SBT
D is the initial diameter of specimen in the interlayer (in mm).
7.4.5 Determine the Shear energy E from the area below the shear force-deflection graph as
SBT
measured between the displacement at maximum shear stress and the intersection of the linear shear
force slope F' with the displacement-axis in Nm to the nearest 1 Nm.
SBT
7.4.6 Determine the Post-Peak Shear energy E from the area below the shear force-deflection
SBT,PP
graph as measured between the displacement at maximum shear stress and the displacement at
termination of the test in (Nm) to the nearest 1 Nm.
Key
1 shear force F in kN 5 displacement at peak shear stress δ
SBT,max
2 displacement δ, in mm 6 end of test at a decrease of the shear force to 70 % of FSBT,max
3 maximum shear force FSBT,max 7 shear energy ESBT
4 slope of shear force F’ 8 post-peak shear energy E
SBT SBT,PP
Figure 4 — Example for a shear stress versus shear displacement graph
7.5 Test report
The test report shall include the following information:
a) name of the organization carrying out the test;
b) reference to this document;
c) test method used,
d) date of test;
e) test conditions (any variation of test temperature or loading mode shall be specified);
f) material descriptions for both layers;
g) type and amount of tack coat / bond coat (if known);
h) the test temperature, expressed to the nearest 0,5 °C;
i) depths of bond interface (mm);
j) conditioning details (duration and temperature);
k) site or laboratory test:
— identification of laboratory interlayer construction method,
— core location,
l) age of the installation / specimen at the time of test;
m) for each specimen tested, report:
— specimen diameter, expressed to the nearest mm,
— layer thicknesses, expressed to the nearest mm,
— maximum force (F ), expressed to the nearest 0,1 kN,
SBT,max
— displacement at maximum shear stress (δ ), expressed to the nearest 0,1 mm,
SBT,max
— maximum shear stress (τ ), expressed to the nearest 0,01 MPa,
SBT,max
— shear stiffness modulus (k ), expressed to the nearest 0,1 MPa/mm,
SBT,max
— shear energy E , expressed to the nearest 1 Nm,
SBT
— post-peak shear energy E , expressed to the nearest 1 Nm,
SBT,PP
— any cracks or other damage.
7.6 Precision
The precision for this test method has not been determined.
NOTE Table 1 contains precision estimation of the shear bond test on asphalt specimens with a diameter of
150 mm from the German test procedure (gap width: 0 mm).
Table 1 — Precision
Repeatability Reproducibility
Standard deviation, σ Standard deviation, σ
r R
Peak shear stress τ 0,074 + 0,04 ⋅ τ 0,037 + 0,11 ⋅ τ
SBT,max SBT,max SBT,max
Displacement at peak shear
0,38 mm 0,76 mm
stress δ
SBT,max
8 Tensile Adhesion Test (TAT)
8.1 Apparatus
8.1.1 Tensile testing machine, capable of loading the specimen at a constant load rate without shocks
with a capacity of at least 30 kN. The load measuring device shall measure the load at failure to a
maximum permissible error of 2 % of the load (examples for suitable test devices are shown in Figure 5).
8.1.2 Test-plunger with a diameter of (100 ± 0,1) mm, at least 10 mm thick made of a suitable steel.
8.1.3 Steel-ring as counter-plate, made of a suitable steel with an internal diameter of between
104 mm and 115 mm and an outer diameter of 300 mm, thickness 25 mm including accessories to ensure
a solid connection between core and support of the tension testing machine (all dimensions are
approximate) or tripod holding a hydraulic jack operated by a hydraulic hand pump.
Other load frames allowing the vertical tensile loading of the ring-grooved specimen centre while holding
the outer specimen ring in constant vertical location may be used.
8.1.4 Suitable adhesive for bonding test plunger to sample.
8.1.5 Thermometers for the measurement of the temperature of the test with a maximum permissible
error of 0,2 °C.
8.1.6 Drilling machine for cores with diamond-bit, inside diameter (100 ± 2) mm, with adjustment for
the drilling depth.
8.1.7 Grinding machine for the preparation of the surface of the core.
8.1.8 Calibrated adjustable air-bath for conditioning cores to be tested at (0 ± 1) °C or (10 ± 0,5) °C
or other temperatures with a tolerance of (± 1 °C) as required.
8.1.9 Calliper to measure the diameter of the circular surface inside the ring-groove area with a
maximum permissible error of 0,1 mm.
Dimensions in millimetres
Key
1 load cell
2 globe joint
3 test-plunger
4 circular counter-plate
5 ring-groove
6 counter plate
7 adhesive glue
8 specimen upper layer
9 interface between specimen upper layer and specimen bottom layer
10 specimen bottom layer
Figure 5 — Example for a test apparatus for Tensile adhesion tests
8.2 Materials
8.2.1 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).
8.3 Specimen
8.3.1 At least three specimens shall be cored from the pavement to be tested.
8.3.2 The test is applied on cores approximately 150 mm diameter with a height of at least 60 mm,
sampled according to EN 12697-27. Damaged cores shall be discarded and the fact noted in the report of
the test.
The surface of the thin-layer shall not be damaged to avoid cracks inside the layer; no marking sprays or
grease crayon shall be on the top of the core to avoid the detachment of the plunger from the core. The
drilled cores shall be handled with care to avoid mechanical damages.
8.3.3 The specimens are cut to a height of (60 ± 5) mm parallel with the top surface. A ring-groove is
cut into the top surface of the specimen with a diamond tipped drilling machine approximately 10 mm
into the layer below the interface being tested. The internal diameter of the ring-groove shall be
(100 ± 2) mm.
It is essential that any damage (for example spalling and edge-outbreaks) occurring while drilling shall
be minimized. For this reason, the drilling action shall be made with an undamaged drilling-bit rotating
with no visible eccentricity smoothly and without imbalance.
8.3.4 The diameter of the specimen shall be determined according to EN 12697-29 to the nearest
0,1 mm.
8.3.5 The top surface of the test core shall ensure a secure bonding of the adhesive. It shall be visually
flat so that the plunger can be bonded on the circular surface inside the ring-groove area. If required (e.g.
in case of loose surface particles, road markings, unevenness), the surface shall be ground or sawn to
ensure an adequate bonding of the plunger.
NOTE The depth of grinding depends on the roughness of the core surface, normally the removal of 2 mm to
3 mm is sufficient. Care can be taken not to overheat the core as it could be distorted.
8.3.6 Before gluing the test-plunger, the test specimen shall be conditioned at laboratory conditions by
(23 ± 5) °C for (24 ± 4) h, to ensure that the ground surface is dry. The ground surface shall be visually
free from dust or grease or any other substance that may prevent bonding. The plunger shall be bonded
to the core surface inside the ring groove using the adhesive in accordance with the manufacturer’s
instructions including the time needed for curing. The ring groove shall remain completely free of
adhesive.
The adhesive shall be used according to the manufacturer technical papers, especially regarding the best-
before date.
8.4 Test procedure
8.4.1 The prepared core with its attached plunger shall be conditioned for at least 12 h at the test
temperature according to 8.1.8.
The test temperature shall be reported.
NOTE The test temperature affects the test result.
8.4.2 After conditioning, the core is installed into the tensile testing machine within 30 s after removing
from the adjustable air bath. The test-plunger with its attached core is connected to the testing machine
in a force fitting manner. The steel-ring as counter plate is fixed in place.
8.4.3 The load on the test-core diameter 100 mm is applied with a constant rate of 200 N/s, until the
specimen fails.
NOTE The constant force rate complies with stress increase of (25 ± 5) kPa/s.
Other loading rates may be applied. The loading rate affects the test result and shall be reported.
8.4.4 Record the maximum force F in N and the diameter of the circular surface inside the ring-
TAT,max
groove area D in mm.
8.5 Calculation and expression of results
8.5.1 The tensile strength σ in MPa is calculated from the maximum force F and the surface area
TAT,max
A in mm inside the ring-groove.
σ = F /A = 4 F /(π D ) (4)
TAT,max TAT,max TAT,max
where
σ is the tensile bond strength in MPa to the nearest 0,1 MPa;
TAT,max
F is the maximum force in N rounded to the nearest 1 N;
TAT,max
2 2
A is the surface area inside the ring-groove in mm to the nearest 0,1 mm ;
D is the diameter of the circular surface inside the ring-groove in mm to the nearest
0,1 mm.
8.5.2 For each individual specimen, a description of the failure surface is recorded in accordance with
the following classification:
A within the thin layer (cohesion-break);
B partly in the interface, partly in the thin layer (mixed break);
C in the interface (adhesion-break);
D partly in the interface, partly in the base, (mixed break);
E in the base;
F partly or completely in the adhesive.
When there is a mixed break, the proportions of each type should be estimated (to 10 %) and reported.
8.6 Test report
The test report shall include the following information:
a) name of organization carrying out the TAT test;
b) identification of site or project;
c) description of the upper layer;
d) date of installation;
e) date of coring;
f) reference to this document;
g) test method used:
h) date of test;
i) test temperature in °C and loading rate in N/s;
j) core number and location;
k) diameter D of the circular surface inside the ring-groove in mm;
l) maximum force F in N;
TAT,max
m) tensile bond strength σ in MPa;
TAT,max
n) classificat
...
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