EN 16306:2022

Natural stone test methods - Determination of resistance of marble to thermal and moisture cycles

This document specifies a laboratory method for determining the resistance to thermal and moisture cycling of marble intended for the external cladding of building facades.
NOTE Bowing and rapid strength loss is known to occur in some marbles when used as exterior cladding.

Prüfverfahren für Naturstein - Bestimmungen der Beständigkeit von Marmor bei zyklischer Belastung mit Wärme und Feuchte

Dieses Dokument legt ein Laborverfahren zur Bestimmung der Beständigkeit von Marmor, der zur Außen-verkleidung von Gebäudefassaden vorgesehen ist, bei zyklischer Belastung mit Wärme und Feuchte fest.
ANMERKUNG   Das Auftreten von Wölbung und schnellem Festigkeitsverlust ist für einige Marmorsorten bekannt, wenn sie als Außenverkleidung verwendet werden.

Méthodes d'essai pour pierres naturelles - Détermination de la résistance du marbre aux cycles thermiques et d'humidité

Le présent document spécifie une méthode de détermination en laboratoire de la résistance aux cycles thermiques et d’humidité du marbre destiné au revêtement extérieur des façades de bâtiments.
NOTE Certains marbres sont connus pour présenter un gauchissement et une perte de résistance rapide lorsqu’ils sont utilisés comme revêtements extérieurs.

Preskušanje naravnega kamna - Ugotavljanje odpornosti marmorja proti cikličnim toplotnim in vlažnostnim obremenitvam

Ta evropski standard določa laboratorijsko metodo za ugotavljanje odpornosti marmorja, namenjenega za obloge stavbnih fasad, proti cikličnim toplotnim in vlažnostnim obremenitvam.
Za znanstveno definicijo marmorja se upošteva standard EN 12670, Terminologija: 2.1.243 a.
OPOMBA:   Za nekatere vrste marmorja je znano, da se upogiba in da hitro izgublja trdnost, če se uporablja kot zunanja obloga.

General Information

• Status: Published
• Publication Date: 13-Sep-2022
• ICS: 73.020 - Mining and quarrying
• ICS: 91.100.15 - Mineral materials and products
• Technical Committee: CEN/TC 246 - Natural stones
• Drafting Committee: CEN/TC 246/WG 2 - Test methods
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 14-Sep-2022
• Due Date: 15-Nov-2021
• Completion Date: 14-Sep-2022
• Ref Project: SIST EN 16306:2022 - Natural stone test methods - Determination of resistance of marble to thermal and moisture cycles

Relations

• Replaces: EN 16306:2013 - Natural stone test methods - Determination of resistance of marble to thermal and moisture cycles
• Effective Date: 05-Jun-2019

Overview - EN 16306:2022 (Natural stone test methods)

EN 16306:2022, published by CEN, specifies a laboratory method to determine the resistance of geologically defined marble to cyclic thermal and moisture exposure when used as external façade cladding. The standard addresses the known risk of bowing (dishing/warping) and rapid flexural strength loss in some marbles used outdoors and provides a reproducible test procedure for durability assessment and quality control.

Key topics and technical requirements

• Scope: Laboratory determination of marble resistance to thermal and moisture cycles for external cladding.
• Specimen requirements: Slabs of (400 ± 5) mm × (100 ± 5) mm × (30 ± 2) mm; at least 6 exposed specimens plus reference specimens; consider foliation orientation and increase specimen count for heterogeneous marbles.
• Pre-conditioning: Dry in a ventilated oven at 40 °C for one week or until weight change < 0.1% between 24‑hour readings; cool to (20 ± 3) °C before exposure.
• Cycling regime: One cycle = 24 hours, surface temperature ramp from 20 °C to 80 °C; heating rate approx. 0.25 °C ± 0.1 °C/min. The heated face is exposed while the reverse face receives continuous moisture.
• Apparatus and measurement: Non‑corrosive test chamber with grating and filter cloth, heating panels, a black reference plate (per EN ISO 4892‑1) with thermocouple for surface control, and a bow‑test rig with support span 350 ± 5 mm. Bowing is measured with a gauge readable to 0.001 mm (system accuracy ±0.01 mm); results are normalized to mm/m.
• Strength assessment: Flexural strength before/after exposure is measured according to EN 12372.
• Ancillary guidance: Annex A (limit values guidance), Annex B (non‑destructive testing), Annex C (enhanced petrographic analysis, recommending more measurement points for heterogeneous materials).

Practical applications and users

• Who uses it: Test laboratories, stone manufacturers and suppliers, façade engineers, architects, specifiers, building contractors, certification bodies, and failure investigators.
• Uses: Pre‑qualification of marble for exterior cladding, production quality control, specification compliance, material selection, forensic analysis of façade problems (bowing, strength loss), and risk mitigation in façade design.
• Benefits: Reproducible assessment of marble durability under realistic thermal/moisture cycling; helps avoid costly façade failures and informs appropriate material choice and detailing.

Related standards

• EN 12372 - Determination of flexural strength (concentrated load)
• EN ISO 4892‑1 - Black reference plate and exposure guidance
• EN 12670 (for geological definition of marble)
• EN 16306:2022 supersedes EN 16306:2013 (updates include clarified procedure and Annex C amendments)

Keywords: EN 16306:2022, marble thermal moisture cycles, natural stone test methods, bowing, flexural strength, façade cladding, CEN, marble durability testing.

Standards Content (Sample)

SLOVENSKI STANDARD
01-november-2022
Nadomešča:
SIST EN 16306:2013
Preskušanje naravnega kamna - Ugotavljanje odpornosti marmorja proti cikličnim
toplotnim in vlažnostnim obremenitvam
Natural stone test methods - Determination of resistance of marble to thermal and
moisture cycles
Prüfverfahren für Naturstein - Bestimmungen der Beständigkeit von Marmor bei
zyklischer Belastung mit Wärme und Feuchte
Méthodes d'essai pour pierres naturelles - Détermination de la résistance du marbre aux
cycles thermiques et d'humidité
Ta slovenski standard je istoveten z: EN 16306:2022
ICS:
91.100.15 Mineralni materiali in izdelki Mineral materials and
products
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 16306
EUROPEAN STANDARD
NORME EUROPÉENNE
September 2022
EUROPÄISCHE NORM
ICS 73.020; 91.100.15 Supersedes EN 16306:2013
English Version
Natural stone test methods - Determination of resistance
of marble to thermal and moisture cycles
Méthodes d'essai pour pierres naturelles - Prüfverfahren für Naturstein - Bestimmungen der
Détermination de la résistance du marbre aux cycles Beständigkeit von Marmor bei zyklischer Belastung mit
thermiques et d'humidité Wärme und Feuchte
This European Standard was approved by CEN on 1 August 2022.

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, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16306:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Symbols . 5
5 Principle . 5
6 Apparatus . 5
7 Preparation of specimens . 9
7.1 Sampling . 9
7.2 Test specimens . 9
7.3 Reference marks on the specimens . 9
7.4 Drying the specimen . 9
8 Test procedure . 9
8.1 Control measurements before cycling . 9
8.2 Procedure for bowing measurement . 9
8.3 Readings, exposure and duration of test . 10
8.4 Measurements after exposure . 11
9 Calculation of results . 11
9.1 Bowing magnitude . 11
9.2 Flexural strength . 12
10 Test report . 12
Annex A (informative) Guidance on limit values . 14
Annex B (informative) Non-destructive testing . 15
Annex C (informative) Enhanced petrographic analysis . 16
Bibliography . 19

European foreword
This document (EN 16306:2022) has been prepared by Technical Committee CEN/TC 246 “Natural
stones”, the secretariat of which is held by UNI.
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 March 2023, and conflicting national standards shall be
withdrawn at the latest by March 2023.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 16306:2013.
In comparison with the previous edition, the following technical modifications have been made:
— inclusion of a more detailed description of the test procedure and several clarifications;
— Clause 10, “Precision” has been deleted since data from precision trials is not yet available;
— Annex C has been amended with the recommendation to increase the number of measurement points
in heterogeneous marble.
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, Türkiye and the United
Kingdom.
1 Scope
This document specifies a laboratory method for determining the resistance to thermal and moisture
cycling of marble intended for the external cladding of building facades.
NOTE Bowing and rapid strength loss is known to occur in some marbles when used as exterior cladding.
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 12372, Natural stone test methods - Determination of flexural strength under concentrated load
EN ISO 4892-1, Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance (ISO
4892-1)
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
bowing
change in shape from flat and planar to a curved or dished shape in a convex or concave direction
Note 1 to entry: Other terms commonly used for the same phenomenon are dishing and warping.
Note 2 to entry: Convex bowing is quantified by positive values, concave bowing by negative values.
3.2
convex bowing
centre part of the specimen is bowing upwards, away from the moist substratum
3.3
concave bowing
centre part of the specimen is bowing downwards, away from the applied heat
3.4
marble
metamorphic rock containing more than 50 % vol. of carbonates (calcite and/or aragonite and/ or
dolomite) formed by metamorphic recrystallization of a carbonate rock
Note 1 to entry: In this document, only geologically defined marble applies. The stones defined as marble only by
the commercial meaning (e.g. polishable limestones) do not need to be tested.
[SOURCE: EN 12670:2019, 3.1.291, modified – deleted Notes to entry and added a new Note 1 to entry]
4 Symbols
T Temperature
H Initial height of the specimen at the measuring point [mm]
H Difference between the initial height and the height after a specified number of cycles [mm]
H The normalized height difference, related to L = 1 m [mm]
N N
B H / L = The normalized bowing value [mm/m]
N N
B Bowing values after n cycles [mm/m]
n
L Distance between the supports under the specimen = 0,35 [m]
L Normalized length = 1 [m]
N
5 Principle
Bowing is measured on test samples placed within a test chamber, exposed to cycles of heat applied to
one face while the reverse face is subjected to moisture. The temperature interval is from 20 °C to 80 °C,
one cycle lasts 24 h. The temperature is measured on a black reference plate, placed on the surface of one
specimen, to control the climate within the test chamber.
The strength loss shall be measured according to EN 12372 on reference and exposed specimens (see
Annex A) and the results compared.
6 Apparatus
All measuring equipment shall be calibrated.
6.1 A non-corrosive test chamber (see Figure 1) of sufficient capacity to hold the required number of
specimens, laid horizontally. The container shall be designed in a way that specimens receive continuous
moisture from one side (the underside) and are exposed to cyclic heating on the other side (the upper
side). The container shall be furnished with a device that ensures a constant water level for the duration
of the test. Lying on the bottom of the container is a grating, which is covered by a sheet of heat stable
filter cloth.
6.2 A non-corrosive grating that fits within the length and width of the container and has a height of at
least 1 cm. The function of the grating is to ensure a water reservoir beneath the filter cloth.
6.3 A soft, heat stable, dimensionally stable, non-hygroscopic needle filter cloth of thickness
approximately 5 mm and without any water-soluble substances or chemicals. The cloth (e.g. Polyester or
PTFE (Polytetrafluoroethylene (PTFE)) needle felt) is to be placed on top of the grating. The function of
the cloth is to deliver moisture and provide uniform support to the specimen.
6.4 Heating panels of sufficient sizes and numbers to cover the container. The panels shall be capable
of providing a uniform heat flow, heating the black reference plate from 20 °C to 80 °C at average rate of
0,25 °C ± 0,1 °C per minute. The maximum permissible temperature difference within the test chamber,
during heating exposure, is 3 °C. Panels of insulating material should preferably be placed around the
container (see Figure 1), to avoid unwanted cooling or air circulation. Before the system is approved for
use, trial measurements of the temperature shall be performed at 9 surface points widely distributed
within the heating frame (see Figure 2). The temperature is measured on a uniform surface preferably
with an infrared thermometer or a surface measuring thermometer. The temperature readings shall be
taken on the surface of the black reference plate.
The heating rate may be adjusted by changing the distance between the heating device and the samples,
or by controlling the effect of the heater. The heating curve is displayed in Figure 5.
6.5 A black reference plate, according to EN ISO 4892-1 (see Figure 3), to ensure proper temperature
development and the maximum surface temperature at 80 °C. A thermocouple (cable type K), attached to
the black reference plate, is connected to a high stability temperature and process controller. A simple
data logger is also possible.
The black reference plate is placed on the surface of a sample, preferably near the middle of the container.
The temperatures for the experimental exposure are programmed in advance. The heating elements are
controlled by the process controller. The temperature of the black reference plate is read and the signal
is sent to the process controller that adjusts the heating. The whole system can thus be computer
controlled and the surface temperature can be monitored online.
6.6 An infrared thermometer or other thermometer capable of measuring the surface temperature of
the specimens. If an infrared thermometer is used it shall be checked against a material similar to marble,
since the response of such a thermometer is influenced by the density and other parameters of the
measured surface.
6.7 A bow-test rig for bowing measurements (see Figure 4). The rig comprises a steel plate, having
three supporting points upon which the specimen is placed, and three cylinders which guide the edges of
the specimen. The supporting points are situated (350 ± 5) mm apart from each other and shall be well
rounded and smooth in order to accommodate for eventual irregularities in the sawn surface of the
specimens. Above the centre of the specimen a gauge is mounted, which shall be readable to 0,001 mm.
The whole system shall have an accuracy better than ± 0,01 mm.
6.8 A reference cylinder (co-planar bases with an accuracy better than ±0,005 mm) consisting of a
material with a low linear expansion coefficient (e.g. quartz glass or invar steel).
6.9 A ventilated oven capable of maintaining a temperature of (40 ± 5) °C.
6.10 A weighing instrument which has an accuracy of at least 0,01 % of the mass to be weighed.

Key
1 heating device 4 filter cloth
2 insulation 5 grating
3 water level
NOTE The front wall is omitted here for a better view of the interior.
Figure 1 — Principle sketch and an example of exposure equipment for testing the potential
bowing properties of marble
Figure 2 — Location of temperature control points

Key
1 black reference plate
2 thermocouple
3 test specimen
Figure 3 — Black reference plate (EN ISO 4892-1:2016) for T-measurements
Dimensions in millimetres
Key
1 stand
2 gauge
3 reference piece
4 support
5 steel plate (corrosion resistant)
6 rubber or polychloroprene studs
7 guide
Figure 4 — Schematic drawing of the bowing test rig
7 Preparation of specimens
7.1 Sampling
Sampling is not the responsibility of the test laboratory except where specially requested to undertake
this.
At least 6 specimens are to be exposed to therma
...