untitled BRITISH STANDARD BS EN 14581 2004 Natural stone test methods — Determination of linear thermal expansion coefficient The European Standard EN 14581 2004 has the status of a British Standard I[.]
Trang 1Natural stone test
methods —
Determination of linear
thermal expansion
coefficient
The European Standard EN 14581:2004 has the status of a
British Standard
ICS 73.020; 91.100.15
Trang 2This British Standard was
published under the authority
of the Standards Policy and
Strategy Committee
on 29 September 2005
© BSI 29 September 2005
ISBN 0 580 46616 7
National foreword
This British Standard is the official English language version of
EN 14581:2004
The UK participation in its preparation was entrusted to Technical Committee B/545, Natural stone, which has the responsibility to:
A list of organizations represented on this committee can be obtained on request to its secretary
Cross-references
The British Standards which implement international or European
publications referred to in this document may be found in the BSI Catalogue
under the section entitled “International Standards Correspondence Index”, or
by using the “Search” facility of the BSI Electronic Catalogue or of British
Standards Online
This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application
Compliance with a British Standard does not of itself confer immunity from legal obligations.
— aid enquirers to understand the text;
— present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep
UK interests informed;
— monitor related international and European developments and promulgate them in the UK
Summary of pages
This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 13 and a back cover
The BSI copyright notice displayed in this document indicates when the document was last issued
Amendments issued since publication
Trang 3NORME EUROPÉENNE
ICS 73.020; 91.100.15
English version
Natural stone test methods - Determination of linear thermal
expansion coefficient
Méthodes d'essai pour pierres naturelles - Détermination
du coefficient linéaire de dilatation thermique Prüfverfahren für Naturstein - Bestimmung des linearenthermischen Ausdehnungskoeffizienten
This European Standard was approved by CEN on 12 November 2004.
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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
C O M I T É E U R O P É E N D E N O R M A L I S A T I O N
E U R O P Ä IS C H E S K O M IT E E FÜ R N O R M U N G
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved
worldwide for CEN national Members. Ref No EN 14581:2004: E
Trang 42
Contents
Page
Foreword 3
1 Scope 5
2 Normative references 5
3 Principle 5
4 Symbols 5
5 Apparatus 6
6 Preparation of the specimens 8
7 Test procedure 10
8 Expression of results 11
9 Test report 12
Bibliography 13
Trang 5Foreword
This document (EN 14581:2004) 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 June 2005, and conflicting national standards shall be withdrawn at the latest by June 2005
This final draft document is one of the series of documents for tests on natural stone
Test methods for natural stone consist of the following parts:
EN 1925, Natural stone test methods – Determination of water absorption coefficient by capillarity
EN 1926, Natural stone test methods – Determination of compressive strength
EN 1936 , Natural stone test methods – Determination of real density and apparent density and of total and open
porosity
EN 12370, Natural stone test methods – Determination of resistance to salt crystallisation
EN 12372, Natural stone test methods – Determination of flexural strength under concentrated load
EN 12407, Natural stone test methods – Petrographic examination
EN 13161, Natural stone test methods – Determination of flexural strength under constant moment
EN 13364, Natural stone test methods – Determination of the breaking load at dowel hole
EN 13373, Natural stone test methods – Determination of geometric characteristics on units
EN 13755, Natural stone test methods – Determination of water absorption at atmospheric pressure
EN 13919, Natural stone test methods – Determination of resistance to ageing by SO 2 action in the presence of humidity
EN 14066, Natural stone test methods – Determination of resistance to ageing by thermal shock
EN 14147, Natural stone test methods – Determination of resistance to ageing by salt mist
EN 14158, Natural stone test methods – Determination of rupture energy
EN 14205, Natural stone test methods – Determination of Knoop hardness
EN 14231, Natural stone test methods – Determination of the slip resistance by means of the pendulum tester
EN 14157, Natural stone test methods – Determination of the abrasion resistance
EN 14579, Natural stone test methods – Determination of sound speed propagation
prEN 14580, Natural stone test methods – Determination of the static elastic modulus
EN 14581, Natural stone test methods – Determination of linear thermal expansion coefficient
Trang 64
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom
Trang 71 Scope
This document specifies two methods to determine the linear thermal expansion coefficient of natural stone, respectively based on mechanical length-change measurements (Method A) or on the use of bonded electric strain gauges (Method B)
Not applicable
3 Principle
After drying to constant mass, the specimen is subjected to length measurement in a direction “i” whilst maintaining
at least two different temperatures The linear coefficient of thermal expansion between the extreme temperatures
is expressed as the unitary change in length for a change of temperature of 1 °C
4 Symbols
s20
l Initial length of the specimen at a temperature of (20 ± 0,5) °C in mm
s80
l Final length of the specimen at a temperature of (80 ± 0,5) °C in mm
( s80 s20)
∆ Change of length of the specimen in mm If ∆ lsis positive, represents an expansion If
negative, a shrinkage (Note 1)
r20
l Initial length of the reference sample at a temperature of (20 ± 0,5) °C in mm
r80
l Final length of the reference sample at a temperature of (80 ± 0,5) °C in mm
( r80 r20)
∆T (60 ± 1) °C, the change in the temperature from (20 ± 0,5) °C to (80 ± 0,5) °C
r
ε Unitary linear thermal expansion of the reference sample in 10-6 (mm/mm)
εsi
s20
s
l
l
∆
(mm/mm)
3
s
2
s
1
s , ε , ε
ε Unitary linear thermal expansion of the specimen along three orthogonal directions in
10-6 (mm/mm)
αr Linear coefficient of thermal expansion of the reference sample in °C-1
αi Linear coefficient of thermal expansion of the specimen in the direction "i" in °C-1
α1,α2, α3 Linear coefficients of thermal expansion of the specimen along three orthogonal
Trang 86
NOTE 1 Due to rock anisotropy, the coefficient of thermal expansion can change with the direction in which the measurement is carried out In some cases the coefficient of thermal expansion can be negative in some directions and positive
in other ones
evaluated, intermediate measurements at different temperature will need to be made and plotted on a graph
5 Apparatus
5.1 A ventilated oven capable of raising the temperature from (20 ± 0,2) °C to (80 ± 0,2) °C at a rate of 0,5 °C/min and maintaining temperatures within that range for at least two hours with an accuracy of at least
± 0,5 °C
5.2 (For Method A) A mechanical measuring device (dilatometer), with an accuracy of at least 1/100 000 of the measuring length (see Figure 1), any other device able to measure length-changes within the given accuracy (e.g electronic dilatometers)
5.3 (For Method B) A strain gauge measuring device, containing the following parts (see Figure 2):
5.3.1 Strain gauges suitable to be used within the foreseen temperature range
Strain gauge length should be at least 8 times the maximum grain size of the rock to be tested In the case of exceptionally large grains, this length could be 3 times the maximum grain size
5.3.2 A measuring device consisting of an electrical bridge (Wheatstone bridge) and a signal amplifier, with at
least four measuring channels The accuracy of the device shall be at least 5×10-6 (mm/mm)
Inner resistances in the electrical bridge shall be fixed to a granite rock or similar one for compensating temperatures
5.4 A calibrated reference sample, with a known coefficient of thermal expansion within test temperature range (20 to 80) °C
A reference sample could be made of different materials with low thermal expansion coefficient (invar steel, etc)
It shall have a length twice the length of strain gauges and a minimum cross section of 50 mm x 50 mm
5.5 A temperature measuring device (e.g a thermocouple) with an accuracy of at least 0,2 °C
Trang 9Key
1 test specimen
2 rivets bonded on the test specimen
3 measuring tips of the device, one is mobile
4 mechanical measuring device
5 temperature measuring device
Figure 1 — Example of a mechanical measuring device
Trang 108
Key
1 reference sample with a couple of bonded strain gauges
2 test specimen with three couples of bonded strain gauges
3 Wheatstone bridge control unit
A heating unit control
B data aquisition system
C terminal box
D fixed resistance
E heating unit
F temperature sensor
Figure 2 — Schematic test set-up of a strain-gauges measuring device
6 Preparation of the specimens
6.1 Sampling
The sampling is not the responsibility of the test laboratory, except when specially requested
The position of any bedding or anisotropy shall be marked on the sample or on each specimen by means of at least two parallel lines
For each direction, at least 2 specimens, shall be selected from an homogeneous batch The number of test specimens may need to be increased if the stone being tested is heterogeneous
should be measured in several directions in order to assess the degree of anisotropy
Production of microcraks during sampling or specimen preparation should be avoided
Trang 116.2 Test specimens
6.2.1 General
The test can be carried out as an identification test or as a technological test
Identification tests are carried out when the use of the stone with respect to the position of the planes of anisotropy and the thickness and the surface finish of the stone elements are not known
Technological tests are those carried out when the use of the stone with respect to the position of the planes of anisotropy and the thickness and surface finish of the stone elements are known In this case, the length of the specimens shall have the same orientation as the most relevant directions of the largest plane
6.2.2 Dimensions
The dimension of the test specimen shall be in accordance with the minimum size of the measuring length, which is related to the accuracy of the measuring device, and to the maximum grain size of the rock
Using mechanical measuring devices, specimens for identification test shall be rectangular prisms, with minimum
50 mm width, 20 mm thickness and 250 mm length (length shall be at least 10 times the largest rock grain size)
If strain gauge devices are used, specimens for identification test shall be cubes or rectangular prisms with minimum 70 mm length, thickness and width Each one of these dimensions shall be, at least, 10 times the largest rock grain size
For technological test, the thickness shall be equal to that of commercial units and, therefore, the specimen may be not thick enough as to enable thermal expansion determinations according to this dimension In this case, the test
is carried out only along the width and the length of the specimen
6.2.3 Fixing rivets or strain gauges
Specimen faces, where the rivets or the strain gauges will be fixed, shall be finished with 600 (FEPA) grain-size sand paper
Fixing adhesive to be used shall be stable within the test temperature range (20 to 80) °C
For identification tests using a mechanical device, two rivets are fixed at adequate distance (minimum 200 mm) along the longitudinal axe of each specimen
For identification tests using strain gauges, three pairs of gauges shall be fixed to each specimen, in three different perpendicular directions
Gauges in each pair shall be fixed in the same arrangement at opposite faces (see Figure 3)
Another pair of gauges shall be fixed at opposite faces of the reference sample
For technological tests, rivets and gauges direction will be lined up with the manufacturing directions
Trang 1210
1) three pairs of gauges fixed at opposite faces
Figure 3 — Arrangement of pairs of strain gauges in each specimen 6.2.4 Drying the specimens
For identification tests the specimens shall be dried at (70 + 5) °C to constant mass before fixing rivets or strain gauges Constant mass is assumed to have been attained when the difference between two weighings made at an interval of (24 + 2) h, is not greater than 0,1 % of the first of these two masses
Therefore it may be helpful in performing technological tests to use specimens in conditions other than dried
7.1 Method A
Place the specimens and the reference sample, each one equipped with a thermocouple and the bonded rivets for measuring, in a ventilated oven at a temperature of (20 ± 1) °C After stabilisation of the temperature of at least
±0,5 °C for at least 30 min, the specimens are retracted from the oven and their length is measured as quickly as possible The length and corresponding temperature of each specimen are registered This procedure is repeated when a temperature of (80 ± 1) °C is reached and stabilised within at least ± 0,5 °C for at least 30 min
Then the same procedure is used for decreasing temperature until the starting temperature of (20 ± 1) °C is reached At least two complete heating and cooling cycles shall be performed consecutively on each specimen to check for changes induced by heating
It is possible to test more specimens at the same time
cycles Then the data are plotted on a graph This procedure also allows the determination of thermal expansion coefficients within different temperature ranges
should be as stated in Clause 4
7.2 Method B
The specimen and the reference sample are introduced in the ventilated oven The oven shall be at a temperature
of (20 ± 1) °C for 2 h before testing
Connect the four gauge pairs (three for the specimen and one for the reference sample) to the measuring device