CEN/TS 17482:2020
(Main)Bitumen and bituminous binders - Determination of acid number of bitumen - Potentiometric method
Bitumen and bituminous binders - Determination of acid number of bitumen - Potentiometric method
This document describes a method for the determination of the free acidic constituents present in bitumen, conventionally known as acid number.
WARNING - The use of this document may involve hazardous materials, operations and equipment. This document does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.
Bitumen und bitumenhaltige Bindemittel - Bestimmung der Säurezahl von Bitumen - Potentiometrisches Verfahren
Dieses Dokument beschreibt ein Verfahren zur Bestimmung der in Bitumen enthaltenen freien sauren Bestandteile, gemeinhin als Säurezahl bekannt.
WARNUNG - Die Anwendung dieses Dokuments kann gefährliche Substanzen, Arbeitsgänge und Ausrüstung einschließen. Dieses Dokument erhebt nicht den Anspruch, auf alle Sicherheitsprobleme hinzuweisen, die mit seiner Anwendung verbunden sind. Es liegt in der Verantwortung des Anwenders dieses Dokuments, geeignete Sicherheits und Gesundheitsschutzmaßnahmen vorzusehen und im Vorfeld die Anwendbarkeit von einschränkenden Vorschriften zu klären.
Bitumes et liants bitumineux - Détermination de l'indice d'acide d’un bitume - Méthode potentiométrique
Le présent document spécifie une méthode de détermination des constituants acides libres présents dans un bitume, conventionnellement désignés sous le terme « indice d’acide ».
AVERTISSEMENT - L'utilisation de ce document implique l'intervention de produits, d'opérations et d'équipements à caractère dangereux. Le présent document n'est pas censé aborder tous les problèmes de sécurité concernés par son usage. Il est de la responsabilité de l'utilisateur de ce document de consulter et d'établir des règles de sécurité et d'hygiène appropriées et de déterminer l'applicabilité des restrictions réglementaires avant utilisation.
Bitumen in bitumenska veziva - Določevanje kislinskega števila bitumna - Potenciometrijska metoda
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-oktober-2020
Bitumen in bitumenska veziva - Določevanje kislinskega števila bitumna -
Potenciometrijska metoda
Bitumen and bituminous binders - Determination of acid number of bitumen -
Potentiometric method
Bitumen und bitumenhaltige Bindemittel - Bestimmung der Säurezahl von Bitumen -
Potentiometrisches Verfahren
Bitumes et liants bitumineux - Détermination de l'indice d'acide d’un bitume - Méthode
potentiométrique
Ta slovenski standard je istoveten z: CEN/TS 17482:2020
ICS:
75.140 Voski, bitumni in drugi naftni Waxes, bituminous materials
proizvodi and other petroleum products
91.100.50 Veziva. Tesnilni materiali Binders. Sealing materials
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
CEN/TS 17482
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
July 2020
TECHNISCHE SPEZIFIKATION
ICS 75.140; 91.100.50
English Version
Bitumen and bituminous binders - Determination of acid
number of bitumen - Potentiometric method
Bitumes et liants bitumineux - Détermination de Bitumen und bitumenhaltige Bindemittel -
l'indice d'acide d'un bitume - Méthode Bestimmung der Säurezahl von Bitumen -
potentiométrique Potentiometrisches Verfahren
This Technical Specification (CEN/TS) was approved by CEN on 1 June 2020 for provisional application.
The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.
CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.
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
© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 17482:2020 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 . 4
5 Products and reagents . 4
6 Apparatus . 5
7 Sampling . 5
8 General instructions. 6
8.1 Preparation of the potentiometry apparatus and electrodes . 6
8.2 Titration of the solution of alcoholic potassium hydroxide and blank test . 6
8.3 Operating procedure . 6
9 Operating procedure . 6
9.1 Titration of the solution of alcoholic potassium hydroxide and blank test . 6
9.2 Titration of the bitumen . 7
10 Calculations . 8
11 Expression of results . 8
12 Precision . 9
12.1 Repeatability . 9
12.2 Reproducibility . 9
13 Test report . 9
Annex A (informative) Method for using a manual titration apparatus . 10
A.1 General . 10
A.2 Operating procedure . 10
Bibliography . 13
European foreword
This document (CEN/TS 17482:2020) has been prepared by Technical Committee CEN/TC 336
“Bituminous binders”, the secretariat of which is held by AFNOR.
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.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: 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 describes a method for the determination of the free acidic constituents present in
bitumen, conventionally known as acid number.
WARNING — The use of this document may involve hazardous materials, operations and equipment. This
document does not purport to address all of the safety problems associated with its use. It is the
responsibility of the user of this document to establish appropriate safety and health practices and to
determine the applicability of regulatory limitations prior to use.
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 58, Bitumen and bituminous binders — Sampling bituminous binders
EN 12594, Bitumen and bituminous binders — Preparation of test samples
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 https://www.iso.org/obp
3.1
acid number
number of milligrams of potassium hydroxide necessary for the neutralization of the free acids contained
in one gram of bitumen
3.2
equivalence point
stage of the titration procedure at which the added volume (equivalent volume) of titration reagent has
allowed to neutralize the acid compounds of the test sample
Note 1 to entry: In potentiometric titrations, this point corresponds to the inflexion point of the potential curve.
4 Principle
The bitumen is dissolved in a solvent-alcohol mixture. The acidic constituents are titrated using a solution
of alcoholic potassium hydroxide. The titration is monitored by potentiometry.
5 Products and reagents
5.1 General
Only use reagents of a quality recognized for analysis.
5.2 Potassium hydroxide RP (analytical grade), in pellets.
5.3 Propan-2-ol (isopropanol) RP (analytical grade).
5.4 Solvent RP (analytical grade), xylene or methyl benzene (toluene).
5.5 Benzoic acid RP (analytical grade).
5.6 Solution of alcoholic potassium hydroxide, 0,1 mol/L.
Dissolve (6,0 ± 0,2) g of potassium hydroxide pellets (5.2) in 1 L of pure propan-2-ol (5.3).
A ready-for-use, off-the-shelf solution can also be used. Only a titration certificate coming from an
authorized supplier can avoid the titration procedure (9.1). The alcoholic potassium hydroxide solution
shall be kept in brown glass containers and stored in the dark.
6 Apparatus
6.1 General
Usual laboratory equipment, together with the following.
6.2 Balance of adequate capacity for weight with precision of ± 1 mg.
6.3 Potentiometry apparatus, for automatic or manual titration:
— apparatus for automatic titration, including a titration device with sensitivity of at least 2 mV,
equipped with an automatic dosage unit with a capacity of 5 mL to 20 mL. Most of these pieces of
equipment offer a program for potentiometric detection with dynamic equivalence point titration. It
means that increment is slowed down near the equivalence point;
— apparatus for manual titration, including a potentiometer with a sensitivity of at least 2 mV and a
burette with a pointed spout.
The equipment shall allow titration steps to be performed at an accuracy of at least ± 0,05 mL in volume.
6.4 Glass combination electrode – Ag/AgCl.
6.4.1 A pH glass electrode for non-aqueous media and a reference electrode of Ag/AgCl (kept in its
inner reference electrolyte).
6.4.2 Combined pH electrode for non-aqueous media instead of the two electrodes cell of 6.4.1.
6.5 Glass beakers, or any glass titration container, specific for the automatic potentiometric titration
device (6.3).
The volume of beakers shall be appropriate for immersing the membrane of electrodes into the tested
solution and shall allow increasing this volume during titration.
The level of solution in the beaker shall be below the filling hole of the electrodes but has to be high
enough to prevent the stirring bar (if it is necessary to use it) from hitting the membranes if the electrodes
have to be close to the bottom of the beaker.
6.6 Magnetic stirrer, with polytetrafluoroethylene (PTFE)-coated bar.
7 Sampling
Take the sample in accordance with EN 58. Prepare the test samples in accordance with EN 12594.
8 General instructions
8.1 Preparation of the potentiometry apparatus and electrodes
The titration device shall be prepared following manufacturer instructions.
Special attention shall be paid to the storing and maintenance of the electrodes:
— before using, the inner body shall be filled with the electrolyte. If necessary, refill and let the electrode
to rest for at least one hour immersed in the reference electrolyte;
— before each titration, let the electrode to rest for at least 5 min immersed in the reference electrolyte;
— when the test is finished, the electrodes shall be cleaned with the solvent (5.4), then rinsed with
water, and finally stored according to the recommendations of the supplier.
8.2 Titration of the solution of alcoholic potassium hydroxide and blank test
The solution of alcoholic potassium hydroxide used is to be titrated in accordance with the procedure
described in 9.1 before starting the titration of bitumen. This titration can only be avoided when using a
certified ready to use solution (5.6). In any case, it is recommended to titrate the solutions when they are
used after storage and to verify this titration on a weekly basis.
The blank test (9.1) is to be done on a daily basis on the same solvent and propan-2-ol samples as those
used for the titration of bitumen.
8.3 Operating procedure
This document concerns the preferential use of an apparatus for automatic titration. In the case of use of
an apparatus for manual titration, the method described in Annex A can be referred to, as a replacement
to 9.1.4 to 9.1.6 and 9.2.5 to 9.2.7 in this document.
The titration procedure described in 9.1.6, 9.2.7 and Annex A considers the usual case where the potential
curve presents a single inflexion point (equivalence point). The possible presence of several acid
compounds with different strengths could however lead to the existence of more than one equivalence
point. To be sure that total neutralization has been achieved, titration shall therefore be contin
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