SIST EN 196-10:2016
(Main)Methods of testing cement - Part 10: Determination of the water-soluble chromium (VI) content of cement
Methods of testing cement - Part 10: Determination of the water-soluble chromium (VI) content of cement
This part of EN 196 specifies the method for the determination of the water-soluble chromium (VI) content of cement.
A reference method is described consisting of two stages, an extraction procedure and an analysis of the filtered extract. Guidance on other extraction procedures, suitable for screening tests, for factory production control or other purposes, is given but in case of dispute or failure to comply with a regulatory limit only the reference method is used. The reference method has alternatives whereby the filtered extract may be subjected to an oxidation step or not. The criteria by which the appropriate procedure is selected are set down. Other instrumental procedures may be used for the analysis of the filtered extract provided they are calibrated against the analysis of the filtered extract using the reference procedure. In the case of a dispute, only the reference method is used.
Annex A sets out a normative procedure to be followed in case this test method is used as the basis for evaluation of conformity of a cement with the regulatory limit in Regulation (EC) No. 1907/2006.
This part of EN 196 describes a method that applies to cements. It may have wider applicability but this would need to be verified by testing on a product-by-product basis. Guidance in the possible application of this European Standard to the determination of the water-soluble chromium (VI) content of cement-containing preparations is given in Annex B.
Annexes C and D provide information on other test procedures based on paste extraction and thus depart from the performance of cement in its normal conditions of use. They may be carried out with or without the oxidation process. Users should be aware that results using these methods might be significantly different to those obtained by the reference method. In the case of dispute or failure to comply with the regulatory limit only the reference method is used.
Annex E provides guidance on a method for determination of the excess reducing agent content of cement as used in the factory internal control system of some countries. Manufacturers using such an internal control method should assure themselves of the relevance of results in comparison with testing by the reference method.
Prüfverfahren für Zement - Teil 10: Bestimmung des Gehaltes an wasserlöslichem Chrom (VI) in Zement
Dieser Teil von EN 196 legt das Verfahren zur Bestimmung des Gehaltes an wasserlöslichem Chrom(VI) in Zement fest.
Es wird ein Referenzverfahren beschrieben, das aus zwei Schritten, d. h. aus einem Extraktionsverfahren und einer Analyse des abfiltrierten Extraktes, besteht. Hinweise zu anderen Extraktionsverfahren, die für Eignungsprüfungen, die werkseigene Produktionskontrolle und andere Zwecke geeignet sind, sind angegeben; in Streitfällen oder bei Überschreitung eines gesetzlich vorgeschriebenen Grenzwertes wird nur das Referenzverfahren angewendet. Das Referenzverfahren enthält alternative Verfahrensschritte, nach denen der filtrierte Extrakt wahlweise einem Oxidationsschritt unterzogen werden darf. Die Kriterien für die Wahl der geeigneten Vorgehensweise sind festgelegt. Andere instrumentelle Verfahren dürfen zur Analyse des abfiltrierten Extraktes verwendet werden, vorausgesetzt, dass sie gegen die Analyse des gefilterten Extraktes mit dem Referenzverfahren kalibriert sind. Im Streitfall wird nur das Referenzverfahren angewendet.
In Anhang A wird ein normatives Verfahren festgelegt, das bei Anwendung dieses Prüfverfahrens als Grundlage für die Bewertung der Übereinstimmung eines Zementes mit dem in der Verordnung (EG) Nr. 1907/2006 angegebenen Grenzwert anzuwenden ist.
Das in diesem Teil von EN 196 beschriebene Verfahren gilt für Zemente. Die Anwendung auf andere Stoffe ist möglich; die Anwendbarkeit müsste jedoch im Einzelfall verifiziert werden. Anhang B enthält Hinweise zur Anwendung dieser Europäischen Norm zur Bestimmung des Gehaltes an wasserlöslichem Chrom(VI) in zementhaltigen Zubereitungen.
Die Anhänge C und D enthalten Angaben zu anderen Prüfverfahren, die auf der Extraktion von Zementleim beruhen und daher von dem Verhalten von Zement unter den üblichen Gebrauchsbedingungen abweichen. Diese Prüfverfahren dürfen mit oder ohne Oxidationsschritt durchgeführt werden. Die Anwender dieser Verfahren sollten sich dessen bewusst sein, dass die mit diesen Verfahren erzielten Ergebnisse sich erheblich von den Ergebnissen mit dem Referenzverfahren unterscheiden können. In Streitfällen oder bei Überschreitung des gesetzlich vorgeschriebenen Grenzwertes wird nur das Referenzverfahren angewendet.
Anhang E enthält Hinweise zu einem Verfahren zur Bestimmung des überschüssigen Reduktions¬mittelgehaltes von Zement, welches in einigen Ländern für die werkseigene Produktionskontrolle Anwendung findet. Hersteller, die ein derartiges System für die werkseigene Produktionskontrolle einsetzen, sollten sich der Verwendbarkeit der Ergebnisse durch Vergleich mit der Analyse nach dem Referenzverfahren vergewissern.
Méthodes d'essais des ciments - Partie 10 : Détermination de la teneur en chrome (VI) soluble dans l'eau des ciments
La présente partie de l’EN 196 décrit une méthode permettant la détermination de la teneur en chrome (VI) soluble dans l’eau des ciments.
La méthode de référence décrite comprend deux étapes : un mode opératoire d’extraction et une analyse de l’extrait filtré. Des lignes directrices relatives à d’autres modes opératoires d’extraction convenant pour les essais de screening, pour le contrôle de la production en usine ou à d’autres fins sont fournies, mais en cas de désaccord ou d’incapacité à satisfaire une limite réglementaire, seule la méthode de référence est utilisée. La méthode de référence offre deux possibilités, l’extrait filtré pouvant être soumis à une étape d’oxydation ou non. Les critères de sélection du mode opératoire approprié sont présentés. D’autres modes opératoires instrumentaux peuvent être utilisés pour l’analyse de l’extrait filtré à condition d’être étalonnés par rapport à l’analyse de l’extrait filtré utilisant le mode opératoire de référence. En cas de litige, seule la méthode de référence est utilisée.
L’Annexe A présente un mode opératoire normatif à suivre en cas d’utilisation de la présente méthode d’essai comme base pour l’évaluation de conformité d’un ciment à la limite réglementaire fixée par le règlement (CE) N° 1907/2006 .
La présente partie de l’EN 196 décrit une méthode qui s’applique aux ciments. Son applicabilité peut être plus large, mais des essais au cas par cas sont nécessaires pour le vérifier. L’Annexe B donne des lignes directrices sur l’application de la présente Norme européenne à la détermination de la teneur en chrome (VI) soluble dans l’eau des préparations de ciment.
Les Annexes C et D fournissent des informations concernant d’autres modes opératoires d’essai s’appuyant sur l’extraction à partir d’une pâte et s’écartent donc des performances du ciment dans ses conditions normales d’utilisation. Ils peuvent être réalisés avec ou sans le processus d’oxydation. Il convient que les utilisateurs soient conscients que les résultats obtenus par ces méthodes peuvent être très différents de ceux obtenus par la méthode de référence. En cas de désaccord ou d’incapacité à satisfaire une limite réglementaire, seule la méthode de référence est utilisée.
L’Annexe E fournit des lignes directrices concernant une méthode de détermination de la teneur en agent réducteur excédentaire du ciment telle qu’elle est utilisée dans le système de contrôle interne en usine de certains pays. Il convient que les fabricants utilisant une telle méthode de contrôle interne s’assurent de la pertinence des résultats par rapport aux essais par la méthode de référence.
Metode preskušanja cementa - 10. del: Določevanje vodotopnega kroma (VI) v cementu
Ta del standarda EN 196 določa metodo za ugotavljanje vodotopnega kroma (VI) v cementu.
Opisana je referenčna metoda, sestavljena iz dveh stopenj – postopka izločanja in analize filtriranega izvlečka. Podana so navodila glede drugih postopkov izločanja, ki so primerni za presejalne preskuse, kontrolo proizvodnje v obratu ali druge namene, vendar se v primeru spora ali neizpolnjevanja predpisane omejitve uporabi le referenčna metoda. Za referenčno metodo obstajajo alternativne možnosti, pri čemer je filtrirani izvleček lahko izpostavljen oksidaciji ali pa ne. Opredeljena so merila, po katerih se izbere ustrezen postopek. Za analizo filtriranega izvlečka se lahko uporabljajo drugi instrumentalni postopki, če so umerjeni glede na analizo filtriranega izvlečka z uporabo referenčnega postopka. V primeru spora se uporabi le referenčna metoda.
Dodatek A opredeljuje normativni postopek, ki ga je treba upoštevati, če se ta preskusna metoda uporablja kot osnova za vrednotenje skladnosti cementa s predpisano omejitvijo v Uredbi (ES) št. 1907/2006.
Ta del standarda EN 196 opisuje metodo, ki se uporablja za cement. Ima lahko široko uporabnost, vendar bi bilo treba to preveriti s preskušanjem vsakega izdelka posebej. Navodila o možni uporabi tega evropskega standarda za ugotavljanje vodotopnega kroma (VI) v cementnih pripravkih so podana v dodatku B.
Dodatka C in D vsebujeta informacije o drugih preskusnih metodah, ki temeljijo na izločevanju paste in se tako odmikajo od zmogljivosti cementa v običajnih pogojih njegove uporabe. Izvedene so lahko s postopkom oksidacije ali brez njega. Uporabniki naj bi se zavedali, da se lahko rezultati, pridobljeni z uporabo teh metod, precej razlikujejo od tistih, ki so pridobljeni z referenčno metodo. V primeru spora ali neizpolnjevanja predpisane omejitve se uporabi le referenčna metoda.
Dodatek E vsebuje navodila o metodi za ugotavljanje prekomerne vsebnosti reducentov v cementu, kot se uporablja v sistemu notranje kontrole proizvodnje v nekaterih državah. Proizvajalci, ki uporabljajo takšno metodo notranje kontrole, naj bi se prepričali o ustreznosti njenih rezultatov v primerjavi s preskušanjem z referenčno metodo.
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.FHPHQWXPrüfverfahren für Zement - Teil 10: Bestimmung des Gehaltes an wasserlöslichem Chrom (VI) in ZementMéthodes d'essais des ciments - Partie 10 : Détermination de la teneur en chrome (VI) soluble dans l'eau des cimentsMethods of testing cement - Part 10: Determination of the water-soluble chromium (VI) content of cement91.100.10Cement. Mavec. Apno. MaltaCement. Gypsum. Lime. MortarICS:Ta slovenski standard je istoveten z:EN 196-10:2016SIST EN 196-10:2016en,fr,de01-julij-2016SIST EN 196-10:2016SLOVENSKI
STANDARDSIST EN 196-10:20061DGRPHãþD
SIST EN 196-10:2016
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 196-10
May
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{ sä s r rä s r Supersedes EN
s { xæ s rã t r r xEnglish Version
Methods of testing cement æ Part
s rã Determination of the Méthodes d 5essais des ciments æ Partie
s r ã dans l 5eau des ciments
Prüfverfahren für Zement æ Teil
s rã Bestimmung des This European Standard was approved by CEN on
t r December
t r s wä
egulations which stipulate the conditions for giving this European Standard the status of a national standard without any alterationä Upætoædate lists and bibliographical references concerning such national standards may be obtained on application to the CENæCENELEC Management Centre or to any CEN memberä
translation under the responsibility of a CEN member into its own language and notified to the CENæCENELEC Management Centre has the same status as the official versionsä
CEN members are the national standards bodies of Austriaá Belgiumá Bulgariaá Croatiaá Cyprusá Czech Republicá Denmarká Estoniaá Finlandá Former Yugoslav Republic of Macedoniaá Franceá Germanyá Greeceá Hungaryá Icelandá Irelandá Italyá Latviaá Lithuaniaá Luxembourgá Maltaá Netherlandsá Norwayá Polandá Portugalá Romaniaá Slovakiaá Sloveniaá Spainá Swedená Switzerlandá Turkey andUnited Kingdomä
EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
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9
t r s x CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Membersä Refä Noä EN
s { xæ s rã t r s x ESIST EN 196-10:2016
EN 196-10:2016 (E) 2 Contents Page European foreword . 3 Introduction . 4 1 Scope . 5 2 Normative references . 5 3 General requirements for testing . 6 3.1 Number of tests . 6 3.2 Repeatability and reproducibility . 6 3.3 Expression of masses, volumes, factors and results . 6 3.4 Blank determinations . 6 4 Reagents . 6 5 Apparatus . 7 6 Preparation of a test sample of cement. 8 7 Extraction procedure . 9 7.1 Principle . 9 7.2 Preparation of mortar . 9 7.3 Filtration . 10 8 Determination of chromium (VI) . 10 8.1 General . 10 8.2 Measurement of absorbance without oxidation . 10 8.3 Measurement of absorbance with oxidation . 11 9 Calculation and expression of results . 12 9.1 Calculation . 12 9.2 Expression of results . 13 10 Reporting of results . 13 11 Repeatability and reproducibility . 13 Annex A (normative)
Evaluation of the compliance of cement with the regulatory limit in 47 to Annex XVII of Regulation (EC) No. 1907/2006 on water-soluble hexavalent chromium content . 14 Annex B (informative)
Guidance on the application of this European Standard to the determination of the water soluble chromium (VI) content of cement-containing preparations . 24 Annex C (informative)
Guidance on screening test method (1) using paste extraction - method based on DS 1020 . 26 Annex D (informative)
Guidance on screening test method (2) using paste extraction – method based on TRGS 613 . 29 Annex E (informative)
Guidance on the photometric determination of chromium reduction capacity in cements . 33 Bibliography . 37
SIST EN 196-10:2016
EN 196-10:2016 (E) 3 European foreword This document (EN 196-10:2016) has been prepared by Technical Committee CEN/TC 51 “Cement and building limes”, the secretariat of which is held by NBN. 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 November 2016, and conflicting national standards shall be withdrawn at the latest by November 2016. 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 196-10:2006. In comparison to EN 196-10:2006, the following changes have been made: — In Clause 2, the normative references have been updated; —
The standard has been editorially revised. EN 196 consists of the following parts, under the general title Methods of testing cement: — Part 1: Determination of strength; — Part 2: Chemical analysis of cement; — Part 3: Determination of setting times and soundness; — Part 4: Quantitative determination of constituents (CEN/TR 196-4); — Part 5: Pozzolanicity test for pozzolanic cement; — Part 6: Determination of fineness; — Part 7: Methods of taking and preparing samples of cement; — Part 8: Heat of hydration - Solution method; — Part 9: Heat of hydration - Semi-adiabatic method; — Part 10: Determination of the water-soluble chromium (VI) content of cement. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 196-10:2016
EN 196-10:2016 (E) 4 Introduction This European Standard specifies the reference method for the determination of water-soluble chromium (VI) content of cement that consists of two stages, an extraction procedure and an analysis of the filtered extract. This European Standard test method has adopted the principle that extraction is carried out under conditions approximating as closely as possible to those during the commercial use of cement. Consequently extraction is by standard mortar and subsequent filtration. Other extraction procedures based on paste extraction have traditionally been used and are included in Annexes C and D for use as screening tests, in factory production control or laboratories not having access to equipment specified in EN 196-1 for the production of mortar. The use of paste extraction is outside the normal conditions of use of cement. This European Standard test method has adopted the principle of analysis by spectrophotometry. The procedures set down generally permit the analysis to be carried out without the need for an oxidation step. On rare occasions some cements may contain reducing species, not controlled by the routine method, that interfere with the analysis and require an oxidation step. Inter-laboratory testing has demonstrated that it is necessary to include an ‘initial assessment test’ in order to observe the effects on the analysis. By comparing the results obtained from the method with and without the oxidation step, it can be determined whether, for that cement, the reference method should include the oxidation step. Other instrumental procedures may be used for the analysis of the filtered extract provided they are calibrated against the analysis of the filtered extract using the reference procedure. In case of dispute or failure to comply with a regulatory limit only the reference method shall be used. This European Standard test method has drawn heavily on the Danish Standard DS 1020 and the extraction procedure developed by the French cement industry association ATILH. Careful consideration has been given to the details of the German TRGS 613 method developed by Germany’s Hazardous Materials Committee in support of Industrial Regulations for Hazardous Materials. Notice was also taken of the British Cement Association ‘inherent colour’ method; the draft method produced by CEN/TC 193/WG1, reference N680, for cement-based adhesives; European Standard method EN 420 for protective gloves; and to the method, reference ID-215, developed by the Occupational Safety and Health Administration, Salt Lake City, UT, USA. The USA Portland Cement Association, Research and Development report Serial No. 2554 “Review and evaluation of analytical methods for the determination of hexavalent chromium in hydraulic cements and clinker” by Waldemar A. Klemm was found to be most helpful in resolving technical issues. CEN/TR 14589 confirmed that chromium species and solubilities are sensitive to pH and redox conditions and care has been taken to address these in this European Standard by controlling sample exposure to air, by adding the indicator to the alkaline filtered extract and by precisely specifying the pH for the analytical procedure. This European Standard test method was developed in order to provide a reference test method for use in the evaluation of compliance of cement with the requirements in entry 47 to Annex XVII of Regulation (EC) 1907/20061 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). A system for the evaluation of compliance of cement is set out in Annex A.
1 Note that Regulation (EC) No 1907/2006 is impacted by Commission Regulation (EU) No 126/2013 of 13 February 2013 amending Annex XVII to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). SIST EN 196-10:2016
EN 196-10:2016 (E) 5 1 Scope This part of EN 196 specifies the method for the determination of the water-soluble chromium (VI) content of cement. A reference method is described consisting of two stages, an extraction procedure and an analysis of the filtered extract. Guidance on other extraction procedures, suitable for screening tests, for factory production control or other purposes, is given but in case of dispute or failure to comply with a regulatory limit only the reference method is used. The reference method has alternatives whereby the filtered extract may be subjected to an oxidation step or not. The criteria by which the appropriate procedure is selected are set down. Other instrumental procedures may be used for the analysis of the filtered extract provided they are calibrated against the analysis of the filtered extract using the reference procedure. In the case of a dispute, only the reference method is used. Annex A sets out a normative procedure to be followed in case this test method is used as the basis for evaluation of conformity of a cement with the regulatory limit in Regulation (EC) 1907/20062. This part of EN 196 describes a method that applies to cements. It may have wider applicability but this would need to be verified by testing on a product-by-product basis. Guidance in the possible application of this European Standard to the determination of the water-soluble chromium (VI) content of cement-containing preparations is given in Annex B. Annexes C and D provide information on other test procedures based on paste extraction and thus depart from the performance of cement in its normal conditions of use. They may be carried out with or without the oxidation process. Users should be aware that results using these methods might be significantly different to those obtained by the reference method. In the case of dispute or failure to comply with the regulatory limit only the reference method is used. Annex E provides guidance on a method for determination of the excess reducing agent content of cement as used in the factory internal control system of some countries. Manufacturers using such an internal control method should ensure themselves of the relevance of results in comparison with testing by the reference method. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 196-1, Methods of testing cement - Part 1: Determination of strength EN 196-7, Methods of testing cement - Part 7: Methods of taking and preparing samples of cement EN ISO/IEC 17020, Conformity assessment - Requirements for the operation of various types of bodies performing inspection (ISO/IEC 17020) EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025) EN ISO/IEC 17065, Conformity assessment - Requirements for bodies certifying products, processes and services (ISO/IEC 17065)
2 Note that Regulation (EC) No 1907/2006 is impacted by Commission Regulation (EU) No 126/2013 of 13 February 2013 amending Annex XVII to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). SIST EN 196-10:2016
EN 196-10:2016 (E) 6 3 General requirements for testing 3.1 Number of tests Determination of water-soluble chromium (VI) content of cement, where the determination is not part of a series subject to statistical control, shall be carried out in duplicate. Where the determination is one of a series subject to statistical control, a single test shall be the minimum required. In the case of a dispute, the number of tests shall be two (see also 3.3). 3.2 Repeatability and reproducibility Repeatability - precision under repeatability conditions where independent test results are obtained with the same method on identical test items (material) in the same laboratory by the same operator using the same equipment within short intervals of time. Reproducibility - precision under reproducibility conditions where test results are obtained with the same method on identical test items (material) in different laboratories with different operators using different equipment. Repeatability and reproducibility in this European Standard are expressed as repeatability standard deviation and reproducibility standard deviation in percent by mass. 3.3 Expression of masses, volumes, factors and results Express masses in the extraction stage in grams to the nearest 0,1 g. Express masses in the analytical stage in grams to the nearest 0,000 1 g and volumes from burettes in millilitres to the nearest 0,05 ml unless otherwise specified. Express the calculated results, where a single test result has been obtained, as a percentage of the cement as received. Express the calculated results, where two test results have been obtained, as the mean of the results, as a percentage of the cement as received. If the two test results differ by more than twice the standard deviation of repeatability, repeat the test and take the mean of the two closest test results. Express the reported water-soluble chromium (VI) content as a percentage of the cement as received, to four decimal places. Where the results of determinations with and without oxidation are to be compared results shall be considered equivalent if they do not differ by more than twice the standard deviation of repeatability. The results of all individual tests shall be recorded. 3.4 Blank determinations Carry out a blank determination without a sample following the same procedure and using the same amounts of reagents. Correct the results obtained for the analytical determination accordingly. 4 Reagents Use only reagents of analytical quality. References to water mean distilled or deionized water with electrical conductivity
¶ 0,5 mS/m. Unless otherwise stated percent means percent by mass. SIST EN 196-10:2016
EN 196-10:2016 (E) 7 Unless otherwise stated the densities of concentrated liquid reagents used in this European Standard 3 at 20 °C. 4.1 Concentrated hydrochloric acid (HCl) = 1,18 to 1,19. 4.2 Dilute hydrochloric acid, 1,0 mol/l. 4.3 Dilute hydrochloric acid, 0,04 mol/l. 4.4 Acetone, (CH3.CO.CH3 = 0,79. 4.5 Indicator solution. Dissolve 0,125 g of s-diphenylcarbazide (C6H5NHNH)2CO,
(1,5-diphenylcarbohydrazide) in 25 ml of acetone (4.4) in a 50 ml volumetric flask. Make up to the mark with acetone. The indicator solution will keep for one week, if kept refrigerated. 4.6 Standard chromate solution. 4.6.1 Stock solution: Dissolve 0,141 4 g dried potassium dichromate (K2Cr2O7), dried to constant mass at (140 ± 5) °C, in water in a 1 000 ml volumetric flask and make up to the mark with water. The stock solution will keep for one month. This solution contains 50 mg Cr (VI) in a litre. NOTE Ready-to-use stock solution is commercially available. 4.6.2 Standard solution: Transfer 50,0 ml stock solution (4.6.1) to a 500 ml volumetric flask and make up to the mark with water. This solution contains 5 mg Cr (VI) in a litre. The standard solution will keep for one month. 4.7 CEN standard sand, in accordance with EN 196-1. 4.8 Sodium peroxodisulfate (sodium persulfate), Na2S2O8. 4.9 Orthophosphoric acid, H3PO4, (85 %). 5 Apparatus 5.1 Balance(s), analytical balance, capable of weighing to an accuracy of ± 0,000 5 g, and a laboratory balance, capable of weighing to an accuracy of ± 1 g. 5.2 Mixer, two speed in accordance with EN 196-1. 5.3 Spectrophotometer, for measuring the absorbance of a solution at 540 nm, or filter photometer equipped with a filter giving maximum transmission at approximately 540 nm. 5.4 Cells, with a light path of 10 mm. 5.5 Volumetric glassware, 50 ml, 500 ml and 1 000 ml volumetric flasks; 1,0 ml; 2,0 ml; 5,0 ml; 10,0 ml; 15,0 ml and 50,0 ml pipettes. 5.6 pH meter, capable of measuring pH to an accuracy of ± 0,05. 5.7 Filtration system, comprising a vacuum source connected to a vacuum flask fitted with a filter crucible, Buchner funnel or other suitable equipment. SIST EN 196-10:2016
EN 196-10:2016 (E) 8 5.8 Filter media, of pore size 7 glass fibre, free from organic binders, or equivalent fritted glass filter. Different filter media may be used provided that they have been shown to give chromium (VI) results which do not differ from those obtained using the reference filter media. Some filter media may become contaminated during manufacture with substances that can reduce chromium (VI). A blank test should be carried out to ensure the suitability of the filter medium selected. 5.9 Filtration equipment.
Key 1 mortar 2 filter funnel 3 to vacuum 4 low form beaker 5 filter flask 6 sand Figure 1 — Typical arrangement of filtration equipment Filtration equipment consisting of a Buchner funnel, (e.g. diameter 205 mm, fitted onto a 2 l filter flask), partially full of sand, inside which is a low form beaker to collect the filtrate, placed on top of the bed of sand. The apparatus is connected to a vacuum pump (see Figure 1). Also other arrangements ensuring filtrate collection into containers may be used. 5.10 Laboratory oven, capable of maintaining a temperature of (140 ± 5) °C. 5.11 Heating plate, capable of maintaining a temperature of (280 ± 10) °C. 5.12 Timer, capable of measuring to an accuracy of ± 1 s. 6 Preparation of a test sample of cement Immediately before chemical analysis, treat the laboratory sample, taken in accordance with EN 196-7, as follows to obtain a homogeneous test sample. Take approximately 1 000 g of the laboratory sample by means of a sample divider or by quartering. SIST EN 196-10:2016
EN 196-10:2016 (E) 9 Transfer this test sample to a clean dry container with an airtight closure and shake vigorously to mix it thoroughly. Carry out all operations as quickly as possible and immediately seal in an airtight. container to ensure that the test sample is exposed to ambient air only for the minimum time. 7 Extraction procedure 7.1 Principle Cement is made into a mortar using CEN standard sand and water. The mortar is mixed for a specified time and then filtered. An aliquot of filtrate is treated with s-diphenylcarbazide and acidified within a narrow range of pH. Chromium (VI) in acid solution forms a red-violet complex the absorption of which is measured spectrophotometrically at 540 nm. The water-soluble chromium (VI) content is determined from a calibration curve. 7.2 Preparation of mortar 7.2.1 Composition of mortar The proportions by mass shall be one part of cement (see Clause 6), three parts of CEN standard sand (4.7), and one half part of water (Clause 4) (i.e. water/cement ratio 0,50). NOTE The water to be used is analytical grade (see Clause 4) Each batch shall consist of (450 ± 2) g of cement, (M), (1 350 ± 5) g of sand and (225 ± 1) g of water, (V1). Where cements to be tested are rapid setting, a water/cement ratio of 0,50 may not yield sufficient filtrate for analysis. In these cases, it is permissible to increase the water content, and hence the water/cement ratio, until sufficient filtrate (see 7.3) is obtained. This deviation should be reported. 7.2.2 Mixing of mortar Weigh the cement and water by means of the laboratory balance (5.1). When water is added by volume it shall be dispensed with an accuracy of ± 1 ml. Mix each batch of mortar mechanically using the mixer (5.2). The timing of the various mixing stages refers to the times at which mixer power is switched on/off and shall be maintained within ± 2 s. The mixing procedure shall be as follows: — place the water and the cement into the bowl, taking care to avoid loss of water or cement; — immediately the water and cement are brought into contact start the mixer at the low speed (see EN 196-1, table of mixer speeds) while starting the timing of the mixing stages. After 30 s of mixing, add the sand steadily during the next 30 s. Switch the mixer to the high speed (see EN 196-1, table of mixer speeds) and continue the mixing for an additional 30 s; — stop the mixer for 90 s. During the first 30 s, remove by means of a rubber or plastics scraper the mortar adhering to the wall and bottom part of the bowl and place in the middle of the bowl; — continue the mixing at the high speed for 60 s. Normally these mixing operations are carried out automatically. Manual control of these operations and timings may be used. SIST EN 196-10:2016
EN 196-10:2016 (E) 10 7.3 Filtration Ensure that the filtration equipment (filter flask, filter crucible or Buchner funnel and filter medium and low form beaker) is dry before each use. Fit the filter crucible or Buchner funnel (5.7) and filter medium (5.8). Do not pre-wet the filter medium. Apply the vacuum and place the mortar into the filtration equipment. Filter for a maximum of 10 min to obtain a volume of 10 ml to 15 ml of filtrate. If 10 ml is not obtained in this time, continue filtering to obtain sufficient quantity to carry out the determination(s). Report this deviation. The filtrate may be stored for up to 8 h before determination of the chromium (VI) content but if the storage period exceeds 30 min it shall be kept in a sealed air-tight container to prevent evaporation. Where a filtrate has a turbidity that cannot be removed by simple filtration, it may be filtered by centrifuge, filter press or filtered over a fine-pore membrane filter. Report the alternative filtration method used. No verification against the reference method is required in these cases. Where the filtrate still has turbidity the blank used with these samples should be a filtrate from the respective sample but without the addition of indicator solution. 8 Determination of chromium (VI) 8.1 General Results of inter-laboratory testing have indicated the importance of following the precise operations, their sequence and the timings in order to obtain the quoted values for repeatability and reproducibility. Some constituents of cement, other than chromium reducing agents purposely added, can contain reducing substances (e.g. sulfide, sulfite) that can, during the determination of soluble chromium (VI) using diphenylcarbazide in acidic conditions, lead to an artificial decrease in the amount of chromium (VI) determined. Addition of diphenylcarbazide while the solution is alkaline should suppress the effect of sulfide but may not suppress other reducing substances. It is necessary to carry out the determination with and without treatment by an oxidising agent initially, in order to observe the effects on the results in accordance with 8.3 and 8.2, respectively. Results shall be assessed as follows: a) if the difference between the results of the two determinations, each carried out in duplicate, is not more than 2 × Sr (i.e. 2 × 0,000 015 %) (see 3.3) then the results are deemed to belong to the same population and the method without the oxidation step can be used for subsequent tests on the cement; b) if the difference between the results of the two determinations, each carried out in duplicate, is greater than 2 × Sr (i.e. 2 × 0,000 015 %) then the results are deemed to belong to different populations and the method (with respect to oxidation/without oxidation) giving the higher result shall then be used for subsequent tests on the cement. 8.2 Measurement of absorbance without oxidation 8.2.1 Construction of the calibration curve Transfer 1,0 ml; 2,0 ml; 5,0 ml; 10,0 ml; and 15,0 ml of standard solution (4.6.2) to 50 ml volumetric flasks. Add 5,0 ml indicator solution (4.5) and 5 ml of 0,04 mol/l hydrochloric acid (4.3). Make up to the mark with water. SIST EN 196-10:2016
EN 196-10:2016 (E) 11 The calibration solutions contain respectively 0,1 mg; 0,2 mg; 0,5 mg; 1,0 mg and 1,5 mg Cr (VI) in a litre. Measure the absorbance values against the procedural blank (3.4) at 540 nm, 15 min to 20 min after addition of the indicator solution. Construct the calibration curve by plotting the measured absorbance values
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.FHPHQWXPrüfverfahren für Zement - Teil 10: Bestimmung des Gehaltes an wasserlöslichem Chrom (VI) in ZementMethods of testing cement - Part 10: Determination of the water-soluble chromium (VI) content of cement91.100.10Cement. Mavec. Apno. MaltaCement. Gypsum. Lime. MortarICS:Ta slovenski standard je istoveten z:FprEN 196-10kSIST FprEN 196-10:2015en,fr,de01-september-2015kSIST FprEN 196-10:2015SLOVENSKI
STANDARD
kSIST FprEN 196-10:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
FINAL DRAFT
FprEN 196-10
June 2015 ICS 91.100.10 Will supersede EN 196-10:2006English Version
Methods of testing cement - Part 10: Determination of the water-soluble chromium (VI) content of cement
Prüfverfahren für Zement - Teil 10: Bestimmung des Gehaltes an wasserlöslichem Chrom (VI) in Zement This draft European Standard is submitted to CEN members for unique acceptance procedure. It has been drawn up by the Technical Committee CEN/TC 51.
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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, 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
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Avenue Marnix 17,
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FprEN 196-10:2015 (E) 2 Contents Page
Foreword .3 Introduction .4 1 Scope .5 2 Normative references .5 3 General requirements for testing .6 3.1 Number of tests .6 3.2 Repeatability and reproducibility .6 3.3 Expression of masses, volumes, factors and results .6 3.4 Blank determinations .6 4 Reagents .7 5 Apparatus .7 6 Preparation of a test sample of cement .8 7 Extraction procedure .9 7.1 Principle .9 7.2 Preparation of mortar .9 7.3 Filtration . 10 8 Determination of chromium (VI) . 10 8.1 General . 10 8.2 Measurement of absorbance without oxidation . 10 8.3 Measurement of absorbance with oxidation . 11 9 Calculation and expression of results . 12 9.1 Calculation . 12 9.2 Expression of results . 12 10 Reporting of results . 13 11 Repeatability and reproducibility . 13 Annex A (normative)
Evaluation of the compliance of cement with the regulatory limit in entry 47 to Annex XVII of Regulation (EC) No. 1907/2006 on water-soluble hexavalent chromium content . 14 Annex B (informative)
Guidance on the application of this European Standard to the determination of the water soluble chromium (VI) content of cement-containing preparations . 24 Annex C (informative)
Guidance on screening test method (1) using paste extraction - method based on DS 1020 . 26 Annex D (informative)
Guidance on screening test method (2) using paste extraction – method based on TRGS 613 . 29 Annex E (informative)
Guidance on the photometric determination of chromium reduction capacity in cements . 32 Bibliography . 36
kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 3 Foreword This document (FprEN 196-10:2015) has been prepared by Technical Committee CEN/TC 51 “Cement and building limes”, the secretariat of which is held by IBN. This document is currently submitted to the Unique Acceptance Procedure. This document supersedes EN 196-10:2006. In comparison to EN 196-10:2006, the following changes have been made: — In Clause 2, the normative references have been updated; —
The standard has been editorially revised. EN 196 consists of the following parts, under the general title Methods of testing cement: — Part 1: Determination of strength; — Part 2: Chemical analysis of cement; — Part 3: Determination of setting times and soundness; — Part 4: Quantitative determination of constituents (CEN/TR 196-4) ; — Part 5: Pozzolanicity test for pozzolanic cement; — Part 6: Determination of fineness; — Part 7: Methods of taking and preparing samples of cement; — Part 8: Heat of hydration - Solution method; — Part 9: Heat of hydration - Semi-adiabatic method; — Part 10: Determination of the water-soluble chromium (VI) content of cement. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 4 Introduction This European Standard specifies the reference method for the determination of water-soluble chromium (VI) content of cement that consists of two stages, an extraction procedure and an analysis of the filtered extract. This European Standard test method has adopted the principle that extraction is carried out under conditions approximating as closely as possible to those during the commercial use of cement. Consequently extraction is by standard mortar and subsequent filtration. Other extraction procedures based on paste extraction have traditionally been used and are included in Annexes C and D for use as screening tests, in factory production control or laboratories not having access to equipment specified in FprEN 196-1 for the production of mortar. The use of paste extraction is outside the normal conditions of use of cement. This European Standard test method has adopted the principle of analysis by spectrophotometry. The procedures set down generally permit the analysis to be carried out without the need for an oxidation step. On rare occasions some cements may contain reducing species, not controlled by the routine method, that interfere with the analysis and require an oxidation step. Inter-laboratory testing has demonstrated that it is necessary to include an ‘initial assessment test’ in order to observe the effects on the analysis. By comparing the results obtained from the method with and without the oxidation step, it can be determined whether, for that cement, the reference method should include the oxidation step. Other instrumental procedures may be used for the analysis of the filtered extract provided they are calibrated against the analysis of the filtered extract using the reference procedure. In case of dispute or failure to comply with a regulatory limit only the reference method shall be used. This European Standard test method has drawn heavily on the Danish Standard DS 1020 and the extraction procedure developed by the French cement industry association ATILH. Careful consideration has been given to the details of the German TRGS 613 method developed by Germany’s Hazardous Materials Committee in support of Industrial Regulations for Hazardous Materials. Notice was also taken of the British Cement Association ‘inherent colour’ method; the draft method produced by CEN/TC 193/WG1, reference N680, for cement-based adhesives; European Standard method EN 420 for protective gloves; and to the method, reference ID-215, developed by the Occupational Safety and Health Administration, Salt Lake City, UT, USA. The USA Portland Cement Association, Research and Development report Serial No. 2554 “Review and evaluation of analytical methods for the determination of hexavalent chromium in hydraulic cements and clinker” by Waldemar A. Klemm was found to be most helpful in resolving technical issues. CEN/TR 14589 confirmed that chromium species and solubilities are sensitive to pH and redox conditions and care has been taken to address these in this European Standard by controlling sample exposure to air, by adding the indicator to the alkaline filtered extract and by precisely specifying the pH for the analytical procedure. This European Standard test method was developed in order to provide a reference test method for use in the evaluation of compliance of cement with the requirements in entry 47 to Annex XVII of Regulation (EC) 1907/2006 of the European Parliament and of the Council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). A system for the evaluation of compliance of cement is set out in Annex A. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 5 1 Scope This part of EN 196 specifies the method for the determination of the water-soluble chromium (VI) content of cement. A reference method is described consisting of two stages, an extraction procedure and an analysis of the filtered extract. Guidance on other extraction procedures, suitable for screening tests, for factory production control or other purposes, is given but in case of dispute or failure to comply with a regulatory limit only the reference method is used. The reference method has alternatives whereby the filtered extract may be subjected to an oxidation step or not. The criteria by which the appropriate procedure is selected are set down. Other instrumental procedures may be used for the analysis of the filtered extract provided they are calibrated against the analysis of the filtered extract using the reference procedure. In the case of a dispute, only the reference method is used. Annex A sets out a normative procedure to be followed in case this test method is used as the basis for evaluation of conformity of a cement with the regulatory limit in Regulation (EC) No. 1907/2006. This part of EN 196 describes a method that applies to cements. It may have wider applicability but this would need to be verified by testing on a product-by-product basis. Guidance in the possible application of this European Standard to the determination of the water-soluble chromium (VI) content of cement-containing preparations is given in Annex B. Annexes C and D provide information on other test procedures based on paste extraction and thus depart from the performance of cement in its normal conditions of use. They may be carried out with or without the oxidation process. Users should be aware that results using these methods might be significantly different to those obtained by the reference method. In the case of dispute or failure to comply with the regulatory limit only the reference method is used. Annex E provides guidance on a method for determination of the excess reducing agent content of cement as used in the factory internal control system of some countries. Manufacturers using such an internal control method should assure themselves of the relevance of results in comparison with testing by the reference method. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 196-1, Methods of testing cement - Part 1: Determination of strength EN 196-7, Methods of testing cement - Part 7: Methods of taking and preparing samples of cement EN ISO/IEC 17020, Conformity assessment - Requirements for the operation of various types of bodies performing inspection (ISO/IEC 17020) EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025) EN ISO/IEC
17065, Conformity assessment - Requirements for bodies certifying products, processes and services (ISO/IEC 17065) kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 6 3 General requirements for testing 3.1 Number of tests Determination of water-soluble chromium (VI) content of cement, where the determination is not part of a series subject to statistical control, shall be carried out in duplicate. Where the determination is one of a series subject to statistical control, a single test shall be the minimum required. In the case of a dispute, the number of tests shall be two (see also 3.3). 3.2 Repeatability and reproducibility Repeatability - precision under repeatability conditions where independent test results are obtained with the same method on identical test items (material) in the same laboratory by the same operator using the same equipment within short intervals of time. Reproducibility - precision under reproducibility conditions where test results are obtained with the same method on identical test items (material) in different laboratories with different operators using different equipment. Repeatability and reproducibility in this European Standard are expressed as repeatability standard deviation and reproducibility standard deviation in percent by mass. 3.3 Expression of masses, volumes, factors and results Express masses in the extraction stage in grams to the nearest 0,1 g. Express masses in the analytical stage in grams to the nearest 0,000 1 g and volumes from burettes in millilitres to the nearest 0,05 ml unless otherwise specified. Express the calculated results, where a single test result has been obtained, as a percentage of the cement as received. Express the calculated results, where two test results have been obtained, as the mean of the results, as a percentage of the cement as received. If the two test results differ by more than twice the standard deviation of repeatability, repeat the test and take the mean of the two closest test results. Express the reported water-soluble chromium (VI) content as a percentage of the cement as received, to four decimal places. Where the results of determinations with and without oxidation are to be compared results shall be considered equivalent if they do not differ by more than twice the standard deviation of repeatability. The results of all individual tests shall be recorded. 3.4 Blank determinations Carry out a blank determination without a sample following the same procedure and using the same amounts of reagents. Correct the results obtained for the analytical determination accordingly. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 7 4 Reagents Use only reagents of analytical quality. References to water mean distilled or deionized water with electrical conductivity ≤ 0,5 mS/m. Unless otherwise stated percent means percent by mass. on the basis of g/cm3 at 20 °C. 4.1 Concentrated hydrochloric acid (HCl)18 to 1,19. 4.2 Dilute hydrochloric acid, 1,0 mol/l. 4.3 Dilute hydrochloric acid, 0,04 mol/l. 4.4 Acetone, (CH3.CO.CH3 4.5 Indicator solution. Dissolve 0,125 g of s-diphenylcarbazide (C6H5NHNH)2CO,
(1,5-diphenylcarbohydrazide) in 25 ml of acetone (4.4) in a 50 ml volumetric flask. Make up to the mark with acetone. The indicator solution will keep for one week, if kept refrigerated. 4.6 Standard chromate solution. 4.6.1 Stock solution: Dissolve 0,141 4 g dried potassium dichromate (K2Cr2O7), dried to constant mass at (140 ± 5) °C, in water in a 1 000 ml volumetric flask and make up to the mark with water. The stock solution will keep for one month. This solution contains 50 mg Cr (VI) in a litre. NOTE Ready-to-use stock solution is commercially available. 4.6.2 Standard solution: Transfer 50,0 ml stock solution (4.6.1) to a 500 ml volumetric flask and make up to the mark with water. This solution contains 5 mg Cr (VI) in a litre. The standard solution will keep for one month. 4.7 CEN standard sand, in accordance with FprEN 196-1. 4.8 Sodium peroxodisulfate (sodium persulfate), Na2S2O8. 4.9 Orthophosphoric acid, H3PO4, (85 %). 5 Apparatus 5.1 Balance(s), analytical balance, capable of weighing to an accuracy of ± 0,000 5 g, and a laboratory balance, capable of weighing to an accuracy of ± 1 g. 5.2 Mixer, two speed in accordance with FprEN 196-1. 5.3 Spectrophotometer, for measuring the absorbance of a solution at 540 nm, or filter photometer equipped with a filter giving maximum transmission at approximately 540 nm. 5.4 Cells, with a light path of 10 mm. 5.5 Volumetric glassware, 50 ml, 500 ml and 1 000 ml volumetric flasks; 1,0 ml; 2,0 ml; 5,0 ml; 10,0 ml; 15,0 ml and 50,0 ml pipettes. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 8 5.6 pH meter, capable of measuring pH to an accuracy of ± 0,05. 5.7 Filtration system, comprising a vacuum source connected to a vacuum flask fitted with a filter crucible, Buchner funnel or other suitable equipment. 5.8 Filter media, of pore size 7 fritted glass filter. Some filter media may become contaminated during manufacture with substances that can reduce chromium (VI). A blank test should be carried out to ensure the suitability of the filter medium selected. 5.9 Filtration equipment.
Key 1 mortar 2 filter funnel 3 to vacuum 4 low form beaker 5 filter flask 6 sand Figure 1 — Typical arrangement of filtration equipment Filtration equipment consisting of a Buchner funnel, (e.g. diameter 205 mm, fitted onto a 2 l filter flask), partially full of sand, inside which is a low form beaker to collect the filtrate, placed on top of the bed of sand. The apparatus is connected to a vacuum pump (see Figure 1). Also other arrangements ensuring filtrate collection into containers may be used. 5.10 Laboratory oven, capable of maintaining a temperature of (140 ± 5) °C. 5.11 Heating plate, capable of maintaining a temperature of (280 ± 10) °C. 5.12 Timer, capable of measuring to an accuracy of ± 1 s. 6 Preparation of a test sample of cement Immediately before chemical analysis, treat the laboratory sample, taken in accordance with EN 196-7, as follows to obtain a homogeneous test sample. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 9 Take approximately 1 000 g of the laboratory sample by means of a sample divider or by quartering. Transfer this test sample to a clean dry container with an airtight closure and shake vigorously to mix it thoroughly. Carry out all operations as quickly as possible and immediately seal in an airtight. container to ensure that the test sample is exposed to ambient air only for the minimum time. 7 Extraction procedure 7.1 Principle Cement is made into a mortar using CEN standard sand and water. The mortar is mixed for a specified time and then filtered. An aliquot of filtrate is treated with s-diphenylcarbazide and acidified within a narrow range of pH. Chromium (VI) in acid solution forms a red-violet complex the absorption of which is measured spectrophotometrically at 540 nm. The water-soluble chromium (VI) content is determined from a calibration curve. 7.2 Preparation of mortar 7.2.1 Composition of mortar The proportions by mass shall be one part of cement (see Clause 6), three parts of CEN standard sand (4.7), and one half part of water (Clause 4) (i.e. water/cement ratio 0,50). NOTE The water to be used is analytical grade (see Clause 4) Each batch shall consist of (450 ± 2) g of cement, (M), (1 350 ± 5) g of sand and (225 ± 1) g of water, (V1). Where cements to be tested are rapid setting, a water/cement ratio of 0,50 may not yield sufficient filtrate for analysis. In these cases, it is permissible to increase the water content, and hence the water/cement ratio, until sufficient filtrate (see 7.3) is obtained. This deviation should be reported. 7.2.2 Mixing of mortar Weigh the cement and water by means of the laboratory balance (5.1). When water is added by volume it shall be dispensed with an accuracy of ± 1 ml. Mix each batch of mortar mechanically using the mixer (5.2). The timing of the various mixing stages refers to the times at which mixer power is switched on/off and shall be maintained within ± 2 s. The mixing procedure shall be as follows: — place the water and the cement into the bowl, taking care to avoid loss of water or cement; — immediately the water and cement are brought into contact start the mixer at the low speed (see FprEN 196-1, table of mixer speeds) whilst starting the timing of the mixing stages. After 30 s of mixing, add the sand steadily during the next 30 s. Switch the mixer to the high speed (see FprEN 196-1, table of mixer speeds) and continue the mixing for an additional 30 s; — stop the mixer for 90 s. During the first 30 s, remove by means of a rubber or plastics scraper the mortar adhering to the wall and bottom part of the bowl and place in the middle of the bowl; — continue the mixing at the high speed for 60 s. Normally these mixing operations are carried out automatically. Manual control of these operations and timings may be used. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 10 7.3 Filtration Ensure that the filtration equipment (filter flask, filter crucible or Buchner funnel and filter medium and low form beaker) is dry before each use. Fit the filter crucible or Buchner funnel (5.7) and filter medium (5.8). Do not pre-wet the filter medium. Apply the vacuum and place the mortar into the filtration equipment. Filter for a maximum of 10 min to obtain a volume of 10 ml to 15 ml of filtrate. If 10 ml is not obtained in this time, continue filtering to obtain sufficient quantity to carry out the determination(s). Report this deviation. The filtrate may be stored for up to 8 h before determination of the chromium (VI) content but if the storage period exceeds 30 min it shall be kept in a sealed air-tight container to prevent evaporation. Where a filtrate has a turbidity that cannot be removed by simple filtration, it may be filtered by centrifuge, filter press or filtered over a fine-pore membrane filter. Report the alternative filtration method used. No verification against the reference method is required in these cases. Where the filtrate still has turbidity the blank used with these samples should be a filtrate from the respective sample but without the addition of indicator solution. 8 Determination of chromium (VI) 8.1 General Results of inter-laboratory testing have indicated the importance of following the precise operations, their sequence and the timings in order to obtain the quoted values for repeatability and reproducibility. Some constituents of cement, other than chromium reducing agents purposely added, can contain reducing substances (e.g. sulfide, sulfite) that can, during the determination of soluble chromium (VI) using diphenylcarbazide in acidic conditions, lead to an artificial decrease in the amount of chromium (VI) determined. Addition of diphenylcarbazide whilst the solution is alkaline should suppress the effect of sulfide but may not suppress other reducing substances. It is necessary to carry out the determination with and without treatment by an oxidising agent initially, in order to observe the effects on the results in accordance with 8.3 and 8.2, respectively. Results shall be assessed as follows: a) if the difference between the results of the two determinations, each carried out in duplicate, is not more than 2 × Sr (i.e. 2 × 0,000 015 %) (see 3.3) then the results are deemed to belong to the same population and the method without the oxidation step can be used for subsequent tests on the cement; b) if the difference between the results of the two determinations, each carried out in duplicate, is greater than 2 × Sr (i.e. 2 × 0,000 015 %) then the results are deemed to belong to different populations and the method (with respect to oxidation/without oxidation) giving the higher result shall then be used for subsequent tests on the cement. 8.2 Measurement of absorbance without oxidation 8.2.1 Construction of the calibration curve Transfer 1,0 ml; 2,0 ml; 5,0 ml; 10,0 ml; and 15,0 ml of standard solution (4.6.2) to 50 ml volumetric flasks. Add 5,0 ml indicator solution (4.5) and 5 ml of 0,04 mol/l hydrochloric acid (4.3). Make up to the mark with water. The calibration solutions contain respectively 0,1 mg; 0,2 mg; 0,5 mg; 1,0 mg and 1,5 mg Cr (VI) in a litre. kSIST FprEN 196-10:2015
FprEN 196-10:2015 (E) 11 Measure the absorbance values against the procedural blank (3.4) at 540 nm, 15 min to 20 min after addition of the indicator solution. Construct the calibration curve by plotting the measured absorbance values against the concentration of chromium (VI). The validity of the calibration shall be checked at least once per month, or before use when infrequently used, by testing the mid-range sample, which shall not depart from the calibration value by more than ± 2 % of the calibrated value. 8.2.2 Sample absorbance Within 8 h after filtration, pipette 5,0 ml, (V2), filtrate (7.3) into a 100 ml beaker. Add 20 ml water, 5,0 ml indicator solution (4.5), shake and adjust pH (5.6) to between 2,1 and 2,5 by addition of 1,0 mol/l hydrochloric acid (normally between 0,2 and 0,6 ml corresponding to 5 to 15 drops). The steps from addition of indicator solution to adjustment of pH shall be completed within 30 s. Record the pH value. Transfer to a 50 ml, (V3), volumetric flask. Make up to the mark with water and shake the flask. Measure the absorbance of the solution against the procedural blank (3.4) at 540 nm, 15 min to
20 min after addition of the indicator solution. NOTE If the concentration of chromium (VI) in the sample is greater than the range of calibration curve, repeat the determination, using a smaller aliquot (V2) of the filtrate (7.3). 8.2.3 Determination of chromium (VI) concentration Determine the concentration, (C), of water-soluble chromium (VI) in mg/litre from the calibration curve. 8.3 Measurement of absorbance with oxidation 8.3.1 Construction of the calibration curve 8.3.1.1 Preparation of calibration solutions Weigh (500 ± 1) mg sodium peroxodisulfate (4.8) into 250 ml wide-necked conical
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