Метод випробування золи-винесення. Частина 1. Визначення вмісту вільного кальцію оксиду / Method of testing fly ash - Part 1: Determination of free calcium oxide content

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1 2 З? 4 5 6 7 8 EN 451-1:2003, CONTENTS

page
1 Scope 1
2 Normative references 1
3 General 2
4 Reagents 2
5 Apparatus 2
6 Procedure 3
7 Results 4
8 Repeatability and reproducibility .... 4
Bibliography 5

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EN 451-1:2003 - - - -

METHOD OF TESTING FLY ASH -

Part 1: Determination of free calcium oxide content 1 2 EN 450 ISO 565 ISO 3534-1 1 SCOPE
This European Standard describes the procedure for the determination of free calcium oxide content in fly ash.
The standard describes the reference procedure. If other methods are used it shall be shown that they give results equivalent to those obtained by the reference method.

2 NORMATIVE REFERENCES

This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments).
EN 450, Fly ash for concrete - Definitions, requirements and quality control
ISO 565, Test sieves - Metal wire cloth, perforated metal plate and electroformed sheet - Nominal sizes of openings.
ISO 3534-1, Statistics - Vocabulary and symbols -Part 1: Probability and general statistical terms.
3.1 3.2 3.3 4 4.1 4.2 4.3 4.4 4.5 4.6 5 5.1 5.2 5.3 5.4 5.5 5.6 3.1 Number of determinations
Carry out twice the procedure for determining the free calcium oxide content.
If the difference between two determinations is more than twice the repeatability standard deviation, repeat the test and take the mean of the closest values.
3.2 Repeatability and reproducibility
The standard deviations of repeatability and reproducibility, as defined in ISO 3534-1, are expressed in absolute percentages by mass.
3.3 Expression of masses and volumes
Express masses in grams to the nearest 0,000 1 g and volumes from the burette in milliliters to the nearest 0,05 ml.

4 REAGENTS

4.1 General
Use only reagents of analytical grade and distilled water, or water of equal purity.
4.2 Butanoic acid, 3-oxo-ethyl ester (= ethyl acetoacetate).
4.3 Butan-2-ol.
4.4 Propan-2-ol.
4.5 Indicator (0,1 g of bromophenol blue in 100 ml of ethanol).
4.6 Hydrochloric acid (0,100 M).

5 APPARATUS

5.1 Balance, capable of weighing to an accuracy of 0,000 1 g or better.
5.2 Test sieve, with 0,063 mm sieve cloth conforming to ISO 565.
5.3 Mortar and pestle, or similar equipment for grinding.
5.4 Desiccator, containing a drying agent, e.g. silica gel.
5.5 Flask, 250 ml.
5.6 Spiral reflux condenser:

5.7 5.8 6 6.1 6.2 6.3 5.7 Absorption tube, filled with sodium hydroxide on an inorganic carrier (to protect the contents of the flask and the condenser from reacting with atmospheric carbon dioxide).
5.8 Filter crucible, with pore sizes of 0,004 mm to 0,010 mm.
NOTE Alternatively also a filter funnel, in which a filter paper with fine pores of a diameter of approximately 0,002 mm and a filter paper with medium pores of a diameter of approximately 0,007 mm can be placed, may be used.

6 PROCEDURE

6.1 Preparation of sample
Subdivide the laboratory sample, prepared in accordance with 6.2.2 of EN 450 by a suitable method to obtain a subsample of about 100 g. Pass this subsample through the test sieve (5.2). Grind any residue in the mortar (5.3) until all the subsample passes through the sieve completely. Homogenize the total subsample and place it in the desiccator (5.4) until tested.
6.2 Determination
Place a weighed portion of 1,0 g to 1,5 g of the sub-sample prepared in accordance with 6.1 into the 250 ml flask (5.5) and add a mixture of 12 ml butanoic acid, 3-oxo-ethyl ester (4.2) and 80 ml butan-2-ol (4.3). Fit the flask with the spiral reflux condenser (5.6) and the absorption tube (5.7) and boil for 3 h. Filter the warm mixture through the filter crucible (5.8). Wash the residue with 50 ml propan-2-ol (4.4). If the filtrate is cloudy, reject it and repeat the extraction with a new weighed portion of the sub sample.
Add a few drops of bromophenol blue indicator (4.5) to the filtrate and titrate with hydrochloric acid (4.6) until the colour changes to yellow.
Record the volume V of hydrochloric acid used.
6.3 Calculations

The free calcium oxide content (WCa0), expressed as a percentage by mass of the dry fly ash, shall be calculated from the following equation:

V - 7 8 where:
V is the volume (in ml) of hydrochloric acid solution used for titration;
m is the weighed proportion (in g) of the dried fly ash.

7 RESULTS

The mean value of two determinations, calculated to two decimal places and expressed to one decimal place, shall be taken as the free calcium oxide content of the sample.

8 REPEATABILITY AND REPRODUCIBILITY

The standard deviation for repeatability is 0,02 % by mass (provisional value). The standard deviation for reproducibility is 0,04 % by mass (provisional value).

BIBLIOGRAPHY

EN 196-7:1989 EN 196-7:1989 Methods of testing cement - Methods of taking and preparing samples of cement