EN 196-6-2010 pdf download.Methods of testing cement – Part 6 : Determination of fineness.
3.4 Procedure
3.4.1 DeterminatIon of the cement residue
Agitate the sample of cement to be tested by shaking for 2 mm in a stoppereci jar to disperse agglomerates. Wait 2 mm. Stir the resulting powder gently using a clean dry rod to distribute the fines throughout the cement.
Fit the tray under the sieve. Weigh (25 ± 0,5) g of cement to the nearest 0,01 g and place it in the sieve, being careful to avoid loss. Disperse any agglomerates. Fit the lid over the sieve. Agitate the sieve by swirling, planetary and linear movements until no more fine material passes through it.
Remove and weigh the residue. Express its mass as a percentage, R1 of the quantity first placed in the sieve to the nearest 0,1 %. Gently brush all the fine material off the base of the sieve into the tray.
Repeat the whole procedure using a fresh 25 g sample to obtain R2. Then calculate the residue of the cement R as the mean of R1 and R2 as a percentage, expressed to the nearest 0,1 %.
When the results differ by more than 1 % absolute, repeat the whole procedure a third time and calculate the mean of the three values.
Sieving by the manual process requires a skilled and experienced operator.
3.4.2 Checking the sieve
Sieves should be cleaned and checked for damage after each sieving (e.g. that the mesh is taut and is not dented or perforated). In addition, check the sieve after every 100 sievings as follows:
Agitate the sample of reference material, to be used for checking the sieve, by shaking for 2 mm in a stoppered jar to disperse agglomerates. Wait 2 mm. Stir the resulting powder gently using a clean dry rod to distribute the fines throughout the reference material.
Fit the tray under the sieve. Weigh (25 ± 0,5) g of the reference material (33) to the nearest 0,01 g and place it in the sieve, being careful to avoid loss. Sieve the material In accordance with 3.4.1 including the repeat determination of residue to yield two values P1 and P2 expressed to the nearest 0.1 %.
The two values of P1 and P2 for a satisfactory sieve should differ by not more than 0,6 %. Their mean P characterizes the state of the sieve.
Given the known residue on the sieve of the reference material, R0, calculate R01P as the sieve factor, F, expressed to the nearest 0,01. The residue, R, determined as in 3.4.1 shall be corrected by multiplying by F, which may have a value of 1,00 ± 0,20.
3.5 Expression of results
Report the value of R to the nearest 0.1 %, as the residue, the sieve mesh size and details of the cement tested.
The standard deviation of the repeatability is about 0,2 % and of the reproducibility is about 0,3 %.
NOTE Where there is local difficulty in obtaining ISO standard sieves, the same procedure can be follod with the nearest available standard sieve but the report should state on which standard sieve mesh the cement residue has been determined
4 Air permeability method (Blame method)
4.1 Principle
The fineness of cement is measured as specific surface by observing the time taken for a fixed quantity of air to flow through a compacted cement bed of specified dimensions and Porosity. Under standardized conditions the specific surface of cement is proportional to t where t is the time for a given quantity of air to flow through the compacted cement bed. The number and size range of individual pores in the specified bed are determined by the cement particle size distribution, which also determines the time for the specified air flow.
The method is comparative rather than absolute and therefore a reference sample of known specific surface is required for calibration of the apparatus.
4.2 Apparatus
4.2.1 PermeabilIty cell. The cell shall be a rigid right cylinder of the dimensions and tolerances shown in Figure 1 a). It shall be of austenitic stainless steel or other abrasion-resisting, non-corrodible material. The top and bottom faces shall be flat and normal to the axis of the cylinder, as shall the upper surface of the ledge at the bottom of the cell. The outer surface of the cylinder shall be tapered to form an airtight fit with the conical socket of the manometer (ISO 383:1976, Joint 19/34).
4.2.2 Perforated disc. The disc shall be of non-corrodible metal, perforated with 30 to 40 holes of
1 mm diameter, and shall have the dimensions and tolerances shown in Figure 1 b). When in position on the ledge in the cell, its plane surfaces shall be normal to the axis of the cell.
4.2.3 Plunger. The plunger is a piston. capable of sliding freely in the measuring cell by means of a clearance to be applied in such a way that, when the cap of the plunger comes to rest on the upper face of the cell cylinder, a distance of (15 ± 1) mm will be maintained between the upper face of the perforated disc and the lower face of the piston.
This piston shall be provided with a flat connected to an annulus around the head to enable air to escape.EN 196-6-2010 pdf download.