EN 196-6: Methods of testing cement — Part 6

Determination of fineness

National example (Turkey): TS EN 196-6 — the technical requirements follow EN 196-6:2018.

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1. Purpose and scope

This part of EN 196 describes how to determine cement fineness using three methods:

1. Sieving method (90 µm) — Detects coarse particles only. Suited to production monitoring; cannot characterize very fine material.
2. Air-jet sieving method — Measures retention on test sieves with a dispersed air stream. Suited to fine fractions and agglomerated ultrafine particles (e.g. 63 µm and 90 µm apertures); material should substantially pass a 2 mm sieve.
3. Air permeability (Blaine) method — Measures time t for air through a compacted bed and calculates specific surface area. Comparative, not absolute; may not suit ultrafine-rich cements — air-jet sieving may be required as a supplement.

The methods apply to cements within the scope of EN 197-1 and other specifications that reference them.

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2. Method 1 — Sieving (90 µm)

2.1 Apparatus and materials

• Test sieve: Cylindrical frame 150–200 mm diameter, depth 40–100 mm; cloth aperture exactly 90 µm stainless steel wire.
• Balance: At least 10 mg (0.01 g) readability.
• Reference material: Calibration material with known sieve residue, stored in airtight containers.

2.2 Procedure and acceptance

Sample preparation: Shake the cement in a closed jar for 2 minutes, wait 2 minutes, then lightly stir with a dry rod to break lumps.

Sieving: Weigh 10.0 g cement (±0.01 g) onto the sieve. Sieve with combined circular and linear motion until no fine material passes through.

Duplicates: Run two separate portions; obtain residue percentages R₁ and R₂. If |R₁ − R₂| exceeds 1 % (absolute), sieve a third portion and report the mean of three.

Sieve factor (F): Check the sieve with reference material every 100 tests. Compute F = R₀ / P (known residue R₀, reference mass P). F must lie within 1.00 ± 0.20.

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3. Method 2 — Air-jet sieving

The standard defines air-jet sieving for cement fineness when mechanical shaking is insufficient or when particle size distribution of fine agglomerates must be reported.

Principle: A controlled vacuum draws air through a rotating nozzle over the test sieve, dispersing agglomerates so only undersize particles pass.

Typical use:

• Fine and ultrafine cement fractions (e.g. 63 µm, 90 µm test sieves).
• Supplementary check when Blaine does not give meaningful results for ultrafine materials.
• Same laboratory climate as other cement tests: 20 ± 2 °C, RH ≤ 65 %.

Laboratories often run air-jet sieving on an Alpine-type analyser with 200 mm test sieves and traceable vacuum control — see compatible equipment below.

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4. Method 3 — Blaine air permeability

4.1 Laboratory conditions

• Temperature: 20 ± 2 °C in the laboratory.
• Relative humidity: Not above 65 %.
• All test and calibration materials shall reach ambient temperature before use.

4.2 Apparatus (Figure 1 essentials)

• Permeability cell: Stainless steel right cylinder; conical connection to the manometer shall be air-tight (ISO 383 ground joint 19/34 where specified).
• Perforated disc: Stainless disc with 30–40 holes of 1 mm diameter.
• Tamper (piston): When inserted, leaves exactly H = 15 ± 1 mm between the disc and the piston face; a flat channel on the edge vents air.
• Manometer liquid: Volatile, non-hygroscopic, low-viscosity liquid (e.g. dibutyl phthalate or fine mineral oil). Align the meniscus to the lowest scale line (line 11).

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5. Bed preparation (critical)

For standard cements the target bed porosity e = 0.500.

Cement mass in the cell (m₁):

m₁ = (1 − e) · ρ · V = 0.500 · ρ · V

• ρ — cement density (g/cm³) from pycnometer.
• V — volume of the cell bed chamber.

Compaction rule: Insert the piston gently. After the head seats, withdraw the piston 5 mm, rotate 90°, and press again. Do not ram the bed — maximum force should be no more than comfortable thumb pressure. Withdraw the piston slowly.

Very fine cements: If the piston cannot seat at e = 0.500 or springs back when released, use a higher porosity e₁ determined experimentally and recalculate m₁.

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6. Permeability test operation

1. Mount the cell in the conical seat (light grease if needed for seal).
2. Close the top, open the valve, and raise the liquid to the upper mark (line 8) with a rubber bulb. Close the valve and verify the level is stable (leak check).
3. Open the top plug; when the liquid reaches line 9, start the stopwatch; stop at line 10.
4. Record time t to 0.2 s and temperature to 1 °C.
5. Repeat on the same bed, or prepare a fresh bed — two measurements per bed, four readings total (two beds × two runs, or equivalent per your procedure).

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7. Calibration and apparatus constant (K)

Calibrate with reference cement (Blaine sand / CRM) of known specific surface to obtain the apparatus constant K.

Re-calibrate bed volume and K when:

• After every 1000 tests;
• Manometer liquid is changed;
• Filter paper type is changed;
• Manometer glass tube is replaced;
• Systematic deviation appears on a secondary reference cement.

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8. Calculation and reporting

8.1 General formula

Specific surface S (cm²/g) from reference values and air viscosity η:

S = (S₀·ρ₀·√η₀) / (ρ·√η) · (√e³·(1−e₀)) / (√e₀³·(1−e)) · √t / √t₀

When reference and test cement both use e = e₀ = 0.500:

S = (524.2 · K · √t) / ρ

8.2 Acceptance and precision

• Parallel tests on the same sample: difference ≤ 1 % (inclusive) — result accepted; otherwise repeat.
• Report S rounded to the nearest 10 cm²/g.
• Repeatability standard deviation: about 50 cm²/g.
• Reproducibility (between laboratories): about 100 cm²/g.

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9. Practical notes

1. Sieving vs air-jet vs Blaine: Use 90 µm sieving for coarse-particle alerts; air-jet for fine PSD and when Blaine is inconclusive; Blaine for grinding consistency against reference cement.
2. Air-jet equipment: Negative-pressure jet sieves (e.g. Vector VTR-1014 Alpine) disperse cohesive fines that mechanical shakers cannot classify reliably.
3. Automatic Blaine equipment: Must be validated against the reference manual procedure and traceable K.
4. Bed quality: Hard tamping, moisture, and worn cells are the main causes of Blaine drift between shifts.
5. Ultrafine cements: When Blaine is unreliable, use air-jet sieving per the full standard and your accredited procedure.
6. US laboratories: For ASTM workflows (23 °C room, 3.4 % single-operator repeatability, NIST SRM 114), see the ASTM C204 summary.

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This document is a comprehensive summary of EN 196-6:2018 (national titles such as TS EN 196-6 may apply in your region). For official use, refer to the standard issued by your national standards body (e.g. TSE for Turkey).