ASTM C204 — Fineness of hydraulic cement

Air-permeability (Blaine) apparatus

Active designation: ASTM C204-25.

---

Legal notice

The information on this page is a summary prepared by Vector Scientific Testing Devices based on a review of the applicable standard; it does not replace the official standard. For the authoritative, complete text, obtain the standard from the relevant standards body (e.g. your national standards institute, ASTM International, CEN) through official channels. Vector accepts no liability for direct or indirect loss arising from reliance on this summary.

---

1. Purpose and principle

This test method determines the fineness (specific surface area) of hydraulic cements using a Blaine air-permeability apparatus.

Principle: Measure the time t for a defined volume of air to pass through a cement bed of fixed volume and porosity.

Important: This is not an absolute measurement. Specific surface is obtained by comparison with a standard reference material — historically and in practice the NIST Standard Reference Material (SRM 114) and its current series, used to standardize the apparatus.

---

2. Apparatus — geometry and tolerances

ASTM C204 specifies tight dimensional limits:

| Component | Requirement | |-----------|-------------| | Permeability cell | Rigid metal cylinder, inner diameter 12.70 ± 0.10 mm, corrosion- and wear-resistant (austenitic stainless steel in current editions) | | Perforated disk | Non-corroding metal (e.g. brass or stainless), ≥ 30 holes of 1 mm diameter, thickness 0.9 ± 0.1 mm, snug fit at cell base | | Plunger | Metal plunger seating flush with cell top; net bed height between disk and plunger face 15.0 ± 1.0 mm; edge vent channel for air | | U-tube manometer | 9 mm outside diameter borosilicate glass; four scale lines with defined spacing (typically ± 0.5 mm between lines) | | Manometer liquid | Non-volatile, non-hygroscopic, low viscosity and density (e.g. dibutyl phthalate or light mineral oil) |

---

3. Test conditions and materials

• Room temperature: 23.0 ± 2.0 °C (73.4 ± 3.5 °F).
• Relative humidity: Not above 65 %.
• Filter paper: Circular disks matching cell ID (~12.7 mm), smooth edges, medium porosity (e.g. qualitative filter class similar to Whatman No. 40).
• Reference cement: Standardization with NIST SRM 114 (or the current certified reference lot per the standard). Store in a desiccator to avoid moisture uptake.

---

4. Test procedure

4.1 Sample preparation and density

• Determine cement density ρ by ASTM C188 before testing; use 0.01 g/cm³ resolution in calculations.
• Shake the cement in a closed container for 2 minutes to disperse lumps before weighing.

4.2 Bed preparation

Default bed porosity e = 0.500 ± 0.005 for hydraulic cements. For ultrafine or special cements, e may be raised (e.g. 0.530 or higher) per the standard.

Cement mass W:

W = ρ · V · (1 − e)

• V — bed chamber volume (cm³)
• ρ — density (g/cm³)
• e — porosity (0–1)

Compaction: Place disk, first filter, weighed cement, second filter; insert plunger and press in one smooth stroke until the head seats on the cell rim. Withdraw the plunger slowly with a slight twist.

4.3 Measurement

1. Seat the cell in the manometer cone (light grease for seal if needed).
2. Raise manometer liquid to the first (upper) line with a rubber bulb; close the valve and verify stable level (leak check).
3. Release flow; start timer when liquid passes the second line, stop at the third line.
4. Record t to 0.2 s and temperature to 1 °C (HMI or log sheet).

---

5. Calibration and re-standardization

Determine the apparatus factor K (or device multiplier) using SRM 114 per the standard. Re-standardize when:

• Manometer liquid is changed or replenished;
• A new filter-paper lot or brand is introduced;
• Manometer tube or permeability cell / plunger set is replaced;
• Periodic QC shows drift beyond allowed limits.

---

6. Calculation and reporting

Units: Report specific surface as m²/kg (SI, emphasized in ASTM documentation) and/or cm²/g (1 cm²/g = 0.1 m²/kg).

When test and calibration cements share the same e and ρ:

S = Sₛ · √t / √tₛ

• Sₛ — reference specific surface; tₛ — reference flow time; t — sample flow time.

Rounding: To nearest 10 cm²/g or 1 m²/kg.

Precision (typical limits from the standard):

• Single-operator (repeatability): difference between consecutive tests by the same operator — ≤ 3.4 %
• Between laboratories (reproducibility): ≤ 6.0 %

---

7. Test Method A and Test Method B

• Test Method A — Reference method using the manually operated standard Blaine apparatus (VTR-1015 class).
• Test Method B — Automated apparatus allowed after it demonstrates acceptable performance against Method A qualification requirements (VTR-1016 class). In disputes, the reference manual method governs unless your quality system states otherwise.

---

8. Comparison with EN 196-6

| Topic | EN 196-6 | ASTM C204 | |-------|----------|-----------| | Room temperature | 20 ± 2 °C | 23 ± 2 °C | | Parallel agreement | ≤ 1 % | ≤ 3.4 % (single-operator) | | Reporting emphasis | cm²/g common | m²/kg (SI) prominent | | Reference material | National / CRM Blaine cement | NIST SRM 114 series |

For European workflows see the EN 196-6 summary. HMI temperature alarms and pass/fail limits should match the selected method.

---

9. Practical notes

1. Enter ρ and e correctly on automatic systems — small errors invalidate S.
2. Qualify automatic testers against Method A before production use.
3. Use the Blaine fineness calculator for training and cross-checks only; binding procedure remains ASTM C204 and your accredited system.

---

This document is a comprehensive summary of ASTM C204-25. For official use, obtain the current standard from ASTM International.