---
code: "ASTM C204"
title: "Standard test methods for fineness of hydraulic cement by air-permeability apparatus"
institution: "ASTM"
category: "testing-analysis-systems"
revision: "2025"
scope: "Determines hydraulic-cement fineness (specific surface area) by the Blaine air-permeability method using comparative calibration against NIST Standard Reference Material (SRM 114 series)."
testMethod: "Test Method A — manual reference Blaine; Test Method B — qualified automatic apparatus. Room (23 ± 2) °C, RH ≤ 65 %, bed porosity e = 0.500 ± 0.005, air-flow time t."
specimenRequirements: "Density ρ per ASTM C188 (0.01 g/cm³); bed mass W = ρ·V·(1−e); 12.7 mm filter disks; SRM 114 in desiccator; single-operator difference ≤ 3.4 %."
url: "https://vectorbtc.com.tr/resources/standards/astm-c204/"
---

# ASTM C204 — Fineness of hydraulic cement

## Air-permeability (Blaine) apparatus

*Active designation: ASTM C204-25.*

---

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---

## 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:**

```text
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**:

```text
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 %**

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## 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.

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## 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](/resources/standards/en-196-6/). HMI temperature alarms and pass/fail limits should match the selected method.

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## 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](/resources/calculators/blaine-fineness/) for training and cross-checks only; binding procedure remains ASTM C204 and your accredited system.

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