⛰️ Aggregate bulk density
Determination of loose bulk density and voids (porosity) of natural and artificial aggregates with grain size up to 63 mm.
Overview
Aggregate bulk density is the mass of aggregate per unit volume, including both grain volume (with internal pores) and intergranular spaces (voids). It is a parameter necessary for converting aggregate mass to volume and vice versa — fundamental for dosing concrete components, designing asphalt mineral mixtures, delivery settlements and quality control.
Standard PN-EN 1097-3 describes a simple gravimetric method — filling a cylinder of known volume with aggregate in loose state (without compaction), weighing and calculating density. The method is used for natural and artificial aggregates with maximum grain size up to 63 mm.
Bulk density depends on: apparent grain density, grain shape and surface texture (angular grains give lower bulk density), particle size distribution (single-fraction aggregates have lower density than continuous), moisture content and degree of compaction. Typical values: sand 1 400–1 700 kg/m³, gravel 1 500–1 800 kg/m³, basalt aggregate 1 300–1 500 kg/m³, expanded clay 300–600 kg/m³.
Based on bulk density, voids (porosity) are determined — percentage of intergranular spaces, important for assessing compactability of mixtures and drainage. Voids are calculated: v = (1 − ρ_b/ρ_a) × 100%, where ρ_b — bulk density, ρ_a — grain density.
Method principle
Metal cylinder of known volume V (calibrated with water) is filled with dry aggregate — it is poured from a trowel from height max. 50 mm above cylinder edge, avoiding segregation. Do not compact or shake. Excess aggregate is scraped off with steel straightedge. Cylinder with aggregate is weighed (m₂), after subtracting empty cylinder mass (m₁) aggregate mass is obtained m = m₂ − m₁. Bulk density ρ_b = m / V [kg/m³ or Mg/m³].
Applications
- Concrete mix design (volumetric method — mass to volume conversion)
- Settlement of aggregate deliveries (ton → m³ converter)
- Selection of asphalt mineral mixture proportions
- Aggregate quality assessment in quarries and gravel pits
- Calculation of aggregate voids (porosity) for drainage
- Control of aggregate batch uniformity
Key parameters
| Parameter | Value |
|---|---|
| Particle size range | Up to 63 mm (coarse and fine fractions) |
| Aggregate state | Dry, loose (without compaction) |
| Cylinder volume (min.) | 1 L (0/4 fraction), 5 L (4/31.5), 10–20 L (>31.5 mm) |
| Typical values sand | 1 400–1 700 kg/m³ |
| Typical values gravel/grit | 1 300–1 800 kg/m³ |
| Repeatability | ±20–50 kg/m³ |
Standard
- Standard number
- PN-EN 1097-3:2000
- Title (PL)
- Badania mechanicznych i fizycznych właściwości kruszyw — Część 3: Oznaczanie gęstości nasypowej i jamistości
- Title (EN)
- Tests for mechanical and physical properties of aggregates — Part 3: Determination of loose bulk density and voids
Step-by-step procedure
1. Aggregate drying
Dry aggregate sample in dryer at 110±5°C to constant mass (mass change <0.1% in 1 h).
2. Cylinder volume calibration
Weigh empty cylinder (m₁). Fill with water to edge, cover with glass plate. Weigh (m₃). V = (m₃ − m₁) / ρ_water.
3. Filling cylinder with aggregate
Pour aggregate with trowel from height ≤50 mm above cylinder edge. Fill with slight excess. Do not compact, do not shake.
4. Surface leveling
With steel rod (straightedge) scrape off excess aggregate, rolling rod over cylinder edge. Fill any depressions.
5. Weighing
Weigh cylinder with aggregate (m₂). Weighing accuracy: ±0.1% aggregate mass.
6. Bulk density calculation
ρ_b = (m₂ − m₁) / V [kg/m³]. Round to 10 kg/m³.
7. Repetition
Perform at least 2 independent determinations. Difference ≤50 kg/m³. Result = arithmetic mean.
8. Voids calculation (optional)
v = (1 − ρ_b / ρ_a) × 100%, where ρ_a = grain density (from PN-EN 1097-6). Result in %.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Calibrated steel cylinder | Controls 55-C0215 (1 L, 5 L, 10 L, 20 L), Matest | 800–3 000 PLN |
| Technical balance (resolution 1 g) | Kern FCB 30K1, Radwag WLC 30/A2, capacity 30 kg | 2 000–5 000 PLN |
| Steel straightedge for scraping excess | Steel rod ∅16 mm × 600 mm, straight | 50–150 PLN |
| Laboratory dryer | Binder FD 115, Memmert UF110, 110±5°C | 5 000–15 000 PLN |
| Trowel / scoop | Steel, for pouring aggregate from low height | 30–100 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Tap water (cylinder calibration) | 7732-18-5 | For determining cylinder volume by weight method: V = m_water / ρ_water |
Health and safety (OHS)
- Heavy samples and cylinders (up to 30+ kg) — lifting ergonomics, work gloves
- Aggregate dust when drying and pouring — P2 mask, ventilation
- Hot dryer (110°C) — heat-resistant gloves when removing samples