Aggregate Specific Gravity & Water Absorption Calculator
Bulk (oven-dry and SSD), apparent specific gravity and water absorption of a coarse aggregate sample from its oven-dry, SSD and submerged mass.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Bulk SG (oven-dry) = A ÷ (B − C)
Bulk SG (SSD) = B ÷ (B − C)
Apparent SG = A ÷ (A − C)
Absorption (%) = (B − A) ÷ A × 100
A = oven-dry mass in air, B = SSD mass in air, C = SSD mass submerged in water
Run the calculation to see each step with your own numbers.
A coarse aggregate sample: 1,000 g oven-dry, 1,020 g SSD in air, 630 g SSD submerged.
Bulk SG (oven-dry) = 1,000 ÷ (1,020 − 630) = 2.564
Bulk SG (SSD) = 1,020 ÷ 390 = 2.615
Apparent SG = 1,000 ÷ (1,000 − 630) = 2.703
Absorption = (1,020 − 1,000) ÷ 1,000 × 100 = 2.00%
- Coarse aggregate tested per ASTM C127 — a sample retained on the 4.75 mm (No. 4) sieve, brought to saturated surface-dry condition before weighing B and C.
- Fine aggregate uses a different procedure (ASTM C128, pycnometer method) with its own formula — not covered by this calculator.
- All three masses should be from the SAME test sample, weighed in the sequence: oven-dry (A) before the test, then SSD in air (B) and SSD submerged (C) during it.
- Why are there three different specific gravity values?
- They differ in whether the aggregate's internal pore volume is counted as part of the aggregate. Apparent SG excludes all pores; bulk SG (oven-dry and SSD) includes the permeable pores, just weighed dry vs. pre-wetted. Mix designers typically use bulk SG (SSD) for concrete proportioning.
- What's a typical specific gravity for aggregate?
- Most natural stone aggregates (granite, limestone, gravel) run about 2.4–2.9. Lightweight aggregates run lower; some heavy aggregates (magnetite, barite) run well above 3.0.
- Why does absorption matter for a concrete mix?
- An aggregate that isn't at SSD condition when batched will either soak up mix water (if dry) or add extra water to the mix (if wet), changing the effective water-cement ratio. Absorption tells the mix designer how much water the aggregate itself will pull from — or add to — the batch.
Test method & formulas
ASTM C127, 'Standard Test Method for Relative Density (Specific Gravity) and Absorption of Coarse Aggregate'.
About the Aggregate Specific Gravity & Water Absorption Calculator
The Aggregate Specific Gravity & Water Absorption Calculator applies the ASTM C127 formulas for coarse aggregate: bulk specific gravity (oven-dry basis), bulk specific gravity (saturated-surface-dry basis), apparent specific gravity, and water absorption — all from three simple mass measurements. These properties feed directly into concrete and asphalt mix design (they set the aggregate's absolute volume and how much mix water the aggregate itself will absorb).
What you enter
- Oven-dry mass in air (A)
- Saturated surface-dry (SSD) mass in air (B)
- SSD mass submerged in water (C)
What you get back
- Bulk specific gravity (oven-dry) — ASTM C127 §12 specifies reporting to the nearest 0.01.
- Bulk specific gravity (SSD) — the exact result of the calculation.
- Apparent specific gravity — the exact result of the calculation.
- Water absorption — %
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Sieve Analysis & Gradation Calculator — Percent passing at each standard sieve and the fineness modulus, for an aggregate or soil sample, from the weight retained on each sieve.
- Los Angeles Abrasion Value Calculator — Percent loss (LA abrasion value) of a coarse aggregate sample from its mass before and after the Los Angeles abrasion test.
- Sand Calculator — Sand by volume and weight for bedding, fill or mixing.
Part of the Materials calculators.