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Aggregate specific gravity and absorption calculator (ASTM C127 and C128)
Pick coarse or fine aggregate and enter the weighings in grams. Coarse aggregate uses the oven-dry, SSD and in-water masses; fine aggregate uses the oven-dry mass, the pycnometer readings and the SSD specimen mass. You get bulk specific gravity on an oven-dry and SSD basis, apparent specific gravity and absorption.
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Key takeaways
- A is oven-dry, B is saturated surface-dry (SSD), C is the mass in water for coarse aggregate.
- Fine aggregate adds the pycnometer readings and uses S for the SSD mass.
- Absorption is based on the oven-dry mass.
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How it's calculated
How is the result calculated?
C127: bulk OD = A ÷ (B − C), bulk SSD = B ÷ (B − C), apparent = A ÷ (A − C), absorption = (B − A) ÷ A × 100.
- 01Coarse aggregate (ASTM C127): A = oven-dry mass in air, B = SSD mass in air, C = apparent mass in water
- 02C127: bulk SG (OD) = A ÷ (B − C); bulk SG (SSD) = B ÷ (B − C); apparent SG = A ÷ (A − C); absorption % = (B − A) ÷ A × 100
- 03Fine aggregate (ASTM C128): A = oven-dry mass, B = pycnometer filled with water, C = pycnometer + specimen + water, S = SSD specimen mass
- 04C128: bulk SG (OD) = A ÷ (B + S − C); bulk SG (SSD) = S ÷ (B + S − C); apparent SG = A ÷ (B + A − C); absorption % = (S − A) ÷ A × 100
- 05Bulk SG (OD), bulk SG (SSD) and apparent SG are reported to the nearest 0.01; the three-decimal values are the calculated values. Absorption is shown to 0.1 %
Rounding: bulk SG (OD), bulk SG (SSD) and apparent SG are reported to the nearest 0.01; the three-decimal values are the calculated values. Absorption to 0.1 %. Full precision is kept between steps.
FAQ
Frequently asked questions about the aggregate specific gravity calculator
What is the difference between bulk OD, bulk SSD and apparent specific gravity?
Bulk OD divides the oven-dry mass by a volume that includes permeable pores. Bulk SSD uses the saturated surface-dry mass over that same volume. Apparent uses the oven-dry mass over the solid volume, excluding permeable pores.
Which value is used in mix design?
That depends on how the mix design method handles aggregate moisture. Use the basis your mix design procedure and project specifications call for.
Why must the SSD mass be at least the oven-dry mass?
A saturated surface-dry specimen holds absorbed water, so it cannot weigh less than the same specimen oven-dry. The calculator flags that as a weighing error.
Can I use this for soil specific gravity (Gs)?
No. These formulas follow the aggregate methods ASTM C127 and C128. Soil specific gravity uses a different test method.
Related guides and pages
- Sieve analysis: aggregate and soil gradation guideHow sieve analysis produces percent retained and passing, how gradation curves support material description, and what the fineness modulus summarizes.
- Construction materials testing: a practical lab guideA practical overview of construction materials testing: how field observations, laboratory methods, calculations and reviewed reports fit together.
- Concrete testing softwareHow ProofGrit handles this test in the lab.
- Standards indexEvery standard explained on this site, with plain-English purpose.
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Sources and further reading
- ASTM InternationalASTM International
- ASTM C136/C136M, sieve analysis of fine and coarse aggregatesASTM International
- AASHTO Store (AASHTO standards, including R18, T 99 and T 180)AASHTO
Standards are summarized in our own words. Read the current edition from the publisher before you test.
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