Written and maintained by CASRAI Editorial Board
Last updated
ASTM D6913/D6913M is the ASTM International test method for measuring the particle-size distribution (gradation) of soils by sieve analysis. This guide covers the 2017 edition, D6913/D6913M-17.
Short answer
ASTM D6913 separates a soil sample into size ranges with a stack of sieves and measures the mass retained in each range. It applies to particles between the 3 in. (75 mm) and No. 200 (75 µm) sieves. It offers two reporting methods, A and B, and three ways of preparing the sample: moist, air dry or oven dry.
Definition and scope
The full title is Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis. Per the standard’s scope, the sieves have square openings and the range covered runs from the 3 in. (75 mm) sieve down to the No. 200 (75 µm) sieve. Coarser and finer particles fall outside it, and the scope points to separate standards for each.
Two points in the scope are easy to miss. First, the title says test methods in the plural: the standard contains Method A and Method B. Second, a typical test takes two to three days, depending on sample size and soil type, which matters when a laboratory plans turnaround.
How it is used in practice
Choosing a sieving approach by maximum particle size
The scope ties the sieving approach to the largest particles in the sample:
- Up to the No. 4 (4.75 mm) sieve: single-set sieving.
- From 4.75 mm to 9.5 mm: single-set or composite sieving.
- 19 mm and above: composite sieving.
Method A or Method B
The two methods differ in how finely results are reported and where they can be used:
| Question | Method A | Method B |
|---|---|---|
| Reporting precision | Results to the nearest 1% | Results to the nearest 0.1% |
| Composite sieving allowed? | Yes; Method A is required for composite sieving | No; single-set sieving only |
| Largest particle size | Single-set or composite; composite is used for larger particles (19 mm and above) | No. 4 (4.75 mm) sieve or smaller |
| Referee role | The referee method, unless the requesting authority specifies otherwise | Not designated as the referee method |
Three sample-processing procedures
The standard describes three ways to process the sample before sieving: moist, air dry and oven dry. Which one applies is set by the standard’s own text and the project specification.
Related standards and where the boundaries sit
D6913 is one of several soil-testing standards that meet at particle size. The rows below summarize each standard’s published scope.
| Standard | What the published scope says |
|---|---|
| ASTM D5519 | Named in the D6913 scope as the standard for particles larger than the 3 in. (75 mm) upper limit. |
| ASTM D6913/D6913M | Sieve analysis from the 3 in. (75 mm) sieve to the No. 200 (75 µm) sieve. |
| ASTM D7928 | Named in the D6913 scope as the standard for particles finer than the No. 200 (75 µm) sieve. |
| ASTM D2487 | The soil classification standard. It states that classification is based on laboratory determination of particle-size characteristics, liquid limit and plasticity index. Its group symbol is based on the portion passing the 3 in. (75 mm) sieve, and a dual symbol is used when the soil contains 5 to 12% fines or when the liquid limit and plasticity index plot in the crosshatched area. It applies to naturally occurring soils. D2487 does not name D6913. |
| ASTM D422 | Published by ASTM as Standard Test Method for Particle-Size Analysis of Soils, status withdrawn in 2016, with no replacement named by ASTM. |
For the same sieving idea applied to aggregates rather than soils, see the CASRAI guide to ASTM C136 sieve analysis of fine and coarse aggregates.
Where it matters for labs and clinics
The practical value of the scope is in deciding what a gradation request actually needs. A sample that contains material larger than 75 mm falls outside D6913, and so does the fraction finer than 75 µm. A report that needs the full size range of a soil therefore draws on more than one standard, and the laboratory should say which standard produced which part of the curve.
The scope also names materials the method is not meant for: fibrous peat that changes particle size during drying, washing or sieving; soils containing extraneous matter such as organic solvents, oil, asphalt or wood fragments; and materials with cementitious components such as cement, fly ash, lime or other stabilization admixtures. For friable soils that break down during sieving, and soils that do not readily disperse, the scope warns that results may be inconsistent and that the precision statement does not apply. In those cases a reported gradation should not be presented as carrying the standard’s stated precision.
For background on the disciplines that use this data, see CASRAI’s guides to soil science, geology and civil engineering.
Common misunderstandings
- “D6913 covers every particle size.” It does not. It is bounded at 75 mm and 75 µm, with other standards named for the coarser and finer fractions.
- “D6913 replaced D422.” ASTM lists D422 as withdrawn in 2016 with no replacement named.
- “There is one D6913 procedure.” There are two methods (A and B) and three sample-processing procedures, and the right combination depends on the maximum particle size and the reporting precision required.
- “Sieving classifies the soil.” Sieve analysis produces gradation data. Classification is a separate step defined in standards such as D2487, which also uses liquid limit and plasticity index.
FAQ
What is ASTM D6913?
It is the ASTM test method for the particle-size distribution (gradation) of soils using sieve analysis, covering particles between the 3 in. (75 mm) and No. 200 (75 µm) sieves.
What is the difference between Method A and Method B?
Method A reports results to the nearest 1% and is required for composite sieving. Method B reports to the nearest 0.1%, is limited to single-set sieving and applies to a maximum particle size of No. 4 or smaller.
How long does the test take?
ASTM states a typical duration of two to three days, depending on sample size and soil type.
Is ASTM D422 still current?
No. ASTM lists D422 as withdrawn in 2016, with no replacement named.
Sources
- ASTM International, D6913/D6913M-17, Standard Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis, checked 2026-10-29.
- ASTM International, D2487-17(2025), Standard Practice for Classification of Soils for Engineering Purposes, checked 2026-10-29.
- ASTM International, D422-63(2007)e2, Standard Test Method for Particle-Size Analysis of Soils (Withdrawn 2016), checked 2026-10-29.
