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ASTM D1140: Determining the Amount of Material Finer than 75-μm (No. 200) Sieve in Soils by Washing
The wash-sieve determination of the silt-and-clay fraction of a soil — the single number that decides whether a material classifies as coarse- or fine-grained and whether it qualifies as select fill.
| Designation | ASTM D1140 |
| Setting | Laboratory |
| Service line | Construction Materials Testing |
Testing is performed to the current edition of ASTM D1140 referenced by your project specification. This page is a plain-language overview, not a substitute for the published standard.
What the ASTM D1140 test measures
ASTM D1140 measures the percentage of a soil finer than the No. 200 sieve, the silt and clay fraction, by washing the sample over that sieve. It is the soils version of ASTM C117 and the single fastest way to tell whether a material is coarse-grained or fine-grained, whether it meets a select fill or drainage layer specification, and whether it will be sensitive to moisture during compaction.
How the ASTM D1140 test works, step by step
A representative specimen is oven dried and weighed. It is soaked, often with a dispersing agent for clayey soils, and then washed over a nested No. 40 and No. 200 sieve until the wash water runs clear. Material retained is dried and weighed. The mass that washed through is the fines content, as a percentage of the original dry mass. Method A soaks in water alone; Method B uses a dispersing solution and is required for soils with plastic fines.
What the numbers mean
Under the Unified Soil Classification System, less than 5 percent fines is a clean sand or gravel, 5 to 12 percent is dual-classified, and more than 12 percent carries a fines modifier. More than 50 percent fines makes the soil fine-grained and moves the classification to ASTM D4318 plasticity. Structural fill specifications commonly limit fines to 15 to 35 percent; drainage aggregate and pipe bedding may be limited to 5 percent or less.
What can throw the result off
Testing without a dispersant on a clayey soil leaves fines clinging to sand grains and underreports the result. Losing material through an overfilled sieve, and reporting a dry sieve minus-200 as if it were a washed value, are the other frequent problems.
Common questions about ASTM D1140
Is this the same as a gradation?
No. It is a single-point determination of the fines content. A full gradation under ASTM D6913 includes a wash step and gives every size, but when the specification only limits fines, D1140 answers the question faster and cheaper.
Why Method B?
Plastic clays do not disperse in plain water. Method B with sodium hexametaphosphate is required when the soil has measurable plasticity.
How we help with ASTM D1140 testing
We run D1140 on fill sources, import material, and in-place subgrade as part of earthwork quality control, with same-day turnaround so a fill source can be approved or rejected before the trucks are dispatched.
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