DRY SIEVE ANALYSIS FOR SANDS AND GRAVELS
(excerpted, with minor modifications, from USGS Open-File Rpt 000-358;
http://pubs.usgs.gov/of/2000/of00-358/text/chapter1.htm)
Introduction
Grain size is a powerful tool for describing a site’s geomorphic setting, interpreting the geomorphic
significance of fluid dynamics in the natural environment, and distinguishing local versus regional sediment
transport mechanisms. Grain size is also a dominant controlling factor in sediment geochemistry. Cations
derived from mineral weathering and pollution sources are preferentially adsorbed onto clay, which has the
highest surface area to volume ratio of any particle size class.
The grain size distribution of a sediment sample is determined by any one of a number of techniques or
combination of techniques, depending on the range of sizes present in a sample. For this procedure, “fines” are
any particle smaller than 63.5 microns. Sand is 63.5 microns to 2 mm in diameter. Gravel is larger than 2 mm.
Theory
Sieving efficiency increases with reduction in load (i.e. smaller sample size) and the maximum sieve
load diminishes with mesh size, but it is the quantity of finer near-mesh size particles that actually determines
sieving efficiency (Royse, 1970). Twenhofel and Tyler (1941) recommended 40 g of sandy sediment as the
maximum load for 8-inch diameter sieves. When selecting a procedure, it is important to remember that sieves
sort material not only according to size, but also according to the shape and roundness of the particles (Sahu,
1965; Kennedy and others, 1985).
Procedures
Separating sizes in samples that are predominantly gravel and sand
As collected, your sample is a mixture of gravel, sand, silt, and mud. You must first separate the fine
fraction from the sand and gravel fractions. First determine if you sample has fines. If you determine that your
sample has less than a few percent of, you should not dry sieve. Follow the pipetting procedures instead.
If you sample contains gravel, you should have between 250 and 500 g of material (depending on the size of the
gravel). If there is no gravel present, 40 to 50 g is usually sufficient. If you have more material than is needed,
homogenize and split the sample. The following procedures are done on the split (subsample).
IMPORTANT: If your sample has more than a few percent fines, you will need to do both pipetting and dry
sieving to determine its grain size distribution. Do the pipetting first!
Disaggregating Unconsolidated Sediments
1. Dry the sample in a drying oven at, or slightly under, 100 C. When the samples are dry (overnight is usually
sufficient), allow them to cool before weighing them. Weight the sample and record the weight on your
data sheet. Gross coarse weight minus the weight of the beaker gives net coarse weight.
2. Spread the dried sample out on a large sheet of paper and gently crush it with your fingertips to disaggregate
the grains, being careful not to break individual grains. Once the dried sample is disaggregated, it is ready
to be sieved.
Sieving
1. Assemble a 0.5 phi sieve set, including a cover and a catch pan.
2. Retain all particles larger than 8mm (or whatever the largest sieve is) as one class, and weigh, and retain.
3. Put the rest of your dried sample in the top sieve and place the sieve stack on the ro-tap, making sure that it
is properly seated.
4. Close the door and agitate for a minimum of 15 minutes.
5. Any fines retained in the bottom pan should retain and weighed to the nearest 0.01 g.
6. Carefully remove the fraction retained on each sieve, being careful not to disrupt the sieve mesh or lose any
of the sediment.
7. Weigh each fraction retained to the nearest 0.01 g. Record the weigh on a data sheet.
8. Examine eaxh sieve fraction (after it is weighed) and estimate the percent of aggregates in each fraction.
Record the percentage of aggregates in each size fraction. If any size fraction has more than 25% aggregate
grains it should be re-dissagregated and re-sieved.
9. If there is a significant amount of very coarse material in your sample (larger than the largest sieve size),
assemble a bank of gravel-fraction sieves (the cover, the sieves, and a catch pan); sieve to separate, weigh
each phi class, and record the weights.
10. Calculate the total weight of the coarse fractions and record this on your data sheet. Any difference between
this weight and your starting weight is error and should be noted as such..
11. Put your data into an Excel spreadsheet and e-mail the spreadsheet to your instructor.
Selected References
Folk, R.L., 1974, The petrology of sedimentary rocks: Austin, Tex., Hemphill Publishing Co., 182 p.
Kennedy, S.K., Meloy, T.P., and Durney, T.E., 1985, Sieve data - size and shape information: Journal
Sedimentary Petrology, v. 55, p. 356-360.
Royse, C.F., 1970, An introduction to sediment analysis: Tempe, Arizona, Arizona State University, 180 p.
Sahu, B.K., 1965, Theory of sieving: Journal Sedimentary Petrology, v. 35, p. 750-753.
Twenhofel, W. H., and Tyler, S. A., 1941, Method of study of sediments. McGraw Hill, New York, 183 p.
Table 1. Correlation of grain size phi classes with sieve sizes and numbers for A.S.T.M.
and Tyler mesh sieves.
PHI
CLASS
NOMINAL SIEVE
OPENING (MM)
4
3
2
1
0
0.062
0.125
0.250
0.500
1.000
-1
-2
-3
-4
-5
2.000
4.000
8.000
16.000
32.000
SIEVE SIZES
A.S.T.M. # TYLER #
230
120
60
35
18
10
5
5/16
5/8
1 1/4
250
115
60
32
16
9
5
2.5
.624
-
SIZE
FRACTION
SAND
GRAVEL
Figure 1. Summary of grain size phi classes, mm sizes, grain size terms, settling velocities, and sieve sizes and
numbers.
SIEVE ANALYSIS DATA SHEET
Sample #: __________________________________
Analyst:________________________________
Sample description:
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
__________________________________________________________________________________________
Total Dry Sample Weight: _____________________
Total Fine-Fraction Weight: ____________________
Total Coarse-Fraction Weight: __________________
MESH
MM
Ø
RAW
%
CORRECTED CUMMULATIVE CUMMULATIVE
WEIGHT AGGREGATE WEIGHT
WEIGHT
PERCENT
add additional rows as necessary . . .
4
5
6
7
8
9
10
>10
Sum of Weights in Phi Classes: ______________________
Minus Initial Aliquot X 50: ______________________
Equals: ______________________
INDIVIDUAL
PERCENT