To:



TEST METHOD FOR THE GRAIN-SIZE ANALYSIS OF GRANULAR SOIL MATERIALS

[pic]

GEOTECHNICAL TEST METHOD

GTM-20

Revision #4

GEOTECHNICAL ENGINEERING BUREAU

APRIL 2007

GEOTECHNICAL TEST METHOD:

TEST METHOD FOR THE GRAIN-SIZE ANALYSIS OF GRANULAR MATERIALS

GTM-20

Revision #4

STATE OF NEW YORK

DEPARTMENT OF TRANSPORTATION

GEOTECHNICAL ENGINEERING BUREAU

APRIL 2007

TABLE OF CONTENTS

1. SCOPE 3

2. SUMMARY OF METHOD 3

3. EQUIPMENT 4

4. SAMPLE SIZE AND PREPARATION 5

4.1 Sample Size for Granular Construction Items 5

4.2 Sample Size for All Other Materials 5

4.3 Condition the Sample 5

4.4 Prepare Sieve Analysis Data Sheet 5

5. TEST PROCEDURE 6

5.1 Initial Separation of the Plus and Minus 1/4 in. (6.3 mm) Particles 6

5.2 Weigh the Plus 1/4 in. (6.3 mm) Portion of the Sample 6

5.3 Sieve the Plus 1/4 in. (6.3 mm) Material 7

5.4 Weigh the Minus 1/4 in. (6.3 mm) Portion of the Sample 7

5.5 Determine the Moisture Content of the Minus 1/4 in. (6.3 mm) Material 7

5.6 Wash the Minus 1/4 in. (6.3 mm) Sample 8

5.7 Sieve the Minus 1/4 in. (6.3 mm) Sample 8

6. COMPUTATIONS 10

6.1 Rounding Numbers 10

6.2 Correct the Weight of Minus 1/4 in. (6.3 mm) Material for Moisture Content 10

6.2.1 Determine the Moisture Content 10

6.2.2 Compute the Dry Weight of the Minus 1/4 in. (6.3 mm) Material 10

6.3 Compute the Total Dry Weight of the Sample 10

6.4 Compute the Particle Size Distribution of the Plus 1/4 in. (6.3 mm) Material 10

6.4.1 Compute the Percent Retained 10

6.4.2 Compute the Percent of Total Sample Passing 11

6.5 Compute the Particle Size Distribution of Minus 1/4 in. (6.3 mm) Material 11

6.5.1 Compute the Percent Retained 11

6.5.2 Compute the Percent Passing Based on Minus 1/4 in. (6.3 mm) Material 11

6.5.3 Compute the Percent Passing Based on Total Weight 11

6.6 Compute the Plasticity Indicator 11

7. CHECKS AND BALANCES 12

7.1 Check the Computed Percent Retained 12

7.1.1 For the Plus 1/4 in. (6.3 mm) Material 12

7.1.2 For the Minus 1/4 in. (6.3 mm) Material 12

7.2 Check the Computed Percent Passing 12

7.2.1 For the Plus 1/4 in. (6.3 mm) Material 12

7.2.2 For the Minus 1/4 in. (6.3 mm) Material 12

APPENDIX 13

A. Sieve Analysis Data A-1

B. Requirements of Sieves B-1

1. SCOPE

This test method describes the determination of particle size distribution in soils and other material items of Departmental Specifications other than topsoil. The method covers material in which the particle sizes are larger than No. 200 (0.075 mm) and smaller than 4 in. (100 mm). For the distribution of particle sizes smaller than No. 200 (0.075 mm), a sedimentation process utilizing a hydrometer is necessary. For material in which the particle sizes are larger than 4 in. (100 mm), the distribution is determined visually.

2 SUMMARY OF METHOD

A weighed sample of material is separated through a series of sieves (or screens) with progressively smaller openings. Particle size distribution is determined by weighing the material retained on each of the sieves and dividing these weights by the total weight of the sample. A correction is made for the moisture content of the sample so that all calculations are based on dry weight. The method requires drying, washing, and a series of separations.

3. EQUIPMENT

The following equipment is required for this test:

Platform Scale - With a capacity of at least 36 lbs. (16 kg). The scale shall be accurate, and be readable to 0.01 lb (5 g).

Balance - Triple beam or other with a capacity of at least 5½ lbs. (2500 g). It shall be accurate, and be readable to 0.1 g.

Sieves - A series of sieves which conform to the requirements of AASHTO M-92-91, page 87 - Table No. 1 (excluding Column 7). See Appendix B.

Containers - Metal pans of sufficient size to contain at least 1.1 lb. (500 g) of material for moisture content determination.

Large Pans - Metal pans of sufficient dimension to contain the total sample for mixing and conditioning.

Drying Apparatus - An infrared dryer, oven, hot plate or stove capable of drying samples without causing alteration of the material’s particle size or shape, and without causing the loss of material. Ovens must have a temperature control and be capable of maintaining a temperature of 230(( 9( F (110( ( 5( C). If a stove or hot plate is used, a bed of sand is required between the sample containers and heat source.

Miscellaneous - A flat bottom scoop, a wood mallet, an assortment of brushes, a large weighing pan for the platform scale and leveling boards for the platform scale and balance.

4. SAMPLE SIZE AND PREPARATION

4.1 Sample Size for Granular Construction Items.

For granular construction items, obtain a sample of the material in accordance with the appropriate Departmental publication. The sample shall be transported to the testing facility in a clean container, as approved by the Geotechnical Engineering Bureau. Check that the sample size meets the minimum weight requirements of the Departmental publication (45 lbs. (20 kg)).

2. Sample Size for All Other Materials.

For materials other than granular construction items, the samples should be large enough to be representative of the material being tested. In general, the larger the nominal maximum particle size, the larger the sample should be in order to be considered representative. The following may be considered a guide (not a requirement) for sample weights based on particle size:

|Nominal Maximum Particle Size |Sample Weight |

|2 in. (50 mm) |45 lbs. (20 kg) |

|¾ in. (19 mm) |15 lbs. (7 kg) |

|¼ in. (6.3 mm) |2 ½ lbs. (1 kg) |

4.3 Condition the Sample.

If the sample is wet, it should be dried to a moist condition. Drying may be accomplished by the use of air, oven, electric hot plate, stove, or infrared dryer.

Note 1. If the sample is a recycled material, or if it contains any bituminous material (asphalt, etc.), drying may only be accomplished by use of air drying or in an oven not exceeding 140( F (60( C).

Note 2. During any drying operation, care shall be exercised so as not to alter particle size or shape, and to prevent the loss of material.

4.4 Prepare Sieve Analysis Data Sheet.

Complete the heading of form SM-15b, "Geotechnical Engineering Bureau Sieve Analysis Data" (Appendix A), and be prepared to enter values from the test. If testing a granular construction item, also complete the specification section of the data sheet (optional).

5. TEST PROCEDURE

During the entire test, care should be exercised to prevent the loss of sample material. This entails proper labeling and organization of the samples as well as careful transference of material during the test. When the procedure requires several separations (or sievings), be sure to keep each of the sieved portions together for further tests and weighings. Only after all of the tests, checks, and balances have been successfully completed, may any portion of the sample be discarded.

When testing small samples, perform all weighings using the balance rather than the platform scale, as prescribed in the procedure. Record the values to the nearest 0.1 g. Form SM 15b uses US Customary Units (lbs.) for recording the larger weights (weight Plus ¼ in. (6.3 mm) material, etc.) and International System of Units (g) for recording the smaller weights (moisture content, weight Minus ¼ in. (6.3 mm) material, etc.).

5.1 Initial Separation of the Plus and Minus ¼ in. (6.3 mm) Particles.

Screen the moist or dry sample on a ¼ in. (6.3 mm) sieve in order to divide it into plus ¼ in. (6.3 mm) and minus ¼ in. (6.3 mm) portions. If an excessive amount of silt or clay adheres to the plus ¼ in. (6.3 mm) material, it should be screened again after additional drying. If the sample does not have any plus ¼ in. (6.3 mm) particles, proceed in accordance with Section 5.4.

Note 1. During this initial sieving, care should be exercised to prevent "overloading" the ¼ in. (6.3 mm) sieve. This condition exists when an excessive amount of soil is placed on the sieve, leaving an insufficient amount of sieve openings for the material to pass through. To avoid "overloading", the sample must be divided into smaller portions and sieved separately.

Note 2. In some soils a significant amount of the particles will adhere together and form silt and/or clay balls, which may be mistaken for plus ¼ in. (6.3 mm) particles. Care must be taken to insure that such balls pass through the ¼ in. (6.3 mm) screen. It may be necessary to run a wood mallet over the material on the screen for this purpose, but be careful not to pulverize the actual particles or damage the sieve.

5.2 Weigh the Plus ¼ in. (6.3 mm) Portion of the Sample.

Once the plus ¼ in. (6.3 mm) portion has fully dried (to the point where there is no visible sign of moisture), weigh the sample to the nearest 0.01 lb. and record this value on Line A of the data sheet.

Note 1. Prior to weighing the plus ¼ in. (6.3 mm) portion, check for particles larger than 4 in. (100 mm). Remove such material and weigh it to the nearest 0.01 lb. and make a note of it on the data sheet. These particles should not be included in the test.

5.3 Sieve the Plus ¼ in. (6.3 mm) Material.

The series of sieves used shall comply with the particle size requirements of the material being tested or as requested by the Engineer or Laboratory Supervisor. The sieves shall be arranged such that the largest opening sieve is on top, with the sizes progressively decreasing. The last sieve shall be the ¼ in. (6.3 mm) followed by a "pan". During the sieving process, some additional material will pass through the ¼ in. (6.3 mm) sieve into the "pan". Weigh this "pan" material to the nearest 0.01 lb. and record on Line B of the data sheet. Add this material to the minus ¼ in. (6.3 mm) material obtained in Section 5.1. Weigh the material retained on each sieve to the nearest 0.01 lb. and record these values in Column 1 of the data sheet. Sum the values in Column 1 and record this value at the bottom of that Column. Compute the total weight of plus ¼ in. (6.3 mm) material by subtracting Line B from Line A, and record this value on Line C.

Check for excessive loss of material during the test. The total dry weight of the plus ¼ in. (6.3 mm) material (Line C) should be within 0.4% of the sum of the weights retained on the sieve (Total of Column 1).

[pic]1

Note 1. If the sieving is performed using a mechanical shaker, the sieves shall be shaken no less than 3 minutes and no more than 5 minutes. If performed manually, the sieve shall be shaken no less than 5 minutes.

Note 2. Very often particles will get stuck in the mesh of a sieve. Such material shall be removed from the mesh and weighed as being retained on that sieve. Do not force particles through the sieves.

5.4 Weigh the Minus ¼ in. (6.3 mm) Portion of the Sample.

Weigh the minus ¼ in. (6.3 mm) portion of your sample to the nearest 0.01 lb. and record this value on Line D of the data sheet.

5.5 Determine the Moisture Content of the Minus ¼ in. (6.3 mm) Material.

Immediately mix the minus ¼ in. (6.3 mm) portion of the sample thoroughly. Obtain a minimum 1 lb. (500 g) sample (see Note 4) of this material and place it into a container of known weight for a moisture content determination. The weight of the container and the weight of the soil and container should be recorded on Lines J and H respectively to the nearest 0.1 g. Dry the sample to a constant weight as noted below. After drying, allow the sample to cool and reweigh it to the nearest 0.1 g and record this value on Line I.

Note 1. If the sample being tested is a recycled material, or if it contains any bituminous material (asphalt, etc.), it shall be dried to a constant weight by air drying or in an oven not exceeding 140( F (60( C).

Note 2. If a hot plate or stove is used, place the container holding the sample on a pan containing a thin layer of sand to prevent spattering and/or fracturing of the soil particles during the drying process.

Note 3. If an oven is used, the sample should be maintained at a temperature of 230( ( 9( F (110( ( 5( C) for a minimum of 12 hours or until it maintains a constant weight.

Note 4. When a sample contains less than 1 lb. (500 g) of minus ¼ in. (6.3 mm) particles, moisture content and gradations (Sections 5.5, 5.6 & 5.7) may be performed on the smaller amount only if the sample is considered to be representative by the requestor.

5.6 Wash the Minus ¼ in. (6.3 mm) Sample.

Obtain a 300 ( 5 g portion of the moisture content sample (from Section 5.5) and record this weight to the nearest 0.1 g on Line N of the data sheet. Wash this sample on a No. 200 (0.075 mm) sieve to remove all fines from the sample. It is suggested to wash the sieve sample over a white basin to make it easier to see when the wash water is clean. After the sample is thoroughly washed, carefully transfer the sample from the sieve to a container for drying. Dry the sample in accordance with the provisions of Section 5.5. Weigh the dried sample to the nearest 0.1 g and record this value on Line O of the data sheet.

Note 1. Examine the No. 200 (0.075 mm) sieve prior to each washing to determine its condition. Replace the sieve if any holes or cracks are noticed in the solder or mesh, or if the sieve's mesh is stretched excessively. A new No. 200 (0.075 mm) sieve must be washed with soap and water prior to initial use.

Note 2. The No. 200 (0.075 mm) sieves are delicate. Fingertips may be used to agitate the sample during washing, but do not apply pressure to the mesh itself.

Note 3. Do not allow water to overflow or splash out of the sieve. This may cause a loss of material and lead to inaccurate results. Tapping the side of the sieve will help break the surface tension as well as eliminate clogging.

5.7 Sieve the Minus ¼ in. (6.3 mm) Sample.

Sieve the dry washed sample remaining from Section 5.6. The series of sieves used shall comply with the particle size requirements of the material being tested or as requested by the Engineer or Laboratory Supervisor. The sieves shall be arranged such that the largest mesh sieve is on top, with the mesh sizes progressively decreasing. The last sieve should be the No. 200 (0.075 mm) followed by a "pan". Weigh the material retained on each sieve and the "pan", and record the weights to the nearest 0.1 g in Column 5 of the data sheet. Sum the values in Column 5 and record this value at the bottom of that Column.

[pic]2

Check for excessive loss of material during the test. Total dry weight of the minus ¼ in. (6.3 mm) material after the wash (Line O) should be within 0.4% of the sum of the weights retained on the sieves (Total of Column 5).

Note 1. If the sieving is performed using a mechanical shaker, the sieves shall be shaken no less than 3 minutes and no more than 5 minutes. If performed manually, the sieves shall be shaken no less than 5 minutes.

Note 2. It is important to weigh all of the material retained on each sieve. Using brushes, remove all of the material on the sieves so that it may be weighed as being retained on that sieve. Cleaning the sieves with brushes will also prevent adding leftover material to subsequent tests.

6. COMPUTATIONS

6.1 Rounding Numbers.

For all computed results, round the values in the following manner: Compute the values to one place beyond the required significant figures. If the extended value is less than 5, leave the last required digit unaltered. If it is greater than 5, round the last required digit up one unit. If the extended value equals 5, round the last required digit to the nearest even number.

6.2 Correct the Weight of Minus ¼ in. (6.3 mm) Material for Moisture Content.

6.2.1 Determine the moisture content.

Compute the weight of water by subtracting Line I from Line H and record this value on Line K. Compute the weight of dry material by subtracting Line J from Line I and record this value on Line L. Compute moisture content by dividing weight of water (Line K) by the weight of the dry material (Line L) and multiply this value by 100 and record to the nearest 0.1% on Line M.

[pic]3

6.2.2 Compute the dry weight of the minus ¼ in. (6.3 mm) material.

Divide the total weight of minus ¼ in. (6.3 mm) material (Line D) by the quantity 1 plus the moisture content (Line M) divided by 100 and record this value on Line E.

6.3 Compute the Total Dry Weight of the Sample.

Compute the total dry weight by adding the dry weight of the plus ¼ in. (6.3 mm) material (Line C) to the dry weight of the minus ¼ in. (6.3 mm) material (Line E) and record this value on Line F.

6.4 Compute the Particle Size Distribution of Plus ¼ in. (6.3 mm) Material.

6.4.1 Compute the percent retained.

Divide the weight retained on each sieve (in Column 1) by the total dry weight of the sample (Line F). Multiply each value by 100 and record the results to the nearest 0.1% in Column 2 opposite the respective sieve. Sum the values in Column 2 and record this value at the bottom of Column 2.

6.4.2 Compute the percent of total sample passing.

The smallest sieve in which all of the sample passes will have 100% total sample passing. For the rest of the sieve sizes, compute the percent total sample passing by subtracting the percent retained (in Column 2) from the percent of total sample passing computed for the previous sieve size. This makes it necessary to work from the top down. Record each of the values computed to the nearest 0.1% in Column 3 of the data sheet. For checking specification criteria, round the values in Column 3 to the nearest one percent and record these values in Column 4.

6.5 Compute the Particle Size Distribution of Minus ¼ in. (6.3 mm) Material.

6.5.1 Compute the percent retained.

Divide the weight retained on each sieve (in Column 5) by the weight of the minus ¼ in. (6.3 mm) sample prior to washing (Line N). Multiply each value by 100 and record the results to the nearest 0.1% in Column 6. Sum the values in Column 6 and record this value at the bottom of the Column.

6.5.2 Compute the percent passing based on minus ¼ in. (6.3 mm) material.

Subtract the percent retained, on the largest sieve used on the minus ¼ in. (6.3 mm) material, from 100% to determine the percent passing for that sieve. For the rest of the sieves, compute the percent sample passing by subtracting the percent retained from the percent sample passing computed for the previous sieve size. Record these values as percents to the nearest 0.1% in Column 7.

6.5.3 Compute the percent passing based on total weight.

Multiply the percents passing, computed in Section 6.5.2 (Column 7), by the percent of the total sample passing the ¼ in. (6.3 mm) sieve (last value in Column 3), for each sieve size. Divide each value by 100 to get percent and record to the nearest 0.1% in Column 8. There is no check for the values in Column 8 so be sure the computations are correct. For checking specification criteria, round the values in Column 8 to the nearest one percent and record these values in Column 9.

6.6 Compute the Plasticity Indicator.

The plasticity indicator is used by the Geotechnical Engineering Bureau to aid in the evaluation of Atterberg Limit test results. Divide the percent passing the No. 200 (0.075 mm) (In Column 7) by the percent passing the No. 40 (0.425 mm) (In Column 7) and record on Line P of the data sheet.

7. CHECKS AND BALANCES

7.1 Check the Computed Percent Retained.

7.1.1 For the plus ¼ in. (6.3 mm) material.

The total weight retained (Total of Column 1) divided by the total dry weight of the sample (Line F) and multiplied by 100, should be no more than (0.2% from the sum of the percents retained (Total of Column 2).

[pic]4

7.1.2 For the minus ¼ in. (6.3 mm) material.

The total weight retained (Total of Column 5) minus the "Pan" material, divided by the weight of dry minus ¼ in. (6.3 mm) material before wash (Line N) and multiplied by 100, should be no more than (0.2% from the sum of the percents retained (Total of Column 6).

[pic]5

7.2 Check the Computed Percent Passing.

7.2.1 For the plus ¼ in. (6.3 mm) material.

The sum of the percent retained (Total of Column 2) plus the percent of total sample

passing the ¼ in. (6.3 mm) sieve (last value of Column 3) must equal 100%.

[pic]6

7.2.2 For the minus ¼ in. (6.3 mm) material.

The sum of the percent retained (Total of Column 6) plus the percent passing the No. 200 (0.075 mm) sieve, based on minus ¼ in. (6.3 mm), (last value of Column 7), must equal 100% .

[pic]7

APPENDIX

[pic]

[pic]

-----------------------

[pic]

[pic]

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download