To:



TEST METHOD FOR RAPID EARTHWORK COMPACTION CONTROL

[pic]

GEOTECHNICAL TEST METHOD

GTM-6

Revision #1

GEOTECHNICAL ENGINEERING BUREAU

APRIL 2007

GEOTECHNICAL TEST METHOD:

TEST METHOD FOR RAPID EARTHWORK COMPACTION CONTROL

GTM-6

Revision #1

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 3

4. PROCEDURE AND RECORDS 9

4.1 Test Location Data 9

4.2 Filling the Volumeter 9

4.3 Testing and Sampling 10

4.4 Failure of Compaction Control Tests 17

4.5 Reports 17

5. IMPORTANT DO'S AND DON'TS FOR THE INSPECTOR 17

APPENDIX 18

A. Equipment A-1

B. Background and Theory B-1

Figure B-1 B-3

Figure B-2 B-4

Figure B-3 B-5

C. Form 384a Compaction Control Data Sheet C-1

1. SCOPE

This test method describes the procedures for rapidly determining whether the percent or degree of compaction obtained by the compaction operations conforms to the requirements of the New York State Department of Transportation Standard Specifications.

This method may be used only for soils where the statewide compaction curves are valid.

2. SUMMARY OF METHOD

The test consists of the following steps which are explained in the test procedure:

- Determining the Field Wet Density

- Determining the weight of a 1/30 ft.3 (944 cm3) volume of the soil after compacting it in a mold in accordance with AASHTO T-99 Method C.

- Reading off the Highest Required and the Lowest Allowable Wet Densities from the Compaction Control Tables contained in this manual.

- Determining whether a test passes or fails by comparing the Field Wet Density against the Highest Required and the Lowest Allowable Wet Densities.

- In some cases, the moisture content has to be found in order to determine whether a test passes or fails.

3. EQUIPMENT

The equipment necessary for compaction control testing on projects supervised by State Forces is issued by the Geotechnical Engineering Bureau to the Regional Geotechnical Engineers, who in turn issues such equipment to each project as needed. One or more compaction control “kits” are issued to each project where required. Each “kit” should consist of the following items:

3.1 Sand Cone Displacement Volumeter (Figure 1): The sand cone displacement volumeter consists of a calibrated container for sand; a conical, stopcock-controlled outlet; and a base plate. The base of the conical outlet shall have a nominal interior diameter of 6 in. (150 mm), and shall be flared flat to fit the base plate. The base plate and container are matched and fitted; they are not to be interchanged with other units. The sand cone displacement volumeter has been calibrated to read volume directly in ft3.

3.2 Density Cylinder: 1/30 ft.3 (944 cm3) volume, in accordance with AASHTO Standard Density Test T-99 or Geotechnical Engineering Bureau Drawing No. SM 1563AR-2.

3.3 Rammer: Refer to AASHTO T-99 or T-180.

[pic]

Figure 1 Volumeter and known Volume Cylinder with Sand Cone Base Plate.

[pic]

Figure 2 5 ½ lb. (2.5 kg) Rammer and 1/30 ft.3 (944 cm3) Density Cylinder

with Base Plate and Collar.

3.4 Scale: Minimum of 30 lb. (13.6 kg) capacity to weigh directly to the nearest 0.01 lb. (5 g).

3.5 Balance: Approximately 1600 g capacity, to weigh directly to the nearest 0.1 g.

3.6 Steel Straight Edge: 9 to 12 in. (230 mm to 300 mm).

3.7 Sieve: ¾ in. (19 mm).

3.8 Pail: 10 qt. (9.5 L) size or larger.

3.9 Knife: Butcher.

3.10 Hammer: 1 lb. (0.5 kg) minimum weight.

3.11 Chisel: 1 in. (25 mm) blade width by 9 in. (230 mm) length.

3.12 Skillet: 12 in. (300 mm) diameter.

3.13 Spoon: Basting type.

3.14 Spatula: 6 in. (150 mm) length of blade.

3.15 Cans: Friction top with covers, 1 gal (3.7 L) size.

3.16 Pans: 24 in. (600 mm) square and 3 to 4 in. (75 mm to 100 mm) high.

3.17 Tares: Numbered cake pans or pie plates for moisture content determinations.

3.18 Paint Brush: 2 in. (50 mm) size.

3.19 Calibrated Sand: Clean dry sand.

(a) Standard Ottawa Sand;

or (b) Washed sand passing the No. 20 (0.85 mm) sieve and retained on the No. 40 (0.425 mm) sieve;

or (c) Flint Shot Grade, Size 2Q.

Two 100 lb. (45 kg) bags of this sand should be available at all times in the project compaction control building.

[pic]1

3.20 Slide Rule (Field Wet Density Calculator): The Field Wet Density Calculator is used to determine the as-compacted density of the minus ¾ in. (19 mm) fraction (See Fig. 3). The Field wet Density Calculator gives the field wet density of the minus ¾ in. (19 mm) fraction by the following formula:

Where:

FWD(-¾) = Field wet density of the minus ¾ in. (19 mm) fraction in lbs/ft3

W(-¾) = Weight of the minus ¾ in. (19 mm) fraction in lbs.

V = Volume of the hole in ft3.

W(+¾) = Weight of the plus ¾ in. (19 mm) fraction in lbs.

SG = Specific gravity of solids (2.65 used)

[pic]

(a)

[pic]

(b)

Figure 3 Field Wet Density Calculators

3.21 Moisture Content Table and a Set of Compaction Control Tables: The moisture content table and set of compaction control tables are used for finding the moisture content and wet densities. These tables are included in this manual.

3.22 Known Volume Cylinder: Used to check volumeter (See Fig. 1).

A gas or electric stove is also required but this is included in the specifications with equipment to be supplied by the Contractor as part of the item for laboratory building.

4. PROCEDURE AND RECORDS

Form SM 384a (Appendix C) is used for recording the compaction control test data on construction projects where the test method described in this manual is used. A description of the test procedure follows (refer to Form SM 384a).

Form SM 384a uses US Customary Units (lbs.) for recording the larger weights (Plus ¾ in. (19 mm) Material, Weight of Cylinder & Soil, etc.) and International System of Units (g) for recording the smaller weights (soil & tare, tare, etc.).

4.1 Test Location Data

Before starting the test, enter the information required at the top of Form SM 384a and fill the Volumeter.

PIN, PROJECT, COUNTY, CONTRACT NO., INSPECTOR, and DATE OF TEST are self-explanatory.

LINES

Test No.: Tests for a project shall be numbered as required by MURK.

Station of Test: The location of the test should be determined accurately.

Offset: The location of the test should be determined accurately.

Type of Compactor: Self-explanatory.

Number of Passes per Layer: Passes are defined in the specifications.

Soil Type: Briefly describe the material tested so that the appropriate Family of Compaction Control Curves is used.

Depth Below Subgrade Surface: The required percent of maximum dry density for embankment material depends on the depth below subgrade surface.

4.2 Filling the Volumeter

To fill the volumeter:

a). Make sure the volumeter is empty.

b). Set the volumeter with the stopcock open on a firm, level area with the cone end up.

c). Fill the plastic container completely by pouring the sand into the cone. Keep the cone full until the sand stops flowing into the container.

d). Close the stopcock carefully and pour off the excess sand remaining in the cone.

e). If the volumeter is subject to movement or vibration during the filling operation or the closing of the stopcock, remove all the sand and start over.

f). At no time should the cone portion of the volumeter be removed from the cylinder. Removal or displacement by tightening or loosening of the cone will affect the calibration.

Keep the reserve container of sand covered (while not taking sand from it) to keep the sand from picking up moisture from the air.

As the volumeter is handled and transported, the sand will compact, and its level within the volumeter will drop. Do not add more sand. The measurement of the volume of the hole by the volumeter is based on loose volume of sand.

Damaged volumeters and/or base plates should be immediately removed from service. Volumeters which have been supplied by the Geotechnical Engineering Bureau and become damaged shall be returned to the Bureau.

4.3 Testing and Sampling

Dig a test hole as soon as possible after final compaction. Remove all loose and disturbed material at the test location. Level a small area and set the base plate firmly in place. Dig a hole through the opening in the plate, approximately equal in diameter to the hole in the base plate, and to a depth of approximately 6 in. (150 mm). The desired volume of the hole is about 0.1 ft.3 (2832 cm3). The volume should never be less than 0.06 ft.3 (1700 cm3). The hole should be dug rapidly and all removed material immediately placed in a previously weighed friction top can. The can should be covered to keep moisture loss from the sample to a minimum. Any material loosened during the digging operation should be removed from the hole and placed in a friction top can. Care should be exercised to avoid undercutting of the base plate and abrupt projections of embedded materials into the hole. After the hole has been prepared, measure its volume. Do not reclaim the sand form the hole.

[pic]

[pic]

[pic]

LINES

1 Volume of Hole: Set the volumeter on the base plate over the hole. Open the stopcock to permit the sand to flow into the hole. Traffic and equipment in the vicinity of the test area should be stopped while the stopcock is open. Vibrations will compact the flowing sand in the hole resulting in an incorrect test value. The test will be invalid if the apparatus is subject to movement or vibrations during the filling of the hole or the closing of the stopcock. After the sand stops flowing, close the stopcock and remove the apparatus. Hold the closed volumeter vertically with the cone end up. Invert the volumeter momentarily and return to the original position. Gently shake (do not jar) the apparatus just enough to level the sand. From the scale indicators on the container, read the top surface of the sand to the nearest 0.001 ft3. Repeat 2 times. Record the average of the 3 readings on Line 1 of the Compaction Control Work Sheet. (No individual reading should be greater than 0.001 ft3 more or less, than the average of the 3 readings.

2 Weight of Plus ¾ in. (19 mm): Sieve the soil material removed form the measured hole through a ¾ in. (19 mm) sieve. Weigh and record the material retained on the ¾ in. (19 mm) sieve to the nearest 0.01 lb.

3 Weight of Minus ¾ in. (19 mm): Weigh and record the material passing the ¾ in. (19 mm) sieve to the nearest 0.01 lb. Reserve a portion of this material in a covered container to be used if it is later found necessary to determine the moisture content.

4 Field Wet Density: Using the Field Wet Density Calculator in accordance with the instructions printed on the calculator, read and record the field wet density (-¾ in. (19 mm) fraction) to the nearest pcf.

Using the slide rule, note that the lower “Volume of Minus ¾ in.” (19 mm) scale increases to the left while the upper “Volume of Minus ¾ in.” (19 mm) scale increase to the right. It is not required to record the volume of minus ¾ in. (19 mm) on Form SM 384a. However, it may be helpful to you to jot down this value when it is obtained from the upper scale, so that you will be sure to set the lower arrow correctly.

5 Weight of Cylinder: Weigh the 1/30 ft.3 (944 cm3) density cylinder with base plate. Do not weigh the collar. Record the weight of the cylinder with base plate to the nearest 0.01 lb. Replace collar.

6 Weight of Cylinder and Soil: Compact the material passing the ¾ in. (19 mm) sieve in a 1/30 ft.3 (944 cm3) compaction cylinder in three layers, giving each layer 25 well distributed blows of the 5 ½ lb. (2.5 kg) rammer, freely dropped from a height of 12 in. (300 mm). The density cylinder shall rest on a uniform, rigid foundation, such as provided by a solid wood block of minimum dimension 10 in. W x 10 in. L x 12 in. H (250 mm W x 250 mm L x 300 mm H). The three layers should be approximately equal in thickness and when compacted, the last compacted layer will extend approximately ¼ to 1 in. (6.3 mm to 25 mm) above the cylinder into the collar. A wide-mouth pint container could be used for measuring the approximate amount of soil required per layer. After compaction, the collar is removed and the sample is trimmed and screeded with the steel straight edge so that the compacted soil is level with the top of the cylinder. Care should be exercised to assure a smooth and level surface. Do not remove the cylinder base plate. The sample and cylinder is then weighed to the nearest 0.01 lb.

7 Weight of Soil: Subtract the Weight of Cylinder (Line 5) from Weight of cylinder and Soil (Line 6) and record the result. Round off to the 0.1 lb. If the result is midway between tenths (ends in 5), round to the nearest even tenth.

8 Specified Density- % of Maximum: The minimum requirement is indicated in the specifications and depends upon whether the layer is being compacted and tested in the embankment above or below the bottom of the subgrade area or part of structure or trench backfill.

9 Compaction Control Table Number: From the soil type, determine the proper Compaction Control Table to use for this test. Record here. If the weight recorded on Line 7 is greater than 4.6, the soil is well graded, and Table II should be used, regardless of the appearance of the soil.

10 Highest Field Wet Density Required: Using the proper table (Recorded on Line 9) read and record the highest wet density indicated on the horizontal linen determine by the Weigh of Soil (Line 7) and Specified Density - % of Maximum (Line 8).

11 Lowest Field Wet Density Allowed: Using the same input as for Line 10, read and record the lowest wet density.

12 PASS: If the Field Wet Density (Line 4) is equal to or greater than the Highest Field Wet Density Required (Line 10), the test passes without further examination. Make a check mark here.

13 FAIL: If the Field Wet Density (Line 4) is less than the Lowest Field Wet Density Allowed (Line 11), the test fails without further examination. Make a check mark here.

14 Run Moisture: If the Field Wet Density (Line 4) is lower than the Highest Field Wet Density Required (Line 10), but not below the Lowest Field Wet Density Allowed (Line 11), it is necessary to determine the moisture content of the soil. Make a check mark here.

Using the portion of the moist minus ¾ in. (19 mm) soil that was reserved as described for Line 3, weigh out a 500 g sample (700 g including the tare weight). Then dry the sample to a constant weight on the stove. Good drying results are obtained if the tare containing the sample is placed in a skillet on a ¼ to ½ in. (6.3 mm to 13 mm) layer of sand. The sand distributes the heat more uniformly and will prevent burning the sample. Occasional stirring will hasten the drying process, but care should be taken not to lose any of the sample. After the sample has dried, it should be permitted to cool before it is weighed. Other method approved by the Deputy Chief Engineer (Technical Services) for determining the moisture content may be used in place of weighing the soil before and after drying.

15 Weight of Dry Soil and Tare: Weigh and record the Dry Soil and Tare to the nearest 1 g.

16 Moisture Content: From the Moisture Content Table, using the Weight of Dry Soil and Tare (Line 15), record the Moisture Content to the nearest %. If, after interpolation, the Moisture Content ends with .5, round off to the nearest even whole number.

17 Field Wet Density Required: From the proper Compaction Control Table (Line 9) using the Weight of Soil (Line 7) and the Moisture Content (Line 16) record the Field Wet Density Required. Interpolate for odd-numbered moisture contents.

If the moisture content is less than the lowest moisture content shown in the Compaction Control Tables, record the Field Wet Density Required shown for the lowest moisture content.

18 PASS: If the Field Wet Density (Line 4) is equal to or greater than the Field Wet Density Required (Line 17), the test passes. Make a check mark here.

19 FAIL: If the Field Wet Density (Line 4) is less than the Field Wet Density Required (Line 17), the test fails. Make a check mark here.

20 Approximate % Maximum Density: The values recorded on this line have no bearing on whether a test passes or fails. Therefore completion of this line is optional. For density test where the moisture content has been determine, the approximate percent of Maximum Density can be found from the Compaction Control Tables. To do this, divide the Field Wet Density (Line 4) by the field wet density required for a specified density of 100% at the moisture content shown on Line 16 and multiply the result by 100.

4.4 Failure of Compaction Control Tests

If a compaction control test fails, the compaction operations on the layer are not achieving results in conformance with the Specifications. The Contractor must adjust or revise the compaction methods and/or equipment in order to meet the requirements of the specifications. Retested areas should be referenced in “Remarks” to previously failing tests.

4.5 Reports

Form SM 384a must be filled out in triplicate and distributed each week as follows:

1. Regional Construction Engineer,

2. Regional Geotechnical Engineer, and

3. Project Files.

All density tests made during the week should be reported, including those tests which showed low values and where retests were made after corrective measures were taken. Ample notes should be included on the form to identify the individual tests.

Whenever periods occur when no grading is done, Form SM 384a should be sent in, regardless, with an explanation, thus providing a continuous documentation of the grading and compaction control.

5. IMPORTANT DO’S AND DON’TS FOR THE INSPECTOR

1. Empty the Volumeter completely before refilling it.

2. Make sure that the top is screwed tightly on the Volumeter and that the alignment marks on the metal top and on the plastic container line up.

3. When filling the Volumeter, place it on level surface not subject to vibrations.

4. Use dry sand, do not re-use sand from the hole.

5. When reading the Volumeter, note that the numbers on the Volumeter scale increase towards the bottom.

6. Note that on the Field Wet Density Calculator (or on the nomograph if one is used) the numbers on the “Volume of minus ¾ in.” scale increase in a direction opposite to those on the other scales.

7. If wet densities greater than 160 pcf are obtained in the test, go back and check carefully all numbers, including the Volumeter reading.

8. Use the correct compaction control table.

9. Use the known volume cylinder periodically to check Volumeter calibration.

APPENDIX

[pic]

Density Cylinder - Geotechnical Engineering Bureau Drawing No. SM 1563A

BACKGROUND AND THEORY

This METHOD UTILIZES A COMPUTATIONAL SYSTEM BASED ON Statewide Compaction Control Curves that permits a majority of compaction tests to be performed without requiring moisture content determinations. The computational system, as well as the special equipment used in this method, were originated by William H. Peak, Assistant Civil Engineer, Region 1 Geotechnical Group.

As shown in Figure B-1, the Statewide Curves are developed on a Dry Density vs. Moisture Content basis. Using an assumed Laboratory Dry Density (113 pcf (17.75 kN/m3)) and a moisture content (6%) a point cam be plotted on the graph. Through this point a curve is drawn parallel and similar to the adjacent curves. The Maximum Dry Density (117 pcf (18.38 kN/m3)) is obtained from the point where this curve intercepts the Locus of Maximum Density. Since the moisture content for the laboratory and the field dry density is identical, the intersection of this moisture content value and the maximum dry density value is the point where the Field Dry Density would plot to be equivalent to the Maximum Dry Density. In Figure B-1 this point is called the Field Dry Density required.

Any point on this graph also represents a certain wet density - the product of the dry density value and of one plus the moisture content value. Points of equal wet density arrange in curves trending fro the upper left to the lower right. Figure B-2 shows the relationship between the wet density curves, the compaction control curves and the points as plotted in Figure B-1.

Using this graph it can be seen that if the Laboratory Wet Density (120 pcf (18.85 kN/m3)) and the moisture content (6%) is known, the Field Wet Density Required (124 pcf (19.48 kN/m3)) to obtain the Maximum Field Dry Density can be established.

Figure B-3 shows that points of equal Laboratory Wet Density (used 120 pcf (18.85 kN/m3)) and varying moisture contents develop different values for the Maximum Dry Density and the Field Wet Density Required. The range of varying moistures and these corresponding values can be limited as follows:

1. A 2% minimum limit for sands and sands containing minor amounts of gravel and silt, and a 4% minimum limit for other soils. Normal embankment material will rarely be found to be drier than there limits.

2. A maximum of 4%+ above Optimum - Embankment material with moistures approaching this limit will rut excessively and no compaction test will be taken.

Within these limits, Figure B-3 shows that the highest Field Wet Density Required (126 pcf (19.79 kN/m3) for Laboratory Wet Density of 120 pcf (18.85 kN/m3)) occurs at the minimum moisture content of 2%. Accordingly, if the Field Wet Density is greater than the Field Wet Density Required at 2% moisture content, the compaction test passes regardless of the actual moisture content of the soil.

As the moisture content is increased above the minimum, the Field Wet Density Required to satisfy the specification requirements, decreases until the lowest Field Wet Density Required (120 pcf (18.85 kN/m3)) is reached. This is at the point where the wet density curve crosses the locus of maximum density (or optimum moisture). It then increases on the wet side of the optimum moisture. This means that, if the Field Wet Density is lower than the Field Wet Density required at the optimum moisture content, the test fails regardless of the actual moisture content of the soil.

If the field wet density of the soil is between the highest and the lowest Field Wet Density Required, a moisture content determination is necessary to evaluate the test. From the known Laboratory Wet Density and the Moisture Content, the actual Field Wet Density Required can be obtained and compared with the measure Field wet Density for a Pass – Fail decision.

[pic]

Figure B-1

[pic]

Figure B-2

[pic]

Figure B-3

[pic]

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

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

Google Online Preview   Download