hydrometer report

8/12/2019 Hydrometer Report

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Laboratory 2Hydrometer Analysis

Atterberg Limits

Sand Equivalent Test

INTRODUCTION

Grain size analysis is widely used for the classification of soils and for specifications of soil

for airfields, roads, earth dams, and other soil embankment construction. The hydrometer

analysis determines the relative proportions of fine sand, silt and clay contained in a given soil

sample. A knowledge of the range of moisture content over which a soil will exhibit a certain

consistency is beneficial to the understanding of how a soil might behave when used as a

construction material. The Atterberg limits, which include the liquid limit and plastic limit, are

readily accepted in the engineering community as an objective measure of consistency.When coarse soil particles (sand and gravel) are used as a construction material, their

suitability and behavior is influenced by the amount of clay fines that may be present after

processing. The Sand equivalent test, developed to provide and indication of the clay content

of a coarse aggregate, may be used as an indicator for specification compliance.

HYDROMETER ANALYSIS

A hydrometer analysis is required to determine the particle size distribution for that portion of

the soil which passes through a No. 200 sieve (0.075 mm). The test is conducted on that

fraction of a soil sample which passes through a No. 10 sieve (2 mm); however the sand


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f f

Prior to the conduct of the hydrometer test, the hydrometer bulb (151 H) is calibrated to the

dispersing solution and prevalent test temperatures. This is simply accomplished by obtaining

hydrometer readings in a 5g/l sodium hexametaphosphate solution at two or moretemperatures. The 151 H hydrometer bulb is manufactured to provide a reading of 1.000

when placed in pure distilled water at 21 oC. Because the sodium hexametaphosphate

solution has a specific gravity greater than 1, a hydrometer reading in excess of 1.000 will be

obtained. The difference between this reading and unity is considered as a composite

correction factor which is applied to all subsequent hydrometer readings of the soil-water

suspension.

To provide reasonably accurate results, a soil sample must be completely broken down into

individual soil grain prior to testing. This is accomplished by thorough wetting and mixing of

the soil in a dispersing agent. A concentrated solution of water and sodium

hexametaphosphate (40g/l) is used for this purpose. After complete dispersion, the soil-water

suspension is introduced into a 1 litre settlement tube and diluted with distilled water such that

the resulting sodium hexametaphosphate solution a concentration of 5g/l. Successive, timed

measurements of the specific gravity of the soil-water suspension, using a calibrated

hydrometer bulb, provides an indication of the maximum size of a soil particle still insuspension and the proportion of soil fines still in suspension. These values are then used to

compute the percent of soil by weight finer than a given diameter.

ATTERBERG LIMITS

When clay minerals are present in fine grained soil, the soil can be remolded in the presence

of some moisture without crumbling. In the early 1900's, a Swedish soil scientist named Albert

Atterberg proposed a set of six rather arbitrary states of soil moisture content to assist

agriculturists in determining field agricultural conditions. He termed the divisions between

these six states as limits, known as the shrinkage, cohesive, sticky, plastic and liquid


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Unlike finer soil particles, gravels and sands do not possess the required cohesiveness which

permits the Atterberg limits tests to be performed. However, the finer sands and silts often

contain sufficient clay coatings to permit the tests to be successfully completed. Thus theAtterberg tests are performed on only that soil fraction which passes through a No. 40 sieve

(0.425 mm).

Shrinkage Limit

The shrinkage limit is defined as the moisture content at which no further volume change

(reduction) occurs with a further reduction in moisture content. An alternative definition defines

the shrinkage limit as the moisture content representing the amount of water required to fill the

voids in a given cohesive soil at its minimum void ratio obtained by drying.

Plastic Limit

The plastic limit is defined as the moisture content at which a soil thread just begins to crack

and crumble when rolled to a diameter of 1/8" (3 mm).

Liquid Limit

The liquid limit is defined as the moisture content at which a 2-mm-wide groove in a soil pat

will close for a distance of " (12.5 mm) when dropped 25 times in a standard brass cup,

falling 1 cm each time at a rate of 2 drops per second.

SAND EQUIVALENT TEST


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CEEN 162 - Geotechnical Engineering - Laboratory Session No. 2

Grain Size Determination (Hydrometer Method), Atterberg Limits, Sand Equivalent Test

OBJECTIVE: To obtain data necessary for the classification of a soil.

EQUIPMENT: 151H Hydrometer bulb, scale, sodium hexametaphosphate dispersion solution, mixing

apparatus, beaker, sedimentation cylinder, thermometer, liquid limit device, porcelain dish, spatula, balance,

moisture content cans, glass plate, distilled water, drying oven, sand equivalent apparatus, working calcium

chloride solution.

REFERENCE SPECIFICATIONS: ASTM D 422-63, D 2419-74

LAB PROCEDURES:

Part 1 - Hydrometer Calibration (Data Sheet 1)

1. Select and clean a 151H hydrometer bulb and record the identifier number.

2. Obtain hydrometer calibration readings in each of the the 1 L graduated cylinders filled with a 5g/L

solution of sodium hexametaphosphate in distilled water. Record the temperature of the solutions to

0.5 oC.

Part 2 - Sedimentation Test (Data Sheet 2)

1. Obtain a 100 g sample of air-dried soil (minus #10 soil from Lab 1) and place in a 400-mL beaker.

Cover with 125 mL of concentrated sodium hexametaphosphate solution (40g/L). Stir until the soil is

thoroughly wetted and allow to soak for at least 15 minutes. After soaking transfer the soil-water slurry

from the beaker into the dispersion cup, washing any residue from the beaker with distilled water. Add

distilled water, if necessary, to fill the dispersion cup approximately half full. Mix the suspension in

the mixer for 1 min.

2. Immediately after mixing, wash the specimen into a 1 L graduated cylinder and add enough distilledwater to bring level to the 1 L mark.

3. Mix soil and water in cylinder by placing a rubber stopper over the open end and turning the graduate

id d d b k f 1 i Th b f t d i thi i t h ld b 60


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3. Place the 200 g of soil on a glass plate and add about 15 ml of distilled water. Mix soil and water

thoroughly using an alternate of repeated stirring, kneading and chopping action with the spatula.

Continue adding water at the rate of 1 to 3 milliliter increments and thoroughly mix each increment into

the soil before adding the next. Enough water should be thoroughly mixed to produce a consistency

that will require 25 to 35 drops of the cup to cause the groove to close.

4. Place a portion of the prepared soil mixture in the cup of the liquid limit device at the point where the

cup rests on the base, squeeze it down, and spread it into the cup to a depth of about 10 mm at its

deepest point, tapering it to form an approximately horizontal surface. Take care to eliminate airbubbles from the soil pat but form the pat with as few strokes as possible. Heap the unused soil on

the glass plate and cover with an inverted storage dish or wet towel.

5. Form a groove in the soil pat by drawing the tool through the soil on a line joining the highest point to

the lowest point on the rim of the cup. Hold the grooving toll against the surface of the cup and draw

in an arc, maintaining the tool perpendicular to the surface of the cup. Avoid tearing the sides of the

soil groove and do not permit the soil pat to slide in the cup. Up to six strokes are permitted to form

the groove.

6. Using a continual motion of the crank, lift and drop the cup at the rate of two drops per second. Record

the number of drops of the cup required to cause the two halves of the soil pat to flow together for a

distance of 13 mm (1/2 in).

7. Remove a slice of soil approximately the width of the spatula, extending from edge to edge of the soil

cake at right angles to the groove and including that portion of the groove in which the soil flowed

together. Record the mass of the moist soil and moisture tin to the nearest 0.01g. Place the tin in

a drying oven.

8. Return the soil remaining in the cup to the glass plate. Wash and dry the cup and grooving tool and

reattach the cup to the carriage. Remix the entire soil specimen on the glass plate adding distilled

water to increase the water content of the soil and decrease the number of blows required to close the

t b t 20 t 30 bl


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2. From the 20 g mass, select a portion of 1.5 to 2.0 g and form into an ellipsoid. Cover the remaining

soil with a moist towel. Roll this mass between the palm or fingers and the glass plate with just

sufficient pressure to roll the mass into a thread of uniform diameter throughout its length. When the

diameter of the thread becomes 3 mm, break the thread into several pieces. Squeeze the pieces

together, knead between the thumb and first finger of each hand, reform into an ellipsoid, an re-roll.

Continue to alternate rolling, gathering, kneading, and re-rolling until the thread crumbles under the

pressure required for rolling and the soil can no longer be rolled into a 3 mm diameter thread.

3.Gather the portions of the crumbled thread together and place in a moisture tin and immediately cover.

4. Repeat steps 2 and 3 until the moisture tin contains at least 6 g of moist soil. Record the mass of

the moist soil and tin (without cover) to the nearest 0.01g. Place the moist soil and tin in a drying

oven.

5. Repeat steps 2 through 4 to produce another moisture tin containing at least 6 g of soil. Record the

mass of the moist soil and tin (without cover) to the nearest 0.01g. Place the moist soil and tin in a

drying oven.

6. Record the mass of the oven dried soil and moisture tin to the nearest 0.01g.

Part 5 - Sand Equivalent Test (Data Sheet 4)

1. Obtain a 500 g sample of soil passing the No. 4 sieve. Fill one tin measure to the brim or slightly

rounded above the brim.

2. Siphon approximately 4 in of working calcium chloride solution into the plastic cylinder. Pour the soil

sample into the cylinder using the funnel to avoid spillage. Allow the wetted specimen and cylinder

to stand for approximately 10 min.

3. After the 10 min soaking period, hold the cylinder in a horizontal position and shake vigorously in a

horizontal linear motion from end to end. Shake the cylinder 90 cycles (back and forth motion) in

i t l 30 d i th f 9 i h


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P '1000 G

SP

10

MS

R & 1

GS & 1

D ' K L

T



CALCULATIONS:

1. Using the hydrometer calibration data from Data Sheet 1, prepare a linear plot of the composite

correction factor vs temperature and develop an equation to predict the composite correction factor for

any intermediate temperature. Using the equation below, complete Data Sheet 2 to determine the grain

size distribution of the soil sample. Plot these results in combination with Lab 1 dry sieve data and

develop a single, smooth grain size distribution curve for the soil sample.

The percentage (P) of soil remaining in suspension and the largest diameter (D) of soil in suspension

at the level of the hydrometer are calculated as:

where: P = percentage of soil in suspension, %

GS= specific gravity of soil particles (Lab 1)

P10= percent of original soil sample which passes No.10 sieve (Lab 1)

Ms= dry mass of soil, g

R = corrected hydrometer reading (hydrometer reading - composite correction factor)

D = diameter of soil particle, mm

K = constant depending temperature and specific gravity of the soil (Table 1)L = effective depth, equal to the distance from the surface of the suspension to the level at which

the density of the suspension is being measured, cm (Table 2).T = time of hydrometer reading, min.


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DATA SHEET 1

HYDROMETER CALIBRATION DATA

HydrometerReading

Temperature of 5g/L

SodiumHexametaphosphate

Solution

C

CompositeCorrection

Factor

SOIL DATA

Weight of Beaker, g

Weight of Beaker + Dried Soil, g

Weight of Dried Soil, g (Ms)

P10(Lab 1)


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9

CEEN 162 - Geotechnical Engineering - Laboratory Session No. 2Grain Size Determination (Hydrometer Method), Atterberg Limits, Sand Equivalent Test

DATA SHEET 2

TimeElapsed

Timemin

Hydrom.Reading

TempoC

Comp.Corr.

Factor

Corr.Hydrom.Reading

R

KFactor

(Table 1)

EffectiveDepth

(Table 2)L

Percent ofSoil in

Suspension

ParticleDiameter

mm


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CEEN 162 - Geotechnical Engineering

Laboratory Session No. 3 - Liquid Limit and Plastic Limit Tests

LAB DATA SHEET 3

LIQUID LIMIT TESTS

Trial 1 Trial 2 Trial 3

Moisture Tin Number

Moisture Tin Wt, g

Number of Drops

Wt. Wet Soil + Tin, g

Wt. Oven-Dry Soil + Tin, g

Calculations

Wt. Water, g

Wt. Oven-Dry Soil, g

Moisture Content, w,%

PLASTIC LIMIT TESTS

Trial 1 Trial 2


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DATA SHEET 4

SAND EQUIVALENT DATA

Soil

Sample

Clay

Readinginch

Sand

Readinginch

Sand

Equivalent(1)

100% S

95%S - 5%C

90%S - 10%C

Lab Sample

(1) Sand Equivalent = 100% x (Sand Reading / Clay Reading)


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Table 1: Values of K for Computing Particle Diameter in Suspension

TemperatureoC

Gs

2.45 2.50 2.55 2.60 2.65 2.70 2.75 2.80

16 0.01510 0.01505 0.01481 0.01457 0.01435 0.01414 0.01394 0.01374

17 0.01511 0.01486 0.01462 0.01439 0.01417 0.01396 0.01376 0.01356

18 0.01492 0.01467 0.01443 0.01421 0.01399 0.01378 0.01359 0.01339

19 0.01474 0.01449 0.01425 0.01403 0.01382 0.01361 0.01342 0.01323

20 0.01456 0.01431 0.01408 0.01386 0.01365 0.01344 0.01325 0.01307

21 0.01438 0.01414 0.01391 0.01369 0.01348 0.01328 0.01309 0.01291

22 0.01421 0.01397 0.01374 0.01353 0.01332 0.01312 0.01294 0.0127623 0.01404 0.01381 0.01358 0.01337 0.01317 0.01297 0.01279 0.01261

24 0.01388 0.01365 0.01342 0.01321 0.01301 0.01282 0.01264 0.01246

25 0.01372 0.01349 0.01327 0.01306 0.01286 0.01267 0.01249 0.01232

26 0.01357 0.01334 0.01312 0.01291 0.01272 0.01253 0.01235 0.01218

27 0.01342 0.01319 0.01297 0.01277 0.01258 0.01239 0.01221 0.01204

28 0.01327 0.01304 0.01283 0.01264 0.01244 0.01225 0.01208 0.01191

29 0.01312 0.01290 0.01269 0.01249 0.01230 0.01212 0.01195 0.01178

30 0.01298 0.01276 0.01256 0.01236 0.01217 0.01199 0.01182 0.01165


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Table 2: Effective Depth vs 151 H Hydrometer Reading

Corrected

Hydrometer

Reading

Effective

Depth, L

(cm)

Corrected

Hydrometer

Reading

Effective

Depth, L

(cm)

1.000 16.3 1.020 11.0

1.001 16.0 1.021 10.7

1.002 15.8 1.022 10.5

1.003 15.5 1.023 10.2

1.004 15.2 1.024 10.0

1.005 15.0 1.025 9.7

1.006 14.7 1.026 9.4

1.007 14.4 1.027 9.2

1.008 14.2 1.028 8.9

1.009 13.9 1.029 8.6

1.010 13.7 1.030 8.4

1.011 13.4 1.031 8.1

1.012 13.1 1.032 7.8

1.013 12.9 1.033 7.6

1.014 12.6 1.034 7.3

1 015 12 3 1 035 7 0


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15

0.001 0.01 0.1 1 10

0

10

20

30

40

50

60

70

80

90

100

Grain Size, mm

%P

assing

CEEN 162 - Hydrometer Test Results


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16

1 10 100

10

12

14

16

18

20

22

24

26

28

30

Drops

WaterCon

tent,%

CEEN 162 - Liquid Limit Test Results

25


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EXAMPLE DATA SHEET 1

HYDROMETER CALIBRATION

Hydrometer

Reading

Temperature of Sodium

Hexametaphosphate

Solution (5g/L)

Composite

Correction

Factor

1.004 21.5 .004

1.002 24.5 .002

SOIL DATA

Weight of Beaker, g 325.8

Weight of Beaker + Dried Soil, g 425.7

Weight of Dried Soil, g 99.9

P10(Lab 1) 89.5

Specific Gravity of Soil Solids, GS, (Lab 1) 2.75


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18

CEEN 162 - Geotechnical Engineering - Laboratory Session No. 2Grain Size Determination (Hydrometer Method), Atterberg Limits, Sand Equivalent Test


Time

Elapsed

Timemin

Hydrom.Reading

TempoC

Comp

CorrFactor

(1)

Corr

HydromReading

R(2)

K

Factor(Table 1)

(3)

Effective

Depth(Table 2)

L(4)

Percent of

Soil inSuspension

(5)

Particle

Diametermm

(6)

9:04:00 0

9:05:30 1.5 1.0380 23.5 0.0026 1.0354 0.012783 6.9 49.9 0.027

9:06:00 2 1.0370 23.5 0.0026 1.0344 0.012783 7.2 48.5 0.024

9:06:30 2.5 1.0360 23.5 0.0026 1.0334 0.012783 7.5 47.1 0.022

9:07:30 3.5 1.0340 23.5 0.0026 1.0314 0.012783 8.0 44.3 0.019

9:10:00 6 1.0310 23.0 0.0029 1.0281 0.012790 8.9 39.6 0.016

9:14:00 10 1.0280 23.0 0.0029 1.0251 0.012790 9.7 35.4 0.013

9:24:00 20 1.0260 23.0 0.0029 1.0231 0.012790 10.2 32.5 0.009

9:34:00 30 1.0250 23.0 0.0029 1.0221 0.012790 10.4 31.1 0.008

9:44:00 40 1.0240 23.0 0.0029 1.0211 0.012790 10.7 29.7 0.007

9:54:00 50 1.0240 23.1 0.0028 1.0212 0.012789 10.7 29.8 0.006

10:04:00 60 1.0230 23.0 0.0029 1.0201 0.012790 11.0 28.3 0.005

(1) Determined from equation developed from hydrometer calibration data(2) Hydrometer reading - composite correction factor(3) Determined from Table 1 based on temperature and specific gravity of soil solids(4) Determined from Table 2 based on corrected hydrometer reading(5) Calculated based on equation provided; P = fn {Gs, P10, Ms, R}(6) Calculated based on equation provided; D = fn {K, L, T}CEEN 162 - Geotechnical EngineeringLaboratory Session No. 2 - Liquid Limit and Plastic Limit Tests


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LIQUID LIMIT TESTS

Trial 1 Trial 2 Trial 3

Moisture Tin Number A1 D1 E4

Moisture Tin Wt, g 25.2 24.9 25.1

Number of Drops 28 22 18

Wt. Wet Soil + Tin, g 45.2 46.2 46.5

Wt. Oven-Dry Soil + Tin, g 41.8 42.3 42.3

Calculations

Wt. Water, g 3.4 3.9 4.2

Wt. Oven-Dry Soil, g 16.6 17.4 17.2

Moisture Content, w,% 20.5 22.4 24.4

PLASTIC LIMIT TESTS

Trial 1 Trial 5

Moisture Tin Number A2 J2

Moisture Tin Wt, g 24.8 25.3

Wt. Wet Soil + Tin, g 30.9 32.2


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DATA SHEET 4

SAND EQUIVALENT DATA

Soil

Sample

Clay

Reading

inch

Sand

Reading

inch

Sand

Equivalent

(1)

100% S 4.3 4.1 96

95%S - 5%C 4.4 3.8 87

90%S - 10%C 5.3 3.6 68

Lab Sample 13.2 1.1 9

(1) Sand Equivalent = 100% x (Sand Reading / Clay Reading)


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21

21 22 23 24 25

1.5

2.0

2.5

3.0

3.5

4.0

4.5

Temperature, C

CompositeCorrectionFactor(x10^-3)

CEEN 162 - Lab 2

Hydrometer Calibration Data

Y = 0.018333 - 0.000667 X


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22

0.001 0.01 0.1 1 10

0

10

20

30

40

50

60

70

80

90

100

Grain Size, mm

%P

assing

CEEN 162 - Hydrometer Test Results


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23

1 10 100

10

12

14

16

18

20

22

24

26

28

30

Drops

WaterCon

tent,%

CEEN 162 - Liquid Limit Test Results

LL = 21.6 = 22

25


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24

0 10 20 30 40 50 60 70 80 90 100

0

10

20

30

40

50

60

70

80

90

100

% Clay

Sand

Equivalent

CEEN 162 - Sand Equivalent Test Results

hydrometer report

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