lab report 2

Soil Mechanics Laboratory

Report #2

CE 3143

Submitted by

Jordan Collins

07/14/2015

Department of Civil Engineering

The University of Texas at Arlington

Table of Contents

Title Page

1. Standard Proctor Compaction Test……….……………………………………………………3

i. Dry Unit Weight Curve…………………………………………….…...5

2. Modified Proctor Compaction Test…………………………………………………………….6

i. Dry Unit Weight Curve…………………………………………………8

3. Constant-Head Permeability Test in Sand……………………..…………………………....9

4. Falling-Head Permeability Test in Sand…………………………………………………...…12

5. Sand-Cone Test……………………..……………………………………………………………….….15

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Standard Proctor Compaction Test

Introduction:

Obtaining maximum dry unit weight when compacted is key for any type of construction.

When in the field it is important to achieve the maximum dry weight to assure that the

surface can be compacted to its maximum potential. Generally field compaction will not

reach 100% of the compaction reached in the lab, so a 90%-95% compaction is acceptable.

Objective:

To determine the maximum dry unit weight of compaction and the optimum water content.

Equipment:

1. Compaction mold2. Standard Proctor hammer with a weight of 5 lb.3. Balance for weighing g and lb.4. Bowl 5. Scoop6. Spatula7. Moisture cans8. Drying oven9. Water bottle

Test Procedure:

1. Add 2 kg of soil, prepared by TA, to the bowl.2. Add 14% or 280 g of water to the soil; mix until the soil is consistent throughout.3. Record the weight of the mold, without the extension, as M 1 (lb).4. Put the extension back on and add soil from step 2 in 3 layers. After each layer

compact uniformly with the standard Proctor, hammer 25 times before laying down the next layer.

5. Remove the extension and scrape off excess soil from the top.6. Record the weigh of the mold + the compacted soil as, M 2(lb).7. Use a jack to remove the compacted soil from the mold.8. Record the weight of the moisture can, label as M 3.9. Collect a sample of the extracted soil and add to the moisture can, then weigh, label

as M 4(kg). Return the rest of the soil to the original sample from Step 2.10. Place moisture can (with moist soil) into the drying oven.

3

11. Add 120 g of water to the soil from Step 9. 12. Repeat Steps 3-10.13. After 24-hours determine the weight of the moisture cans with the now dry soil.

Label as M 5.14. Label the calculated weight of water as M 6. (M 4-M 5)

15. Calculated water content= M 6

M5−M 3

Calculations:

γ bulk= weight of soilvolume of mold

=2.205(M 2−M1)

130

; volume of mold= 1

30ft3

γ dry=γbulk1+w

zero-air void line= γ dry=

γw

( w100

)+( 1Gs

)

water content=M 6

M 5−M 3

Test Results:

Water Content (%)(Approximate) 14 20

Weight of Mold, M 1 (kg) 4.225 4.225

Mold + Compacted Soil, M 2 (kg) 6.087 5.861

Weight of moisture can, M 3 (g) 35.2 35.5

Moisture can + sample, M 4 (g) 62.8 78.8

Moisture can + dry sample, M 5 (g) 59 71

Weight of water, M 6 (g) 3.8 7.8

Calculated water content (%) 15.96638655 21.97183099γ bulk 123.1500732 108.2027496γ dry 106.1946283 88.71126122

Class Results:

Class Results: w (%) γ dry

11.11 105.4

4

13.2 109.6216 106.2

18.56 108.222 88.7

Graphs:

10 11 12 13 14 15 16 17 18 19 20 21 22 2380

85

90

95

100

105

110

115

120

f(x) = − 0.391267824844621 x² + 11.5546988726512 x + 24.8961287652095

Zero-Void Line

Summary & Conclusion:

Some of the points in the graph did not match the bell curve needed, so a trend line was

created to better show a consistent graph. With the trend line the maximum y value was

recorded along with the x-value, giving the optimum water content and maximum unit

weight. The actual values are wopt= 14.765%, while the γmax= 110.2 lb

ft3 . Also graphed, in red,

is the zero-air void line (with a Gs of 2.65).

5

References:Das, Braja M. (2012). Soil Mechanics Laboratory Manual, 8th ed., Oxford University Press, New York, N.Y.

Das Braja M. (2009). Principle of Geotechnical engineering, 7th ed., Cengage Learning, Stanford, CT.

Modified Proctor Compaction Test

Introduction:

Modified proctor compaction test is similar to the standard proctor test, in that, it helps

determine the maximum dry unit weight, as well as, the optimum moisture content. The

modified compaction test is more beneficial when it comes to designing highways, runways

etc. The modified compaction test is compacts soil more than the standard compaction test.

Objective:

To determine the maximum dry unit weight of compaction and the optimum water content.

Equipment:

1. Compaction mold2. Standard Proctor hammer with a weight of 10 lb.3. Balance for weighing g and lb.4. Bowl 5. Scoop6. Spatula7. Moisture cans8. Drying oven9. Water bottle

Test Procedure:

1. Add 2 kg of soil, prepared by TA, to the bowl.2. Add 8% or 160 g of water to the soil; mix until the soil is consistent throughout.3. Record the weight of the mold, without the extension, as M 1 (lb).4. Put the extension back on and add soil from step 2 in 3 layers. After each layer

compact uniformly with the standard Proctor, hammer 25 times before laying down the next layer.

5. Remove the extension and scrape off excess soil from the top.6. Record the weigh of the mold + the compacted soil as, M 2(lb).

6

7. Use a jack to remove the compacted soil from the mold.8. Record the weight of the moisture can, label as M 3.9. Collect a sample of the extracted soil and add to the moisture can, then weigh, label

as M 4(kg). Return the rest of the soil to the original sample from Step 2.10. Place moisture can (with moist soil) into the drying oven. 11. Add 80 g of water to the soil from Step 9. 12. Repeat Steps 3-10.13. After 24-hours determine the weight of the moisture cans with the now dry soil.

Label as M 5.14. Label the calculated weight of water as M 6. (M 4-M 5)

15. Calculated water content= M 6

M5−M 3

Calculations:

γ bulk= weight of soilvolume of mold

=2.205(M 2−M1)

130

; volume of mold= 1

30ft3

γ dry=γbulk1+w

Zero-air void line= γ dry=

γw

( w100

)+( 1Gs

)

water content=M 6

M 5−M 3

Test Results:

Water Content (%)(Approximate) 8 12Weight of Mold, M 1 (kg) 4.334 4.334Mold + Compacted Soil, M 2 (kg) 6.162 6.274Weight of moisture can, M 3 (g) 35.2 35.2Moisture can + sample, M 4 (g) 67.8 83.1Moisture can + dry sample, M 5 (g) 65 77.6Weight of water, M 6 (g) 2.8 5.5Calculated water content (%) 9.395973154 12.97169811γ bulk 120.9013608 128.308884γ dry 110.5171948 113.5761311

Class Results:

7

Class Results:

w (%) γ dry

9.4 110.510.9 112.2

13 113.616 113.7

18.99 104.6

Graphs:

9 10 11 12 13 14 15 16 17 18 19104

109

114

119

124

129

134

139

f(x) = − 0.295950274639285 x² + 7.89830244134039 x + 61.8082858070056

Modified ProctorPolynomial (Modified Proctor)Zero-Air Void


A trend line was created to better show a consistent graph. With the trend line the

maximum y value was recorded along with the x-value, giving the optimum water content

and maximum unit weight. The actual values are wopt= 13.34%, while the γmax= 114.50 lb

ft3 .

Also graphed, in red, is the zero-air void line (with a Gs of 2.7).

8



Constant-Head Permeability Test in Sand

Introduction:

Permeability is the ability for water to flow through a particular soil. For civil engineers

this is important for many key reasons. It helps determine what soils are better for

different situations. With the constant-head permeability test we can find the permeability

of a soil sample and classify it as to what type of soil it is.

Objective:

To obtain the coefficient of permeability of sand with the constant-head test method.

Equipment:

1. Constant-head permeameter

2. Funnel

3. Beaker/Graduated Cylinder

4. Balance

5. Thermometer

6. Timer

7. Tubing

Test Procedure:

1. Apparatus and soil prepared by TA.

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2. Deposit water through the funnel, keeping the water constant on the line.

3. Once the flow is steady through the end of the tube place beaker/graduated cylinder

under the water that is being discharged.

4. Start the timer

5. Once a sufficient amount of water has been collected stop the time and remove the

beaker/cylinder at the same time.

6. Record the time, T and also record the volume, V.

7. Repeat Steps 2-7 two more times.

Tables:

Temperature T (˚C)(ηT ˚ Cη20 ˚C

)Temperature T (˚C)

(ηT ˚ Cη20 ˚C

)

15 1.135 23 0.93116 1.106 24 0.91017 1.077 25 0.88918 1.051 26 0.86919 1.025 27 0.85020 1.000 28 0.83221 0.976 29 0.81422 0.953 30 0.797

Table 2 (from manual)Soil k (cm/s)

Clean gravel 102 - 100

Coarse sand 100- 10−2

Fine sand 10−2- 10−3

Silty clay 10−3 - 10−5

Clay Less than 10−6

Calculations:

q = kiA

q = flow rate

10

i = hydraulic gradientk = coefficient of permeability

i = hL

k = qLAh

q = Vt

k 20˚ C=k T∗(ηT ˚ C

η20 ˚C

)

Test Results:

Test 1 Test 2 Test 3

Volume (cm^3) 111.6 141.3 760.6

Time (s) 7.43 10.44 67.06

q (cm3

s)

15.02018843 13.53448276 11.34208172

L (cm) 10.16 10.16 10.16

h (cm) 44.45 44.45 44.45

A (cm2) 81.07319666 81.07319666 81.07319666

k (cm/s) 0.042346744 0.038158062 0.031976978k 20˚ C (cm/s) 0.039424819 0.035525156 0.029770566


From the test ran it is seen that the k 20˚ C values for test 1, 2, and 3 are, 3.94∗10−2, 3.55∗10−2,

and 2.98∗10−2 respectively. From this it was determined that the average k 20˚ C value is

3.49∗10−2, which is appropriate for course sand (as seen in table 2).

11



Falling-Head Permeability Test

Introduction:

As stated in the Constant-Head test above, permeability is the ability for water to flow

through a particular soil. The falling-head test is another way to find the permeability of a

soil. This test is more beneficial when determining the permeability of clays, since majority

of the water will not pass through it. Some water does pass through, but, more times than

not, it is not sufficient enough to record the volume of it.

Objective:

To obtain the coefficient of permeability of sand with the falling-head test method.

Equipment:

1. Falling-head permeameter

2. Balance

3. Thermometer

4. Stopwatch

Test Procedure:

12

1. Measure the height of the apparatus.

2. Pour water into the water inlet of the burette.

3. Record a height of water, h1.

4. Record the time it takes for water to drop a certain distance. Record the new height

as, h2. Record the time it took to get to the height as, t.

5. Determine the volume, V w.

6. Record the room temperature as T.

Tables:

Temperature T (˚C)(ηT ˚ Cη20 ˚C

)Temperature T (˚C)

(ηT ˚ Cη20 ˚C

)

15 1.135 23 0.93116 1.106 24 0.91017 1.077 25 0.88918 1.051 26 0.86919 1.025 27 0.85020 1.000 28 0.83221 0.976 29 0.81422 0.953 30 0.797

Table 2 (from manual)Soil k (cm/s)

Clean gravel 102 - 100

Coarse sand 100- 10−2

Fine sand 10−2- 10−3

Silty clay 10−3 - 10−5

Clay Less than 10−6

Calculations:

13

k=2.303aLAt

log (h1

h2

)

a=V w

h1−h2

k 20˚ C=k T∗(ηT ˚ C

η20 ˚C

)

Test Results:

ItemTest No.

1 2 3Diameter of specimen,

D (cm)3.175 3.175 3.175

Length of specimen,L (cm)

6.604 6.604 6.604

Area of specimen,A=[(pi/4)(D^2)] (cm^2)

7.9173 7.9173 7.9173

Beginning head difference,h1 (cm)

70 55 40

Ending head difference,h2 (cm)

60 45 30

Test duration, t (s) 74.63 86.49 107.83Volume of water flow

through specimenV w (cm^3)

10 10 10

k=[(2.303V wL)/[(h2-h1)tA]log(h1/h2) (cm/s)

0.001723 0.001936 0.002226


14

Based on the falling-head test the average permeability of the 3 tests ran is k = 0.001962 cms

. With the correction factor added from table 2 the value of k 20˚ C=¿ 0.001826 cms

. Base on

table 2 above this soil can be determined to be fine sand.



Sand-Cone Test

Introduction:

In fieldwork, it is sometimes necessary to find the dry unit weight of compaction. There are

many different ways to determine the dry unit weight like the rubber balloon method and

the nuclear density gauge, but the sand-cone test proves to be the most accurate for the

price.

Objective:

To determine the dry unit weight of compaction in the field.

Equipment:

1. Sand-cone apparatus

2. Base plate

3. Ottawa sand

4. Scale

15

5. Items to dig a hole

6. Straight-edge

7. Drying oven

Test Procedure:

1. Calibrate the Ottawa Sand by:

a. Determine the weight of the mold, W 1.

b. Fill the mold with sand and weigh it, W 2

c. Volume of the mold is 1

30ft3

, V 1.

d. Determine the dry weight of the sand, γ d (sand ).

2. Calibrate the cone by:

a. Determine the weight of the bottle + cone + sand, W 3.

b. Weight of the bottle + cone + sand, after use, W 4.

c. Weight of the sand used to fill the cone, W S.

3. Determine the weight of the bottle + cone + sand, W 6.

4. Go to the field and place the base plate on a flat surface and dig a hole. Be sure to

recover all of the soil removed from the ground.

5. Determine the weight of the bottle + cone + sand, after use, W 8.

6. Determine the volume of the hole, V 2.

7. Determine the weight of the moisture can, W 5.

8. Determine the weight of the moisture can + moist soil, W 7.

9. Place the moisture can + moist soil into the drying oven for 24 hours then record the

weight, W 9.

16

10. From the recorded values determine the moist unit weight, the moisture content,

and the dry unit weight in the field.

Calculations:

γ d ( sand )=weight of sandvolume of mold

=W 2−W 1

V 1

Weight of sand in the cone = W s=W 4−W 3

Volume of the hole = V 2=W 6−W 8−W S

γd (sand )

Test Results:

Item QuantityCalibration of Unit Weight of Ottawa Sand

Weight of Proctor mold, W 1 (lb) 9.37Weight of Proctor mold + sand, W 2 (lb) 12.63

Volume of mold, V 1 (ft^3) 0.033333Dry unit weight,

Yd(sand)=(W 2-W 1)/V 1 (lb/ft^3) 97.80097801

Calibration ConeWeight of bottle+cone+sand

(before use), W 3 (lb) 10.21

Weight of bottle+cone+sand(after use), W 4 (lb) 6.24

Weight of sand to fill cone,W S=W 3-W 4 (lb)

3.97

Results from Field TestsWeight of bottle + cone + sand

(before use), W 6 (lb) 10.14

Weight of bottle+cone+sand(after use), W 8 (lb) 4.48

17

Volume of hole, V 2=(W 6-W 8-W S)/γ d (sand) (ft^3)

0.017279991

Weight of moisture can, W 5 (lb) 0.077823Weight of moisture can + moist soil, W 7

(lb)0.139663

Weight of moisture can + dry soil, W 9 (lb) 0.134261Moist unit weight of soil in field,

γ=(W 7-W 5)/V 2 (lb/ft^3) 3.57870561

Moisture content in field,w(%)=(W 7-W 9)/(W 9-W 5 ¿x100 9.571565257

Dry unit weight in field, γ d=γm/(1+(w (%)/100)) (lb/ft^3)

3.266089702


From the field report, it can be seen that the dry unit weigh in the field is 3.27 lb

ft3 . This

value is an average based on the 2 moisture cans used to get the moisture content. Some

possible errors that could have taken place is some of the soil from the hole may not have

been retrieved.

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lab report 2

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