FLORIDA A&M UNIVERSITY — FLORIDA STATE UNIVERSITY
COLLEGE OF ENGINEERING
STANDARD TEST METHOD FOR PLASTIC LIMITS AND LIQUID LIMITS
OF SOILS
(according to ASTM D 4318)
By
ANDREW ALDERMAN
Group 1
A Laboratory Report submitted to the
Department of Civil and Environmental Engineering in partial fulfillment of the requirements for the Civil Materials Laboratory
Casagrande cup with groove in soil sample . . . . . . . . . . . . . . .
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ABSTRACT
For this experiment it was desired to determine the Plastic Limits and Liquid
Limits of different soil samples. This was done by performing Plastic Limits Test and Liquid Limits Test in accordance with ASTM D4318. After finding the Plastic
Limit and Liquid Limit for the sample the Plasticity Index can then be determined by subtracting the Plastic Limit from the Liquid Limit. Determining the Plasticity
Index of a soil is important since plasticity affects the shear strength and workload of the soil. From Group 1 it was determined that Tan 200 has a Plasticity Index of
24. Another group had a Plasticity Index of 0. This should not be possible and an error probably occurred in the experiment.
CHAPTER 1: INTRODUCTION
1.1
Introduction
It is generally understood that soil has a moisture content and also a Plastic Limit
(PL), Liquid Limit (LL), and Plasticity Index (PI). The PL and LL are known as the Atterburg Limits and are a defining characteristic of a specific soil. The Liquid
Limit is determined by a graph of moisture content verses blows of a soil sample on Casagrande device. The Plastic Limit is determined by averaging the moisture content of different trials of the Plastic Limit test in ASTM D4318. The Plasticity
Index is the difference of the Plastic Limit from that of the Liquid Limit.
1.2
Problem Statement
The purpose of this report is analyze test performed to determine Atterburg Limits for different soil samples.
1.3
Research Objective
The objective is to determine the Atterburg Limits for different soil samples. This is done by performing Plastic Limit and Liquid Limit test per ASTM D4318.
1.4
Research Scope
This experiment was done on only a sample sample of two different types of soils.
Further test should be done on more samples of the two different soils.
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1.5
Chapter Overview
Chapter 2 provides a background for this experiment. Chapter 3 details the experiment procedure. The results of the experiments are found in Chapter 4. The analysis of the experiment results are in Chapter 5. Chapter 6 contains the discussion. Finally Chapter 7 has the concluding remarks.
CHAPTER 2: BACKGROUND
2.1
Introduction
The Atterburg Limits determines the Plastic Limits (PL) and the Liquid Limits
(LL). The Plastic Limits is the water content where soil starts to exhibit plastic behavior. The Liquid Limits is the water content where soil changes from plastic behavior to liquid behavior. These limits are used to determine the soil consistency for different water content values.
CHAPTER 3: EXPERIMENTAL PROGRAM
3.1
Introduction
To determine the Plastic Limits and Liquid Limits of a soil sample the Plastic Limit test and Liquid Limit test of ASTM D4318 is used. These two limits are then used to determine the Plasticity Index for the soil.
3.2
Experimental Methodology
The idea is to determine the Plasticity Index of a soil sample by performing ASTM
D4318.
3.3
Materials
Materials used for this experiment are different soil samples of different soil types.
For this specific experiment soil samples of Tan 200 and White 200 where used.
3.3.1
Tan 200
Tan 200 is a clay-like soil that is a dark tan to brown in color.
3.3.2
White 200
White 200 is a clay-like soil that is white in color.
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3.4
Specimen Preparation
The soil samples are thoroughly dried and then sifted through a No. 40 sieve to remove any large particles and rocks.
3.5
Test Devices and Equipment
For this experiment the following equipment is used:
• No. 40 Sieve
• Scale (0.1g sensitivity)
• Soil- mixing dish and mixing tools
• distilled water
• Oven can and can holder
• Casagrande cup (Liquid limit device)
• Grooving tool
• 1/8 in. nail
3.6
Test Procedure
ATSM D4318 is used to perform the plastic limits and liquid limits test.
3.6.1
Liquid Limits Test
The first step is to make sure the air-dried soil sample passes through a No. 40 sieve.
Next, add distilled water and thoroughly mix the soil sample in the mixing dish until the soil appears as a uniform paste. Roughly 3/4 of the prepared soil sample is place into the cup of the Casagrande cup of the Liquid limit device. spread the soil into the cup to a depth of about 10 mm and squeeze the sample down to eliminate air pockets. Form a horizontal surface for the sample.
Form a groove in the soil sample by drawing the grooving tool through the soil from the highest to the lowest point in an arc while maintaining the grooving tool perpendicular to the surface of the Casagrande cup
Verify that there are no crumbs of soil present on the base of on the underside of the Casagrande cup itself. Lift and drop the cup at a rate of 2 drops per second until the two halves of the soil sample come in contact at the bottom of the groove for a distance of 13 mm. Do not hold the base of the Liquid limit device while the crank is turning.
Verify that air bubbles did not cause premature closing and record the number of drops, N, required to close the groove. Remove a slice of the sample perpendicular to the groove approximately the with of the grooving tool. Include the portion of
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Figure 3.1: Casagrande cup with groove in soil sample
the groove which the soil sample came together and place in a labeled oven can of known mass. Return the remaining soil to the mixing dish and wash and dry the
Casagrande cup and grooving tool.
Remix the soil specimen in the dish and add more distilled water to increase the water content of the soil sample and to decrease the number of blows required to close the groove Repeat the procedure for at least two additional trials until the number of blows required to close the groove falls into one of the three groups: 25 to 35 blows; 20 to 30 blows; and 15 to 25 blows.
Determine the water content, Wn , of each trial in accordance with Test Method
ASTM D2216. Of note the initial mass of the sample should be taken no more than
15 minutes after the Liquid Limits Test. Calculate the water content of each trial after they have been in the oven for at least 16 hours.
Plot the relationship between the water content, Wn , and the corresponding number of drops, N, on a semi-logarithmic graph. The Number of drop will be on a logarithmic scale on the x-axis and the water content on a arithmetic scale on the y-axis. Draw a best straight line through all the data points. Take the water content corresponding to the line with the 25 drop as the Liquid Limit, LL, rounded to the nearest whole number.
3.6.2
Plastic Limits Test
Select a 1.5 to 2.0 g sample of the soil and form into an ellipsoidal mass. Roll the soil mass by hand. Roll the mass between palm and fingers and a glass plate. Use sufficient pressure to roll the mass to a uniform diameter of of 1/8 in. by comparing the diameter of the mass to that of the 1/8 in. nail. The amount of pressure varies greatly according to the soil. When the diameter reaches 1/8 in. break the sample
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into several pieces. Squeeze the pieces together and knead between the thumb and forefinger. Reform into an ellipsoidal mass, and re-roll. Continue to perform these steps until the thread can no longer be rolled into a diameter of 1/8 in.
Once the thread crumbles at a diameter greater than 1/8 in. the test is complete as long as the thread as previously been rolled into a diameter of 1/8 in. Gather the portions of the crumbled thread and place into an oven can of known mass. Repeat this procedure until at least 6g is collected in two different oven cans of known mass.
Determine the water content of the soil sample in accordance with Test Method
ASTM D2216. Compute the average of the two water contents for the plastic limit samples. Round the average to the nearest whole number and this is the Plastic
Limit, PL, for the soil sample
3.6.3
Plastic Index Calculation
The plastic index is calculated using the following equation:
P I = LL − P L
(3.1)
where:
PI = Plastic Index
LL = Liquid limit
PL = Plastic limit
CHAPTER 4: EXPERIMENTAL RESULTS
4.1
Introduction
The results of each group test are shown below. The first table for each group shows the Plastic Limit Test. The second table shown for each group is for the
Liquid Limit Test. The graph shown for each group is used to determine the Plastic
Limit by comparing the number of blows to the water content of each trail.
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Table 4.1: Liquid Limit Test Group 1
Property
Test 1
Test 2
Test 3
Blows (Number of Drops)
Oven Can ID
Mass of Oven Can
Mass of Oven Can and Wet Soil
Mass of Oven Can and Dry Soil
Mass of Dry Soil in Oven Can
Mass of Water in Oven Can
Moisture Content
4.2
Unit
[-]
[-]
[g]
[g]
[g]
[g]
[g]
[%]
35
A-1(a)
49.47
68.32
63.68
14.21
4.64
32.65
28
A-1(b)
50.64
69.16
64.37
13.73
4.79
34.89
19
A-1(c)
49.73
63.29 4.6
59.58
9.85
3.71
37.66
Results - Tan 200
60
Liquid Limit
LL = 35.8% ⇒ 36%
40
30
25 Blows
Water Content (%)
50
20
10
10
20
Actual Data
Line of best fit
30
40
50
60
Number of Blows — Log Scale
Table 4.2: Plastic Limit Test Group 1
Property
Unit
Test 1
Test 2
Oven Can ID
Mass of Oven Can
Mass of Oven Can and Wet Soil
Mass of Oven Can and Dry Soil
Mass of Dry Soil in Oven Can
Mass of Water in Oven Can
Moisture Content
[-]
[g]
[g]
[g]
[g]
[g]
[%]
A-1(1)
12.49
18.84
18.15
5.66
0.69
12.19
A-1(2)
13.19
19.67 ??
18.95
5.76
0.72
12.5
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The Plastic Index for Group 1 was determined to be 24.
Table 4.3: Liquid Limit Test Group 4
Property
Unit
Test 1
Test 2
Test 3
Test 4
Blows (Number of Drops)
Oven Can ID
Mass of Oven Can
Mass of Oven Can and Wet Soil
Mass of Oven Can and Dry Soil
Mass of Dry Soil in Oven Can
Mass of Water in Oven Can
Moisture Content
[-]
[-]
[g]
[g]
[g]
[g]
[g]
[%]
27
A41
30.95
39.93
37.60
6.65
2.53
35.0
24
A42
30.58
45.38
41.62
11.04
3.76
34.1
36
A43
25.01
37.20
34.24
9.23
2.96
32.1
17
A44
30.96
46.06
42.47
11.51
3.59
31.2
60
Liquid Limit
LL = 34.5% ⇒ 35%
40
30
25 Blows
Water Content (%)
50
20
10
10
20
Actual Data
Line of best fit
30
40
50
60
Number of Blows — Log Scale
Table 4.4: Plastic Limit Test Group 4
Property
Unit
Test 1
Test 2
Oven Can ID
Mass of Oven Can
Mass of Oven Can and Wet Soil
Mass of Oven Can and Dry Soil
Mass of Dry Soil in Oven Can
Mass of Water in Oven Can
Moisture Content
[-]
[g]
[g]
[g]
[g]
[g]
[%]
A4A
13.42
21.10
19.00
5.58
2.10
37.6
A4B
11.97
20.36
19.93
7.96
0.43
5.4
12
4.4
4.3
The Plastic Index for Group 4 was determined to be 13.
4.3
Results - White 200
Table 4.5: Liquid Limit Test Group 2
Property
Unit
Test 1
Test 2
Test 3
Blows (Number of Drops)
Oven Can ID
Mass of Oven Can
Mass of Oven Can and Wet Soil
Mass of Oven Can and Dry Soil
Mass of Dry Soil in Oven Can
Mass of Water in Oven Can
Moisture Content
[-]
[-]
[g]
[g]
[g]
[g]
[g]
[%]
21
A-2-1
25.7
53.43
46.78
21.08
6.65
31.55
19
A-2-2
27.02
47.4
42.42
15.40
4.98
32.34
35
A-2-3
26.46
46.23
41.51
15.05
4.72
31.36
60
Water Content (%)
50
LL = 31.55% ⇒ 32%
40
Liquid Limit
25 Blows
30
20
10
10
20
Actual Data
Line of best fit
30
40
50
Number of Blows — Log Scale
The Plastic Index for Group 2 was determined to be 8.
CHAPTER 5: ANALYSIS
5.1
Introduction
The results of this experiment varied greatly for each soil tested.
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4.6
Table 4.6: Plastic Limit Test Group 2
Property
Test 1
Test 2
Test 3
Oven Can ID
Mass of Oven Can
Mass of Oven Can and Wet Soil
Mass of Oven Can and Dry Soil
Mass of Dry Soil in Oven Can
Mass of Water in Oven Can
Moisture Content
5.2
Unit
[-]
[g]
[g]
[g]
[g]
[g]
[%]
A-2-4
13.48
22.82
20.77
7.29
2.05
28.12
A-2-5
13.04
22.12
20.13
9.08
1.99
21.92
A-2-6
13.11
21.33
19.53
8.22
1.80
21.89
??
Tan 200
The Plasticity Index for Tan 200 where determined to be 24 and 13.
5.3
White 200
The plasticity Index for White 200 where determined to be 8, 3, and 0. The PI of
0 is not possible.
CHAPTER 6: DISCUSSION
There were several errors in determining the Atterburg Limits during each group test. This is shown by having an outlier in one of the groups and another group the
Plasticity Index was determined to be 0 which is not possible.
CHAPTER 7: CONCLUDING REMARKS
7.1
Conclusions
• The findings for each soil sample were inconclusive as each group was not conclusive with the other group/groups.
• There were errors while performing the experiments.
