Lab 2 - Sieve and Hydrometer Analysis PDF

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Sieve and Hydrometer Analysis Lab 2 CIVE 334 Dr. Song Due February 6th, 2018

Equipment Used

Figure 1. ASTM Sieves

Figure 2. Sieve Shaker

Figure 3. Hydrometer

Figure 4. Soil Dispersion Cup and Mixer

Other Equipment : -

Scale Soil 2x 1000mLGraduated Cylinder Sodium Hexametaphosphate Deflocculant Spatula

-

Distilled Water No. 12 Rubber Stopper Beaker Thermometer

Test Procedure Sieve The test procedure was carried out by first obtaining the mass of the soil sample that was to be put into the sieves. The mass of this soil was found to be 496.71 grams. Next, we assembled the sieves, using the Number 4, 10, 20, 30, 40, 60, 140, and 200 sieves. We placed the soil into the sieve, placed it into the sieve shaker and secured it, then set the timer on the shaker for 15 minutes. After 15 minutes, we carefully removed each sieve, and poured the retained soil into a metal bowl that sat on a zeroed-out scale. The mass recorded was the mass retained on each sieve. This process was repeated for each sieve, as well as the pan. We then calculated the percent of mass retained, as well as the percent finer for each sieve. Next, the data was processed in Excel, where D60, D30, and D10 values were determined via a semilogarithmic plot of the grain size distribution. These values were necessary to calculate the Cu, and Cc for the soil.

Hydrometer We did not start on number 1 of the procedure, as Brian, the TA, completed steps 1 – 6 for us so that we may complete the Lab in a timely manner. He mixed an oven dried, 50g sample of well pulverized clayey soil with Calgon, a deflocculating agent, and then determined the Fz (zero correction factor) and the Fm (meniscus correction factor) for us. The first step we accomplished, was step 7, where we mixed the deflocculated thoroughly by way of spatula. We then filled the mixing cup two-thirds full of distilled water, and then attached the mixing cup to the mixer, where we mixed the deflocculated sample for 2 minutes. After the sample had been mixed, it was poured into a 1000mL graduated cylinder, making sure that all solids had been washed out of the cup and into the cylinder. A No. 12 Rubber stopper was then affixed to the top of the cylinder, and the sample was mixed again by rotating the cylinder up and down, ensuring uniform dispersion of clay particles. We then recorded the temperature again, with a reading of 22 °C. The hydrometer was then inserted into the cylinder with the sample, and the position of the hydrometer was measured. Such measurements were recorded at 0.25, 0.5, 1, 2, 4, 8, 15, 30, 60, 120, and 1440-minute intervals. These readings were then processed in Excel, where other data was calculated.

Results Sieve

Data Table Table 1. Sieve Analysis Data Sieve Opening (mm)

Sieve Number 4

Mass of Soil Retained, Mn (g)

4.75

Percent of Mass Retained, Rn

Cumulative Retained

Percent Finer

0

0.00

0.00

100

10

2

63.02

12.69

12.69

87.31

20

0.841

151.32

30.46

43.15

56.85

30

0.595

74.16

14.93

58.08

41.92

40

0.42

88.8

17.88

75.96

24.04

60

0.25

85.12

17.14

93.10

6.90

140

0.105

33.14

6.67

99.77

0.23

200

0.074

0.54

0.11

99.88

0.12

Pan

0

0.52

0.10

99.98

0

Mass of Oven-Dry Specimen, M = 496.71 g

Cu, Cc = 3.07, 0.829 (respectively)

Mass Retained = 496.62 g

Mass Loss = 0.018 %

D10, D30, D60 = 0.296, 0.472, 0.908 (respectively)

Sample Calculations

Percent of mass retained on sieve Mass of Soil retained ∗100 Mass of Oven Dry specimen 63.02 ∗100=12.69 % 496.71

Cumulative percent of mass through nth sieve i=n

∑ Rn (column 5 of Table 1) i=1

30.46 + 12.69=43.15 % retained on No 20 Sieve

Percent Finer 100−Cumulative Retained %=Percent Finer 100− 43.15=56.85 % finer than No20 Sieve Uniformity Coefficient, Cu Cu = Cu =

D 60 D 10

0.908 =3.07 0.296

Coefficient of Curvature, Cc C c=

C c=

Figures

D 302 D 60∗D 10

0.4722 =0.829 0.908∗0.296

Grain-Size Distribution, Sieve Only 100.00

100 90 80

87.31

Percent Finer

70 60 50 40

56.85 41.92

30 20 10 0

24.04

6.90 10

0.23 0.1 0.12

1

0.01

Grain Size, D

Figure 5. Semilogarithmic Grain Size Distribution - Sieve Only *

* = Includes labeled data points for estimation of D10, D30, and D60 values

Hydrometer Data Table Table 2. Hydrometer Analysis Data Time (min)

Hydrometer Reading, R

Temperature of Test (°C)

RcP

Percent Finer

RcL

L (cm)

A

D (mm)

0.25

38

22

31.65

62.667

39

10.1

0.0131

0.083

0.5

37

22

30.65

60.687

38

10.2

0.0131

0.059

1

36

22

29.65

58.707

37

10.4

0.0131

0.042

2

34

22

27.65

54.747

35

10.7

0.0131

0.03

4

31

22

24.65

48.807

32

11.2

0.0131

0.022

8

29

22

22.65

44.847

30

11.5

0.0131

0.016

15

27

22

20.65

40.887

8

11.9

0.0131

0.012

30

25

22

18.65

36.927

26

12.2

0.0131

0.0084

60

24

22

17.65

34.947

25

12.4

0.0131

0.006

120

23

22

16.65

32.967

24

12.5

0.0131

0.0042

1440

20

22

13.65

27.027

21

13

0.0131

0.0012

Gs = 2.7

Meniscus Correction (Fm) = 1

FT = 0.65

Zero Correction Factor (Fz) = +7

Dry Mass of Soil (Ms) = 50 g

a = 0.99

Sample Calculations

Corrected hydrometer readings, Rcp for calculation of percent finer R + FT − F z =Rcp 38 + 0.65 −7=31.65

Percent Finer a∗R cp ∗100=% Finer Ms

0.99∗31.65 ∗100=66.67 % Finer 50

Corrected reading RcL for determination of effective lengths R + F m=RcL 38 +1=39

Diameter, D A

√

0.0131

Figures

L( cm) =D ( mm) t (min)

√

10.1cm =0.083 mm 0.25 min

Grain-Size Distribution, Hydrometer Only 0.160 0.140

Percent Finer

0.120 0.100 0.080 0.060 0.040 0.020 0.000

0.1

0.01

0

Grain Size, D

Figure 6. Semilogarithmic Grain-Size Distribution – Hydrometer only

Discussion Overall, the execution of the sieve analysis went well as there was little mass loss. The interpretation of the data was a little bit tricky though. This is because the different % Diameters (10, 30 & 60) were all estimates based off of the semilogarithmic grain size distribution for the sieve. This estimation led to diameters of 0.296, 0.472, and 0.908 for the 10, 30 and 60 respectively. Using the equations in the lab manual for the uniformity coefficient and the coefficient of curvature, each were able to be determined using the estimated diameters. The coefficients, Cu = 3.07 and Cc= 0.829, as well as the shape of the curve, lead to the assumption that the soil is poorly graded. The execution of the hydrometer was more time consuming and intricate than the sieve, it was not very difficult. Both tests were not technically tested on the same soil, but the graphs were to be connected. Using the data from both the sieve and hydrometer, the fraction of gravel, sand, silt and clay are as follows:

Table 3. Soil Classification

Sieve Number 4

% Finer 100

Amount Retained 0

Classification Gravel Fraction

10

87.31

12.69

40

24.04

63.27

200

0.12

23.92

0.002mm

0

0.12

Coarse sand fraction Medium Sand fraction Fine Sand fraction Sand and Clay fraction

Approximately where Sieve analysis ends, and Hydrometer analysis begins

Figure 7. Semilogarithmic Grain-Size Distribution - Sieve and Hydrometer combined

Sources of Error There may be several potential sources of error for both the sieve and the hydrometer. For the sieve, a common error may be a large mass loss rate due to soils stuck within each sieve, however this did not affect our group too heavily. Another common error would be to use a different balance for each measurement of mass retained on a sieve. This would lead to a bias in each different measurement, giving inaccurate results. Since the procedure for the hydrometer was more intricate, there was more potential for errors. Errors could arise from an unevenly mixed sample, leading to a rate of settling that was incorrect. A higher concentration of solids higher in the cylinder would make the rate of settling appear slower, and a high concentration of solids towards the bottom of the cylinder would make the rate of settling appear higher. Using a stopwatch or timer that was not correctly calibrated would yield inaccurate times measuring, leading to data that would deviate from it’s true value.

Although Brian, the TA, took care of mixing the deflocculant with the clayey soil, error could arise from not letting the soil soak in the deflocculant for the correct time or not mixing the correct amount of deflocculant with the soil. This would lead to particles being much larger than the size called for in the experiment design, yielding inaccurate settling rates....