GeotechnicalEngineeringResearchLaboratory EdwardL.Hajduk,D.Eng,PEOneUniversityAvenue LecturerLowell,Massachusetts01854 PA105DTel:(978)934‐2621 Fax:(978)934‐3052e‐mail: Edward_Hajduk@uml.eduwebsite:http://faculty.uml.edu/ehajduk

DEPARTMENTOFCIVILANDENVIRONMENTALENGINEERING

14.330 2013 Assignment 2 Solution Page 1 of 10

14.330 SOIL MECHANICS Assignment #2: Soil Classification Solution.

PROBLEM #1 (60 Points): GIVEN: Table 1. Soil Index Testing Summary.

Sample D422 D4318

Sieve Number

% Retained LL PL

1

10 0.1

NA NA

30 0.7

40 0.9

60 8.3

100 57.2

120 17.5

200 11.9

Pan 3.1

2

10 0.0

21 15

30 1.2

40 2.0

60 22.7

100 35.2

120 5.7

200 14.6

Pan 18.4

3

10 0.0

54 31

30 0.4

40 1.2

60 19.4

100 47.9

120 6.4

200 14.9

Pan 9.8

REQUIRED: Determine USCS and AASHTO soil classifications for each soil sample.

14.330 2013 Assignment 2 Solution Page 2 of 10

SOLUTION: USCS Classification: Plot grain size distribution for all soils and determine D60, D30, and D10 when necessary for Soil Samples #1, #2, and #3.

Figure A. Grain Size Distributions and D60, D30, and D10 for Samples #1, #2, and #3. Calculate Cc and Cu using information in Figure A for Samples #1 and #3 and the equations shown below. See Table A for summary of Cu and Cc calculations.

Coefficient of Uniformity = Cu = D60

D10

Coefficient of Curvature (a.k.a. Gradation) = Cc = (D30 )2

(D60xD10 )

14.330 2013 Assignment 2 Solution Page 3 of 10

Table A. Summary of Cu and Cc calculations.

Parameter Sample #1 Sample #3

D60 (mm) 0.172 0.208

D30 (mm) 0.15 0.147

D10 (mm) 0.106 0.076

Cc 1.62 2.74

Cu 1.23 1.37

Knowing that PI = LL-PL, LL vs. PI was plotted for Samples #2 and #3 on Figure B.

Figure B. Atterberg Limits Test Results Plotted on Casagrande’s Chart.

Since each soil sample has a % Passing a #200 sieve < 50%, use Figure 3 of ASTM D2487 to classify soil. See Figures C thru E for soil classification using ASTM D2487 Figure 3 for Soil Samples #1 thru 3, respectively.

14.330 2013 Assignment 2 Solution Page 4 of 10

Figure C. USCS Soil Classification of Sample #1 (using Figure 3 of ASTM D2487).

Figure D. USCS Soil Classification of Sample #2 (using Figure 3 of ASTM D2487).

SC-SM- Silty, Clayey Sand

SP - Poorly Graded Sand

Cu = 1.23

No Gravel

No Gravel

FC = 18%

FC = 3%

14.330 2013 Assignment 2 Solution Page 5 of 10

Figure E. USCS Soil Classification of Sample #3 (using Figure 3 of ASTM D2487). AASHTO Classification: Use Table 2 from ASTM D3282. Determine % Passing #10, #40, and #200 sieves (see Figure A for grain size distribution plots). See Figure F for soil classification using ASTM D3282 Table 2 for Samples #1 thru 3.

Figure F. AASHTO Soil Classification of Sample #1, #2, and #3 (using Table 2 of ASTM D3282).

TABLE 2 Classification of Soils and Soil-Aggregate Mixtures

General ClassificationGranular Materials

(35 % or less passing No. 200 (75 µm))Silt-Clay Materials

(More than 35 % passing No. 200 (75 µm))

Group classification

A-1

A-3

A-2

A-4 A-5 A-6

A-7

A-1-a A-1-b A-2-4 A-2-5 A-2-6 A-2-7A-7-5,A-7-6

Sieve analysis, % passing:No. 10 (2.00 mm) 50 max ... ... ... ... ... ... ... ... ... ...No. 40 (425 µm) 30 max 50 max 51 min ... ... ... ... ... ... ... ...No. 200 (75 µm) 15 max 25 max 10 max 35 max 35 max 35 max 35 max 36 min 36 min 36 min 36 min

Characteristics of fraction passingNo. 40 (425 µm):

Liquid limitPlasticity index

...6 max

...N.P.

40 max10 max

41 min10 max

40 max11 min

41 min11 min

40 max10 max

41 min10 max

40 max11 min

41 min11 minA

Usual types of significant consti-tuent materials

Stone Fragments,Gravel and Sand

FineSand

Silty or Clayey Gravel and Sand Silty Soils Clayey Soils

General rating as subgrade Excellent to Good Fair to Poor

APlasticity index of A-7-5 subgroup is equal to or less than LL minus 30. Plasticity index of A-7-6 subgroup is greater than LL minus 30 (see Fig. 1).Reprinted with permission of American Association of State Highway and Transportation Officials.

Cu = 1.37 MH SP-SM - Poorly

Graded Sand with Silt

No Gravel

FC = 10%

Sample #3Sample #1

Sample #2

14.330 2013 Assignment 2 Solution Page 6 of 10

Problem #1 Summary:

Sample Soil Classification

USCS Group Symbol & Name AASHTO

#1 (SP) Poorly Graded Sand A-3

#2 (SC-SM) Silty, Clayey Sand A-2-4

#3 (SP-SM) Poorly Graded Sand with Silt A-2-7

PROBLEM #2 (40 Points): GIVEN:

Figure 1. Mechanical Sieve and Hydrometer Results for Problem #2.

Table 3. Atterberg Limits (ASTM D4318) for Problem #2.

Soil LL PL

#1 61 31

#2 NA NA

#3 37 10

Soil #2

Soil #3

Soil #1

14.330 2013 Assignment 2 Solution Page 7 of 10

REQUIRED: Classify the soils in accordance with the Unified Soil Classification System (USCS) and AASHTO. USCS Classification: Calculate % Gravel, % Sand, and % Fines from Figure 1. A summary of these percentages is provided in Table B. Table B. Summary of % Gravel, % Sand, and % Fines from Figure 1.

Soil % Gravel % Sand % Fines Soil

1 0 0 100 Fine Grained

2 2 98 0 Coarse Grained

3 0 50 50 Fine Grained

Knowing that PI = LL-PL, PI vs. LL was plotted for Soils #1 and #2 on Figure G.

Figure G. Atterberg Limits Test Results Plotted on Casagrande’s Chart. Therefore, use Figure 1 from ASTM D2487 for Soils #1 and #3 and Figure 3 from ASTM D2487 for Soil #2 to classify the soils. See Figures H thru J for soil classification using ASTM D2487 Figures for Soils #1 thru #3, respectively.

14.330 2013 Assignment 2 Solution Page 8 of 10

Figure H. USCS Soil Classification of Soil #1 (using Figure 1 of ASTM D2487).

For Soil #2 (Using Figure 3, ASTM D2487):

10

60u

1060

230

c D

DC;

)DD(

)D(C

Soil D10

(mm) D30

(mm) D60

(mm) Cc Cu

#2 0.32 0.58 0.85 1.1 2.7

CH – Fat Clay

LL = 61

0% Plus #200

14.330 2013 Assignment 2 Solution Page 9 of 10

Figure J. USCS Soil Classification of Sample #2 (using Figure 3 of ASTM D2487).

Figure I. USCS Soil Classification of Soil #3 (using Figure 1 of ASTM D2487).

CL – Sandy Lean Clay

LL = 39

50% Plus #200

SP – Poorly Graded Sand

2% Gravel

FC = 0% Cu = 2.7, Cc = 1.1

14.330 2013 Assignment 2 Solution Page 10 of 10

AASHTO Classification: Use Table 2 from ASTM D3282. Determine % Passing #10, #40, and #200 sieves (see Figure 1 for grain size distribution plots). See Figure K for soil classification using ASTM D3282 Table 2 for Soils #1 thru 3.

Figure K. AASHTO Soil Classification of Soils #1, #2, and #3 (using Table 2 of ASTM

14.332D3282). Problem #2 Summary:

Sample Soil Classification

USCS Group Symbol & Name AASHTO

#1 (CH) Fat Clay A-7 (Acceptable)

A-7-5

#2 (SP) Poorly Graded Sand A-1-b

#3 (CL) Sandy Lean Clay A-6

EXTRA CREDIT (+5 Points): Which discipline of civil engineering you would like to work in when you graduate? Write a paragraph or two why you have selected this discipline. Use Guest Lecture assignment guidelines. Self-explanatory.

Soil #2 Soil #3

Soil #1