Geotechnical Engineering Research Laboratory Edward L. Hajduk, D.Eng, PE

One University Avenue Lecturer

Lowell, Massachusetts 01854 PA105D

Tel: (978) 934-2621 Fax: (978) 934-3052

e-mail: Edward_Hajduk@uml.edu

web site: http://faculty.uml.edu/ehajduk

DEPARTMENT OF CIVIL AND ENVIRONMENTAL ENGINEERING

14.330 2015 Assignment 3 Solution Page 1 of 13

14.330 SOIL MECHANICS Assignment #3: Soil Compaction Solution.

PROBLEM #1 (40 Points): GIVEN: Table 1. ASTM D698 and D1557 Test Results on Soil Sample 2 for Problem #1 (Assignment #2).

Point

D698 D1557

w

(%) γ

(pcf)

w

(%) γ

(pcf)

1 5.4 111.5 5.5 115.7

2 8.7 115.5 7.9 119.3

3 11.1 118.8 10.4 124.8

4 13.8 122.1 12.9 126.8

5 18.3 123.8 15.1 126.2

6 17.4 125.3

REQUIRED: Determine the following:

1. The Maximum Dry Density (γd,max) and Optimum Moisture Content (OMC) from the compaction test results. Plot the results and the zero air voids curve.

2. Determine the ranges of γd,field and OMC required for field compactions of 90%, 95%, and 98%.

3. What type(s) of compaction equipment should you recommend a contractor use

to compact this soil? SOLUTION: Part 1:

Determine γd for the Proctor test points and plot w vs. γd. Note γd = γ/(1+w). See Table A

and Figure A for calculations and w vs. γd plots for both Proctor tests. Compaction characteristics for both Proctor tests are shown in Figure A.

14.330 2015 Assignment 3 Solution Page 2 of 13

Table A. Summary of γd Calculations.

Point

ASTM D698 ASTM D1557

w

(%) γ

(pcf) γγγγd

(pcf) w

(%) γ

(pcf) γγγγd

(pcf)

1 5.4 111.5 105.8 5.5 115.7 109.7

2 8.7 115.5 106.2 7.9 119.3 110.6

3 11.1 118.8 106.9 10.4 124.8 113.0

4 13.8 122.1 107.2 12.9 126.8 112.3

5 18.3 123.8 104.6 15.1 126.2 109.6

6

17.4 125.3 106.7

Figure A. Water Content vs. Dry Unit Weight Plot.

14.330 2015 Assignment 3 Solution Page 3 of 13

Part 2:

Knowing that Relative Compaction in % (RC in %) = (γd,field/γd,max) x 100 and using the

values for γd,max in Figure A, calculate ranges of γd,field and Optimum Moisture Content (PMC) for 98%, 95%, and 90% compaction. See Figures B and C for ranges of OMC for these compaction values for ASTM D1557 and ASTM D698, respectively. Tables B and C provide a summary for ASTM D1557 and ASTM D698, respectively.

Figure B. ASTM D1557 Results with 98%, 95%, and 90% γd,max.

Table B. ASTM D1557 Results with 98%, 95%, and 90% γd,max.

% Compaction γγγγd,field (pcf) w (%)

Min. Max.

98% 111.0 8.3 14.0

95% 107.6 NA 16.7

90% 102.2 NA NA

NOTES: 1. NA = Not Applicable. Could not be determined from data provided.

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Figure C. ASTM D698 Results with 98%, 95%, and 90% γd,max.

Table B. ASTM D698 Results with 98%, 95%, and 90% γd,max.

% Compaction γγγγd,field (pcf) w (%)

Min. Max.

98% 105.4 NA 16.7

95% 102.2 NA NA

90% 96.8 NA NA

NOTES: 1. NA = Not Applicable. Could not be determined from data provided.

Part 3:

The soil is a Poorly Graded Sand with Clay (SP-SC) with FC ≈ 10%. Use smooth drum or vibratory roller.

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PROBLEM #2 (25 Points): GIVEN: Table 2. Field Compaction Test Results (1st Soil Lift).

Column Location

γγγγ

(pcf) w

(%)

A-5 122.8 3.5

B-14 130.2 7.8

K-8 123.8 6.5

F-1 129.5 7.1

W-9 121.8 13.0

REQUIRED: From the provided information, determine the following:

1. The relative compaction at the field test locations with respect to both the standard and modified Proctor tests.

2. Do the field compaction test locations meet the project specifications? The

project specifications state that placed soil should be compacted to at least 98% of ASTM D1557.

3. If the soil does not meet the project specification compaction requirements, what

recommendations would you provide the contractor such that he/she can meet the requirements? Be specific for each location.

SOLUTION:

Determine γd,field for the data in Table 2 using γd,field = γ/(1+wfield). These calculations are summarized in Table D.

Knowing that Relative Compaction in % (RC in %) = (γd,field/γd,max) x 100 and using the

values for γd,max for both ASTM D1557 and D698 in Figure A, calculate RC. These calculations are also summarized in Table D. Are the values for Relative Compaction for ASTM D1557 greater than or equal to 98% (i.e. the project specification requirements)? This comparison is also summarized in Table D.

14.330 2015 Assignment 3 Solution Page 6 of 13

Table D. Field Compaction Calculation Summary.

Column Location

γγγγ

(pcf) w

(%) γγγγd,field

(pcf) D698 RC

(%) D1557 RC

(%) Meets

Specs?

A-5 122.8 3.5 118.6 110.3 104.7 Yes

B-14 130.2 7.8 120.8 112.2 106.6 Yes

K-8 123.8 6.5 116.2 108.0 102.6 Yes

F-1 129.5 7.1 120.9 112.4 106.7 Yes

W-9 121.8 13.0 107.8 100.2 95.1 No

Note that in Table D, ASTM D698 results are provided. However, they are not required. For the failed field compaction test location W-9, compare wfield with OMC (11.3%) to determine if the soil needs to be dried or water needs to be added. After moisture is added/taken away, recompact. A summary of these comparisons is presented in Table E. Table E. Failed Compaction Test Recommendation Summary.

Column Location

D1557 RC (%)

w

(%)

Wet or Dry of OMC?

Recommend?

W-9 95.1 13.0 Wet Let soil dry. Recompact.

14.330 2015 Assignment 3 Solution Page 7 of 13

PROBLEM #3 (25 Points): GIVEN: The results of an ASTM D698 compaction test for a SP soil are presented in Table 3. Table 3. ASTM D698 Test Results for Problem #3.

Point

D698

w

(%) γ

(pcf)

1 11.0 117.0

2 13.1 121.6

3 15.2 126.8

4 17.2 127.7

5 18.7 127.8

REQUIRED: From the provided information, determine the following:

1. The Maximum Dry Density (γd,max) and Optimum Moisture Content (OMC) from the compaction test results. Plot the results and the ZAV curve using a Gs = 2.60.

2. Determine the ranges of γd,field and OMC required for field compactions of 90%, 95%, and 98%.

3. What type(s) of compaction equipment should you recommend a contractor use

to compact this soil? SOLUTION: Part 1:

Determine γd for the Proctor test points and plot w vs. γd. Note γd = γ/(1+w). See Table F

and Figure D for calculations and w vs. γd plot. Compaction characteristics are shown in Figure D.

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Table F. Summary of γd Calculations.

Point

ASTM D698

w

(%) γ

(pcf) γγγγd

(pcf)

1 11.0 117.0 105.4

2 13.1 121.6 107.5

3 15.2 126.8 110.0

4 17.2 127.7 108.9

5 18.7 127.8 107.7

Figure D. Water Content vs. Dry Unit Weight Plot.

14.330 2015 Assignment 3 Solution Page 9 of 13

Part 2:

Knowing that Relative Compaction in % (RC in %) = (γd,field/γd,max) x 100 and using the

values for γd,max in Figure D, calculate the ranges of γd,field and Optimum Moisture Content (PMC) for 98%, 95%, and 90% compaction. See Figure E for these compaction characteristics ranges, while Table G provides a summary.

Figure E. ASTM D698 Results with 98%, 95%, and 90% γd,max.

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Table G. ASTM D698 Results with 98%, 95%, and 90% γd,max.

% Compaction γγγγd,field (pcf) w (%)

Min. Max.

98% 108.0 13.6 18.3

95% 104.7 NA NA

90% 99.2 NA NA

NOTES: 1. NA = Not Applicable. Could not be determined from data provided.

Part 3:

The soil is a Poorly Graded Sand (SP). Use smooth drum or vibratory roller. PROBLEM #4 (10 Points): GIVEN: You have been given the results of a one point Proctor test from a South Carolina Department of Transportation (SCDOT) site in South Carolina in Table 4. You have also been given the results of field compaction testing for the same project in Table 5. Table 4. SC-T-29 Test Results for Problem #3.

Point

D698

w

(%) γ

(pcf)

1 13.8 115.3

Table 5. Field Compaction Test Results (1st Soil Lift).

Station γγγγ

(pcf) w

(%)

135+25 113.0 10.6

250+50 119.5 18.9

375+50 110.5 8.5

14.330 2015 Assignment 3 Solution Page 11 of 13

REQUIRED: From the provided information, determine the following:

1. If the field compaction testing results meet the required compaction of 98% of D698 from the project specifications.

2. If the soil does not meet the project specification compaction requirements, what

recommendations would you provide the contractor such that he/she can meet the requirements? Be specific for each location.

SOLUTION: Use the provided moist unit weight and water content in Table 4 within Figure SC-T-29A

(the Family of Curves) for SCDOT SC-T-29 standard test method to determine γd,max and OMC for this soil. Note: You would need to look on the internet for this document or use the figure provided in the class lecture notes. See Figure F for results. Since the plot falls ~ halfway between curves 14 and 15, use linear extrapolation to

determine the compaction characteristics of γγγγd,field = 105.2 pcf and OMC = 18.1%.

Determine γd,field for the data in Table 5 using γd,field = γ/(1+wfield). These calculations are summarized in Table H. Knowing that Relative Compaction in % (RC in %) =

(γd,field/γd,max) x 100 and using the values for γd,max, calculate RC. These calculations are also summarized in Table H. Table H. Field Compaction Calculation Summary.

Station γγγγ

(pcf) w

(%) γγγγd,field

(pcf) D698 RC

(%) Meets

Specs?

135+25 113.0 10.6 102.2 97.1 No

250+50 119.5 18.9 100.5 95.5 No

375+50 110.5 8.5 101.8 96.8 No

Are the values for Relative Compaction for ASTM D1557 greater than or equal to 98% (i.e. the project specification requirements)? This comparison is also summarized in Table H. For the failed field compaction test locations, compare wfield with OMC (18.1%) to determine if the soil needs to be dried or water needs to be added. After moisture is added/taken away, recompact. A summary of these comparisons is presented in Table I.

14.330 2015 Assignment 3 Solution Page 12 of 13

γγγγ = 115.3 pcf

w = 13.8%

14.330 2015 Assignment 3 Solution Page 13 of 13

Table I. Failed Compaction Test Recommendation Summary.

Station D698 RC

(%) w

(%)

Wet or Dry of OMC?

Recommend?

135+25 97.1 10.6 Dry Add water.

Recompact.

250+50 95.5 18.9 Wet Let soil dry. Recompact.

375+50 96.8 8.5 Dry Add water.

Recompact.