GE-20: IMPACT OF SHELL CONTENT ON COMPRESSIBILITY OF GRANULAR - - PowerPoint PPT Presentation

GE-20: IMPACT OF SHELL CONTENT ON COMPRESSIBILITY OF GRANULAR MATERIAL FOR LAND RECLAMATION

Theresa Loh Lai Teng

Scope of presentation

• Objectives
• Carbonate Test
• Soil Properties and Test Procedures
• Oedometer Tests
• Constant Rate of Strain (CRS) Tests
• Conclusions and Recommendations

Source 1 Source 1 Source 2

• urce 2

Source 3

• urce 3

Shell hell 0% 6% 0% 39% 1% 7% 1% 43% 0.3 – 1.7% 8.5 – 25.1% 0.2 – 1.2%

• Carbonate Test (BS1377-3:1990 & BS6463-2:1984)

Basic Soil Properties

Soi Soil Properti Properties es Source Source 1 1 Source

• urce 2

2 Source

• urce 3

3

Specific Gravity Specific Gravity 2.64 - 2.68 2.69 - 2.71 2.65 - 2.69 ρd, d, max

max

1.79 1.74 1.71 ρd, d, min

min

1.51 1.45 1.35 emax

max

0.75 0.85 0.96 emin

min

0.48 0.55 0.55 Coefficient of Coefficient of Uniformity Uniformity 1.5 3.8 3.4 Coefficient of Coefficient of Curvat Curvature 0.9 2.3 1.0 USCS USCS SP SP SP

Sieve Analysis (British Standard)

Preparation Method for Oedometer

Oedometer size: 63 x 19.2mm Sand from all 3 Sources

• Sand sieved through 2mm sieve

Shell from Source 2

• Shell greater than 1.18mm are separated

manually

Soil Density and Void Ratio in Oedometer

Void Ratio Relative Density Source 1 Source 2 Source 3 Loose (28-35%) 0.65 – 0.66 0.75 – 0.78 0.82 – 0.85 Medium (42 – 45%) 0.62 – 0.64 0.71 – 0.74 0.76 – 0.79 Dense (68 – 72%) 0.55 – 0.56 0.63 – 0.66 0.66 - 0.68

Oedometer Result (S1-M-20)

Original Behaviour of Sand (0%)

Effect of Shell Content (Source 1)

Repeated Dense Sand

Compression Index, Cс (Source 1)

Compression Index, Cс (Source 2)

Compression Index, Cс (Source 3)

Convert Shell Content to Carbonate Content

Dean, 1974:

LOI at 1000ºC / 0.44 = % of CaCO3

Average carbonate content of 100% shell from Source 2 is: 0.5 * (89.5% + 97.9%) = 93.7% For 30% Shell Content, Carbonate Content is: 30% * 93.7% = 28.1% BS1377 BS6463

Soil Type Location Carbonate content (%) Cc Cr Initial Void Reference Artificial carbonate sand

97 0.275 0.012 0.9

Grine,2007 Silicate sand Samyang

5 0.055

• 0.925

Kim et al., 2008 Silicate sand Samyang

5 0.075

• 0.925

Kim et al., 2008 Carbonate sand Gymnyeong

89 0.14

• 1.3

Kim et al., 2008 Carbonate sand Gymnyeong

89 0.205

• 1.3

Kim et al., 2008 Silicate & carbonate sand Jeju harbor

54 0.2

• 1.46

Kim et al., 2008 Silicate & carbonate sand Jeju harbor

54 0.225

• 1.46

Kim et al., 2008 Dogs Bay Sand West of Republic of Ireland

88 0.335 0.0075

• Coop MR,1990

Carbonate Content: 5 to 97%

Cс and Cr from Literature Review

Soil Type Dr= 0% Dr= 20% Dr= 40% Dr= 60% Dr= 80% Dr= 100% Medium to coarse sand, some fine gravel (SW)

• 0.005
• Medium to coarse sand (SW/SP)

0.010 0.008 0.006 0.005 0.003 0.002 Fine to coarse sand (SW) 0.011 0.009 0.007 0.005 0.003 0.002 Fine to medium sand (SW/SP) 0.013 0.010 0.008 0.006 0.004 0.003 Fine sand (SP) 0.015 0.013 0.010 0.008 0.005 0.003 Fine sand with trace fine to coarse silt (SP - SM)

• 0.011
• Fine sand with little fine to coarse

silt (SM) 0.017 0.014 0.012 0.009 0.006 0.003 Fine sand with some fine to coarse silt (SM)

• 0.014
• Modified from Coduto, 2001

Cс from Literature Review

For 93.7% carbonate content

Cс from Literature Review

Sand with shells Fine Sand

Cс from Literature Review

Settlement (Source 1)

Constant Rate of Strain (CRS) Test

• Loading rate: 0.005 mm/min
• Unloading rate: 0.003 mm/min

CRS vs Oedometer

S3-D-0 CRS

Conclusion

• Carbonate

content tests by BS1377 and BS6463 are comparable.

• Effect of relative density on Cc is less than

effect of shell content on Cc .

• Cr is less affected by shell content
• The effect of shell content on Cc is small when

shell content is less than 20%.

• CRS

tests and

• edometer

tests are comparable.

Recommendation

• Influence of inclusion of particles bigger than 2mm
• Effect of the strength of the shells
• Effect of rate of loading for CRS tests