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  • Mitigation of Expansive Soils Damages

    Joseph Muhirwa Richard Benda Robert Sargent

    REU Program University of Texas at Arlington

  • This presentation will focus on four main sections

    Introduction and Background

    Experimental Program

    Results and Conclusion

    Additional Work

  • Introduction and Background

    Experimental Program

    Results and Conclusion

    Additional Work

  • Clay is the most common particle that makes soils expansive because of its ability to retain large amounts of water.

    Very fine particles (less than 2 microns) Large surface area (plates with negative charge)

  • Kaolinite Montmorillonite Illite

    How expansive clay is depends on the minerals in the clay

    Montmorillonite is the most expansive mineral. One pound of it can have a surface area of 800 acres.

  • Expansive soil behaves like a sponge. It expands when it soaks up water and then shrinks back down when it loses water

    Water being attracted to the negatively charged clay plates

  • The damage to infrastructure by expansive soils costs close to 9 billion dollars per year

    structural damage

    Pavement uplift and cracking

    Slope failure

  • Austin, Texas is located in an area of highly expansive soil

    Austin

    USGS (1989)

  • The main objective of our research was to understand the concepts behind soil stabilization and determine the best percentage of lime to stabilize our soil

    UCS

  • Introduction and Background

    Experimental Program

    Results and Conclusion

    Additional Work

  • 1. Atterberg Limits Test

  • The Swelling Potential of Expansive soils Can be determined indirectly from Atterberg Limits

    Liquid Limit(LL) Plastic Limit (PL)

    Plastic index (PI)

    PI=LL-PL

    (ASTM 4318)

  • 2. Determination of Sulfate Content

  • Ettringite formation, Heave-inducing crystal, can be avoided by checking the sulfate content

    of Soil before lime stabilization

    Day 1: Sample Preparation

    Day 2: Filtration and Precipitation

    Day: Precipitate Filtration

    Day 4: Final Weight of Soluble Sulfate

    Modified UTA method (2000)

  • On the first day, Pulverization and Dilution of the soil are performed

    1:10 Dilution

    Modified UTA method (2000)

  • On the second day, Stirring, centrifigution and Filtration of the soil solution are the major tasks

    Modified UTA method (2000)

  • On the Third day, The filtration of the precipitate solution is performed

    Start/End

    Modified UTA method (2000)

  • On the Fourth Day, The final Weight of the dry precipitate is determined.

    Removal Of Weighing Tin and precipitate from the oven

    Modified UTA method (2000)

  • 3. Additive Selection/ Mix Design

  • Samples with different % of lime are tested to determine the most effective amount of lime

    Common % of Lime: 3%-8%

    Required mellowing time: at least 24 hrs

    OMC of control soil is the starting point

    Nelson and Miller (1992)

  • 4. One-Dimensional Swell Test

  • A Direct Indication of Swell Potential can be obtained through 1-D Swell Test

    (ASTM 4546)

  • 5. Unconfined Compressive Strength Test

  • The UCS Test helps to estimate the strength of Treated and Non-Treated Soils

    Extrusion

    Unconfined Compression

  • Introduction and Background

    Experimental Program

    Results and Conclusion

    Additional Work

  • 1.Results and Discussion

  • Austins soil was found to be a high-plasticity clay

    51.00

    51.50

    52.00

    52.50

    53.00

    53.50

    0 5 10 15 20 25 30

    Moi

    stur

    e co

    nten

    t (%

    )

    Number of blows

    Moisture content vs. Number of blows

    Soil Property Results Liquid Limit (LL) 51.04% Plastic Limit (PL) 19.76% Plasticity Index (PI=LL-PL)

    30.84%

    USCS Classification CH

  • Sample 1 Sample 2 Sample 3

    *W1 (grams) 1.2116 1.2198 1.2156

    *W2 (grams) 1.2182 1.2263 1.2216

    Sulfate content (ppm) 271.63 267.514 246.936

    Avg. Sulfate content

    (ppm)

    261

    The Sulfate content was within the Acceptable range

    W1 = Mass of weighing tin and filter paper W2 = Mass of weighing tin, filter paper, and precipitate

    1Puppala et al. (1999) and Viyanat (2000)

    Acceptable Range = 1000 to 2000 ppm1

  • 00.005

    0.010.015

    0.020.025

    0.030.035

    0.040.045

    0.050.055

    0.060.065

    0.070.075

    0.08

    0.001 0.01 0.1 1 10 100

    disp

    lace

    men

    t (in

    )

    Time (hr)

    Time vs. Displacement

    0 percent2 percent4 percent6 percent

    All of the specimens with lime performed better than the control sample

    In the time-displacement curve, 6% was observed to have reduced swell the most

  • The 6% lime sample had the overall highest strength

    In general, all lime treated samples had a higher shear strength than the control

    Stiffer and softer specimens 01000

    2000

    3000

    4000

    5000

    6000

    7000

    8000

    9000

    0 0.5 1 1.5 2 2.5 3 3.5 4

    Stre

    ss,

    (lb/

    ft2)

    Axial Strain, (%)

    Stress vs. Axial Strain Austin's soil with 0%limeAustin's soil with 2%limeAustin's soil with 4%lime Austin's soil with 6%Lime

    qu =8061 lb/ft2

    qu = 7368 lb/ft2

    qu =4952 lb/ft2

    qu =3433 lb/ft2

  • 2. Conclusions

  • Performance benefits from lime stabilization reduce maintenance costs

  • 6% lime and 4% lime were found to be suitable to reduce swelling and increase bearing capacity

    4% lime could be used in situations requiring reduced cost 6% lime could be used in situations requiring additional

    strength

  • For future research, additional additives could be tried in combination with lime (such as cement)

    + =

  • Introduction and Background

    Experimental Program

    Results and Conclusion

    Additional Work

  • 1.Field Stabilization

  • Reduction of Slope and Embankment Failure at Grape Vine and Joe Pool Lakes

    Slope Testing Area

    Monitoring of Horizontal Movement by Inclinometer

    Monitoring of vertical Movement by surveying

  • 2. Three-Dimensional Swell Test

  • The 3-D Swell Test can be Conducted Using Double Inundation

  • Lime Stabilization reduces the swelling potential considerably

  • 3. Hydrometer Test

  • The size Distribution of Silt and Clay can be Obtained through Hydrometer Test

  • References Anand J. Puppala et al. (1999). Evaluation of a Sulfate Induced Heave by

    Mineralogical and Swell Tests. XI Pan-American Conference on Soil Mechanics and Geotechnical Engineering, Foz do Igacu, Brazil.

    Anand J. Puppala et al. (2002). Evaluation of a Modified Soluble Sulfate Determination Method for Fine-Grained Cohesive Soils. ASTM International, West Conshohocken, PA.

    ASTM. (n.d.). Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils, ASTM D4318, West Conshohocken, PA.

    ASTM. (n.d.). Standard Test Methods for One-Dimensional Swell or Settlement Potential of Cohesive Soils, ASTM D4546-96, West Conshohocken, PA.

    Miller, D. J., Nelson, J. D. (1992). Expansive Soils: Problems and Practice in Foundation and Pavement Engineering, John Wiley & Sons, Inc., Toronto, Canada.

    Viyanant, C., (2000). Laboratory Evaluation of Sulfate Heaving Mechanisms Using Artificial Kaolinite Soil. Masters thesis, The University of Texas at Arlington, TX.

  • Acknowledgements

    We are very grateful to all the people who made this research possible, especially Dr. Anand Puppala, Dr. Nur Yazdani, Dr. Yvette Weatherton, Dr. Stephanie Daza,Mr. Aravind Pedarla, Mr. Justin Thomey, Mr. Minh Lee and Mr. Naga Talluritinnu.

  • Questions???????

    Mitigation of Expansive Soils DamagesThis presentation will focus on four main sectionsSlide Number 3Slide Number 4Slide Number 5Slide Number 6Slide Number 7Slide Number 8Slide Number 9Slide Number 101. Atterberg Limits TestThe Swelling Potential of Expansive soils Can be determined indirectly from Atterberg Limits2. Determination of Sulfate ContentEttringite formation, Heave-inducing crystal, can be avoided by checking the sulfate content of Soil before lime stabilizationOn the first day, Pulverization and Dilution of the soil are performedOn the second day, Stirring, centrifigution and Filtration of the soil solution are the major tasksOn the Third day, The filtration of the precipitate solution is performedOn the Fourth Day, The final Weight of the dry precipitate is determined. 3. Additive Selection/ Mix DesignSamples with different % of lime are tested to determine the most effective amount of lime4. One-Dimensional Swell TestA Direct Indication of Swell Potential can be obtained through 1-D Swell Test5. Unconfined Compressive Strength TestThe UCS Test helps to estimate the strength of Treated and Non-Treated SoilsSlide Number 251.Results and DiscussionAustins soil was found to be a high-plasticity claySlide Number 28Slide Number 29Slide Number 302. ConclusionsSlide Number 326% lime and 4% lime were found to be suitable to reduce swelling and increase bearing capacityFor future research, additional additives could be tried in combination with lime (such as cement)Slide Number 351.Field StabilizationSlide Number 372. Three-Dimensional Swell TestSlide Number 39Lime Stabilization reduces the swelling potential considerably3. Hydrometer TestThe size Distribution of Silt and Clay can be Obtained through Hydrometer TestReferencesAcknowledgements Questions???????

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Mitigation of Expansive Soils Damages Joseph Muhirwa Richard Benda Robert Sargent REU Program University of Texas at Arlington
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