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Grouting Considerations for Natural Cementation in Sands

Grouting Considerations for Natural Cementation in Sands. Presented by Brian Martinez. Considerations. The Ideal Chemical Grout and Microbial-Induced Calcite Precipitation (MICP) Strength of Grout pH Considerations Gel Time Grouting Technology Complications Solutions Concluding Remarks.

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Grouting Considerations for Natural Cementation in Sands

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  1. Grouting Considerations for Natural Cementation in Sands Presented by Brian Martinez

  2. Considerations • The Ideal Chemical Grout and Microbial-Induced Calcite Precipitation (MICP) • Strength of Grout • pH Considerations • Gel Time • Grouting Technology • Complications • Solutions • Concluding Remarks

  3. The Ideal Chemical Grout • Low-viscosity solution • Stable under normal temperatures • Nontoxic, non-corrosive, non-explosive • Common, inexpensive materials • Insensitive to salts and other chemicals • Controlled for varying gel times • Appreciable acceptance of dilution • Permanence • Stable pH • High strength (Karol. Chemical Grouting and Soil Stabilization. 2003)

  4. How does MICP Fit? • Low-viscosity solution (Close to water) • Stable under normal temperatures • Nontoxic, non-corrosive, non-explosive • Common, inexpensive materials • Insensitive to salts and other chemicals • Controlled for varying gel times • Appreciable acceptance of dilution • Permanence (Occurs naturally) • Stable pH • High strength

  5. High Strength • Comparable to gypsum cemented sands • How does the strength vary? • Composition • Temperature • pH • Synerisis (DeJong et al. Microbial Induced Cementation to Control Sand Response. 2006)

  6. Stable pH • Commercial grouts need stable pH • MICP needs 9>pH>8.3 (alkaline) • How do other parameters relate to pH? • Strength • Permeability • Composition • Gel Time (DeJong et al. Microbial Induced Cementation to Control Sand Response. 2006)

  7. Gel Time • Time solution takes to precipitate calcite and cement the soil • Optimal gel time? • Composition • Strength • Permeability • pH • Grouting Technology (Karol. Chemical Grouting and Soil Stabilization. 2003)

  8. Hayward Baker Geotechnical Construction Grouting Technology • Permeation • Point Injection • Complications • Dilution • Pumping rates • Ground water flow • Stratification • Solutions • Short gel times • More is better • New ideas? (Karol. Chemical Grouting and Soil Stabilization. 2003)

  9. Complications Dilution Ground Water Flow Stratification (Karol. Chemical Grouting and Soil Stabilization. 2003)

  10. Solutions: Short Gel Times • Time efficient • Cost effective • Unifies grout in stratified soils (Karol. Chemical Grouting and Soil Stabilization. 2003)

  11. Solutions: More is Better • Grout Curtains • Systematic planning • Injection grid (Karol. Chemical Grouting and Soil Stabilization. 2003)

  12. Solutions: New Ideas • Obtaining a uniform grout zone • Using groundwater flow Sand Grout Drawdowns

  13. Concluding Remarks • Strength test have proven MICP to be beneficial for field use • Further testing for relationships between: • Strength • Permeability • pH • Gel Time • Sensitivity • Grouting techniques to improve for centrifuge testing

  14. THE END

  15. References DeJong, J., Fritzges, M., Klaus Nusslein. Microbial Induced Cementation to Control Sand Response to Undrained Shear. Journal of Geotechnical and Geoenvironmental Engineering-ASCE. November 2007 Karol, Reuben. Chemical Grouting and Soil Stabilization. Marcel Dekker, Inc. New York, NY 2003. Hawyard Baker Geotechnical Engineering Construction. 2003. 12/1/2006 – 12/5/2006. http://www.haywardbaker.com

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