Nanotechnology for Ground Improvement. Amro El Badawy, Ph.D. W.M. Keck Foundation Postdoctoral Fellow Global Waste Research Institute Jan 27 th, 2015

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1 Nanotechnology for Ground Improvement Amro El Badawy, Ph.D. W.M. Keck Foundation Postdoctoral Fellow Global Waste Research Institute Jan 27 th, 2015

2 Who cares about nanotechnology?!!

3 Soil Stabilization Soil stabilization improves soil properties such as durability, permeability, and strength Stabilization can be chemical or mechanical or a combination of both Chemical stabilization is achieved by changing the chemical make of the soil matrix through addition of polymers, enzymes, cement, NANOMATERIALS and other compounds Mechanical stabilization is the reinforcement of soil through mechanical means such as compaction

4 Nanotechnology is still evolving and there doesn t seem to be one definition that everybody agrees on. Nanotechnology deals with matter on a very small scale (one nanometer is 10-9 m) Nanomaterials are loosely defined as materials with at least one external dimension in the size range from approximately nanometers

5 Examples of Nanomaterials Metallic nanoparticles (e.g., silver, gold, iron) Metal Oxide nanoparticles (e.g.,tio 2, ZnO) Carbon-based nanomaterials (e.g., carbon nanotubes, fullerene) Others (e.g., quantum dots) TiO 2 Different color AgNPs based on aspect ratio Y. Andrew Wang,

6 At the nanoscale, nanomaterials exhibit unique sizedependent properties relative to the bulk materials. The following slides provide examples of the change in the materials properties at the nanoscale.

7 Optical Properties Gold looks gold at the bulk scale. However, gold stops looking gold at the nanoscale and the color depends on the size of the gold particles

8 Optical Properties (Cont d) Sunscreens using micron size titanium dioxide looks white (left side of the face) while sunscreens using nano-titanium dioxide nanoparticles looks transparent(right side of the face)

9 Mechanical Properties Carbon nanotubes are 100 to 200 times stronger than steel but a fraction of its weight (six times lighter)

10 Thermal Properties Thermal Conductivity of Carbon is 1.7 (W/m-K) Thermal Conductivity of Carbon nanotubes ranges from 1800 to 2000 (W/m-K) Marquis, F. D. S., & Chibante, L. P. F. (2005). Improving the heat transfer of nanofluids and nanolubricants with carbon nanotubes. Jom, 57(12), 32-43

11 The melting point of gold is 1,064 C. However, the melting point of nano-gold changes depending on the size of the particle as shown below.

12 Other Properties of Nanomaterials Conductors can become semi-conductors and semi-conductors can become insulators Unique superparamagnetic properties Unique antimicrobial properties And More!

13 What is going on at the nanoscale? Why the properties of the materials change once the reach the nanoscale?

14 1- Nanomaterials have huge surface area to volume ratio. Higher surface area means higher reactivity. e.g., A one gram of 35 nm Fe nanoparticles has a surface are of 50 m 2

15 2- Quantum effects dominate: the size of nanomaterials is very close to the size of atoms. Quantum effects dominate and that is why nanoparticles interact differently with light compared to the bulk scale materials

16 Interesting!! But who cares?

17 Nanotechnology Rush (Applications)

18 Nanotechnology has no single focus Almost every industry is currently investing in nanotechnology in order to develop new products or improve existing products Nanoyou.eu

19 More than 1200 consumer products containing nanomaterials are in the market

20 Food Companies Integrating Nanotechnology

21 Other Companies Integrating Nanotechnology (to name a few) 21

22 Graphene is a nanomaterial composed of a sheet of carbon that is one atom thick

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26 Imaginary picture that shows that nanotechnology will be around us everywhere

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34 Polypropylene Nanocomposite Improves CH Clay Alexandria Engineering Journal, 2014, 53(1),

35 Polymer Nanocomposite Reduces Atterberg Limits Polymer nanocomposite reduced Atterberg limits of CH clay Increase soil strength Alexandria Engineering Journal, 2014, 53(1),

36 Polymer Nanocomposite Improves Compaction Polymer nanocomposite acted as a nanofiller and improved compaction of clay soil Alexandria Engineering Journal, 2014, 53(1),

37 Polymer Nanocomposite Increases Shear Strength Alexandria Engineering Journal, 2014, 53(1),

38 Non treated clay: Brittle failure (well-defined shear plane) Treated clay: Plastic failure (buckling)

39 Polymer Nanocomposite Reduces Volumetric Shrinkage Alexandria Engineering Journal, 2014, 53(1),

40 Polymer Nanocomposite Reduces Desiccation Cracks Untreated clay specimens left in air: deep and wide cracks formed Treated clay samples with polymer nanocomposites significantly reduced the intensity and depth of desiccation cracks without decreasing hydraulic conductivity of the clay Minimization of surface cracking of landfill clay covers is critical

41 One of the reasons for using NMs for soil stabilization over conventional stabilizing materials: Conventional materials decrease shrinkage but increase hydraulic conductivity Using NMs for stabilization decrease shrinkage without increase hydraulic conductivity

42 elangor,%20malaysia)%20721.pdf Source: Carbon Nanotubes in Clay Capacity for water is higher with the addition of nanotubes (more water can be taken inside the tubes) Increased PI means reduction in hydraulic conductivity (good for landfill clay covers and liners)

43 Research Questions Which Nanoparticle to Use? Which Soil to Improve? What Concentration of Nanoparticle? Which Test to Use? Challenges with using current standard methods for nanomaterials testing? What is missing from the study?

44 Geo-environmental Improvement of Soil Using Nanomaterials Nanomaterials can be used for: Improving Cation Exchange Capacity (good from contaminant standpoint, for example in landfill liners) Nanomaterials for soil remediation

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48 Geo-Denver 2007: New Peaks in Geotechnics

49 Acknowledgement This lecture is part of an educational project Exploring Emerging Waste Streams Created by Advances in Technology: Bringing Real World Issues into the Undergraduate STEM curriculum at Cal Poly, San Luis Obispo implemented by the Global Waste Research Institute at Cal Poly and funded by W.M. Keck Foundation

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