Hershey Lodge Preconference Symposium 17 March 2008

1. Hershey Lodge Preconference Symposium 17 March 2008 State-of-the-Art Technological Developments in Concrete “Nanotechnology Applied to Bulk Concrete” Barry E. Scheetz Department of Civil and Environmental Engineering The Pennsylvania State University

2. Presentation Outline • *Who first defined nano-? • Where are we using nano-stuff? • Why the big deal with nano-? • What exactly is a nano? • *How does this work in bulk concrete? • *The future of nanotechnology and bulk concrete?

3. Who first defined nano-? The term "nanotechnology" was first defined by Tokyo Science University, Norio Taniguchi in a 1974 paper (N. Taniguchi, "On the Basic Concept of 'Nano-Technology',"

4. Where are we using nano-stuff? Medicine cell imaging cancer therapy --- contact agents drug-delivery vehicles Catalysis fuel cells catalytic converters photocatalytic devices

5. Cosmetics sunscreens Textiles water and stain repellent wrinkle-fee invisibility coat – military Optics scratch resistant coatings Foods anti-microbial packaging

6. Vehicle manufacturing hard coatings for wear resistance Electronics quantum dots semiconductors

7. Why the big deal with nano-? At the scale of a cluster of a few unit cells [nanometers], conventional ideas of structure-property relationships no long hold. The nano-materials behave nonlinearly i.e. hard materials become ‘super’ hard

8. What exactly is a nano? 1 grain of sand in 200 lbs A billionth of a meter 10-9

9. Nanotechnology and bulk concretepractices In 1974 when Dr. Taniguchi first defined ‘nano-,’ nano-seeding of portland cement concrete was being practiced in Philadelphia for 2 years.  In 1974, it was being practiced in Europe for about 30 years.  It took almost 20 more year, until 1995, before I was able to recognize the phenomena

10. Applications of this technology Humana Inc. Headquarters Building – Louisville, Kentucky - 1983 *basement structure had to withstand hydraulic head of 16 feet *repeated exposure to salt Philadelphia International Airport Parking Garages -1976

11. * Shotcrete application for fast and easy construction of water channels Camden Aquarium Penguin Exhibit – Camden, NJ - 1998 *water treatment facilities NSF Standard 61 approved

12. How does this work in bulk concrete? nano nano nano

13. Principal Mineralogical Components Of Portland Cement • tri-calcium silicate [C3S] • di-calcium silicate [C2S] • tri-calcium aluminate [C3A] • tetra-calcium aluminoferrite [C2AF]

14. Mineralogical Composition of Hydrated Portland Cement

15. C3S + H2O C-S-H + CH 3CaO . SiO2 + (3+m-n)H2O nCaO.SiO2.mH2O + (3-n)Ca(OH)2

16. Hydration of C3A Induction Period Q Hydration of C2S Hydration of C3S t Heat of Hydration of Portland Cement

17. Solubility of C3S in Portland Cement Slurry Point at which nucleation occures in ordinary non-seeded systems supersaturation On set of nucleation with the use of nano-seeds Equilibrium saturation curve

18. Impact of Seeding of Heat of Hydration

19. SEM image of AES seeds

20. TEM image of AES 5nm

21. Schematic vs. Actual Images of C-S-H 3 nm 200 nm

22. At recommended mass loadings of 1% by weight of cement in the concrete ~ 1023 seeds get added to 100 pounds of cement 100,000,000,000,000,000,000,000 : 100

23. Microstructure without Individual hydrated cement grain with Ca(OH)2

24. Large Proportion of Hydration Products are Deleterious In unmodified Portland Cement Concrete

25. Electron Backscatter Images of Ohio DOT bridge

26. Benefits of microstructure control on the nanometer scale • *Uniformity of the microsturcture • >minimize stress concentrators • >homogeneous bonding to filler materials *Reduction in critical flaw size KIC = Y σ (c)1/2 by the dispersion of portlandite

27. The Material The primary function of the admixture is for the manufacture of “watertightconcrete and reinforcement corrosion protection.” Ref: CIAS Report: 02-1

28. * compositionally it is an Alkaline Earth Silicate [AES] C-S-H * it is sold in the form of a liquid * dosage rate is 1% by weight of portland cement [equivalent to 400 ppm concrete]

29. Water Permeability Performance 0.2 microdarcys* Raw data PA turnpike <1 nanodarcy * sample taken from section that was not compromised by deterioration

30. ASTM C 441 w/o w

31. Carbon Dioxide Penetration After 25 Years 25.4mm

32. “The Big House” University of Michigan Stadium Repair method: alkaline earth silicate modified repair mortar * 460,000 sq.ft. repair to risers and tread surface area; * depth of replacement: 1/8” to 6” * 1972 to 1979 Ref: Concrete International (Sept 1980)

33. 1972 2001 Repaired surfaces --- 25 + years later. Melting snow 2001 Damage to riser and tread area

34. * cast the same day at the same pre-cast facility * mix designs ‘identical’ > one had AES > one had corrosion inhibitor

35. Pennsylvania Turnpike * seven structures in 5 mile stretch; 6 control and 1 with admixture * AES modified placed 1973; 6 control placed 1974

36. Wiss, Janney & Elstner Evaluation of PA Turnpike Bridge Deterioration

37. A The Mechanism B

38. MIP results of pore size distribution in slag-OPC blended concrete Total porosity 9.2% With AES 91.4% Total porosity 14.5% 6 sack concrete mix 50% OPC/50% slag W/C = 0.43 Cured 28 days 78.9%

39. Water flow will follow the path of least resistance. Tortuosity is a ratio of the “actual”length of the flow path, which often is very sinuous and the shortest distances between the end points of the flow. Lmin Lmax Lintermediate Case #1 - ordinary concrete T = Lmin Case #2 - mineral admixture concrete T = Lintermediate/Lmin Case #3 AES concrete T = Lmax/Lmin

40. 3-3 composite 3D solid matrix and 3D void structure Sheriann Ki Sun Burnham Tortuosity #9

41. Tortuosity Deff. = Dint  Deff. =effective diffusion coefficient Dint = intrinsic diffusion coefficient  = porosity  = tortuosity factor

42.  = 2 / c 2 = tortuosity C = constricivity

43. The future of nanotechnology and bulk concrete? > Nano-materials must be incorporated into cementitious systems in an aqueous media. > The result is that small mass loadings of very small seed results in extremely large numbers of individual particles. • > At conventional low levels of addition, there is • not enough material added to impact the • physical properties

44. Future continued: > Distributing seed uniformly throughout a concrete body therefore controls the ‘entire’ volume of the concrete body > calcium carbonate is reported to enhance the mechanical strength of pastes made with 100,000 to 200,000ppm addition of nano-particles

45. Future continued: > At concentrations greater than 100,000ppm [ a situation not hitherto examined] these seeds offer a significant potential, when used with a system such as DSP cement, to further enhance densification resulting in enhanced mechanical properties