Hershey Lodge Hershey Lodge Preconference Sympos Preconference Symposi 17 March 2008 17 March 2008 State-of-the-Art Technological State-of-the-Art Technological Developments in Concrete Developments in Concrete Nanotechnology Applied to Bulk Concrete Barry E. Scheetz Barry E. Scheetz Department of Civil and Environmental Engineering The Pennsylvania State University
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Hershey LodgeHershey Lodge
Preconference SymposiumPreconference Symposium17 March 200817 March 2008
Hershey LodgeHershey Lodge
Preconference SymposiumPreconference Symposium17 March 200817 March 2008
Barry E. ScheetzBarry E. ScheetzDepartment of Civil and Environmental
EngineeringThe Pennsylvania State University
Presentation Outline
*Who first defined nano-?•Where are we using nano-stuff?•Why the big deal with nano-?Why the big deal with nano-?•What exactly is a nano?What exactly is a nano?*How does this work in bulk concrete?*How does this work in bulk concrete?**The future of nanotechnology and bulk concrete?
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',"
<1 nanodarcy<1 nanodarcy* sample taken from* sample taken fromsection that was notsection that was notcompromised bycompromised by deteriorationdeterioration
* mix designs ‘identical’ > one had AES > one had corrosion inhibitor
* seven structures in 5 mile stretch; 6 control and 1 with admixture* AES modified placed 1973; 6 control placed 1974
Pennsylvania Turnpike
0
50
100
150
200
250
Det
erio
rati
on
Ind
exS
um o
f lin
ear
ft. c
rack
ing,
sq.
ft. s
pallin
g an
d sq
. ft.
dala
min
atio
ns
Control Concrete (average of 6) Concrete w ith Admixture
Cracking (lin. ft.)
Spalling (sq. ft.)Delaminations (sq. ft.)
Wiss, Janney & Elstner Evaluation of PA Turnpike BridgeWiss, Janney & Elstner Evaluation of PA Turnpike BridgeDeteriorationDeterioration
The MechanismThe Mechanism
A
B
MIP results of pore size distributionMIP results of pore size distributionin slag-OPC blended concretein slag-OPC blended concrete
Total porosity9.2%
Total porosity14.5%
78.9%
91.4%
6 sack concrete mix50% OPC/50% slag
W/C = 0.43Cured 28 days
6 sack concrete mix50% OPC/50% slag
W/C = 0.43Cured 28 days
With AES
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 - mineraladmixture concreteT = Lintermediate/Lmin
Case #3 AESconcrete
T = Lmax/Lmin
Sheriann Ki Sun BurnhamTortuosity #9
3-3 composite3-3 composite
3D solid matrix3D solid matrix andand3D void structure3D void structure
> 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
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
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