how nanotechnology can change the concrete world i

8/3/2019 How Nanotechnology Can Change the Concrete World I

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H o w N a n o t e c h n o lo g y C a n C h a n g e t h e

C o n c r e t e W o r l dPart O ne of a Two-Part Series

Successfully mimicking nature's bottom-up construction

processes is one oft h e

most prom ising directions.Konstantin Sobolev and

Miguel Ferrada Gutierrez

Facultod de Ingenieria Civil

Universidad Autonoma de Nuevo Leon

San Nicolas de los Garza, M exico

he next industrial revo lutionwill be nanotechnology.Nanotechnology was firstintroduced in the famouslecture of Nobel Laureate

Richard P. Feynman,"There's Plenty of

Room at the Bottom," given in 1959 atthe California Institute of Technology.'

There have been revolutionary develop-ments in physics, chemistry and biologyduring the past 25 years.These develop-ments have proved Feynman's ideas ofmanipulating and controlling matter atan extremely small scale, even to the levelof molecules and atoms; i .e. , ^^

Nanotechnology deals with the produc-tion and application of physical, chemicaland biological systems at scales ranging

from a few nanometers to subm icrondimensions. It also deals w ith the integra-tion of the resulting nanostructures intolarger systems. N anotechnology alsoinvolves the investigation of m atter toindividual atoms.

Drexler^ gave one of the earlier defini-tions of nanotechnology as "the controlof matter based on molecule-by-mole-cule control of products and byproducts

through high-precision systems as well asthe products and processes of molecularmanufacturing, including molecularmachinery."

This defin ition involves the applicationof the botto m -up approach of molecularnanotechnology. Here, organic and inor-

ganic structures are constructed atom -by-atom or molecule by-molecule.However, contemporary technology con-tinues to rely on the top -do wn approach.

Here, bulk materials are broken downinto nanoparticles by mechanical attri-tion and etching techniques ( F i g . 1 ). "



According to Whatmore and

Corbett,^ the subject of nanotechnol-

ogy includes "almost any m aterials or

devices which are structured on the

nanom etre scale in order to perform

functions or obtain characteristicswhich could not otherwise be

achieved."

The science related to nano techno l-

ogy is new. However, nanosized

devices and objects have existed on

earth as long as l ife.The e xceptiona l

mechanical performance of biomate-

rials, such as bones or mo llusk shells,

is due to the presence of nan ocrys-

tals of calcium compounds.^

The nanocom posi te m aterial of the

abalone shell consists of nanosized

particles of calcium carbonate

bou nd by a glue made of a carbo-

hydrate pro tein mix.^ This type of

comp osi te nanostructure leads to

high strength and toughness of the

shell because of interlocking of

nanoblocks of calcium carbonate

responsible for crack arrest and ener-

gy diss ipat ion.

Better understanding and mimick-

ing of the processes of bo tto m -u p

con structio n successfully used by

nature is one of the most promising

directions in nanotechnology.^

Ancient peoples used nanosized

ma terials in glass. A later e xam ple is

photography, which uses si lver

nanoparticles sensit ive to l ight.

N a n o t u b e s

The most promis ing contemporary

developments include the synthesis

of new forms of carbon: ful lerene

(C60) and carbon nanotubes ( F i g . 2) .

Carbon nanotubes are sometimes

represented as a graphene sheet

rol led into a cyl inder with specif ic

al ignment of hexagonal rings and

hemiful lerenes attached to the t ips

The favorable diameter o f a single-walled nanotube (SWNT) is '~ ^ A nm

because of energetic requirements.

Also, 0.4-2.5 nm diameter SWNTs

have been synthesized.^ The leng th

of SWNTs is not restricted and can

reach micron or mil l imeter range,

SWNTs can be classified as a single

molecu le with a high aspect ratio.

The synthe sis of SWNTs is ach ieved

under precisely control led condi-

tions in the presence of a catalyst. A

deviat ion from the product ion route

leads to m ul t iwal l carbon nanotubes

(MWNTs). MWNTs can be represent-

ed as a family of SWNTs of variou s

diameters that are combined wi thin

a single en ti ty. An exa mple is the

concentr ic-type MWNT ( F i g , 2).

Advertisement

Roiled graphene layers generate nanospace.

Journeys In NanospaceCharacterizing SWNTs, MWNTs and Nanopores

For a moiecute traveling thro ugh nanospace the

likelihocd of crashing is great! If not w ith other

molecules, certainly into the wal ls of the

canyon-l ike nanopores through which nano-

flight Is taken. And a s the canyon narrows and

the tempefa ture fal ls, the chance of escaping

the crash site diminishes.

Such is the scenario presented by hydrog en

sorpt ion in act iva ted carbons, between

SWNTs, MWNTs, metal-organic-frameworks

(MOFs) and other porcxis nanoscale materials.

P o r e S i z e F r o m A d s o r p t io n

Current state<rf-tbe-art nnanometHc adsorptionequipment (Autosorb-l-MR QuantachromeInstruments, Boynton Beach FL) is alreadybeing used to measure hydrogenadsorption isotherms, since at cryogenictemperatures appreciable adsorption ofhydrogen begins at about 10' atm fornano- a n d microporous materials.

Pore size distribution calculations are donefrom sub atmospheric data using newmodels that have been specially developedusing Density Functional Theory (DFT).

A T o o l f o r O t h e r

N a n o s c a l e M a t e r ia l s

This new developm ent in size analysis andcharacterization of sub-nano pores (small

micropores), though created to meet theneed to investigate the hydrogen storagepotential of various materials, willundoubtedly be adopted for thech a r a c t e r i za t i o n o f o t h e r m a t e r i a lstructures bearing nanospace, and/or fordifferent nanoscale applications.

They might include narxjpartide-enhancedfilters for separating compounds at themolecular level, or porous frameworksutilized as nanoflasks for polymer synthesis.I n h i s testimony t o t h e Senate Committee onEnergy and Natural Resources, Nobel prizewinner Professor Richard Smalley fore told of

massive electrical power transmission overcontinental distances. He envisages thatnanotechndogy in the form of single-walledcarbon nanotubes,forming w hat h e calls theArmchair Quantum Wire, may play a big rolein this new electrical transmission system.

For more inform ation contqct

Quantochrome Instruments by phone:

(561) 731.4999, fax: (561) 732.9888,

email:QC.nano(^quantachrome.com

or visit www.quantathrome.com.



HOW NANDTECHNOLDGY CAN ...

Mechani{a l a t t r i t ion

(ball milling)

l i t l iDg r a p h y /e t t h in g

B o t t o m - u p

Assemble from nanosized

building blocks

Schematic ofa variety afnanostructuresynthesis and assembly approaches.

N a n o t u b e a p p l i c a ti o n s i n c l u d e

n a n o e l e c t r o n i c d e v ic e s ( t ra n s i s t o r s ),

t ip s fo r s c a n n i n g p r o b e m i c r o s c o p e s ,

b i o / c h e m i c a l s e n s o r s , c a t a l y s t s u p -

p o r t s , g a s s t o r a g e / s e p a r a t i o n d e v i c e s ,

d r u g d e l iv e r y s y s t e m s , s e l f -h e a l in g

t e c h n o l o g i e s , c o m p o s i te m a t e ri a ls

a n d s t r e n g t h e n h a n c e m e n t s . Fo r

e x a m p l e , s u p e r - h i g h - t e n s i l e -s t re n g t h n a n o t u b e s h a ve b e e n c a lc u -

l a t e d to b e 2 0 t im e s s t r o n g e r t h a n

s t e e l ; i.e.,-45 GPa (Fig. 3).

N a n o t u b e s a r e a n id e a l r e i n f o r c in g

c o m p o n e n t of m o d e r n f i b e rs . A p o s -

s i b le a p p l ic a t i o n is in s u p p o r t i n g

i o n g - s p a n or h i g h - r i s e s t r u c t u r e

c a b l e s . S u ch c a b l e s c a n b e a m a t e r i a l

o f c h o i c e for r e c e n t l y p r o p o s e d

s p a c e e l e v a t o r s .^

O t h e r N a n o m a t e r i a l s

T h r e e g r o u p s of n a n o m a t e r i a l s c a n

b e s p e c if ie d b a s e d o n t h e i r g e o m e -

t ry / s h a p e : q u a n t u m w e l l (o n e n a n o -

s iz e d d i m e n s i o n ) , q u a n t u m w i re ( tw o

n a n o s i ze d d i m e n s io n s ) a n d q u a n -

t u m dot (t h re e n a n o s i z e d d i m e n -

s io n s ) ( F i g . 4 ) .' 'O n e o f t h e p r i n c i p a l

s t r u c t u r a l u n i t s in n a n o t e c h n o l o g y is

q u a n t u m dot or n a n o p a r t i c l e . T h i s

c a n be r e p r e s e n t e d a s a c lu s t e r of

t e n s to t h o u s a n d s ofa t o m s 1 - 1 0 0

n m in d i a m e t e r .

W h e n n a n o p a r ti c le s a r e c re a t e d

u s in g t h e b o t t o m - u p a p p r o a c h , t h e

s iz e a n d t h e s h a p e of a p a r t i c le c a n

b e c o n t r o l le d byp r o d u c t i o n c o n d i -

t i o n s . T h e s e p a r t ic l e s a l so c a n be

c o n s i d e r e d a s n a n o c r y s ta l s .T h e

a t o m s w i t h i n t h e p a r t i c le a r e p e r-f e c t l y o r d e r e d , or c r y s t a l l i n e .

W h e n t h e d i m e n s i o n s of a m a t e r i a l

a r e d e c re a s e d f r o m m a c ro s iz e to

n a n o s i z e , s i g n i f ic a n t c h a n g e s in e l e c -

t r o n i c c o n d u c t i vi ty , o p t ic a l a b s o r p -

t i o n , c h e m i c a l r e a c t iv it y a n d m e c h a n -

ic a l p r o p e r t i e s occur. W i t h d e c r e a s e

i n s iz e , m o r e a t o m s a r e l o c a t e d on

t h e s u r f a c e of t h e p a r t ic l e .

N a n o p o w d e r s h a ve a r e m a r k a b l e

s u r f a c e a r e a (Fig. 5 ). Th e s u r f a c e a r e a

i m p a r t s a se r io u s c h a n g e of s u r f a c e

e n e r g y a n d s u r fa c e m o r p h o l o g y . A l l

t h e s e f a c t o r s a lt e r t h e b a s ic p r o p e r -

t ie s a n d t h e c h e m i c a l r e a c t i vi ty of

t h e n a n o m a t e r i a l s . ^ ^ ' ^ ^ T h e c h a n g e in

p r o p e r t ie s c a u s e s im p r o v e d c a t a l y ti c

a b i li t y ,''' t u n a b l e w a v e l e n g t h - s e n s i n g

a b i l i t y ' ^ a n d b e t t e r - d e s i g n e d p i g -

m e n t s a n d p a i n t s w i t h s e l f-c l e a n i n g

a n d s e l f - h e a l i n g

N a n o s i z e d p a r t i c l e s h a v e b e e n u s e d

t o e n h a n c e th e m e c h a n i c a l p e r f o r m -a n c e of p las t i c s and rubbers .^ ' ^ ' ^ "Th e y m a k e c u t t i n g t o o l s h a r d e r a n dc e r a m i c m a t e r i a l s m o r e d u c -j|g_9,io,2i,22 PQ,. e x a m p l e , d u c t i le

b e h a v i o r h a s b e e n r e p o r t e d f o r

n a n o p h a s e c e r a m i c s , s u c h a s t it a n i a

a n d a l u m i n a , p r o ce s s e d b y c o n s o l i-

d a t i o n of c e r a m i c n a n o p a r t ic l e s .^ ^

Hevj n a n o m a t e r i a l s b a s e d on m e t a l

a n d o x id e s of s il ic o n a n d g e r m a n i u m

h a ve d e m o n s t r a t e d s u p e r p la s t ic

b e h a v i o r , u n d e r g o i n g 1 0 0- 10 0 0%

e l o n g a t i o n b e f o r e f a i lu r e . ^'^^

F u r t h e r r e s e a r c h in n a n o t e c h n o l o g y

p r o m i s e s b r e a k th r o u g h s in m a t e r i a l s

a n d m a n u f a c t u r in g , n a n o e l e c t ro n i c s

m e d i c i n e a n d h e a l th c a r e , e n e r g y ,

b i o t e c h n o l o g y , i n f o r m a t i o n t e c h n o l -

o g y a n d n a t io n a l secur ity.^'^^-^^ ' ^

S u b s t a n t i a l p r o g r e s s a l s o i s e x p e c t e d

in c o n s t r u c t io n a n d c o n s t r u c t i o n -

m a t e r i a l s

N a n o t e c h n o l o g y a n d C h a n g eN a n o t e c h n o lo g y h as c h a n g e d a n d

w i ll c o n t i n u e to c h a n g e o u r v i s i o n ,

e x p e c t a t i o n s a n d a b i li ti e s to c o n t r o l

t h e m a t e r i a l s w o r l d . T h e s e d e v e l o p -

m e n t s w i ll d e f i n i t e l y a f fe c t c o n s t r u c -

t i o n a n d c o n s t r u c t io n m a t e ria l s.

R e c e n t m a j o r a c h i e v e m e n t s i n c l u d e

t h e a b i l it y to o b s e r v e s t r u c t u r e at its

I 000.000

' 100,000

- 10.000

1,000

100

10

I

0 1

0.01

: i p i w ^ ^ ^ ^ ^ ^ ^

Nano engin »«red concrete

- High-strength/high-perform an ce con crete

Conventional concrete —

Finely ground Par il and cem enimlneia l oddl t lve i

Fly o ih Aggreg ate nrvai

1,000 10,000 IX.OOO 1.000.000 10.000,000 100,000.000

Part ic le s ize (nm)

'ce-area scale related oc o n c r e t e materiais.



atomic level and measure thestrength and hardness of microscop-ic and nanoscopic phases of com-posite materials.

More-specific achievements are dis-covery o f a highly ordered crystalnanostructure of amorphous C-S-Hgel; development of paints and fin-ishing m aterials w ith seif-cleaningproperties, discoloration resistance,graffiti protection, and high scratchand wear resistance; self-cleaningtile, window glass, paints and mor-tars based on photocatalyst technol-ogy; and nanometer-thin coatingsthat protect carbon-steel againstcorrosion and enhance thermal insu-

lation of window glass.

Among new nanoengineered poly-mers are highly efficient superplasti-cizers for concrete and high-strengthfibers with exceptional energy-absorbing capacity. Nanoparticles,such as silica, are effective additives

to polymers and concrete, a develop-ment realized in high-performanceand self-compacting concrete withimproved workability and strength.Portland cem ent, one of the largest

commodities consumed wo rldwide,is obviously the product withgreat—but at the same time — notcompletely explored potential.

Better understanding and preciseengineering of an extremely com-plex structure of cement-basedmaterials at the nanolevel w ill appar-ently result in a new generation ofconcrete tha t is stronger and m oredurable, w ith desired stress-strainbehavior and possibly possessing arange of newly introduced proper-ties, such as electrical cond uctivity aswell as temperature-, moisture- andstress-sensing abilities.

At the same time, this new concreteshould be sustainable as well ascost-and-energy effective—in

essence, exh ibiting the qualitiesmodern society demands. Nano-binders or nanoengineered cement-based materials with a nanosizedcementitious com ponent or othernanosized particles may be the nextground-breaking development.

Nanotechnology remains in its pre-exploration stage; it is just emergingfrom fundamental research to theindustrial application.Therefore, full-scale applications, especially in con-struction, are limited . However, thetremendous potential of nanotech-nology to improve the performanceof conventional materials andprocesses is most promising. •

Editor's Note

Figures 2,3 and 4 , and the references tothis article can be found as part of the pdf

online at w ww.ceramicbullet in.org.Thesecond part of this two-part series will

appear in the November 2005 issue of the

Bulletin. It will present the potential appli-cations of nanotechnology to concrete.

how nanotechnology can change the concrete world i

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