polymer impregnated concrete - journal of materials science - 1986

8/16/2019 Polymer Impregnated Concrete - Journal of Materials Science - 1986

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T A B L E l I E f fe c t o f v a r i o u s p a r a m e t e r s o n t h e f l e x u r a l s t r e n g t h a n d f i ex u r a l m o d u l u s o f e l a st ic i ty o f c o n t r o l c o n c r et e a n d

c o n c r e t e ~ P M M A c o m p o s i te

~ l i H i l i l t

W a t e r / c e m e n t P o r o s i t y ( ) P o l y m e r A v e r a g e p o l y m e r F l e x u r a l s t r e n g t h F l e x u r a l m o d u l u s o f

r a t i o l o a d i n g d e n s i t y i n p o r e s ( M N m - 2 ) e l a st i ci t y ( M N m 2 )

C o n t r o l C o m p o s i t e ( ) ( g c m _ 3 ) C o n t r o l C o m p o s i t e C o n t r o l C o m p o s i t e

0.50 23.00 3.76 7.94 0.848 1 I 18.9 42.2 178.5

0.45 21.85 2.98 7.07 0.78 4 1.4 18.6 52.4 175.0

0.40 20.00 3.14 5.87 0.742 2.0 15.9 54.0 165.3

0.35 19.13 2.44 5.89 0.756 2.0 18.7 52.7 176.5

0.30 17.77 1.90 6.13 0.83 2 2.4 21.7 6 1.5 194.1

t h e p o r e s , t h e d e g r e e o f e v a c u a t i o n o f t h e s a mp l e , t h e

i mp r e g n a t i o n t e mp e r a t u r e a n d t h e t ime o f i mm e r s i o n

o f t h e c o n c r e t e s p e c i me n i n t o t h e mo n o me r .

T h e a v e r a g e d e n si ty o f P M M A f o r m e d i n si de t h e

p o r e s o f v a r i o u s t y p e s o f c o n c r e t e s p e c ime n s h o w s t h a t

the average po lymer dens i ty f i r s t decreases wi th

i n c r ea s i n g w / c , r e a c h e s a m i n mu m a t w / c = 0 . 40 a n d

f ina l ly increases aga in . The lowes t average dens i ty o f

t h e p o l y me r i mp r e g n a t e d i n th e c o n c r e t e s p e c i me n a t

w / c = 0 . 4 0 ma y b e d u e t o ( a ) p a r t i a l o r i n c o mp l e t e

f il li ng o f the micro pore s a nd (b ) t rapp ing o f a i r

bubb les ins ide the cap i l l a ry pores .

W h i l e t h e c o mp r e s s i v e s t r e n g th o f t h e c o n t r o l s p e ci -

men decreases wi th increas ing w/c , tha t o f the

c o n c r e t e - PMMA s a mp l e f i r s t d e c r e a s e s , a t t a i n s a

mi n i m u m v a l u e a t w / c = 0 . 40 a n d t h e n i nc r e a se s . T h e

o b s e r v a t i o n i n t h e c a s e o f t h e c o n t r o l s p e c i me n i s

exp la ined by the fac t tha t wi th increas ing w/c the

poros i ty increases , wh ich in tu rn decreases the

s t r e n g th p r o p e r t y . T h e c o m p r e s s i v e s tr e n g t h o f c o n -

cre te i s , t herefo re , s ign i f i can t ly improved due to pore

f i l l i ng by po lymer . S imi la r a rguments have a l so been

a d v a n c e d b y o t h e r w o r k e r s [ 1 3 ] .

S imi la r resu l t s a re ob ta in ed f o r the in f luence o f w/c ,

p o r o s i t y , p o l y me r l o a d i n g , a n d a v e r a g e p o l y me r d e n -

s i ty in the pores on the f l exura l s t reng th and f l exura l

m o d u l u s o f e la s ti ci ty o f c o n c r e t e - P M M A c o m p o s i te s

(Tab le I I ) . Th i s may a l so be due to the f i l l i ng up o f

p o r e s i n th e c o n c r e t e b y p o ly me r . H o w e v e r , imp r o v e d

b o n d i n g b e t w e e n s a n d - c e m e n t a n d p o l y m e r m a y p l a y

a s ign if i can t ro le in the enhanc em ent o f the mec han-

i c al p r o p e r t i e s o f t h e c o m p o s i t e s.

3 2 E f fe c t o f s a n d / c e m e n t r a tio

T h e e f f e c t o f t h e s a n d / c e m e n t r a t i o ( s /c ) o n t h e c o m -

p r e ss iv e a n d f le x u ra l s tr e n g th o f c o n c r e t e - P M M A

c o m p o s i t e s is s h o w n i n T a b l e I I I . I t i s f o u n d t h a t f o r

a cons tan t w/c , h igher va lue o f s / c resu l t s in h igher

s t re n g t h . T h i s b e h a v i o u r c a n b e e x p l a in e d i n t e r ms o f

w a t e r a b s o r b e d b y t h e s a n d o r a g g r e g a t e . A l a r g e r

a m o u n t o f sa n d o r a g g r e g a te a b s o r b s a greater

quan t i ty o f water , t hus redu cing the e f fec t ive w/c . As

a resu l t t he e f fec t ive w/c in a con cre te m ix wi th h igh s / c

i s lower than in a r i ch mix . Th i s in tu rn resu l t s in a

l es ser poros i ty and consequen t ly a h igher s t reng th .

3 3 Ef fec t of cur ing tempera ture

T h e c u r i n g t e mp e r a t u r e o f th e mo r t a r s a m p l e ha s a

p ro fou nd ef fec t on i t s com press ive and f l exura l

s t reng ths . Wi th increas ing cur ing t empera tu re the

c o mp r e s s i v e s t r e n g th o f t h e c o n c r e t e g r a d u a l l y

i n c r e a s e s , r e a c h e s a ma x i mu m a t a r o u n d 8 0 °C a n d

then s lowly decreases (Tab le IV) . U p to 80 ° C the

rate

o f h a r d e n i n g o f c e me n t t h r o u g h h y d r a t i o n a n d

hydro lys i s i s increased wi th increas ing t empera tu re .

Bu t a b o v e 8 0 °C t h e c o n c r e t e s t r u c t u r e g r a d u a l l y

b e c o m e s m o r e a n d m o r e p o r o u s a n d t h e in c r ea s e d

poro s i ty e f fec t ou twe ighs the e f fec t o f fas t e r hydra t ion

and hydro lys i s . The same t rend i s a l so observed in the

c a s e o f P M M A - i m p r e g n a t e d c o n c re t e.

3 4 E f fe c t o f c u r i n g t i m e

T h e e f f ec t o f c u r i n g t i me o n t h e c o mp r e s s iv e a n d

f l ex u r al s t r en g t h s o f c o n t r o l a n d PM M A - i m p r e g n a t e d

c o n c r e t e i s s h o w n i n T a b l e V . W i t h i n c r e a si n g c u r i n g

t i me t h e s tr e n g t h p r o p e r t i e s o f t h e mo r t a r s a mp l e

g r a d u a l l y i n cr e a se . C o n t r o l s a mp l e s w i t h s a n d / c e me n t

r a t i o 1 : 4 a n d w a t e r / c e me n t r a t i o 0 . 4 0 w e r e c u r e d i n

wa ter a t 35 ° +_ 2 ° C fo r 3 , 7 and 28 days . I t w as fo und

t h a t m a x i mu m s t r e n g th w a s d e v e l o p e d a f t e r 2 8 d a y s .

S t r e n g t h d e v e l o p me n t i n c o n c r e t e t a k e s p l a c e

t h r o u g h t h e h y d r a t i o n a n d h y d r o l y s i s o f t h e ma i n

c o n s t i tu e n t s o f ce me n t . D u r i n g c u r i n g , i n o r g a n i c c o n -

s t it u e n ts o f c e me n t l i ke Ca O ( 6 5 . 3 ) a n d S i O 2

( 2 1 . 9 6 ) u n d e r g o h y d r o l y s is t o p r o d u c e Ca ( O H ) 2 a n d

s i l i c i c ac id respec t iv ly . At room tempera tu re the

hydro lys i s reac t ion i s s low and p rogresses s lowly to

c o mp l e t i o n ; i n 2 8 d a y s h y d r o l y s i s o f t h e a b o v e c o n -

s t i tuen t s o f cemen t is v i r tua l ly comple te l ead ing to the

ma x i mu m c o mp r e s s i v e a n d f l e x u r a l s t r e n g t h s .

H o w e v e r , t h e c u r i n g t i me h a s n o e f f ec t o n t h e s t r e n g th

p r o p e rt ie s o f P M M A - i m p r e g n a t e d c o n c re t e. F o r

T A B L E I I I I n fl u en c e o f s an d / c e m e n t r at i o o n t h e co m p r e ss i ve a n d f l ex u r al s tr e n g th s o f c o n c r e t e - P M M A c o m p o s it e

S a n d / c e m e n t

P o l y m e r C o m p r e s s i v e P o l y m e r F l e x u r a l

l o a d i n g s t r e n g t h l o a d i n g s t r e n g t h

( ) ( M N m - z ) ( ) ( M N m - 2 )

1 : 9 5.12 43.4 6.24 16.9

1 : 4 3.95 45.3 4.93 19.2

3 : 7 3.76 47.7 3.04 22.3

2 : 3 3.21 57.0 3.94 26.3

1 : 1 2.98 62.1 3.05 31.9

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T A B L E I V E f fe ct o f c u r i n g t em p e r a t u r e o n t h e c o m p re s si v e an d f le x u ra l s t re n g t h s o f c o n t r o l co n c r e te a n d c o n c r e t e - P M M A

c o m p o s i t e

C u r i n g P o l y m e r C o m p r e s si v e s t r e n g th ( M N m - 2 ) P o l y m e r

t e m p e r a t u r e l o a d i n g l o a d i n g

( ° C ) ( ) C o n t r o l C o m p o s i t e ( )

F l e x u ra l s t r e n g th ( M N m - 2 )

C o n t r o l C o m p o s i t e

60 7.03 9.0 27.6 7.81 2.7 10.8

70 7.13 l l .1 35.2 4.32 3.0 l 1.9

80 7.29 12.8 40.0 7.91 3.4 13.9

85 7.18 12.7 39.3 7.03 3.2 13.4

90 7.23 12.5 38.4 7.09 2.9 11.1

95 7.33 12.3 37.8 7.56 2.8 10.5

e x a mp l e , t h e i n c r e me n t i n c o mp r e s s i v e s t r e n g t h f r o m

3 to 28days cu r ing i s exac t ly the same, i . e .

3 . 1 4 M N m - 2, in b o t h c o n t r o l a n d P I C s a m p l es

(Tab le V) .

3 5 Ef fect of polyme r loading and nature of

polymer

Tab le VI p resen t s da ta fo r the e f fect o f po lym er load ing

o n t h e c o mp r e s s i v e a n d f le x u ra l s t re n g t h s o f PM M A -

i mp r e g n a t e d c o n c r e t e . I t i s f o u n d t h a t c o mp r e s s i v e

and f l exura l s t reng ths increase wi th po lymer load ing .

A t c o mp a r a b l e p o l y me r l o a d i n g , t h e c o mp r e s s i v e a n d

f t ex u r a l s tr e n g t h s o f p o l y m e r i mp r e g n a t e d c o n c r e t e

d e p e n d o n t h e n a t u r e o f t h e imp r e g n a t i n g p o l y m e r

(Tab le VII ) . I t i s found tha t the s t reng th p roper t i es fo r

c o m p o s i t e s w i th P M M A , p o l y a cr y lo n i tr i le ( P A N ) a n d

p o l y s ty r e n e ( P S ) a r e i n t h e o r d er : c o n c r e t e - P M M A >

c o n c r e t e - P A N > c o n c r e t e - P S . T h i s in d ic a te s t h a t

t h e p o l a r i ty o f th e i mp r e g n a t i n g m o n o me r h a s a s ig -

n i f i can t ro le in enhancing the s t reng th p roper t i es o f

P I C s . P o l a r m o n o m e r s s u c h a s m e t h y l m e t h a c r y l a t e

( M M A ) a n d a c r y l o n i tr i le ( A N ) a r e a b l e t o in c r e a s e th e

s t r e n g th p r o p e r t i e s o f c o m p o s i t e s mo r e t h a n n o n -

p o l a r s t y r e n e u n d e r i d e n t i c a l p o l y me r l o a d i n g . T h e

i mp r o v e m e n t o f th e a d h e s i o n b e t w e e n s a n d a n d

c e me n t b y p o l y m e r i mp r e g n a t i o n w ill b e g r e a t e r w i th

h i g h e r p o l a r i t y o f th e mo n o m e r .

3 6 Mechan ical behaviour of copolym er

impregnated concrete

T a b l e V I I I s h o w s t h e c o mp r e s s i v e a n d f l e x u r a l

s t r e n g t h s o f t h e c o mp o s i t e w i t h c o p o l y ( s t y r e n e - b u t y l

acry la t e ) (con cre te -P (S -BA)). Sam ples fo r s t reng th

me a s u r e me n t s w e r e p r e p a r e d w i t h f i x e d v a l u e s o f s / c

a n d w / c . T h e c o m o n o m e r f e e d c o mp o s i t io n w a s v a r ie d

be tw een 100 s ty rene (S) and 100 bu ty l acry la t e

( BA ) . I n c o r p o r a t i o n o f b u t y l a c r y la t e w i t h s t y re n e

adverse ly a f fec t s bo th compress ive and f l exura l

s t reng ths in i ti a l ly up to 25 BA . Af te rwa rds the

s t reng th p roper t i es a re found to par t i a l ly recover the i r

original value s (with 100 S).

S i mi la r t r e n d s a r e o b s e r v e d i n t h e c o m p r e s s i v e a n d

T A B L E V E ff ec t o f c u r i n g t im e o n t h e c o m p r e s s i v e a n d f l e x u r al

( s / c = l :4 , w /c = 0 .40)

f le x u r al s t r e n g th s o f t h e c o m p o s i t e w i t h c o p o l y -

( s t y r e n e -b u t y l m e t h a c ry l a te ) ( c o n c r e t e - P ( S - B M A ) )

( T a b l e I X ) . H e r e a l s o t h e s t r e n g t h v a l u e s a r e mi n i mu m

a t 2 5 b u t y l m e t h a c r y l a te (B M A ) i n t h e m o n o m e r

feed.

T h e s i t u a t i o n is c o mp l e t e ly r ev e r s e d w h e n M M A i s

u s e d as a c o m p o n e n t o f t h e c o m o n o m e r m i x tu r e. F o r

e x a mp l e , t h e c o mp r e s s i v e s tr e n g t h o f t h e c o m p o s i t e

w i t h c o p o l y ( me t h y l me t h a c r y l a t e - b u t y l a c r y l a t e )

( c o n c r e t e - P ( M M A - B A ) ) a t ta i n s i ts lo w e s t v a lu e a t a

m o n o m e r f e e d c o m p o s i t i o n o f 2 5 M M A . S im i la r

resu l t s a re ob ta ined in fo r the f l exura l and t ransverse

rup tu re s t reng ths (Tab le X) .

Tab le XI l i s t s da ta fo r compress ive , f l exura l and

t r a n s v e rs e r u p t u r e s t r e n g th s o f t h e c o mp o s i t e w i t h

c o p o l y ( me t h y l me t h a c r y l a t e - e t h y l a c r y la t e ) ( c o n c r e t e -

P ( MMA - E A ) ) . H e r e a g a i n a l l t h e s t r e n g t h p r o p e r t i e s

a t t a i n mi n i mu m v a l u e s a t a mo n o me r - f e e d

c o m p o s it io n o f 2 5 M M A .

I n o r d e r t o e x p l a i n w h y s u c h mi n i ma o c c u r i n t h e

s t r e n g th p r o p e r t i e s a s a f u n c t i o n o f in i ti a l mo n o m e r

c o mp o s i t i o n , a n d w h y t h e mi n i ma o c c u r a t a h i g h e r

c o n c e n t ra t io n o f s t yr e n e i n S - B A a n d S - B M A s y s-

t e m s th a n i n M M A - c o n t a i n i n g c o m p o s i te s , i t m a y b e

a r g u e d t h a t t h e me c h a n i c a l b e h a v i o u r o f th e

c o p o l y me r i s v e r y mu c h a f f e c te d b y s e g m e n t a l a l ig n -

ment in the so l id phase , in add i t ion to the in f luence o f

t h e i n d iv i d u a l h o m o p o l y m e r s [ 14 ]. T h e a d d i t i o n o f a

c o mo n o me r u s u a l l y c a u s e s a ma r k e d l o s s i n c r y s t a l -

l in i ty , wh ich in tu rn reduces many phys ica l p roper t i es

and s t reng th va lues . In many cases , a r ig id f ib re-

fo rming po lymer i s conver t ed in to a h igh ly e l as t i c and

r u b b e r y p r o d u c t b y s u c h mi n o r mo d i f i c a t i o n . T h e

d e p e n d e n c e o f th e me c h a n i c a l p r o p e r t i e s o n

c o p o l y me r c o m p o s i t i o n i n s y st e ms w h i c h d o n o t c r y s -

t a l l i ze resu l t s p r imar i ly f rom changes in in t e r -

mo l e c u l a r f o r c e s a s me a s u r e d b y c o h e s i v e e n e r g y .

Higher cohes ive energy resu l t s in h igher s t i f fness and

h a r d n e s s , a n d g e n e r a l l y i mp r o v e s t h e me c h a n i c a l

p roper t i es .

T h e c o m o n o m e r s B A a n d e t h y la c r y la t e ( E A ) d o n o t

c r y s t a l l i z e i s o mo r p h o u s l y w i t h MMA a n d S . T h e

s t r en g t h s o f c o n t r o l co n c r et e a n d c o n c r e t e - P M M A c o m p o s i t e

C u r i n g P o l y m e r

t i m e l o a d i n g

(da ys ) ( )

C o m p r e s s i v e s t r e n g t h ( M N m - 2

F l e x u r a l s t r e n g t h ( M N m - 2 )

C o n t r o l C o m p o s i t e C o n t r o l C o m p o s i t e

3 7.52 10.0 37.1 2.6 1 0.2

7 7.47 l 1.9 38.8 2.8 10.4

28 7.38 13.1 40.4 3.4 11.1

337


4/6

TAB LE VI Effect of polymer loading on the compressive and

flexural strengths of c onc ret e-P MMA composite (s/c = 3: 1,

w/c = 0.35)

Polymer Compressive Polymer Flexural

loading strength loading strength

( ) (MN m -2) ( ) (MN m -2)

0 (contro l) 24.5 0 (control) 5.0

1.85 28.3 1.64 6.7

2.87 33.0 2.85 10.3

3.80 40.2 3.55 15.7

4.50 53.1 3.82 23.9

5.11 54.8 5.05 33.8

c opo lym e r s a re , t he r e f o r e , o f l owe r c r ys t a ll i n it y t ha n

the i nd iv idua l hom opo lym e r s , whic h l e a ds to a l ow e r

m e c ha n ic a l s t r e ng th o f t he c onc r e t e r e in f o r c e d by

the m . A l so the p r e se nc e o f b ig pe nda n t g r oup s i n

po lybu ty l a c r y l a t e ( PBA) a nd po lye thy l a c r y l a t e

( PE A) r e su l t s i n l owe r c ohe s ive e ne r gy in ( S - BA) ,

( S - B M A ) , ( M M A - B A ) a n d ( M M A - E A ) s y s t e m s ,

whic h l e a ds t o l owe r m e c ha n ic a l s t r e ng th i n t he c on-

c r e te s r e in f o r c e d by the m . A dr a s t i c f a ll o f s t r e ng th

w i t h t h e i n c o r p o r a t i o n o f o n l y 2 5 B A o r B M A i n t h e

s ty r e ne - ba se d c opo lym e r s m a y be due to m uc h l e s s

c ohe r e n t se gm e nta l a s soc i a t i on in t he c opo lym e r . A

f u r t h e r i n c r e a s e i n t h e p r o p o r t i o n o f B A o r B M A

c ould , howe ve r , s l owly r e s to r e t he c ohe s ion th r ough

a l ignm e nt o f a l a r ge r p r opor t i o n o f a c r y l ic segm e nt s .

T he va r i a t i on in s t r e ng th p r ope r t i e s i s no t ve r y w ide in

M M A - b a s e d c o p o l y m e r s y s t e m s . T h i s m a y b e

expla ined by the c loser s t ruc tura l s imi la r i t ies be tween

M M A , B A a n d E A .

R e c e n t ly C h a n g e t a l [15] repo r ted th a t a s igni f icant

im pr o ve m e nt in s t r e ng th p r ope r t i e s c a n be a c h i e ve d

b y i m p r e g n a t in g m o r t a r o r c o n c r e te w i th c o p o l y m e rs .

For e xa m ple , a c om p os i t e im p r e gna te d w i th a

5 0/5 0 w t c o m o n o m e r m i x t u r e o f s t y re n e a n d m e t h y l

m e th a c r y l a t e ha s h ighe r s t r e ng th p r ope r ti e s t ha n w he n

e i the r s ty r e ne o r m e thy l m e tha c r y l a t e a lone i s use d f o r

i m p r e g n a t i o n . C h a n g e t a l sugge s t e d tha t c opo ly

( S - M M A ) o f fe rs e n h a n c e d c e m e n t - p o l y m e r in t er -

a c t i o n t h r o u g h t h e p o l a r e s t e r g r o u p o f M M A ,

c ouple d w i th t he r i d ig i ty a nd toughne ss im pa r t e d by

the s ty r e ne m oie ty o f t he c opo lym e r .

TA B L E V 11 Effect of nature o f polymer on the compressive and flexural strengths of composites (s/c = 1:4, w/c = 0.50)

Monomer used Monomer polarity* Polymer loading Compressive strength Flexural strength

( ) (MN m -2) (MN m -2)

MM A P 7.40 58.4 13.8

AN P 7.18 46.2 12,3

S NP 7.35 37.6 11,9

*P, polar; NP, non-polar.

TA B L E V I I 1 Compressive and flexural strengths of concrete--P(S-BA) composite (s/c = 1:4, w/c = 0.50, BPO = 1.1 wt of total

monomer, polymerization for 10h at 90°C)

Impregnating system



( ) (MN m -2) ( ) (MN m 2)

100 S 7.20 36.8 6.88 17.6

75 S + 25 BA 7.40 15.3 7.00 3.6

50 S + 50 BA 7.10 19.4 7.08 4.5

25 S + 75 BA 6.99 22.6 7.13 5.9

100 BMA 6.87 24.3 7.32 7.2

TA B LE I X Compres sive and flexural s trengths of conc rete -P(S- BMA) composit e (s/c = 1 : 4, w/c = 0.50, BPO = 1.1 wt of total

monome r, polymerization fo r 10 h at 90 ° C)

Impregnating system



( ) (MNm -2) ( ) (MNm -2)

100 S 7.20 36.8 6.88 17.6

75 S + 25 BMA 7.15 18.2 6.99 6.2

50 S + 50 BMA 7.35 19.0 7.43 7.3

25 S + 75 BMA 7.23 22.2 7.14 8.6

100 BMA 6.98 25.3 7.32 9.2

TAB LE X Compressive, flexural and t ransverse rupture strengths of concre te-P (MMA BA) composit e (s/c = 1:4 , w/c = 0.50,

BPO = I. 1 wt of total monom er, polymerization for 10 h at 90 ° C)

Impregnating system

Polymer Compressive Flexural Transverse

loading strength strength ruputure strength

( ) (MNm -2) (MNm -2) (MNm -2)

100 M 6.9 50.0 16.4 32.1

75 MMA + 25 BA 7.1 29.8 10.5 19.7

50 MM A + 50 BA 7.4 18.6 5.3 12.2

25 MMA + 75 BA 6.9 7.4 4.6 7.2

100 BA 7.5 14.7 6.5 8.7

8


5/6

TA BL E X I Compressive, flexural and transverse rupture strengths of con cre te- P(M AA- EA) composite (s/c = 1:4, w/c = 0.50,

BPO = 1.I wt of total monomer , polymerizat ion for 10h at 90 ° C)

Impregnating system

Polymer Compressive Flexural Transverse

loading strength strength ruputure strength

( ) (MN m -2) (MN m -2) (MN m -2)

100 MM A 6.9 50.0 16.4 32.1

75 MMA + 25 EA 7.5 16.1 6.5 22.9

50 MM A + 50 EA 7.3 12.5 4.7 9.6

25 MMA + 75 EA 7.1 8.2 4.3 8.2

100 EA 7.0 14.9 6.3 14.9

H o w e v e r , o u r d a t a i n T a b l e X l I f a il to s u b s t a n t i a t e

t h e o b s e r v a t io n o f C h a n g e t a l [15] . Ou r resu l t s sho w

t h a t b o t h c o m p r e s s i v e a n d f l e x u ra l s t re n g t h s o f c o m-

p o s i t e s r e i n f o r c e d b y c o p o l y me r s a r e i n t e r me d i a t e

b e t w e e n t h o s e o f c o mp o s i t e s r e i n fo r c e d b y t h e c o r r e -

s p o n d i n g h o m o p o l y m e r s . T h u s a c o m p o s i t e w i t h a

c o p o l y me r o f s ty r e n e w i th a c r y l o n it r il e ( S - A N ) s h o w s

a c o m p r e s s iv e s t re n g th o f 4 0 . 3 M N m - 2, c o m p a r e d

w i t h 3 7 .6 a n d 4 6 .2 M N m - 2 fo r c o n c r e t e - P S a n d c o n -

c r e t e - P A N c o m p o s i t e s r e s p e c ti v e ly ( al l t h r e e

c o mp o s i t e s b e i n g a t c o mp a r a b l e p o l y me r l o a d i n g ) .

T h e s a m e b e h a v i o u r i s o b s e r v e d i n th e c a s e o f c o n c r e te

r e in f o rc e d b y s t y r e n e - m e t h y l m e t h a c r y l a te c o p o l y m e r

( S - M M A ) . S i mi la r ly , t h e fl e x u ra l s tr e n g t h o f c o n c r e t e

r e in f o rc e d b y a c o p o l y m e r o f st y re n e a n d M M A i s

1 3 . 6 M N m - 2, w h e r e a s t h e f l e x u ra l s t re n g t h s o f

c o n c r e t e - P S a n d c o n c r e t e - P M M A s p e c im e n s a r e 12

a n d 1 3 .8 M N m- 2 r e s p ec t iv e l y .

3 7 Ef fect of cross l ink ing agent

I f a c ross link ing ag en t i s add ed to e i ther a s ing le

m o n o m e r o r a m o n o m e r m i x t u re , t h e c o m p r e ss i ve a n d

f te x u r al s t r e n g t h s o f t h e r e s u l ti n g c o m p o s i t e b e c o m e

s ign i f i can t ly g rea te r . Thus concre te impregnated wi th

a mi x t u r e o f s t y r e n e a n d d i v i n y l b e n z e n e ( a c r o s s -

l in k e r ) s h o w s a c o m p r e s s i v e s tr e n g t h o f 4 3 . 9 M N m -2 ,

w h i c h is 1 7 h i g h e r t h a n t h e c o mp r e s s i v e s t r e n g th o f

c o n c r e t e - PS . A g a i n , c o n c r e t e i mp r e g n a t e d w i t h a

mix tu re o f s ty rene , acry lon i t r i le an d d iv iny l benzen e

s h o w s a c o m p r e s s i v e st r e n g t h o f 4 8 M N m 2 w h i c h i s

1 9 h i gh e r t h a n th a t o f c o n c r e t e - P A N . T h e e ff e ct o f

d iv iny l benzene as c ross l ink ing agen t on the f l exura l

s t reng th i s s imi la r ; i t imp roves the f l exura l s t reng th by

1 2 . 3 o v e r t h e n o n - c r o s s l i n k e d c o mp o s i t e .

3 8 Interpretation of resu lts

T h e e f f e c t o f v a r i o u s p a r a m e t e r s i n t h e i m p r e g n a t i o n

o f m o n o m e r / m o n o m e r m i x tu r e , a s w e ll as t h e h i s to r y

o f t h e s a n d - c e m e n t m o r t a r p r e p a r a ti o n , o n i ts m e c h -

a n i c al b e h a v i o u r h a s l e d t o t h e s i t u a ti o n w h e r e e i t h e r

o r bo th o f the fo l lowing fac to rs a re a f fec ted . F i r s t , t he

f ill in g u p o f p o r e s in t h e c o n c r e t e - p o l y m e r c o m p o s i t e

c a n b e a l t e r e d b y v a r i a t i o n o f su c h p a r a me t e r s . I f th e

cond i t ions a re favourab le to pore f i l l i ng , a marked

i mp r o v e m e n t i n t h e p h y s c i a l p r o p e r ti e s o f th e c o n c r e t e

s p e c i me n i s o b s e r v e d . T h e i mp r e g n a t e d p o l y me r

r e p a i rs t h e m i c r o c r a c k s a n d v o i d s , a n d r e i n f o r c e s th e

mi c r o p o r e s o f t h e c e me n t b o d y b y f o r mi n g a n i n te r -

p e n e t r a t i n g n e t w o r k w i t h t h e i n o r g a n i c c e me n f i t i o u s

s i li ca te s t ruc tu re . Sec ond , an enhanc m ent o f the

m u t u a l i n t e ra c t io n b e t w e e n s a n d - c e m e n t a n d p o l y -

me r p h a s e s ma y t a k e p l a c e . Bo t h g r e a t e r p o r e - f i l l i n g

a n d b e t t e r in t e r a c t io n b e t w e e n p o l y m e r a n d s a n d -

c e me n t p h a s e s r e s u l t in a n e n h a n c e me n t o f t h e me c h -

a n i c a l s tr e n g t h s o f t h e p o l y me r - i mp r e g n a t e d c o n c r e t e .

S ince c ross l ink ing wi l l resu l t i n a g rea te r in t e rcha in

f o r c e , t h e u s e o f a c r o s s li n k i n g a g e n t f u r t h e r i mp r o v e s

t h e me c h a n i c a l p r o p e r t i e s o f th e c o m p o s i t e .

Ho we ver , t i gh t f i ll ing o f pores wi ll p rod uce a

s t r o n g e r c o m p o s i t e t h a n l o o s e fil lin g o f p o r e s . W h e n

t h e i mp r e g n a t in g p o l y m e r c h a i n i s p o o r l y a l i g n e d a n d

h e n c e mo r e a m o r p h o u s , t h e r e in f o r c e me n t a c h i e v e d is

p o o r c o m p a r e d t o t h a t o f a p e r f e c tl y a l ig n e d ma c r o -

mo l e c u l a r c h a i n . Co p o l y me r s g e n e r a l l y h a v e p o o r e r

c h a in s y m m e t r y th a n h o m o p o l y m e r s , a n d c o p o l y m e r -

i mp r e g n a t e d c o n c r e t e t h e r e f o r e h a s i n t e r me d i a t e

s t reng th p roper t i es .

P o l a r it y o f t h e m o n o m e r o r c o m o n o m e r p a i r u se d

fo r impregnat ion con t r ibu tes s ign i f i can t ly to the in te r -

f a c i a l f o r c e s b e t w e e n s a n d - c e me n t a n d p o l y me r . A

h igh ly po lar monomer resu l t s in a h igher in t e r rac ia l

f o r c e , a n d c o n s e q u e n t l y t h e c o n c r e t e p r e p a r e d b y

us ing such a monomer as impregnan t i s s t ronger . I t i s

o b s e r v e d , t h e re f o r e , t h a t t h e p o l a r i t y o f th e mo n o m e r

p lays a s ign if i can t ro le in the s t reng th p rope r t i es o f a

p o l y me r .

TA BL E X I 1 Influence of polymer on the compressive and flexural strengths of PIC (s/c = 1:4, w/c = 0.5, BPO = 1.1wt of total

monom er, polymerization for I0 h at 90 ° C, comonomer composi tion 50/50 wt wherever used)

Impregnating system



( ) (MNm -2) ( ) (MNm -2)

S-AN 6.62 40.3 3.72 12.1

S- MM A 7.91 55.0 3.57 13.6

S DVB* 8.35 43.9 3.50 13.4

S- AN-DVB* 7.04 48.0 3.55 I3.2

MM A 7.40 58.4 3.50 13.8

S 7.35 37.6 3.48 11.9

AN 7.18 46.2 3.51 12.3

*DVB = divinyl benzene (used as a crosslinking agent, 2 wt of total monome r used).

9


6/6

4 C o n c l u s i o n s

T h e me c h a n i c a l s t r e n g t h ( a s me a s u r e d b y c o mp r e s s i v e

s t reng th , f l exura l s treng th , s t reng th o f t ransverse

r u p t u r e a n d f l e xu r al m o d u l u s ) o f s a n d - c e m e n t m o r t a r

h a s b e e n i n c r e a se d b y t h r e e t o f i ve t ime s , b y p o l y m e r

o r c o p o l y m e r imp r e g n a t i o n t o a n e x t e n t o f o n l y 4

to 8 .

T h e me c h a n i c a l s t r e n g t h o f a c o n c r e t e c o m p o s i t e

i mp r e g n a t e d w i t h a c o p o l y me r s y s t e m d e p e n d s u p o n

t h e c o m p o s i ti o n o f t h e im p r e g n a ti n g c o m o n o m e r p a i r

a n d t h e n a t u r e o f t h e c o m o n o m e r s . T h e me c h a n i c a l

p r o p e r t i e s o f c o p o l y m e r - i mp r e g n a t e d c o n c r e t e a r e

f o u n d t o b e b e in t e r me d i a t e b e t w e e n t h o s e o f t h e

r e s p e c t i v e h o mo p o l y me r - i mp r e g n a t e d c o n c r e t e s .

T h e e f fe c t s o f v a r i o u s p a r a m e t e r s i n t h e i mp r e g -

n a t io n o f p o l y m e r s a n d t h e p r e p a r a t io n o f th e s a n d -

c e me n t mo r t a r s p e c i me n o n t h e me c h a n i c a l b e h a v i o u r

o f t he p o l y m e r - i mp r e g n a t e d c o n c r e t e ma y b e e x p l a i n ed

on the bas i s o f two fac to rs : (a ) f i l l i ng up o f the pores

o f t h e s a n d - c e m e n t m o r t a r b y i m p r e g n a te d p o l y m e r

o r c o p o l y me r , a n d ( b ) i mp r o v e m e n t o f t h e a d h e s i o n

b e t w e e n s a n d a n d c e m e n t t h r o u g h t h e p o l y me r . S i n c e

c r o s s li n k in g i n c r e a s e s t h e s t r e n g t h o f b o n d i n g b e t w e e n

p o l y m e r c h a i ns , t h e a d d i t i o n o f c r o s s li n k i ng a g e n t

i mp r o v e s t h e me c h a n i c a l s t re n g t h o f th e c o n c r e t e -

p o l y me r c o mp o s i t e .

A c k n o w l e d g m e n t s

T h e a u t h o r s w i s h t o t h a n k t h e D e p a r t m e n t o f A t o m i c

E n e r g y , G o v e r n m e n t o f In d i a f o r p a r t i a l f in a n a c i a l

s u p p o r t ; N a t i o n a l O r g a n i c Ch e mi c a l I n d u s t r i e s L t d

( N O CI L ) , B o m b a y , f o r a g if t o f me t h y l m e t h a c r y l a t e

mo n o me r a n d B . Mo n d a l , Me t a l l u r g i c a l E n g i n e e r i n g

D e p a r t m e n t , a n d S . B a n d o p a d h y a y , M i n i n g

Engineer ing Depar tmen t , fo r t echn ica l as s i s t ance .

J. E. BACKSTORM and S. RUBENSTEI N, First

Topical Report BNL 50134 (T 509) (Brookhaven National

Laboratory, Upton, New York, 1968).

2. M. STEINBERG, J. T. DIKE OU, L. E. KUK ACK A,

J. E. BACKSTORM, P. COLOMBO, K. B. HICKEY,

A. AUSKERN, S. RUBENSTEIN, B. MANOWITZ and

C. W. JONES, Second Topical Repor t BNL 50218

(T-560) (Brookhaven National Laboratory, Upton, New

York, 1969).

3, J. T. DIKEOU , L. E. KUK ACK A, J. E. BACKSTORM

and M. STEINBERG, J . Amer. Concr. lns t . 66 (1969) 928.

4. Y. OHAMA, Proc . J pn Congr . Mate r . Re s . 17 (1974) 137.

5. M. R. MIKNOV and L. M. SAZONOVA, Tr. Naue htro-

I ss le d . Ins t . Be tona Zhle zobe ton a

I1 (1974) 21.

6. S. OHGIS HI, K. ARAK I and H. ONO,

Mech. Behav.

Mate r . Proc . Sy mp. 2 (1974) 443.

7. G. GUNISAMY and P. VENKA TARAMA NUJA M,

Te c hnology Coimbatore ) 22 (1974) 102.

8. M. YU. BUTT and G. V. TOPI LSKII,

Zh, Pre k l . Khim .

49 (1976) 1462.

9. M. STEINBERG, P. COLOMBO, L. E. KUKA CKA

and B. MANOWITZ, US Patent 3567496 (1971).

10. M. STEINBERG and P. COLUMBO, BNL-50255

(Brookhaven National Laboratory, Upton, New York, 1970)

Che m. Abs t . 77 (1972) 92310).

11. K. R. KI RTANIA, Ph D thesis (IIT, Kharagpur, 1984) p.

116.

12. V. K. BHATTACHARYA, K. R. KIRTANI A, M. M.

MAITI and S. MAITI, Proceedings of National Seminar

on Building Materials, New Delhi, 1982, Paper No. III-7.

13. D. G. MANNING and B. B. HOPE,

Chem. Concr. Res . 1

(1971) 63.

14. F. W. BILLMEYER, Jr. Textbook of Polymer Science,

2nd edn (Wiley Interscience, New York, 1970) p. 239.

15. T. Y. CHANG, H. L. STEPHENS and R. C. YEN,

Transpn. Res . Rec . , Transpn. Res . Board USA) 542 (1975) 50.

R e f e r e n c e s

1. M, STEI NBERG, L. E. KUK ACK A, P. COLOMBO,

J. J. KELSCH, B. MANOWITZ, J .T . DIKEOU ,

Received 1 October 1984

and accepted 29 March 1985

3 4

polymer impregnated concrete - journal of materials science - 1986

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