Comparative Study of Epoxy and Polyester Resin-based Polymer Concrete

8/18/2019 Comparative Study of Epoxy and Polyester Resin-based Polymer Concrete

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Com parative stu d y of ep ox y and

po lyester resin ba sed polym er

concretes

P . M a n i , A . K . G u p t a a n d S . K r i s h n a m o o r t h y

( Indian Inst itute of Technology, De lhi, India)

This pap er presents a com parat ive evaluation of tw o types of po lym er concretes,

prepared wi th two d i f ferent po ly me r b inders epoxy and polyes ter resins) w i th an

identica l aggreg ate in both cases crushe d qua rtzite and sil ica sand). Comparison is

a lso ma de w i th a convent ional cem ent concrete. Proper t ies stud ied inc lude st reng th

compressive, s pl i t - tensi le, f lexural and impact) , sett in g shr inkage, abrasion and

resistance to various chemicals. Both polye ster concrete and epoxy concrete sh ow fa r

super ior proper t ies than cem ent concrete. I t is fur ther shown that the polyester

concrete p roper t ies can be imp roved upon to approach those of the epoxy concrete by

modi f icat ions such as incorporat ion of ca lc ium carbonate micro f i l ler an d/o r addi tion o f

a suitable si lane coupling agent.

K e y w o r d s :

polymer concretes; epoxy concrete; polyester concrete; strength; setting

shrinkage; abrasion; skid resistance; cavitation resistance; chemical resistance; water

absorption; resin/agg regate adhe sion; silane coupling agen t

New materials composed of inorganic aggregates and

polymeric resin binders are being developed for

applications as construction materials with superior

properties than the conventional cement concrete.

These materials, also known, as polymer concretes,

form a wide range depending on the nature of resin

binder and the aggregates used and the technology of

their preparation. It is well recognized that the

properties of these materials are governed mainly by

the adhesion between the resin binder and the

aggregate, and therefore present day research is

directed towards improving the adhesion between the

two components, so as to achieve improved strength of

the polymer concrete.

Since, for the cost considerations, the binder content

used in such composiste materials is quite low, the

adhesion of aggregates takes place through a fine layer

of resin around the aggregates 1 2. A larger contact area

is therefore desirable, which necessitates a proper space

filling of the gaps by smal ler aggregates or microfiller

particles. Use of a silane coupling agent (which

strengthens the adhesion between the resin and the

aggregate) and the addition of microfiller (which

increases the contact surface area of particles coated

with thin layer of the binder) improves the adhesion

and thus the ultimate strength of the polymer

concretes.

Polymer concretes are finding many applications in

various civil engineering fields where the conventional

cement concrete is inadequate due to its lower strength,

poor chemical resistance, tendency towards crack

formation, etc. Furthermore, owing to its improved

bondab ility with old cement concrete 3-5 and more

rapid setting than the conventional cement concrete,

the polymer concrete may be used in the repair of

concrete pavements, highways and airfield runways

(where quick setting is desirable) and in the repair of

cracks in old buildings4-1°. Some other applications o f

polymer concretes may be in the construction of

off-shore or hydraulic structures prone to erosion and

cavitation, the construction o f flooring in chemical

industry facilities.

In this paper we present a comparative study of a

cement concrete and two polymer concretes -- one

based on an unsaturated polyester resin binder

('polyester concrete') and the other on an epoxy resin

binder ('epoxy concrete'), both with identical aggregate

constitutions. Properties studied include: compressive,

split-tensile, flexural and impact strengths, abrasion

resistance, skid resistance, resistance to various

chemicals, water absorption, cavitation resistance and

setting shrinkage. Attempts are made to further

improve the properties of the polyester concrete by

incorporation of a micro filler and a silane coupling

0 1 4 3 - 7 4 9 6 / 8 7 / 0 3 0 1 5 7 - 0 7 0 3 . 0 0 © 1 9 8 7 B u tte rw o rth ~ C o (P ub lis he rs )

Ltd

INT.JJ~DHESION AND ADHESIVES VO L.7 NO .3 JUL Y 1 987

1 5 7


2/7

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

r e a c h i n g t h e p r o p e r t i e s e q u i v a l e n t t o t h e e p o x y

c o n c r e t e b y u s i n g t h e l e s s e x p e n s i v e b i n d e r

( u n s a t u r a t e d p o l y e s t e r r e s in ) .

E x p e r i m e n t a l

M a t e r i a l s

Polymer ic b inders

T h e u n s a t u r a t e d p o l y e s t e r r e s in ( C r y s ti c- 1 9 6 , g e n e r a l

p u r p o s e g r a d e ) , a s s u p p l i e d b y C r y s t i c R e s i n s ( I n d i a )

P v t L td , w a s u s e d w i th t h e c a ta l y s t ( 5 0 s o l u t i o n o f

d i m e t h y l p h t h a l a t e i n m e t h y l e t h y l k e to n e p e r o x i d e )

a n d t h e a cc e l e ra t o r (1 s o l u t io n o f c o b a l t n a p h t h a n a t e

i n s t y r e n e ) . B o t h c a t a l y s t a n d a c c e l e r a t o r w e r e a d d e d t o

2 b y w e i g h t o f t h e r e si n . A c i d v a l u e , v o l a t i l e c o n t e n t

a n d i n i t ia l v i s c o s it y o f t h e r e s i n a t 2 5 ° C w e r e

21 mg KO H/g , 38 an d 800-900 cP , re spec t ive ly .

T h e e p o x y r e s i n ( g r a d e G Y - 2 5 7 ) w i t h p o l y a m i d e

h a r d e n e r ( g r a d e H Y- 84 0 , C i b a - G e i g y ) w e re u s e d

m a i n t a i n i n g t h e r e s i n : h a r d e n e r r a t i o a t 1 : 0 . 5 . T h e

e p o x y v a l u e a n d i n i t i a l v i s c o s it y o f t h e r e s i n a t 2 5 ° C

were 5 .2-5.4 E q/kg an d 600 cP , re spec t ive ly an d the

i n i t ia l v i s c o s it y o f t h e h a r d n e r a t 2 5 ° C a n d 4 50 0 cP .

norganic aggregates

C o a r s e a g g r e g a t e s c o m p r i s i n g c r u s h e d q u a r t z i t e o f s i z e

ranging f rom I0 mm to 2 .36 ram, spec i f i c g rav i ty 2 .72 ,

a n d n e g l i g i b l e o r g a n i c i m p u r i t i e s a n d m o i s t u r e c o n t e n t ,

w e r e u s e d .

F i n e a g g r e g a te s c o m p r i s i n g s i l i c e o u s s a n d o f s i ze

rang ing f rom 1 .18 m m (s i eve s ize BSS-14) to 15 0p v /m

(s ieve s i ze BSS-100), spec i f i c g rav i ty 2 .6 an d negleg ib le

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

used .

T h e s i z e d i s t r i b u t i o n o f t h e a g g r e g a t e s w a s c h o s e n a s

s h o w n i n T a b l e 1. T h i s i s b a s e d o n o u r p r e v i o u s

s tud ies on po lye s t e r re s in conc re te 1L 12, where the

o p t i m u m s i z e d i s t r i b u t i o n f o r m a x i m u m m e c h a n i c a l

p r o p e r t i e s s u c h a s c o m p r e s s i v e a n d s p l i t - t e n s i l e

s t r e n g t h s w a s f o u n d .

Silane coupling agents

As pe r the i r su i t ab i l i t y for the re spec t ive re s ins a s

r e c o m m e n d e d b y t h e m a n u f a c t u r e r s , t w o s il a n e

c o u p l i n g a g e n t s w e r e u s e d : D y n a s i l DEMO

T a b l e 1 G r a d i n g o f a g g r e g a t e s i ze u s e d f o r t h e

p o l y m e r / c o n c r e t e

S ie v e s i z e

wt retained Cumulative wt passing

10 mm 0 100

4.75 mm 45.00 5 5

2 3 6 m m 1 8 3 3

37

1.18 mm 3.66 33

600.um 7.33 26

300 pm 16.50 9

150/zm 9.18 0

G r a d i n g m o d u l u s 1 9 = 6 . 4 2 m m - 1

ean

d i a m e t e r

TM

= 4 . 1 2 r n m

F i n e n e s s m o d u l u s 1 9 = 4 . 4 0

( y - m e t h a c r y l o x y p r o p y l t r i m e t h o x y s i la n e ) t b r t h e

p o l y e s t e r r e s i n a n d D y n a s i l MEO ( y - a m i n o p r o p y l

t r i e thoxy s i l ane ) fo r the epoxy re s in .

Micro i l le r

F i n e c a l c i u m c a r b o n a t e p o w d e r ( l a b o r a to r y g r a d e,

part ic le s ize 2.0 to 2.5 pro, specif ic gravity, 2.7) was use d

a s m i c r o f i l le r i n t h e c a s e o f t h e p o l y e s t e r r e s i n

concre te .

M e t h o d o f p r e p a r a ti o n

Polym er concretes

A g g r e g a t e s o f a p p r o p r i a t e g r a d i n g w e r e k e p t i n a n

e n a m a l l e d t r a y . T h e r e s i n m i x ( i e , r e s i n m i x e d w i t h

c a t a ly s t a n d a c c e le r a to r o r h a r d n e r ) w a s p o u r e d o n t h e

a g g r eg a t es a n d a h o m o g e n o u s m i x i n g w a s d o n e w i th

t h e h e l p o f a s p a t u l l a .

T h e b i n d e r a g g r e g a t e r a t i o w a s 1 2 :8 8 b y w e i g h t . I n

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

w a s 1 2 b i n d e r w h i l e t h e r e m a i n i n g 8 8 c o m p r i s e d t h e

a g g r e g a t e s a n d t h e C a C O 3 m i c r o f i l l e r i n a 9 4 : 6

p r o p o r t i o n b y w e i g h t.

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

d i r e c t l y t o t h e r e s i n - c a t a l y s t - a c c e l e r a t o r m i x (1 b y

w e i g h t o f t h e r e s i n m i x ) . T h i s m e t h o d o f a p p l y i n g s i l a n e

c o u p l i n g a g e n t a s a ' i n t e g r a l b l e n d a d d i t i v e ' , u s e d i n

prev ious s tud ies 13-15 on po lym er con cre te s , p ro du ced

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

w h i c h w e r e a t t r i b u t a b l e t o t h e s i l a n e c o u p l i n g a g e n t .

H o w e v e r , i n c o m p a r i s o n w i t h o t h e r m e t h o d s , t h e

' i n te g r a l b l e n d a d d i t i v e ' m e t h o d p r o d u c e s 1 0 t o 20

l o w e r c o m p r e s s iv e s t r e n g t h t h a n t h e m e t h o d s i n v o l v i n g

d i r e c t t r e a t m e n t o f a g g r e g a te s w i t h s i l a n e i n m e t h a n o l

o r a n a q u e o u s m e d i u m l L

T h e h o m o g e n o u s p a s te s t h u s p r e p a r e d w e r e p la c e d

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

A f t e r 2 4 h c u r i n g t h e m o u l d a t a m b i e n t t e m p e r a t u r e .

t h e s p e c i m e n s w e r e f u r t h e r c u r e d a t 7 0 ° C f o r 24 h i n

a n a i r o v e n . C y l i n d r i c a l s p e c i m e n s o f d i m e n s i o n s : ( i )

5 c m d i a m e t e r a n d 1 0 c m l e n g t h ( f o r te s t in g c o m p r e s s i v e

a n d s p l i t- t e n s il e s t re n g t h s , c h e m i c a l r e s i st a n c e a n d

w a t e r a b s o r p t i o n e tc .) a n d ( ii ) 2 .5 4 c m d i a m e t e r a n d

2 .54 cm length ( for ab ras ion t es ts ), were cas t . Rec tan gula r

b e a m s o f d i m e n s i o n s : ( i) 6 × 6 × 3 0 c m ( f o r f le x u r a l

tes ts ) , ( i i ) 2.5 x 2.5 × 25 cm (for se t t ing shrinkage

m e a s u r e m e n t s ) , a n d ( ii i) 1 X 1 x 7 . 5 c m ( f o r i m p a c t

t e s t s ) , were cas t . Spec ia l ly curved rec tangula r spec imens

w e r e c a s t i n t h e m o u l d p r o v i d e d w i t h t h e s k i d

r e s i st a n c e t e s t i n g i n s t r u m e n t .

C e m e n t c o n c r e t e

A s a r e f e r e n c e m a t e r i a l , c e m e n t c o n c r e t e o f th e

f o l lo w i n g c o m p o s i t i o n w i th a m e d i u m w a t e r - c e m e n t

r a t i o (0 .5 5 ) c o n c r e t e m i x w a s u s e d . A p r o p o r t i o n o f

1 1 .6 :2 .4 ( c e m e n t : s a n d : a g g r e g a t e s) w i t h P o r t l a n d

c e m e n t , s i l i c a s a n d a n d q u a r t z i t e a g g r e g a t e s w a s u s e d .

S p e c i m e n s o f t h e p r e v i o u s ly d e s c r ib e d s h a p e s a n d

d i m e n s i o n s w e r e c a s t a f t e r m i x i n g t h e i n g r e d i e n t s o f

t h e c e m e n t c o n c r et e in a m e c h a n i c a l m i x e r a n d

c o m p a c t i n g i n a t a b l e v i b r a t o r . T h e c a s t s p e c i m e n s

w e r e d e m o u l d e d a f t e r 2 4 h c a s ti n g a n d w a t e r c u r e d f o r

28 days .

158 INT.J.ADHESION AND ADHESIVES JULY 1987


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M e a s u r e m e n t s

Compressive, split-tensile and flexural strengths were

measured on a Universal testing machine, according to

the test procedure aS: 1881 part IV, 197016. Static

loading on cylindrical specimens parallel to the axis of

the cylinder was used for compressive strength

measurements. For split-tensile strength, the cylindrical

specimen was kept in the horizontal position and

loaded in compression along its diameter until ultimate

splitting. Flexural strength tests were conducted on

rectangular beam specimens by the three-point

bending method maintaining the span length 2.5 cm

between the point supports.

Impact tests were carded out on an Izod impact

tester, involving cantilever type loading of the

rectangular beam specimens through a pendu lum

hammer. Abrasion tests were conducted on a Dorry's

abrasion tester to determine the coefficient of hardness,

as per the test procedure Is: 2386, 196317. Skid

resistance tests were conducted on the well polished

surfaces of the specimens, according to the test

procedure BS: 812 Part III, 197516 and the results are

expressed in terms of the coefficient of friction.

Resistance to chemicals, measured according to the

method used by Fukuchi and Ohama Is, is expressed in

terms of 'total evaluacti.'on poin ts' based on percentage

weight loss and surface appearance characteristics of

the samples after a prolonged (180 days) exposure of

the specimen to the chemical reagent. Reagents used

were the following aqueous solutions: 5 HC1,

5 H2SO 4, 5 CHaCOOH, 15 NaOH, 15 NaCl, and

0.2 MgSO4.

Setting shrinkage was measured at ambient

temperature using a Demec strain gauge, of gauge

length 20.32 cm (8 inch) with a total range of

2500 x 10-5 strain units, and an accuracy of

measurement within 10 -5 strain units per division. Two

Demec points were marked on the specimens at the

time of casting. Measurements were made at intervals

of 10 rain for the first hour and thereafter at intervals

o f l h .

Water absorption tests in cold and boiling water

were conducted by immersing the specimens in

distilled water at ambient temperature for 72 h

(denoted as C 7 2 and in boiling water for 5 h (denoted

as Bs). Cavitation resistance was measured in a

Ruemelling utility sand blast cabinet, and represented

as the specimens' weight loss due to impingement of

the sand.

Results of all tests are presented as average values

obtained from measurements on at least five samples

in each case. Variation was less than 10 in the results

on the various samples for any given test.

R e s u l t s a n d d i s c u s s i o n

M e c h a n i c a l p r o p e r t i e s

Po ly m e r c o n c re t e s w i t h o u t s i l a n e o r m ic r o f i l l e r

Compar ison of compressive, split-tensile, flexural and

impact strengths, from the data presented in Table 2,

clearly reveals that both the polyester concrete

(specimen B) and epoxy concrete (specimen E), without

silane and microfiller, have considerably superior

properties than the cement concrete (specimen A). Of

the two polymer concretes, the epoxy concrete has

much superior properties tha n the polyester concrete

(compare, eg, specimens B and E without any silane or

microfiller in Table 2),

The split-tensile to compressive strength ratio, which

is an important property for the selection of these

polymer concretes (specimens B, E) over the cement

concrete (specimen A). Thus, in addition to a superior

load bearing capacity (owing to high compressive and

flexural strengths) these polymer concretes also have a

lower crack generation t endency (owing to high split-

tensile strength) than the cement concrete.

Impact resistances of both the polyester concrete

and the epoxy concrete were also superior to that of

the cement concrete. Of the two polymer concretes the

epoxy concrete had the greater impact strength over the

polyester concrete.

Ef fec t o f s i ane cou p l ing agen t

Incorporation of a silane coupling agent further

improves the properties of these polymer concretes.

Compressive strength goes up by 30 for the polyester

concrete (compare specimens B and C) and 36 for the

epoxy concrete (compare specimens E and F). Split-

T a b l e 2 . M e c h a n i c a l p r o p e r t ie s o f c e m e n t c o n c r e te p o l y e s t e r c o n c r e t e a n d e p o x y c o n c r e t e

Property Cem ent concrete Polyester concrete Epoxy

c o n c r e t e

A) B) a C) b D) c E) d F) e

C o m p r e s s i v e s t rength (MPa) 24 .0

Sp l i t - t e n s i l e

streng th (MPa) 3.2

S p l i t - t e n s i l e / C o m p r e s s i v e 0 . 1 4

s t rength ratio

Flexural s t rength (MPa) 3.6

Izod impact s t rength 3.3

(kg cm X cm -2 )

4 1 .2 53 .0 6 8 .0 71 .6 97 .7

1 0 . 8 1 1 . 8

12.1 13.7

1 8 . 9

0 .2 6 0 . 2 2 0 .18 0 . 2 1 0 .19

1 2 . 2 1 3 . 9 1 9 . 3 2 1 . 0 2 1 . 6

3 . 5 4 . 7 4 . 3 6 . 6 7 . 5

aVVithout

s i lane or

f i l ler

bw i th s i lane MEMO and wi tho ut f i l le r

cVVith si lane MEMO

a n d C a C O

f i l ler

d W i th o u t silane

eWith si lane AMEO

INTJ .ADHESION AND ADHESIVES JULY 198 7 159


4/7

t e n si le , f le x u r a l a n d l z o d i m p a c t s t r en g t h s o f b o t h

p o l y e s t e r a n d e p o x y c o n c r e t e s a l so i m p r o v e d w i t h t h e

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

e x p e c t ed o u t c o m e o f t he i m p r o v e d i n t er fa c i al b o n d i n g

d u e t o t h e s i l a n e c o u p l i n g a g e n t . T h e e f f e c t o f s i la n e

c o u p l i n g a g e n t is m o r e p r o n o u n c e d i n t h e c a se o f t h e

e p o x y c o n c r e t e t h a n i n t h e p o l y e s t e r c o n c re t e .

T h e s p l i t - t e n s i l e s t r e n g t h t o c o m p r e s s i v e s t r e n g t h

r a t io d e c r e a s e s o n i n c o r p o r a t i o n o f th e s i t a n e c o u p l i n g

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

c o m p r e s s i v e s t r e n g t h t h a n t e n s i l e s t r e n g t h i n t h e

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

d e f o r m a t i o n i n v o l v e s d i s p l a c e m e n t o f s e v e r a l

n e i g h b o u r i n g a g g r eg a t es t o c re a t e r o o m t o a l lo w m o t i o n

o f a n y tw o m u t u a l l y a p p r o a c h i n g a g g r eg a t es , w h e r e a s

i n t e n s i l e d e f o r m a t i o n f r a c t u r e i n i t i a t i n g a t a n y s i t e

p a s s e s t h r o u g h o t h e r i n t e r f a c ia l a r e a s w i t h o u t i n v o l v i n g

a n y c o o p e r a t i v e d i s p l a c e m e n t o f th e a g g r e g a te s . T h e

s t r o n g e r b i n d e r a g g r e g a te b o n d i n g i n p r e s e n c e o f th e

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

r e s i st a n c e t o c o m p r e s s i v e d e f o r m a t i o n , o w i n g t o t h e

c o o p e r a t i v e m o t i o n o f a la r g e n u m b e r o f ag g r e g a te s

i n v o l v e d i n t h e p r o c e s s o f c o m p r e s s i v e d e f o r m a t i o n .

T h i s e x p l a i n s t h e o b s e r v e d d e c r e a s e i n s p l i t - t e n s i l e

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

o f th e s i l a n e c o u p l i n g a g e n t . F u r t h e r m o r e , a

c o m p a r i s o n o f t h e c o m p r e s s i v e s t re n g t h o f t h es e

d i f f e re n t c o n c r e t e s w i t h o u t s i l a n e ( s p e c i m e n s B a n d E )

c l e a r l y sh o w s t h a t t h e s t r o n g e r b i n d e r ( e p o x y r e si n )

g i ve s a h i g h e r c o m p r e s s i v e s t re n g t h t h a n t h e w e a k e r

b i n d e r ( p o l y e s t e r r e s i n ) .

f f ec t o f CaCO m ic r o f i l l e r in p o l y e s t e r c o n c re t e

F ro m th e a b o v e c o m p a r i s o n s o f t h e m e c h a n i c a l

p r o p e r t i e s o f t h e t w o p o l y m e r c o n c r e te s , t h e e p o x y

r e s in w o u l d s e e m t o b e a s u p e r i o r b i n d e r t o t h e

p o l y e s t e r re s i n. H o w e v e r , t h e h i g h c o s t o f e p o x y r e s i n

m a y r e s tr i ct i ts u s e t o o n l y v e r y e x c e p t i o n a l

a p p l i c a t i o n s . F u r t h e r s t u d i es o n t h e p o l y e s t e r c o n c r e t e

b y i n c o r p o r a t i o n o f C a C O 3 m i c r o f i l l e r i n d i c a t e a c l e a r

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

t h e p r o p e r t i e s o f t h e p o l y e s t e r c o n c r e t e . T h e r o le o f t h e

m i c r o f i l l e r i s to a c h i e v e b e t t e r f i l li n g o f t h e s p a c e s

b e t w e e n t h e a g g r e g a t e s s o t h a t t h e r e s i n b i n d e r i s

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

t h e e m p t y s p a c e s b e t w e e n t h e a g g r e g at e s.

D a t a o n s p e c i m e n s C a n d D , w h i c h d i f f e r o n l y in

m i c r o f i l l e r c o n t e n t , i n T a b l e s 2 a n d 3 re v e a l s t h e e f fe c t

o f C a C o 3 m i c r o f i l l e r o n t h e p r o p e r t i e s o f t h e p o l y e s t e r

c o n c r e t e . T h e c o m p r e s s i v e a n d f l e x u ra l s t r e n g th s o f t h e

p o l y e s t e r c o n c r e t e a r e g r e a t l y i m p r o v e d o n

i n c o r p o r a t i o n o f t h e C a C O 3 m i c r o fi l le r ( c o m p a r e

s p e c i m e n s C a n d D ) . T h e s p l i t - t e n s i l e s t r e n g t h s h o w s

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

d e p e n d s o n 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 t h e r e si n

a n d t h e a g g re g a te s , w h i c h r e m a i n s u n a l t e r e d b y t h e

i n c o r p o r a t i o n o f C a C o 3 m i c r o f il l e r. H i g h e r c o m p r e s s i v e

s t r e n g t h ( o r l o w e r s p l i t - t e n s i l e t o c o m p r e s s i v e s t r e n g t h

r a t io ) f o r s p e c i m e n s w i t h C a C O 3 m i c r o f il l e r is o w e d

n o t n e c e s s a r i l y to t h e s t r o n g e r b o n d i n g b u t p o s s i b l y t o

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

l e a v i n g l es s r o o m f o r c o m p r e s s i v e d e f o r m a t i o n .

C o m p r e s s i v e a n d f l e x u r a l st r e n g th o f t h e p o l y e s t e r

c o n c r e t e o n i n c o r p o r a t i o n o f C a C O 3 m i c r o f il l er r e a c h

v a l u e s s u f fi c i e n tl y c o m p a r a b l e w i t h th e c a s e o f e p o x y-

c o n c r e t e w i t h o u t s i l a n e ( s p e c i m e n E ). I m p a c t s t re n g t h

o f t h e p o l y e s t e r c o n c r e t e , h o w e v e r , i s p o o r e r i n

p r e s e n c e o f t h e C a C O 3 m i c r o f il l e r.

A b r a s i o n a n d s k i d r e s i s t a n c e

T h e c o e f f i c ie n t o f h a r d n e s s o f t h es e p o l y m e r c o n c r e t e s

a r e s l ig h t l y s u p e r i o r t o t h a t o f th e c e m e n t c o n c r e t e

( T a b l e 3 ), i m p l y i n g g o o d a b r a s i o n r e s is t a n c e s f o r b o t h

p o l y e s t e r a n d e p o x y c o n c re t e s . T h e e p o x y c o n c r e t e h a s

a s o m e w h a t g r e a t e r a b r a s i o n r e s i s t a n c e t h a n t h e

p o l y e s t e r c o n c r e t e .

T a b l e 3 . H a r d n e s s , f r i c t io n , s e t t i n g - s h r i n k a g e , c a v i t a t i o n r e s i s t a n c e a n d w a t e r a b s o r p t i o n p r o p e r t i e s o f t h e

v a r i o u s c o n c r e t e s

Proper ty Cemen t

c o n c r e t e Po ly e s te r c o n c r e t e Ep o x y c o n c r e t e

A) B)a C)b D) c E)d F)e

C o e f f i c ie n t o f h a r d n e ss 1 8 .6

(Dory s abras ion res is tance

a t 2 0 ° C

C o e f f i c ie n t o f f r i c tio n ( s k id 0 .5 1

r e s is t a n c e) a t 2 0 ° C

S e t t i n g s h r i n k a g e ( 1 0 - 6 *

strain units)

C a v i ta t io n r e s is t a n c e 3 9 .0

( w t lo s s in g )

W a t e r a b s o rp t io n

(%)

in

co ld w t e r

C 7 2 ) 3 . 6 9

in bo i l ing water (B75)

5 . 3 3

1 8 . 6 1 8 . 8 1 8 . 9 1 9 . 0 1 9 . 0

0 . 5 3 0 . 5 5 0 . 5 0 0 . 5 4 0 . 5 5

2 9 0 0 * 4 2 0 0 11 O 0 *

2 8 . 5 2 3 . 0 2 3 . 5 * *

0 . 1 9 0 . 1 4 0 . 1 1 0 . 0 3 0 . 0 3

0 . 3 3 0 . 2 6 0 . 2 6 0 . 1 3 0 . 1 3

* N o t m e a su r e d '

~ N i t h o u t

s i l a n e a n d

f i l l e r

/ ' W i t h s i l a n e M EM O a n d w i t h o u t f i l l e r

cVVith s i lane M EMO a n d C a C O f i ll e r

d ~ v i t h o u t

s i l a n e

eVVith s i l a n e AMEO

1 60 IN T .J .A D H E S IO N A N D A D H E S IV E S J U L Y 1 9 8 7


5/7

Coefficients of friction for both polyester and epoxy

concretes are distinctly superior to that of the cement

concrete, except in the case of polyester concrete

conta ining CaCO 3 microfiller. This shows that the skid

resistance of these polymer concretes are not inferior to

that of the cement concrete.

The abrasion and skid resistance properties are

especially relevant for end uses such as bridge-decks,

airport runway, motor-highway surfaces. For very

specific applications these polymer concretes may

prove useful in spite of the high cost of the binders.

S e t t i n g s h r i n k a g e

Volume change on solidification of the liquid

polymeric resins gives rise to significant shrinkage of

polymer concretes during the resin setting or curing

processes. When measured as a function of time, the

shrinkage remains insignificantly small in the first few

hours (up to 5 h). After the ini tial 5 h cure, the

shrinkage increases with time and reaches a plateau

after 15-20 h. The plateau value of the shrinkage is

taken as the setting shrinkage . As shown in Table 3,

setting shrinkage of the polyester concrete (specimen B)

is much higher than that of the epoxy concrete

(specimen E). Addition of CaCO3 microfiller, produces

an adverse effect on the setting shrinkage of the

polyester concrete (compare specimens B and D).

Use of shrinkage reducing agents is essential,

particularly in applications where shrinkage of

concrete during setting cannot be accomodated, as for

example in the case of polymer concrete mortar used

in the repair of cracks in cement concrete structures or

in the surfacing of roads and pavements etc. Use of a

polymer concrete mortar is sometimes preferable in the

repair of the cracks in old cement concrete due to the

fact that bonding between old and new cement

concrete and the polymer concrete is remarkably good.

Studies of shrinkage reduction in polyester concrete,

reported in detail in a previous publica tion ]2 showed

that the shrinkage could be reduced to zero or could

even be negative (ie, expansion), depending on the

composition and quant ity of shrinkage reducing agent

added to the resin. The problem of shrinkage reduction

is overcome in a number of ways not only for the

concretes but also for many other applications of the

binder resins.

W a t e r a b s o r p t i o n a n d c a v i t a t i o n r e s i s t a n c e

Both the polymer concretes show considerably smaller

water adsorption tendencies than the cement concrete,

as shown in Table 3; the epoxy concrete showing a

lower water absorption than the polyester concrete. The

effects of the silane coupling agent and CaCO3

microfiller on water absorption of the polymer

concretes are insignificant. Water absorption, which is

greater in boiling water than in cold (ambient

temperature) water, is considerably smaller for these

polymer concretes than the cement concrete. Amongst

the two polymer concretes the epoxy concrete has

significantly lower water absorption than the polyester

concrete. Incorporation o f the silane coupling agent

produces a slight decrease in water absorption

tendency of the polyester concrete and no significant

change in case of the epoxy concrete. Water absorption

at these two temperatures (ambient and the boiling

temperature of water) clearly suggest a still lower value

of water absorption around the water freezing

temperature, thus indicating a greater freeze-thaw

resistance for these polymer concretes than the cement

concrete.

Tendency to cavitation is compared in terms of the

weight loss on sand blasting under identical

conditions; the lower value of weight loss implies

greater resistance to cavitation. Values shown in Table

3, indicate greater cavitation resistance of the polyester

concrete than the cement concrete; silane coupling

agent further enhances the cavitation resistance of the

polyester concrete, while the CaCO3 microfiller does

not produce any significant effect. This suggests better

durability unde r adverse weather conditions of the

polyester concrete than the cement concrete.

e s i s t a n c e t o c h e m i c a l s

The chemical resistance study was carded out with

chemical reagents relevant to the general applications

of concrete. The six chemical reagents used were He1,

H2SO4 CH3COOH, NaOH, NaC1, MgSO4 representing

the effects of strong and weak acids, alkali, saline water

and sulphate resistance respectively. Other chemicals

relevant to specific end-uses of polymer concrete, such

as diesel and petrol for highways or some specific

chemicals for polymer concretes used in floor surfacing

in chemical industries etc, are not included in this

study. Overall resistance to a given chemical is

determined after constant exposure for 180 days in all

cases and the results are expressed in the units of total

evaluation points as defined by Fukuchi and Ohama is.

The specimens, after exposure to the chemicals, were

examined for changes of weight, surface appearance

and colour and graded according to the scheme

described in Table 4. The total evaluation points were

calculated according to expression given in Table 4.

Higher values of total evaluation points imply greater

resistance to the chemical concerned.

From the results shown in Table 5 it can be seen

that, in most cases the chemical resistance of these

polymer concretes is superior to that o f the cement

concrete, with the exception of the resistance to alkali

(NaOH) of the polyester concrete. The alkali resistance

of the polyester concrete is comparable with that of the

cement concrete and is decreased in presence of the

CaCO3 microfiller. There is a possibility of

saponification of the polyester component in the

presence of NaOH, which might be the cause of the

lower alkali resistance of the polyester component

observed in presence of NaOH, which could explain

the lower alkali resistance of the polyester concrete.

Addition of the CaCO3 microfiller decreases the

resistance of polyester concrete to, not only the alkali,

but to most of the chemicals used. This is unavoidable

owing to the considerable reactivity of CaCO3 with

these chemical reagents. Thus, although the addi tion of

CaCO3 microfiller enhances the strength of the

polyester concrete it does have an adverse effect on its

chemical resistance. Hence a compromise of the

properties for specific applications, or a search for an

alternative microfiller would be necessary.

Epoxy concretes, which show superior resistance to

alkali, show somewhat lower resistance to sulphuric

acid and acetic acid than the polyester concretes

INT.J.ADHESION AN D ADHES IVES JUL Y 19 87 161


6/7

Table 4 . Eva lua t ion

c r i te r ia for

c hem i c a l r es i s t anc e

o f p o l y m e r c o n c r e t e

Evaluation i tem Standard value for evaluation (Grading points)

Excel lent (4) Good (3) Fair (2) Poor (1)

W eigh t change (A) _+ 2%

Surface appearance No change

change (B)

Colour change (C) No change

+ 2 t o + 1 5 %

- 2 t o - 4

Light scal ing

Slight discolouration

+ 1 5 to + 2 0 %

- 4 to - 6 %

Medium scal ing

Fair discolouration

> + 2 0 %

< - 6 %

Complete col lapse

Rem arkable discolouration

Total evaluation points =

1 . 5 A + B + 0 . 5 C

T a b l e 5 . R e s i s t a n c e t o v a r io u s c h e m i c a l s o f t h e c e m e n t c o n c r e t e a n d t h e p o l y m e r c o n c r e t e s a f te r 1 8 0 d a y s

e x p o s u r e ( v a lu e s e x p r e s s e d i n u n i t s o f t o t a l e v a l u a t i o n p o i n t s d e s c r ib e d i n th e t e x t )

Sample numb er R e a g en t Cement concrete Polyester concrete Epoxy concrete

wi thout s i lane

A) B) C)

1 5% HCI 2 .5 4 .0 4 .0 3 .8 4 .0

2 5 %

H 2 S O 4

3.0 4 .0 4 .0 3 .8 3 .7

3 5% CH3COOH 2 .2 4 .0 4 .0 3 .5 3 .7

4 1 5% NaCI 3 .7 4 .0 4 .0 3 .8 4 .0

5 1 5% NaOH 3.0 3 .0 3 .0 2 .5 4 .0

6 0 .2% MgSO4 3 .2 4 .0 4 .0 3 .8 4 .0

(A)Without silane or microfiller

(B)With silane MEMO

(C)With CaCO and silane MEMO

( w i t h o u t C a C O 3 m i c r o f i l l e r ) . R e s i s t a n c e t o H C 1 , s a l i n e

w a t e r a n d s u l p h a t e s a lt o f th e e p o x y c o n c r e t e s i s q u i te

c o m p a r a b l e w i t h t h a t o f t h e p o l y e s t e r c o n c r e t e s

( w i t h o u t C a C O 3 m i c r o f i l l e r ) .

C o n c l u s i o n

T h e u s e o f p o l y m e r i c r e si n b i n d e r s , i n s t e a d o f c e m e n t ,

g i v es st r o n g e r c o n c r e t e t h a n t h e c o n v e n t i o n a l c e m e n t

c o n c r e t e . P o l y m e r c o n c r e t e s b a s e d o n u n s a t u r a t e d

p o l y e s t e r r e s in s a n d e p o x y re s i n b i n d e r s s h o w

c o m p r e s s i v e s t r e n g t h s h i g h e r b y a f a c t o r 2 t o 4 a n d

s p l i t -t e n s i l e a n d f l e x u r a l s t r e n g t h s h i g h e r , b y a f a c t o r 3

t o 6 , t h a n t h e c o n v e n t i o n a l c e m e n t c o n c r e t e . E p o x y

c o n c r e t e i s, i n g e n e r a l , s t r o n g e r t h a n p o l y e s t e r c o n c r e t e

b u t t h e c o s t o f e p o x y r e s in b i n d e r m a y r e s tr i c t i ts u s e.

P r e s e n t s t u d i e s s h o w t h a t t h e c o m p r e s s i v e , s p l i t - t e n s i l e

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

f u r t h e r e n h a n c e d b y i n c o r p o r a t i o n o f a s il a n e c o u p l i n g

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

c o m p a r a b l e w i t h t h e e p o x y c o n c r e t e w i t h o u t s il a n e' . I n

o t h e r p r o p e r t ie s , s u c h a s i m p a c t s t r e n g t h a n d w a t e r

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

c e m e n t c o n c r e t e w h i l e i n a b r a s i o n a n d s k i d re s i s t an c e

t h e y a r e c o m p a r a b l e ( o r a t le a s t n o t i n f e r io r ) t o c e m e n t

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

i s m a r k e d l y s u p e r i o r t o t h a t o f th e c e m e n t c o n c r e t e ,

w i t h t h e e x c e p t i o n o f t h e a l k a l i r e s i s t a n c e o f t h e

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

r e s i st a n c e i n t h e p r e s e n c e o f C a C O 3 m i c r o f il l e r.

R e f e r e n c e s

1 Ga ms ki. K. R esinous binder concrete' Proceedings of 1st

In ternat ional Congress on Polymers in Concrete

The C oncrete

Society, London (1975) p 223

2 Gupta, A.K., lear, B. and Men i, P. J Reinforced Plas tics a nd

Composites

1 (1982) p 370

3 Ma ni , P.

PhD Thes is

(Indian Institute of Technology, New Delhi,

1983)

4 Ma ni , P., Kr ishnam oorthy, S. and Gupta, A.K. Proceedings of

Nat ional Sympo s ium on Binder Economy and Al ternat ive Binders in

Road and Bui ld ing Cons t ruc t ion

Cement Research nstitute, New

Delhi. India (1981) pp 1~3

5 B lake,

L S . and

Pu ller-att acke r, P. 'Epoxy resins for repair of

concrete',

R I LEM Bu l l e t in

No. 28, (September 1965) p 25

6 Trem 0er, B. 'Repair of damaged concrete with epoxy resins', J AC I

82 No. 2 (1960) p 173

7 Kukamka ,L.E. and F ontana, J . 'Concrete-polymer materials

f o r

highway appl ications final report' BNL 50462 and PHWA-RD-75-

86, (Radiation Division, 6NL, N ew Yo rk, 1975)

8 Ch andra, H, and Pando, S.N.

Ind ian R oad Congress Journal 7

( 1 9 7 6 ) p 45 5

9 G holh , R.K., Phu l l , Y.R. and Pant, C.S. Polymers in Concrete',

(ACI Publ ication. Michigan, 1978) p 10 3

10 M elkote , R.$. and Sur i , S.B. Proceed ings o f 44 t h An nua l

Research Session

(Central Board of Irrigation and P ower, New Delhi,

Publ ication No. 123, 1975) p 146

11 Ma ni , P., Kr ishnam oorthy, S, and Gupta, A.K.

Proceedings of

I n t e rna t iona l Sem ina r on Po l y m er i c M a t e r i a ls

(College of

Engineering, Trivandrum. 1981 ) p 13

12 Me ni , P. , Kr ishnam oorthy, S. and Gupta, A.K ./n t J Adhes ion and

Adhesives

3 (1983) p 101

162 INT.J .ADHESION AND ADHESIVES JULY 198 7


7/7

13 Gupta, A.K., Mani , P. and Kr ishnamoorthy, S.

Int J Adhesion and

Adhesives

3 (1983) p 149

14 Ma ni , P. , Gupta, A.K. and Kr ishnam oorthy,

S J Mater Sci 18

(1983 ) p 3599

15 Sterman, S. and Marsde n, J .G.

Proceedings of SPI 18th Annual

Technical Conference

(Chicago, USA . 1963 Section ID)

16 'Methods o f Tests for Mechan ical Properties of Concrete' (British

Standards institute Publication, London, 1975)

17 Methods of Test for Aggregates for Concrete (Indian Standards

Institute Publication, New Delhi, 1978)

18 Fuku chi, T. and Ohama, Y.

Trens Japan Concrete Institute

(1979)

p 100

1 9 J a c k s o n N .

'Civil Engineering Materials' (ELBS Macmillan

Publ ications, Hong Kong, 1978) p 12 4

Authors

The authors are with the Centre for Materials Science

and Technology, Indian Institute of Technolgy, Hauz

Khas, New Delhi-110 016, India. P. Mani is presently

at the Materials Division, Regional Research

Laborat ory CSIR), Trivandmm-695019, India.

Inquiries should be directed to Dr Gupta in the first

instance.

I N T J A D H E S I O N A N D A D H E S I V E S J U L Y 1 9 8 7 1 6 3

Documents

Comparative Study of Epoxy and Polyester Resin-based Polymer Concrete