Strength and elastic properties of powdered and aqueous polymer-modified mortars

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Cementand ConcreteResearch,VoL24, No.7, pp. 1199-1213.1994 i!ilili!iiiiiiiiill
Copyright© 1994 ElsevierScienceLtd iiiiiiili~ii
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Pergamon

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0008-8846(94) 00064-6
STRENGTH AND ELASTIC PROPERTIES
AND AQUEOUS POLYMER-MODIFIED

OF POWDERED
MORTARS

i~ii:~iiii~'ii
i!i'iii'ii~ii',li~
i~'~:~i' !:' ~:iiiii,

Musarrat Ullah Khan Afridi and Zia Ullah Chaudhary
Cement Research and Development Institute, State Cement Corporation,
Near Lahore Race Club, Kot Lakhpat, Lahore, Pakistan.

Yoshihiko Ohama

and Katsunori Demura

Department of Architecture, College of Engineering, Nihon University,
Koriyama, Fukushima-ken, 963 Japan.

Muhammad Zafar Iqbal
Institute of Chemistry, University of the Punjab, Lahore, Pakistan.
(Communicated by M. Daimon)
(Received October 29, 1993; in finalform February 9, 1994)

ABSTRACT
The effectiveness of powdered emulsions (powdered cement modifiers) and aqueous
polymer dispersions (aqueous cement modifiers) on improvements in strength and elastic
properties of mortars is investigated in this paper. Polymer-modified mortars using various
powdered and aqueous cement modifiers were prepared with variation in polymer-cement
ratio, and tested for flexural strength, compressive strength, tensile strength, deflection,
extreme tensile fiber strain and tensile strain. It is concluded from the test results that
powdered cement modifiers affect the properties of mortars similarly as the aqueous
cement modifiers and the powdered polymer-modified mortars can be used in the same
manner as the aqueous polymer-modified mortars for practical applications.
Introduction

Polymer-modified mortars using aqueous cement modifiers are widely used as high
performance, low-cost construction materials particularly for finishing and repairing works
because of their excellent performance and durability. A recent advance for the preparation
of polymer-modified mortars is the invention of powdered cement modifiers with improved
qualities. Much interest is focussed nowadays for the usage of mortars modified by such
powdered cement modifiers in U.S.A., U.K., Germany, Japan and elsewhere in the advance
countries of the world. But sufficient data are not available on the performance of

powdered cement modifiers or on the properties of mortars modified by them.
The purpose of this paper is to evaluate and compare the performance of powdered
and aqueous cement modifiers in improving the strength and elastic properties of mortars
or to evaluate and compare the strength and elastic properties of powdered and aqueous
polymer-modified mortars. In this paper, polymer-modified mortars using four types of
commercially available powdered cement modifiers and two types of commercially available
aqueous cement modifiers were prepared with various polymer-cement ratios and tested
for flexural strength, compressive strength, tensile strength, deflection, extreme tensile
fiber strain and tensile strain.
1199


1200

M.U.IC Afridiet al.

Vol. 24, No. 7

Materials
Cement and Fine Aggregate

Ordinary portland cement and Toyoura standard sand as specified in JIS (Japanese
Industrial Standard) were used in all mixes.
Cement Modifiers

Commercially available, four powdered and two aqueous cement modifiers were
used. The powdered cement modifiers used included one brand of poly (vinyl acetate-vinyl
carboxylate) (VA/VeoVa) type and three brands of poly (ethylene-vinyl acetate), (EVA)
type. The aqueous cement modifiers used were one brand of EVA emulsion and one brand
of styrene-butadiene rubber (SBR) latex type. Their typical properties are given in Table 1.

Before mixing, a silicone emulsion type antifoamer containing 30% silicone solids was
added to the cement modifiers in a ratio of 0.7% of the silicone solids in the antifoamer to
the total solids in the powdered and aqueous cement modifiers.

Table 1. Typical Properties o f C e m e n t Modifiers.

Type of
Cement
Modifier

Stabilizer
Type

Powdered
VA/VeoVa
Emulsion

Anionic

Powdered
EVA-1
Emulsion

Anionic

Powdered
EVA-2
Emulsion

Anionic

Appearance

Milky-White
Powder
without
Coarse
Particles
Milky-White
Powder
without
Coarse
Particles
Milky-White
Powdcr
without

Specific
Gravity
(20 °C)

pH

Viscosity

(20 °C)

(20 °C,cP)

Total

Solids

1.100

1.180

1.120

Coarse

Particles
Powdered
EVA-3
Emulsion

Anionic

Milky-White
Powder
wilhout
Coarse
Parliclcs

1.180

EVA
Emulsion

Anionic

Milky-White
Aqueous
Dispersion

1.056

5.2

16()0

44.4

SBR
Latex

Anionic

Milky-White
Aqueous
Dispersion

1.019

8.5

155

45.8

Vol. 24, No. 7

STRENGTH,ELASTICPROPERTIES,AQUEOUSPOLYMERS,MORTARS

Testing
Preparation

1201

Procedures

of Mortars

Powdered and aqueous polymer-modified m o r t a r s were mixed according to J I S A
1171 (Method of Making Test Sample of Polymer-Modified M o r t a r in Laboratory) as
follows: cement: s t a n d a r d sand = 1:3 (by weight), p o l y m e r - c e m e n t ratios, P / C (calculated
on t h e basis of total solids in powdered and aqueous c e m e n t modifiers) of 0,5,10,15 and 20%
a n d t h e i r flows were adjusted to be constant at 170 + 5. The mix proportions of polymermodified m o r t a r s are given in Table 2.
Table 2. Mix Proportions of Polymer - Modified Mortars.

rype of
Mortar
Unmodified
Powdered
VA/VeoVaModified
Powdered
EVA-IModified
Powdered
EVA-2Modified
Powdered

EVA-3Modified

EVAModified

SBRModified

Cement:Sand
(by weight)

Polymer - Cement
Ratio (%)

1:3

1:3

1:3

1:3

1:3

Flexural and Compressive

Flow

77.5

165

5
10
15
20

72.2
75.5
76.2
75.0

172
172
173
168

5
10
15
20

73.8
75.2
73.0
73.8

170
173
170
172

5
10
15
20

76.2
76.5
76.2
76.2

167
168
172
168

5
10
15
20

76.2
76.5
77.5
77.5

168
170
168
169

5
10
15
20

72.5
66.8
63.0
59.8

I70
167
167
168

5
10
15
20

74.2
70.6
62.8
57.7

172
168
168
168

1:3

1:3

Water-Cement
Ratio (%)

Strength Tests

Beam type m o r t a r specimens 40x40x160 m m were moulded, and subjected to a 2day-20°C-80% r.h.-moist, 5-day-20°C-water, and 21-day-20°C-50% r.h.-dry cure. The cured
specimens were t h e n t e s t e d for flexural and compressive s t r e n g t h s according to JIS A 1172
(Method of Test for S t r e n g t h of Polymer-Modified Mortar) using I n s t r o n - a n d Amsler-type
universal t e s t i n g machines.


1202

M.U.K.Afridiet al.

Vol.24, No. 7

Tensile Strength Test
Briquet mortar specimens were moulded, and given a 2-day-20°C-80% r.h.-moist, 5day-20°C-water and 21-day-20°C-50% r.h.-dry cure. The cured specimens were then tested
for tensile strength according to ASTM C 190 (Standard Test Method for Tensile Strength
of Hydraulic Cement Mortar) using an Amsler-type universal testing machine.

Deflection and Extreme Tensile Fiber Strain Measurements
During the flexural strength test as mentioned above, deflection and extreme tensile fiber
strain (the fiber strain on the tension side of the specimens) were also measured. The
deflection was measured by attaching glass plates to the specimens and with the help of

non-indicating displacement transducers. Whereas, the extreme tensile fiber strain was
measured by means of wire strain gauges attached to the center of the specimens. The
data so obtained were recorded on automatic recorders.

Tensile Strain
During the tensile strength test as mentioned above, tensile strain was also
measured by attaching wire strain gauges to the center of the specimens where the tensile
stress occurs along the longitudinal direction. The data so obtained were recorded on a
automatic recorder.

1~o

Powdered

Powdered

Powdered

Powdered

F'.VA -

SBR -

VA/VeoVa-

EVA - I -

EVA-2-

EVA-3-

Modified

Modified

Modified

Modified

Modified

Modified

./.

IOO

i

f

50
h

I

o

Ib,'s

6 Lbl] o
Polymer

-

b ab zo

C~meflt

Ratio

b tbl o

6stbt 2b

(%)

Figure 1. Polymer-Cement Ratio vs. Flexural Strength of Powdered and Aqueous PolymerModified Mortars


Vol. 24, No. 7

STRENGTH,ELASTICPROPERTIES,A Q ~ U S POLYMERS,MORTARS

Test

Results

1203

and Discussion

Figure 1 shows the polymer-cement ratio vs. flexural strength of powdered and
aqueous polymer-modified mortars. Figure 2 depicts the polymer-cement ratio vs.
compressive strength of powdered and aqueous polymer-modified mortars. Figure 3
represents the polymer-cement ratio vs. tensile strength of powdered and aqueous
polymer-modified mortars. It is apparent from the above figures that except for powdered
VA/VeoVa-modified mortar with a P/C of 5%, the addition of both powdered and aqueous
cement modifiers to mortars generally increases their flexural, compressive and t e n s i l e
strengths. The powdered and aqueous polymer-modified mortars (PAAPMMs) show an
improvement in flexural and tensile strengths mainly due to an improved bond between
aggregate and matrix(i) or due to an improvement in sand-matrix adhesion level or due to
an overall improvement in cement-hydrate-aggregate bond because of a decrease in watercement ratio and higher flexural and tensile strengths of polymer films present in
PAAPMMs(2,3,4,5). Whereas, the increase in compressive strength of PAAPMMs is
attributed mainly due to a reduction in water-cement ratio(6,7) which ultimately affects
the gel - space ratio thereby causing a reduction in the capillary porosity of the system(6,8)
and helping the pore maxima of pore size distribution range to shift towards the pores of
the finer porosity(9). Polymer films present in such PAAPMMs may also contribute
towards the compressive strength hike but to a lesser extent(10AD. On the other hand,
the slight reduction in compressive strength of powdered VA/VeoVa-modified mortar with
a P/C of 5% is associated with its highest air content i.e. 13.1% (9).
The results reveal higher and pronounced gains in flexural and tensile strengths of
PAAPMMs as compared to those in their compressive strength. However, the magnitude to
which the flexural, compressive and tensile strengths of PAAPMMs are improved, depends

4O0

F~owdered
VA/VeoVaMedified

Powdered
EVA --I Modified

Powde.red

Powdered

EVA - 2 -

EVA -5 --

Modified

Modified

EVA Modified

S BR -Modified

c

_.*,
i.

tO0

O
t.J

i

0

t

5 IO 1520

I

!

I

I

/

I

0 5 IO 15 20

I

I

I

I

0 5 '0 15.--'43

P o l y m e r - Cement

Figure 2.

Polymer-CementRatio vs.
M o d i f i e d Mortars

I

I

I

I

i

0 5 IO 1520
Rotio

t

i

t

0 5 I0 1520

i

i

i

i

I

0 5 101520

(%)

Compressive Strength o f Powdered and Aqueous Polymer-


1204

M.UJK. Afridi et a l .

6C

5O

~

30

Powdered

VAIVsoVctModified

Powdered
EVA-I Modified

Powdered
EVA -2Modified

Vol. 24, No. 7

PoNdered
EVA - o
- Modified

EVA °
Modified

SB R Mo dlfied

/j;;X

to

5. iOI5

0

~0 1520
Polymer

0
-

IO

20

5 I0

Cement

R~io

0

0 5 IO 1520

0 5 I0t520

(0/.)

Figure 3, Polymer-Cement Ratio vs. Tensile Strength of Powdered and Aqueous PolymerModified Mom~"s

50C

PdymerCement
Ratio
(%)
20

40C

30C
o
_.J

20(
x
EL

iCK

......

0

|

0.5
Def lection (X lO-Imm)

!

1.0

Figure 4. Flexural Load-Deflection Curves for Powdered VA/VeoVa-Modified Mortars


Vol. 2,4, No. 7

STRENGTH, ELASTIC PROPERTIES, AQUEOUS POLYMERS, MORTARS

1205

on the type of cement modifier used, polymer-cement ratio or both. Generally, a rise in
polymer-cement ratio also raises the flexural and tensile strengths of all PAAPMMs while,
such a consistent relationship between polymer-cement ratio and compressive strength is
present only in powdered EVA-2-modified, EVA-modified and SBR-modified mortars. The

t
40{

PolymerCement
Relic

/

50,
o
d

(°/:,)
z

15

I0

20

20(

o

"

IOC

0

¢

I

I

0.5

I.O

Deflection (X lO'tmm)

Figure 5. Flexural Load-Deflection Curves for Powdered EVA- 1-Modified Mortars

//

500

400

/

PolymerCement
Ratio

(%)
500

IO

8

2O

15

..J

200

It.

bOO

0

I

!

0.5

I-0

Deflection (X IO-Imm)

Figure 6. Flexural Load-Deflection Curves for Powdered EVA-2-Modified Mortars


1206

M.U.K. Afridi et al.

Vol. 24, No. 7

rest of the powdered polymer-modified mortars show an optimum level of P/C on which
compressive strength is maximum.
The results show that generally the performance of powdered cement modifiers in
improving the flexural and compressive strengths of mortars is almost comparable to those
of aqueous cement modifiers. However, powdered cement modifiers seem less effective
than those of aqueous cement modifiers in improving the tensile strength of mortars
500

J

f

400
v
v

300

PolymerCemenl
R~tio

O

J

(%}
200

I0

15

2o

u_

I00

0

0.5
Deflection

I.O
(X IO-Imm)

Figure 7. Flexural Load-Deflection Curves for Powdered EVA-3-Modified Mortars

5O0

PolymerCement

400

Ratio
(%)

C"

500
0
0

.J

"6

200

e

h

I00

0

O,5

I.
1.0

Deflection (X IO-Imm)

Figure 8. Flexural Load-Deflection Curves for EVA-Modified Mortars


Vol. 24, No. 7

STRENGTH, ELASTICPROPERTIES, AQUEOUS POLYMERS, MORTARS

1207

probably because [i] the powdered cement modifiers are less effective in reducing the
water-cement ratio of the mix(9), [ii] the powdered cement modifiers form inferior quality
polymer films having lesser sand-matrix adhesion level or lesser overall improvement in
cement-hydrate-aggregate bond(9).
Figures 4-9 show the flexural load deflection curves of various PAAPMMs. Figures
10-15 depict the flexural stress - extreme tensile fiber strain curves of various PAAPMMs.
Figures 16-21 represent the tensile stress - tensile strain curves of various PAAPMMs. It is

400
A
'v'

I

,

/

Polymer Cement

300

Ratio

0
.J

/

(%)

200
X

20

I0

It

15

IO0

0

fi

°

I

0.5
Deflection (XlO-Imrn)

1.0

Figure 9. Flexural Load-Deflection Curves for SBR-Modified Mortars

N

E

Polymer - Cement

30

R~tio

(%)

zo

I/)

20
t..O

Lt.

I0

/11 Ij/
•

0

,

I

I

200
400
600
Extreme Tensile Fiber Slroin

I

800
(XlO -~)

|

IO00

Figure 10. Flexural Stress-Extreme Tensile Fiber Strain Curves of Powdered
VA/Veo-Va-Modified Mortars

I

12oo


1208

Vol. 24, No. 7

M.U.K. Afridi et at.

apparent from the above figures that the addition of both powdered and aqueous cement
modifiers to mortars markedly improves their deflection (flexural deformation behaviour),
extreme tensile fiber strain and tensile strain. Such properties of PAAPMMs are improved
because of their modified structure due to the presence of rubbery regions or polymer films
which themselves are highly ductile as compared to that of cement hydrate(12) and are
capable to arrest the advancing cracks. It is significant to note that PAAPMMs are more
extensible than the unmodified mortar not at the cost of strength. Moreover, PAAPMMs
also show improved toughness over the unmodified mortar in conformity to the earlier
results(13).

o0E

P o l y m e r - Cemenf

30

F~tio

(°Io)

jSz°

in
G)

2O

.I=
03

8

i"7

I0

I

0

200

400

Extreme

600

I

800

1200

IO~

Tensile Fiber Strain (XIO-6)

Figure 11. Flexural Stress-Extreme Tensile Fiber Strain Curves of Powdered
EVA- 1-Modified Mortars

Polymer-

Cement

Rotio (%)
50

ZO

E

o ~j / > ~

~

-

t

20
(/l

03

o I0
It
P

0

20O

I

400

Extreme

I

L_

(300

Tensile

Fiber

800

[

___

lOOO

I

1200

Strain (x I0- 6 )

Figure 12. Flexural Stress-Extreme Tensile Fiber Strain Curves of Powdered
EVA-2-Modified Mortars


Vol. 24, No. 7

STRENGTH, ELASTIC PROPERTIES, AQUEOUS POLYMERS, MORTARS

1209

However, the magnitude to which the deflection, extreme tensile fiber strain and
tensile strain of PAAPMMs are improved, depends on the type of cement modifier used,
polymer-cement ratio or both. Generally, a rise in polymer-cement ratio also raises the
deflection, extreme tensile fiber strain and tensile strain of PAAPMMs.

P o l y m e r - Cement

Ratio (%)

30

\o
f

/

_20

~

20

:2

I0

,7
I

0

200

1

I

t

I

400

600

CO0

Extreme

_

I00O

!

I2o0

Tensile ,Fiber Strain (xlO-~

Figure 13. Flexural Stress-Extreme Tensile Fiber Strain Curves of Powdered
EVA-3-Modified Mortars
POlymer -- Cement

Ratio (%)
\0
3O

~E

20
O0

x

I0

h

|

0

2OO

400
600
800
Exlr~me

Tensile Fiber Stain (xlO-6)

!

1000

Figure 14. Flexural Stress-Extreme Tensile Fiber Strain Curves of
EVA-Modified Mortars

!

1200


1210

M.U.K. Afridi ¢t el.

Vol. 24, No. 7

It is apparent from the results that powdered cement modifiers are mostly more
effective in improving the deflection, extreme tensile fiber strain and tensile strain of
mortars in comparison to aqueous cement modifiers. This is because the powdered cement
modifiers may be more effectively accumulated, along with the bleeding water, at the
surfaces of the mortars than the aqueous cement modifiers(14).
Conclusions

1.

The addition of both powdered and aqueous cement modifiers to mortars increases

Polymer -- Cement
Ratio (%)
30
NE

~3

~0

v
¢/)

20

o~
10

u_
f

0

200

!

i

I

400
600
Extreme Tensile Fiber

I

!

800
I000
Statn (xlO - e )

1200

Figure 15. Flexural Stress-Extreme Tensile Fiber Swain Curves of
SBR-Modified Mortars

Polymer- Cement Rol,io (%)

6O
E

50

15

5~
~

40

5 j j J J

g, 3o

~

"N 20
e-.

IO

J
0

r
Ioo

Tensile

i

i

I

20 o

300

4O0

Strain (xlO "6 )

Figure 16. Tensile Stress-Tensile Strain Curves of Powdered
VA/Veo-VA-Modified Mortars

_ _


Vol. 24, No. 7

STRENGTH,ELASTIC PROPERTIES, AQUEOUS POLYMERS, MORTARS

1211

their flexural, compressive and tensile strengths. The gains in flexural and tensile
strengths of PAAPMMs are higher and pronounced as compared to those noticed in
compressive strength. However, the magnitude to which such strengths of
PAAPMMs are improved, depends on the type of cement modifier used, polymer cement ratio or both.
2.

The addition of both powdered and aqueous cement modifiers to mortars markedly
improves their deflection, extreme tensile fiber strain and tensile strain. However,
the magnitude to which such elastic properties of PAAPMMs are improved, depends
on the type of cement modifier used, polymer - cement ratio or both.

6O
f

Polymer-Cement Ratio (%)

,¢

40
I/I

3O

-

20
I0
,

I00

0

1--

400

200
300
Tensile 31rain (xlO -6)

Figure 17. Tensile Slress-Tensile Strain Curves of Powdered
EVA-l-Modified Mortars

6O
N

f

E 50
40

•'- 50
=

Polymer- Cement

20
/

C

////

Ratio (%)

\ 2o
-

IO

0

I,

I

|

1o0

2O0

3OO

Tensile

_ _

I

4OO

Strain (xlO -6 )

Figure 18. Tensile Stress-Tensile Strain Curves of Powdered
EVA-2-Modified Mortars


1212

.

M.U.K.Afridiet al.

Yol. 24, No. 7

The powdered cement modifiers affect the properties of the mortars similarly as
those of aqueous cement modifiers. Accordingly, it is r e c o m m e n d e d that powdered
polymer - modified mortars can be used in the same m a n n e r as those of aqueous
polymer - modified mortars for practical applications.
References

1°

2.

Pomeroy, C.D.,Magazine of Concrete Research, V. 28, No. 96, S e p t e m b e r 1976,
pp.121-129.
Ohama, Y., AC1 Materials Jounral, V. 84, No.6, N o v e m b e r - December 1987,
pp. 511-518.
6O
Polymer- Cement

E
-.~ 5O

Ratio (%)

40
3O
¢-

20

/•

I0

I

I

I00

0

I

_

200
300
TencJile Stroin ( x l O - 6 )

I
400

Figure 19. Tensile Stress-Tensile Strain Curves of Powdered
EVA-3-Modified Mortars
Polymer--

Cement

Ratio

(%)

60
NE

50

"~

40

3o
-~

20

Io
0

I

I

I

I

I00

200

300

400

Tensile

Strain

(x I 0 - 6 )

Figure 20. Tensile Stress-Tensile Strain Curves of EVA-Modified Mortars


Vol. 24, No. 7

STRENGTH, ELASTIC PROPERTIES, AQUF~US POLYMERS, MORTARS

1213

Polymer-- Cement Ratio (%}

6O
E
50

L

20

U~

v

4O
30
¢.

20
IO
0

I

I00
Tensile

I"

200

I

SO0

I

400

Strain (xlO -s)

Figure 21. Tensile Stress-Tensile Strain Curves of SBR-Modified Mortars
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.

Ohama, Y., Proceedings of the 14th Japan Congress on Materials Research, The
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Wagner, H.B., Chemical Technology, V. 3, No.2, February 1973, pp. 105-108.
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1967, pp. 223-231.
Brown, J.H., Pomeroy, C.D., Technical Report, CI/SfB/I/Yq 4/-/UDC 666 - 974. 017:
678-6-7, 42-507, Cement and Concrete Association, March 1975, pp. 1-24.
Sun, P.F., Nawy, E.G., and Sauer, J.A., Journal of the American Concrete Institute,
V. 72, No.ll, 1975, pp. 608-613.
Wagner, H.B., I&EC Product Research and Development, V. 5, No.2, June 1966,
pp. 149-152.
Afridi, M.U.K., Ph.D. Thesis, Institute of Chemistry, University of the Punjab,
Lahore, Pakistan, 1992, pp. 151-191.

Ohama, Y., Proceedings of the Second Australian Conference on Engineering
Materials, Sydney, July 1981, pp. 163-172.
Sugata, T., and Ueda, T., Technology Reports of Kansai University, Japan, No.15,
1974, pp. 133-141.
Bean, D.L., Husbands, T.B., Final Report, Department of Army, U.S. Army Corps
of Engineers, Washington DC 20314-1000, Under Work Unit 32303, July 1986,
pp. 1-27.
Frondistrou-Yanns, S.A., and Shah, S.P., Supplement to Jounral of the American
Concrete Institute, Title No. 69-7, 1972, pp. 1-17.
Yamada, K., Sakata, K., Nakajima, K., Watanabe, N., and Inokawa, H., Review of the
Thirty-Fifth General Meeting, Technical Session, The Cement Association of Japan,
Tokyo, May 1981, pp. 127-129.