Premix copolymer cement materials

CEMENT and CONCRETE RESEARCH. Vol. 6, pp. 235-244, 1976. Printed in the United States.

Pergamon Press, Inc

PREMIX COPOLYMER CEMENT MATERIALS D. J. Cook, D. R. Morgan and V. Sirivivatnanon School of Civil Engineering The University of New South Wales and R. P. Chaplin School of Chemical Technology The University of New South Wales (Communicated by F. H. Wittmann) (Received Dec. 2, 1975) ABSTRACT Studies to determine the influence of mixtures of monomers (and subsequently copolymers) on the behaviour of premix copolymer cement materials are described in this paper. Five systems viz styreneacrylonitrile, styrene-vinyl acetate, methyl methacrylate - vinyl acetate, butyl methacrylate - methyl methacrylate and butyl acrylate methyl methcrylate, were investigated. Setting time and hydration studies were carried out on premix cement pastes while compressive strength tests were carried out on premix mortars, to determine the influence of monomer volume, surfactants and polymerisation method. The results indicated, as has most of the work on premix systems, that the influence of the copolymers was to increase setting time, decrease the degree of hydration as measured by percentage of chemically combined water and decrease strength relative to that of specimens continuously moist cured.

Ce texte rapporte les r~sultats d'une Etude portant sur l'influence des melanges de monom~res (et par la suite des co-polymeres) vis-a-vis du comportement des mat~riaux a base de ciment-polym~res "pr~m~lang~s". Les essais ont ~t~ effectu~s sur cinq diff~rents syst~mes, ~ savoir: les m~langes styr~ne-acrylonitrile, styrene-acetate de vinyle, m~th acrylate de methyle-acetate de vinyle, methacrylate de butyle-m~th acrylate de m~thyle, et acrylate de butyl-m~thacrylate de methyle. Les tests de la dure~ de d£position et de l'hydratation ont ~t~ appliques sur les p~tes de ciments "pr@m~lang~s", tandis que les tests de la force de compression ont @t~ effectu~s sur les mortiers "pr~m~langes" afin de d~terminer l'importance du volume des monom~res, des surfactants et des modes de polym~risation. Les r~sultats obtenus, comparables ~ ceux des travaux d~ja effectu~s sur les syst~mes de "pr~mdlangd", ont montre clairement que les copolym~res ont pour effet d'accro~tre la dur~e de deposition, de diminuer le degr@ de l'hydratation (d'apr~s l'analyse du pourcentage d'eau chimiquement li~e) et par le fait m~me ddcroitre la force associ~e aux systems continuellement rem~dr~s ~ l'humidit@.

235

236

Vol. 6, No. 2 D. J. Cook, D. R. Morgan, V. Sirivivatnanon,

R. P. Chaplin

Introduction In previous papers CI,2), the authors have described the behaviour of premix polymer cement pastes and mortars.

This paper covers the behaviour

of pastes and mortars when copolymers are incorporated and concludes the present study of premix systems at the University of New South Wales.

It is

anticipated that future work will be concerned with polymer systems which exist as polymers prior to incorporation in the mix. On the basis of work carried out in this and previous studies, suitable polymers and copolymers, dosage rates and treatment regimes, for a research program investigating the fracture toughness of premix polymer concrete, will be selected. As in previous progran~s (1,2), both control and master were cast with each test series.

Control specimens contain no monomer and undergo the same

curing cycle as the treated specimens; master specimens also contain no monomer but are continuously moist cured.

The use of control and master speci-

mens enables the effect of the curing cycle on the properties of the premix polymer

(or copolymer) cement materials to be evaluated. Experimental Details

Ymterials and Mix Proportions Premix copolymer cement pastes and mortars were made with five monomer systems i.e. styrene-acrylonitrile, styrene-vinyl acetate, methyl methacrylate-vinyl acetate, butyl methacrylate-methyl methacrylate and butyl acrylate-methyl methacrylate.

Three ratios of monomer mixtures were considered

viz, 1:3, i:i and 3:1, so that in all fifteen copolymer systems were investigated.

These systems were all used together with the catalyst benzoyl

peroxide (BZP) added at a dosage of 1% by weight of the monomer mix=ure.

In

addition, with the exception of those systems containing acrylonitrile, the cross-llnking agent divinyl benzene (DVB) was added at a dosage of 2% by weight of the monomer mixture. In the compressive strength tests on mortars two series of mixes were investigated, one incorporating the surfactant

~ICOL

LZV/D (an ionic surface

active agent), added at a dosage of 0.1% by weight of the monomer mixture, and the other series without the surfactant.

Further, the monomer mixture

was added at two dosage rates for each series investigated; at 5% and 10% by weight of cement.

The mortar was made with 240 grams of normal Portland

Vol. 6, No. 2

237 POLYMER-CEMENT, PREMIX, PROPERTIES

cement (S.A.A. Type A), 600 grams of fine "Sydney" sand and 120 grams of water.

Master and control cubes were cast from this mortar.

In the monomer

mixes, the monomer mixture (and catalyst, cross-linking agent and surfactant) was simply added to the plain mortar without any change to the proportions of cement, sand and water. In the setting time and hydration studies tests master and control specimens were made from 700 grams of cement and 210 grams of water (i.e. w/c ratio = 0.30).

The monomer mixture was added at only one dosage rate

viz 5% by weight of cement.

Thus each monomer mix contained 35 grams of mono-

mer, 0.35 grams of BZP and 0.70 grams of DVB, and the same quantities of cement and water as the plain cement paste. Settin~ Time Tests Setting time tests on the control specimen were carried out according to the procedure specified in the Australian Standard AS - 1315, 1974, with the exception that: (i) (ii)

an automated Vicat apparatus, or "Speisograph" was used, the water/cement ratio in the pastes was 0.30, whereas a paste of "normal consistency" for the cement used had a water/cement ratio of 0.27.

The following mixing procedure was adopted for the monomer series of pastes. The monomer mixture, catalyst (BZP) and cross-linking agent (DVB) were mixed together, until each component was thoroughly dispersed.

The water

was added and the mixture stirred together for 15 seconds before being added to the cement.

The same mixing procedure was then followed as for the plain

cement paste. Results of the setting time tests were continuously recorded on the rotating chart drums of the "Speisograph" and the times of "initial set" and "hard set" determined.

Hydration Studies Studies were carried out on the influence of the various monomer systems on the hydration characteristics of the premix polymer cement pastes.

There

are several methods available for determining the "degree of hydration" of Portland cement paste systems, but it was decided in this investigation to

238

Vol. 6, No. 2 D. J. Cook, D. R. Morgan, V. Sirivivatnanon,

adopt the method used by Mills

(3) and Morgan

mination of the state of combination

R. P. Chaplin

(4), which is based on a deter-

of the various

categories of water in

the hydrated paste structure. The following experimental The water-monomer

mixture

procedure was adopted: (prepared as described

in the setting time

tests) was added to the cement and mixed at slow speed for 90 seconds in a "Hobart" mixer.

The paste was allowed to stand for 30 seconds

(to cater for

any false set which might occur) and then remixed at slow speed for a further 60 seconds.

The weight of the mixing bowl and paddle, and materials

were determined

in it

immediately prior to, and after the mixing cycle, so that

monomer loss during mixing could be established. Three 50 mm cubes were cast for each mix. glass plates and transferred relative humidity. moulded,

The moulds were covered with

to a fog room controlled at 22 ° ± l°C and 98 ± 2%

Twenty four hours after casting the specimens were de-

and placed in lime-saturated water baths in the fog room, where they

were cured for 6 days.

Curing under water helped minimize monomer loss.

specimens were then subjected copolymerize

to either radiation or thermal treatment

The

to

the monomer mixture.

Radiation specimens were removed from the water bath and wrapped and sealed in polythene sheets to minimize moisture and monomer loss. placed in rigid metal containers Research Establishment

They were

and sent to the Australian Atomic Energy

at Lucas Heights

for radiation

treatment.

The specimens

were irradiated at between 7 and 8 days after casting using gamma radiation from the Establishment's styrene were subjected der were subjected rads per hour.

cobalt-60

irradition

to a radiation

to 5 megarads;

The irradiated

source.

Specimens containing

dosage of i0 megarads while the remain-

the dosage rate in both cases was 157,000

specimens were once again placed in the lime-

saturated water baths from the age of 9 to 14 days. Thermally polymerised

specimens were removed from the water baths at

the age of 7 days after casting and boiled in water at 99 ± l°C for 8 hours, and then returned

to the water baths in the fog room until the age of 14 days.

At the age of 14 days after casting, both irradiated and thermally treated cubes were cut into 3 mm thick slices. formed on 3 slices for each mix investigated. differential

thermal analysis

(D.T.A.),

and scanning electron microscopy

Hydration studies were per(Other slices were cut for

thermogravimetric

(S.E.M.) studies.

analysis

(T.G.A.)

Vol. 6, No. 2

239

POLYMER-CEMENT, PREMIX, PROPERTIES

The sliced specimens were first towelled to the saturated surface dry state (removal of visible surface moisture sheen) and then weighed (Wss d) to 0.001 gram.

The specimens were placed in an oven maintained at ii0 ° ± l°C

until such time as they had reached constant weight (Wod).

The specimens

were then transferred to a furnace where they were fired at a temperature of 1000°C for 4 hours, cooled in a desiccator and weighed (Wfd).

In addition

the ignition loss of the dry cement powder on being fired at 1000°C was determlned. Compressive Strength of Mortars Three 50 --, cubes were cast for each mix and the thermal and irradiation treatment processes were the same as those carried out in the hydration studies. At the age of 14 days after casting, specimens were tested in compression in a Shimadzu universal testing machine.

The specimens were loaded at a

constant rate of 20 ± 2 MPa per minute until no further load was sustained.

Results and Discussion Strensth Tests The results of the compressive strength tests are given in Figs. 1-5. As was found in the homopolymer series (2), the presence of the surface active agent reduced the compressive strength of the mortar significantly.

The dif-

ference between the thermal and radiation treated samples was also similar to that obtained previously

(2) and need not be further discussed here.

It is apparent that the interactions between the copolymer, additive, treatment and hydrating cement were not only complex but in some cases conflicting.

Also the results indicated that in general the incompatibility

between a particular polymer and the hydrating cement was not significantly improved by copolymerisation with another polymer (see, for example, Fig. 4). Within a particular series, some strength improvement over the master and control mixes was observed for the GIOZR and L5ZR mixes.

Mixes U5ZR, HIOZR

and T5ZR had strengths in excess of the control series only. Hydration Studies The effect of the various copolymer systems on the hydration characteristics of the premix copolymer cement pastes is tabulated in Table i.

The terms

We, W n ' W p and W cw represent the percentage evaporable substance at ll0°C, percentage non-evaporable substance lost at 1000°C, percentage copolymer in

240

Vol. D. J. Cook, D. R. Morgan, V. S i r i v i v a t n a n o n ,

~,,,J

6, No. 2

R. P. Chaplin

&f}-J 10%

e,.

P~'"

wzm<~m '

10%

ul w~GG

10% 'additive

5 % + addlt ive |

G:,-

~u ~

-

0

o

loo

25 75

50

'75

lOO'/, s

50

2s

o% A

PERCENTAGE OF EACH MONOMER IN THE COPOLYMER

ul <{..J

i

ww

THERMAL TREATMENT

:[uJ On u

~,~ so'

I

,. w Z

RADIATIC N TREATI lENT

{n <[.J

~.~

lO%

,.z o¢uJ ~

S%+oddl tire

25 75

50 SO

"/5 25

100% S 0% A

~

s.,. ~,~

..... ?~

o

~ 50 "~1~ -°--Z "'#" 10"/o~ additive m t,uJ z \ 5 % ~ i additive OCLd o.. u iTHERMAL TREATM NT Z¢ 0 OLd UO0 25 S0 -/5 100 % M M A 100 "/5 S0 25 0 % VA PERCENTAGE OF EACH MONOMER IN THE COPOLYMER u~ <.J

=,--

t w~

m tn < m u j z~ ¢¢w u ~

I~.s-~ " "*

10%~ additive

.- : - ~ l a%+~ 5 dditive I

25 -/5

50 50

5%+ additive

1oo.,. s o .,. VA

; 5;/o

/ "'IF-'10% 1

~<

I

~ -~"~10%~ additive

THERMAL 7REATM "NT 0

~J to
25 50 75 100% BMA 100 75 50 25 O % MMA PERCENTAGE OF EACH MONOMER IN THE COPOLYMER

i ~.~%

. odditive

! / 5 ~

P't~. &n o t~ W

~
/-...1

. . . .

< ~.% ....

10 %

ujz

'/S 25

, ,

v~

4 ~--

""

~ 0 %+ additive RADIATICN TREAT ,lENT

RADIATIO TREATIWENT

0~ 100

~o so

I/

S1°°

~_- ~ ' .~. T F_.~÷ .--"~ ;

. ,/s

FIG. 2 Compressive Strength of Styrene: Vinyl Acetate Mortar Series.

LOP" ZZ

~S ~°°, , ~ - - - - ~ = = - . " ~ . ~ ,_~.

.....

o ,oo

P E R C E N T A G E OF" E A C H MONOMER IN THE CO'Ol Y M E R

FIG. i C o m p r e s s i v e S t r e n g t h of S t y r e n e : Acrylonitrile Mortar S e r i e s .

io,~.

10% + oddit ive

RADIATIC N TREAI MENT

0

PERCENTAGE OF EACH MONOMER IN THE COPOLYME R

)~

,s'/.

-"

,o..,

U'IP-

100

NT

0 25 50 75 100% S 100 75 S0 25 0 % VA PERCENTAGE 0F EACH MONOMER IN THE COPOLYMER

oo

~' 100

10%4 additive

lTHERMALTREATM

0

100"1, MMA 0% VA

PERCENTAGE OF EACH MONOMER IN THE COPOLYMER

FIG. 3 C o m p r e s s i v e S t r e n g t h of Methyl M e t h a c r y l a t e : V i n y l A c e t a t e Mortar Series.

uo"

G0 100

25 "/5

50 50

T5 25

100 % BMA 0 % MMA

PERCENTAGE OF EACH MONOMER IN THE COPOLYMER

FIG. 4 Compressive Strength of Butyl Methacrylate: Methyl Methacrylate Mortar Series.

Vol. 6, No. 2

241 POLYMER-CEMENT, PREMIX, PROPERTIES (n

o 100

O o. (J

FIG. 5 Compressive Strength of Butyl Acrylate: Methyl Methacrylate Mortar Series.

25 76

PERCENTAGE THE

so 50

?S 25

lOO % B A 0 % MMA

OF E A C H

HONOMER

IN

COPOLYMER

Ut ..I

~1oo' E~

'

U) tU

-/---~.:;~----

~,=,,

?""~'-'--I

10 %

i

TREATP~NT

RADIATION

I 25

U 100

50 50

75

PERCENTAGE THE

OF EACH

75 25

100%BA 0 % MMA

MONOMER

IN

COPOLYMER.

the paste and percentage of combined water in the paste respectively, and are defined in detail in the Appendix.

Also shown in Table i are the hydration

characteristics of the polymers forming the copolymers when the polymers were used individually as premix additives. Of most interest in Table i is the influence of the copolymer (or polymer) system on the degree of hydration of the premix pastes, as reflected in the

TABLE Hydration

Characteristics o f P r e m i x C o p o l y m e r - C e m e n t Copoiyn~, of Swnm* a~l Acr~itriie

Monomer T y ~ Pmaw'~

t'rmm'~t Contm~ Id~ter A

Wt

S

M

1

V

B

F

A:S 3:1

A:6 1:1

A:6 1:3

Coo~vmm' of Swr~e and Vinyl Aoetom 6:V 3:1

6:V 1:1

S:V 1:3

Pastes Cooolym~r of MMA Vlnyl Aoetete M:V

3:1

Copoiymer of MMA aetd Buty~ A~ykne

M:V M:V I F:M 1:1 1:3 3:1

F:M I:1

Cooolymer st MMA and Butyl uem*m-y~w

F:M 1:3

It:M 3:1

|:M 1:1

|:M 1:3

Radiation 20.16" 20.36" 2124 19.77 r2.99 31.66 2123 21.36 20,,39 20.25 191| 21.1] 21.62 21.(~ 21.70 20.M 20.71 21.67 ~'~.9~ 24.11 21.10 21.M 13.76 Thern~l 19.60" 19.82 ;16.39 ~2,13 22.00 20.57 20.67 19,17 19.17 16.1( 20.6~ 21.001202e 21.17 19.N 2Q.31121.N 21.90 22.04 20.74 21.73 |3.21 t

Wn

Redla~an 13.60° 13.38" 16.80 i5.76 r3.97 16.19 15.1:13.82 16.16 16.10 16.7¢ 14.74 14.97! 16.4( 14.77 tS.ll 16.H 114.01 13.61 13.43 145211444 14.13 Thermal 14.26" 16.79 15.83 14.01 16.30 15.57 14.34 161ii 16.90 16.4~ 14.74 16.31~16.31e;14M 16.10 15,(17 i4.N |4.34 14."m )S~2 14.76 ~4.46

Wp

Wcw

--

3.71 3.00 4.57 2.79 3.00 3.43 3.43 3.14 3.43 2,H

2.57 2.43 2.43 3JM 3.21 3.36 2.79 3.07 3.14

Radiation 13.80" 13.03 11.19 10.16 13.19 10.56 11.03 13.15 12.97 1327 11.90!11.54il2.54 1220 12.73 13.13 11.31 10.40 10.07 11.73 ;127 10.99 Thermal 142~;" 13.30" 1322 11~9 10,30 12.30 11.00 11.55 13.61 13.17 13.90 11.60 11.98 12.49 12,41112,70 13,24 11.04 11.13 10.N ;223 I1JMI 1122

Sitting Initild Set Time IMim*tesl HerdSets

*

3.57 4.67

12g+

2215 130

430

140

146

136

206

160

215+

386

620

240

2qH5

235

315

270 : 220

average o f 3 tests

+ average o f 2 tests

200

1gO 110 170! 16~ 33G

2410

4301 266

170

13Q

11i0 1SO 166

166

170

S301 3 6

290

200

310

~S

320

3801 238 I

242

Vol. 6, No. 2 D. J. Cook, D. R. Morgan. V. Sirivivatnanon,

values of the chemically

combined water

W '

.

R. P. Chaplin

The calculation of the percen-

CW

tage of combined water takes into account

the monomer mixture loss which oc-

curred during mixing, but does not include any loss which occurred during moulding or curing. series

Except for the 75:25 and 25:75 acrylonitrile:

(thermally treated),

decreased

all the copolymer

the degree of hydration relative

styrene

(and individual polymer)

to the master specimens

series had a reduced degree of hydration relative

systems

and all

to the control specimens.

Setting Time Tests The results of the setting time tests are given in Table i. seen that the influence

of a particular polymer

in the copolymer

It can be is most con-

sistent in the setting time tests than for any other of the tests performed. This is probably due to the fact that the complex interactions mix constituents

between the

has only recently commenced.

The results indicate that both initial and hard set are related to the ratios of the monomers as acrylonitrile

comprising

the monomer mixture.

and methyl methacrylate

because of their pronounced

influence were more dominant in the monomer mixture is interesting

However, monomers

to note that the 3:1 styrene:

such

retarding

than other monomers.

It

vinyl acetate mix had an initial

set less than either the styrene or vinyl acetate mixes and also less than the control mix.

The hard set however was more consistent with the general pat-

tern of the results mentioned above. Conclusion As the papers presented at the recent International Concrete

(London, May, 1975) indicated,

tems contribute mortar.

to any improvement

It is also apparent

way.

few premix polymer

in the strength properties

(subsequently polymeric)

of the fresh and hardened

strengths series.

of concrete or

materials

affects

Of the fifteen sys-

only the GIOZR, L5ZR, HIOZR, U5XR, J5ZR and T5ZR had

greater than or equal to the strengths of the master and control It will be noticed that all these series were radiation

only the U5XR mix contained

by the percentage

treated and

the surfactant.

All the copolymer systems decreased the degree of hydration

mens.

sys-

concrete in a generally deleterious

The results reported herein provide no exception.

tems investigated,

(or copolymer)

that the interaction between the hydrating

Portland cement and the monomer the properties

Congress on Polymer

of chemically

as measured

combined water relative to the control speci-

The copolymers of methyl methacrylate

and butyl acetate had the lowest

Vol. 6, No. 2

243 POLYMER-CEMENT, PREMIX, PROPERTIES

degree of hydration compared to the master and control specimens.

The mono-

mer loss during mixing ranged from 31 to 52% for the copolymer systems tested. With the exception of the 3:1 styrene: vinyl acetate mix all the series had increased initial and

hard setting times.

The 3:1 styrene: vinyl acetate

mix had an initial set of ii0 mins. compared to 125 mins. for the control mix.

Acknowledgements The work d e s c r i b e d i n t h i s

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

concrete technology being undertaken in the Department of Civil Engineering Materials

at the University of New South Wales.

acknowledge

the assistance

aspects of the program. Australian

The authors would llke to

given by the laboratory staff in the experimental

The authors would also like to acknowledge

Institute of Nuclear Science and Engineering

the

for their assistance

with this project through Grant 74/40.

References 1.

D.R. Morgan, D . J . Cook, R.P. C h a p l i n and V. S i r i v i v a t n a n o n . New South Wales UNICIV R e p o r t No. R - I 3 2 , (1974).

Univ. o f

2.

D . J . Cook, D.R. Morgan, R.P. C h a p l i n and V. S i r i v i v a t n a n o n . F i r s t I n t . Cong. on Polymer C o n c r e t e s , London, (1975).

P a p e r D-6,

3.

R.H. M i l l s ,

4.

D.R. Morgan, Ph.D. T h e s i s , Univ. o f New South Wales,

T r a n s , South A f r i c a n I n s t .

of C i v i l E n g i n e e r s ,

(1973).

Appendix Notation Premix copolymer cement mortar mixes are denoted as follows: Details Monomer T ~ e

Copolymer TTpe

Symbol

Acrylonitrile

A

Styrene ~ t h y l Methac~late

S

Vi~iAcetate Butyl Acrylate Butyl Methac~late

VA BA BMA

BA :MMA

U W Z G

A:S

-

1:3 i:I 3:1 1:3 i:i 3:1

Nov. (1965).

H

J