premix copolymer cement materials

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

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 styrene- acrylonitrile, 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~ ap- pliques 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. Sir ivivatnanon, 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 mono-

mer 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 methacry-

late-vinyl acetate, butyl methacrylate-methyl methacrylate and butyl acry-

late-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 inves-

tigated. 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 ce-

ment 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) an automated Vicat apparatus, or "Speisograph" was used,

(ii) 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 rota-

ting 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. Sir ivivatnanon, R. P. Chaplin

adopt the method used by Mills (3) and Morgan (4), which is based on a deter-

mination of the state of combination of the various categories of water in

the hydrated paste structure.

The following experimental procedure was adopted:

The water-monomer mixture (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 in it

were determined 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. The moulds were covered with

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

relative humidity. Twenty four hours after casting the specimens were de-

moulded, 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. The

specimens were then subjected to either radiation or thermal treatment to

copolymerize the monomer mixture.

Radiation specimens were removed from the water bath and wrapped and

sealed in polythene sheets to minimize moisture and monomer loss. They were

placed in rigid metal containers and sent to the Australian Atomic Energy

Research Establishment 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 cobalt-60 irradition source. Specimens containing

styrene were subjected to a radiation dosage of i0 megarads while the remain-

der were subjected to 5 megarads; the dosage rate in both cases was 157,000

rads per hour. The irradiated 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. Hydration studies were per-

formed on 3 slices for each mix investigated. (Other slices were cut for

differential thermal analysis (D.T.A.), thermogravimetric analysis (T.G.A.)

and scanning electron microscopy (S.E.M.) studies.


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 de-

termlned.

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 con-

flicting. 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 characteris-

tics of the premix copolymer cement pastes is tabulated in Table i. The terms

and W represent the percentage evaporable substance at ll0°C, We, W n W ' p cw

percentage non-evaporable substance lost at 1000°C, percentage copolymer in

240 Vol. 6, No. 2 D. J. Cook, D. R. Morgan, V. S i r i v i v a t n a n o n , R. P. Chapl in

~,,,J

e,. P~ ' "

wzm~'m < 10% 10% 'additive G:,- ~u ~ 0 THERMAL TREATMENT

- o 25 50 '75 lOO'/, s loo 75 50 2 s o % A

PERCENTAGE OF EACH MONOMER IN THE COPOLYMER

ul <{..J

i ~' 100

~,~ so' I , o . . , -" U'IP-

, . Z RADIATIC w N TREATI lENT

25 50 "/5 100% S 100 75 SO 25 0% A

PERCENTAGE OF EACH MONOMER IN THE COPOLYME R

FIG. i Compress ive S t r e n g t h of S t y r e n e : A c r y l o n i t r i l e Mortar S e r i e s .

&f}-J

ul w ~ G G

w w

:[uJ On u

{n <[.J

5 % + addlt ive |

0 l THERMAL 0 25 50 75 100% S

100 75 S0 25 0 % VA PERCENTAGE 0F EACH MONOMER IN

THE COPOLYMER

10%

10%4 addit ive

TREATM NT

~.~ lO% ,s ' / . o o

S%+oddl tire 10% + oddit ive , . z o¢uJ

~ RADIATIC N TREAI MENT ~ 0 .....

o . ~o , 1oo.,. s ,oo ,/s so , o .,. VA PERCENTAGE OF" EACH MONOMER IN

THE CO'Ol YMER

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

)~ io,~. s.,. ~,~

o ..... ?~ ~ 50

"~1~ - ° - -Z " ' # " 10"/o~ additive m t,- uJ z \ 5 % ~ i additive OCLd o.. u iTHERMAL TREATM NT Z ¢ 0 OLd UO- 0 25 S0 -/5 100 %MMA

100 "/5 S0 2 5 0 % VA


u~ < . J

~S ~°° ~ - ~ ' ~ T _ ~ - " , _ ~ . , , ~ - - - - ~ = = - . " ~ . ~ _ . . F . ÷ . - ~ ;

m I~.s- ~ " "* 10%~ additive

< .- : - ~ l a%+~ tn m ~ 5 ddit ive I u j z ¢¢w u RADIATIO TREATIW ENT

~ 0~ 25 50 '/S 100"1, MMA 100 -/5 50 25 0% VA


FIG. 3 Compress ive S t r e n g t h of Methyl M e t h a c r y l a t e : Vinyl A c e t a t e Mortar Series.

=,-- t

v~

~ <

~J

to <l[.j

LOP" Z Z i

S 1°° P't~. &n o t~ W ~<so u j z

uo" G

w~ 5%+ addit ive ; 5;/o

I/ / " ' I F - ' - I ~ -~" ~-

10% 1 10%~ additive

THERMAL 7REATM "NT 0

25 50 75 100% BMA 100 75 50 25 O % MMA


~ . ~ % . odditive ! / 5 ~

/ - . . . 1 . . . . < ~ . % . . . . 4 ~ - - " " 10 % ~0 %+ additive

RADIATICN TREAT ,lENT

0 25 50 T5 100 % BMA 100 "/5 50 25 0 % MMA


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


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

(n

O o. (J

o 25 so ?S lOO % B A 100 76 50 25 0 % MMA

P E R C E N T A G E OF E A C H H O N O M E R IN

T H E C O P O L Y M E R

Ut ..I

~1oo' E ~ ' U) tU

~,=,,

U

- /---~.: ;~---- 10 % ? " " ~ ' - ' - - I

R A D I A T I O N I

25

i T R E A T P ~ N T

50 75 1 0 0 % B A 100 75 50 25 0 % M M A

P E R C E N T A G E OF E A C H M O N O M E R I N

T H E C O P O L Y M E R .

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

T A B L E 1

H y d r a t i o n Character ist ics o f P remix Copo lymer -Cemen t Pastes

Monomer Ty~

Pmaw'~ t'rmm'~t Contm~ Id~ter

A S M V B F

Wt Radiation 20.16" 20.36" 2124 19.77 r2.99 31.66 2123 21.36 Thern~l 19.60" 19.82 ;16.39 ~2,13 22.00 20.57 20.67

Redla~an 13.60 ° 13.38" 16.80 i5.76 r3.97 16.19 15.1:13.82 Wn Thermal 14.26" 16.79 15.83 14.01 16.30 15.57 14.34

Wp -- 3.57 4.67 3.71 3.00 4.57 2.79

Radiation 13.80" 13.03 11.19 10.16 13.19 10.56 11.03 Wcw Thermal 142~;" 13.30" 1322 11~9 10,30 12.30 11.00 11.55

Sitting Initild Set 12g + 2215 130 430 140 146 136 Time

IMim*tesl Herd Sets 215+ 386 200 620 240 2qH5 235

* average o f 3 tests

+ average o f 2 tests

Copoiyn~, of Coo~vmm' of Swnm* a~l Swr~e and A c r ~ i t r i i e Vinyl Aoetom

A:S A:6 A:6 6:V 6:V S:V 3:1 1:1 1:3 3:1 1:1 1:3

20,,39 20.25 191| 21.1] 21.62 21.(~ 19,17 19.17 16.1( 20.6~ 21.001202e

16.16 16.10 16.7¢ 14.74 14.97! 16.4( 161ii 16.90 16.4~ 14.74 16.31~ 16.31e

3.00 3.43 3.43 3.14 3.43 2,H

13.15 12.97 1327 11.90!11.54il2.54 13.61 13.17 13.90 11.60 11.98 12.49

206 160 1gO 110 170! 16~

315 270 : 220 33G 2410

Cooolym~r of MMA

Vlnyl Aoetete

M:V M:V M:V 3:1 1:1 1:3

21.70 20.M 20.71 21.17 19.N 2Q.31

14.77 tS. l l 16.H ;14M 16.10 15, (17

2.57 2.43 2.43

1220 12.73 13.13 12,41112,70 13,24

4301 266 170

S301 3 6 290

Copoiymer of Cooolymer st MMA aetd MMA and Butyl

Buty~ A~ykne uem*m-y~w

I F:M F:M F:M It:M | :M | :M 3:1 I:1 1:3 3:1 1:1 1:3

21.67 ~'~.9~ 24.11 21.10 21.M 13.76 121.N 21.90 22.04 20.74 21.73 |3.21

t

114.01 13.61 13.43 145211444 14.13 i4.N |4.34 14. "m )S~2 14.76 ~4.46

3JM 3.21 3.36 2.79 3.07 3.14

11.31 10.40 10.07 11.73 ;127 10.99 11.04 11.13 10.N ;223 I1JMI 1122

13Q 11i0 1SO 166 166 170

200 310 3801 238 ~S 320 I

242 Vol. 6, No. 2 D. J. Cook, D. R. Morgan. V. Sir ivivatnanon, R. P. Chaplin

values of the chemically combined water W . 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. Except for the 75:25 and 25:75 acrylonitrile: styrene

series (thermally treated), all the copolymer (and individual polymer) systems

decreased the degree of hydration relative to the master specimens and all

series had a reduced degree of hydration relative to the control specimens.

Setting Time Tests

The results of the setting time tests are given in Table i. It can be

seen that the influence of a particular polymer in the copolymer 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 between the

mix constituents has only recently commenced.

The results indicate that both initial and hard set are related to the

ratios of the monomers comprising the monomer mixture. However, monomers such

as acrylonitrile and methyl methacrylate because of their pronounced retarding

influence were more dominant in the monomer mixture than other monomers. It

is interesting to note that the 3:1 styrene: 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 Congress on Polymer

Concrete (London, May, 1975) indicated, few premix polymer (or copolymer) sys-

tems contribute to any improvement in the strength properties of concrete or

mortar. It is also apparent that the interaction between the hydrating

Portland cement and the monomer (subsequently polymeric) materials affects

the properties of the fresh and hardened concrete in a generally deleterious

way. The results reported herein provide no exception. Of the fifteen sys-

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

strengths greater than or equal to the strengths of the master and control

series. It will be noticed that all these series were radiation treated and

only the U5XR mix contained the surfactant.

All the copolymer systems decreased the degree of hydration as measured

by the percentage of chemically combined water relative to the control speci-

mens. The copolymers of methyl methacrylate and butyl acetate had the lowest


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 in t h i s paper forms p a r t o f a r e s e a r c h program in

concrete technology being undertaken in the Department of Civil Engineering

Materials at the University of New South Wales. The authors would llke to

acknowledge the assistance given by the laboratory staff in the experimental

aspects of the program. The authors would also like to acknowledge the

Australian Institute of Nuclear Science and Engineering for their assistance

with this project through Grant 74/40.

1.

2.

3.

4.

R e f e r e n c e s

D.R. Morgan, D . J . Cook, R.P. Chap l in and V. S i r i v i v a t n a n o n . Univ. o f New South Wales UNICIV Repor t No. R- I32 , (1974).

D.J . Cook, D.R. Morgan, R.P. Chap l in and V. S i r i v i v a t n a n o n . Paper D-6, F i r s t I n t . Cong. on Polymer C o n c r e t e s , London, (1975).

R.H. M i l l s , 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 , Nov. (1965) .

D.R. Morgan, Ph.D. T h e s i s , Univ. o f New South Wales , (1973).

Appendix Notation

Premix copolymer cement mortar mixes are denoted as follows:

Monomer T~e

Copolymer TTpe

Details Symbol

Acrylonitrile A

Styrene S ~ thy l Methac~late Vi~iAcetate VA

Butyl Acrylate BA

Butyl Methac~late BMA

BA :MMA 1:3 U

i:I W

3:1 Z

A:S - 1:3 G

i:i H

3:1 J

premix copolymer cement materials

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