Conductive Terrazzo Flooring

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NATIONAL RESEARCH COUNCIL CANADA

DIVISION OF BUILDING RESEARCH

CONDUCTIVE TERRAZZO FLOORING

by P.J. Sereda

bu his

r e p o r t has been prepared f o r information and r e c o r d purposes and i s not t o be

r e f e r e n c e d i n any p u b l i c a t i o n ) Report N o .

88

of t h e D i v i s i o n of B u i l d i n g Research Ottawa June

1956

PREFACE

Requests f o r i n f o r m a t i o n on e l e c t r i c a l l y conducting f l o o r s f o r h o s p i t a l o p e r a t i n g rooms d i r e c t e d t h e a t t e n t i o n of t h e D i v i s i o n t o t h i s s p e c i a l f l o o r i n g problem and t o t h e need f o r r e s e a r c h . Most of t h e common f l o o r i n g m a t e r i a l s a r e n o t s u f f i c i e n t l y conducting a s normally used, and must be modified through t h e use of a d d i t i v z s such a s carbon b l a c k which a r e i n c o r p o r a t e d d u r i n g manufacture. Conduc- t i v e t e r r a z z o , which must be manufactured i n p l a c e ,

p r e s e n t s s p e c i a l problems and has been t h e s u b j e c t of s p e c i a l s t u d i e s . T h i s r e p o r t which i s one of s e v e r a l i n p r e p a r a t i o n , d e s c r i b e s t h e r e s u l t s o b t a i n e d w i t h c e r t a i n m o d i f i c a t i o n s which were introduced i n t h e manufacture of

conductive t e r r a z z o i n t h e l a b o r a t o r y .

Ottawa,

CONDUCTIVE TERRAZZO FLOOR~AQLA by

P . J . S e r e d a

The r e a s o n s f o r t h e need of s e m i - c o n d u c t i n g f l o o r i n g i n h a z a r d o u s l o c a t i o n s s u c h a s h o s p i t a l o p e r a t i n g rooms have a l r e a d y been d i s c u s s e d ( 1 ) " The p r o p e r t i e s of a number of commercially a v a i l a b l e c o n d u c t i v e f l o o r i n g m a t e r i a l s have

a l s o been p r e s e n t e d ( 2 ) . A s n o t e d i n ( 2 ) , c o n d u c t i v e t e r r a z z o p r e s e n t s s p e c i a l problems and t h e r e f o r e , some r e s e a r c h on

t h i s m a t e r i a l was done i n a n a t t e m p t t o answer t h e f o l l o w i n g q u e s t i o n s : 1. What i s t h e s t a b i l i t y and r e p r o d u c i b i f i t y of t h e e l e c t r i c a l r e s i s t a n c e of c a r b o n t e r r a z z o f l o o r i n g ; 2 . Can a w e t t i n g a g e n t such a s i s o p r o p y l a l c o h o l be used t o d i s p e r s e t h e a c e t y l e n e c a r b o n ' i n t h e cement and w a t e r mix; 3. Would t h e a d d i t i o n of m e t a l f i l i n g s i n t h e s u r f a c e of t h e f l o o r succeed i n d e c r e a s i n g o r e l i m i n a t i n g t h e h i g h c o n t a c t r e s i s t a n c e t o t h e m a t e r i a l ;

4 .

Can t e r r a z z o s e a l e r s be used i n t h e s u r f a c e of c o n d u c t i v e t e r r a g z o f l o o r i n g w i t h o u t i m p a i r i n g i t s c o n d u c t i v i t y ;

5.

Are s u p e r a b r a s i o n f u r n a c e b l a c k s s u i t a b l e f o r u s e i n t e r r a z z o f l o o r i n g t o i m p a r t c o n d u c t i v i t y . M a t e r i a l s and Samples T e r r a z z o f l o o r i n g samples m s a s u r i n g by 18 i n c h e s were made from p o r t l a n d cement and K O . 1 and No. 2 w h i t e

marble c h i p s i n t h e p r o p o r t i o n s of 1 of cement and 2 of c h i p s . A c e l y t e n e c a r b o n b l a c k s u p p l i e d by Shawinigan Chemicals,

b r a s s f i l i n g s , s u p e r a b r a s i o n f u r n a c e b l a c k d e s i g n a t e d a s P h i l b a c k E s u p p l i e d by P h i l l i p s Chemical Company were t h e a d d i t i v e s used t o i m p a r t e l e c t r i c a l c o n d u c t i v i t y

.

These were p r o p o r t i o n e d by w e i g h t based on t h e weight of cement u s e d . Chemically p u r e i s o p r o p y l a l c o h o l w a s used as a

w e t t i n g a g e n t i n t h e s e e x p e r i m e n t s . Chicken w i r e mesh w i t h 1 - i n c h openings was used i n t h e base of t h e s a m p l e s ,

Samples were made by mixing t h e i n g r e d i e n t s i n a Hobbart mixer i n s m a l l b a t c h e s . Each b a t c h made one sample.

When t h e w e t t i n g a g e n t w a s n o t used, t h e b l a c k was mixed w i t h t h e d r y cement and c h i p s , t h e n w a t e r was added and mixed

t h o r o u g h l y . When t h e w e t t i n g a g e n t was u s e d , t h e cement and c h i p s were mixed w i t h one h a l f of t h e t o t a l w a t e r r e q u i r e d . The i s o p r o p y l a l c o h o l was added t o t h e r e m a i n d e r of t h e w a t e r i n c o n c e n t r a t i o n of

1.5

p e r c e n t t h e n t h e b l a c k was mixed i n t o t h i s s o l u t i o n making a p a s t e . T h i s p a s t e was t h e n added t o t h e cement mix and t h e t o t a l mixed f o r n o t more t h a n

3 mlnut e s

.

The f i r s t s e r i e s of samples c o n s i s t e d of t h e t o p p i n g mix c o n t a i n i n g 2 p p r c e n t a c e l y t e n e c a r b o n b l a c k t r o w e l l e d t o a t h i c k n e s s of ii i n c h o v e r a $ - i n c h m o r t a r underbed c o n t a i n i n g 3 p e r c e n t a c e t y l e n e b l a c k . The w i r e mesh was used i n t h e underbed, S u b s e q u e n t l y t h e underbed was l e f t o u t and t h e to2p:ng mix a l o n e w a s t r o w e l l e d i n t o forms 9 by

18

i n c h e s by

,,

l n c h deep w i t h t h e w i r e mesh a t t h e bottom of t h e f o r m s . The samples were c o v e r e d w i t h p o l y t h e n e membrane and a l l o w e d t o c u r e f o r two weeks. They were t h e n ground and p o l i s h e d u s i n g wet s t o n e s i n a r o t a r y p o l i s h i n g machine. R e s u l t s and D i s c u s s i o n

A l l samples of t e r r a z z o made w i t h 2 p e r c e n t a c e l y t e n e carbon b l a c k showed a remarkable r e p r o d u c i b i l i t y i n e l e c t r i c a l r e s i s t a n c e even though t h e t e c h n i q u e of f a b r i c a t i o n w a s

v a r i e d . T a b l e s I and I1 show t h a t even d r y i n g t h e samples f o r p e r i o d s of 10 d a y s a t 1 3 0 ~ ~ . and 2 2 0 ~ ~ . and d r y i n g i n a room c o n t r o l l e d below 15 p e r c e n t r e l a t i v e h u m i d i t y f o r

s e v e r a l months had l i t t l e e f f e c t on t h e c o n d u c t i u i t y . The low v a l u e of r e s i s t a n c e o b t a i n e d w i t h t h e sample d r i e d slowly i n a room c o n d i t i o n e d below

15

p e r c e n t r e l a t i v e h u m i d i t y may be e x p l a i n e d by t h e f a c t t h a t t h i s sample was n o t washed and some e f f l o r e s c i n g s a l t s may have been brought o u t from t h e sample d u r i n g slow d r y i n g .

T a b l e I11 i n d i c a t e s t h a t t h e c o n d u c t i v i t y of t e r r a z z o was n o t changed a p p r e c i a b l y a s t h e c o n c e n t r a t i o n of a c e t y l e n e

b l a c k was d e c r e a s e d t o

li

p e r c e n t .

Acetylene c a r b o n b l a c k was found most d i f f i c u l t t o d i s p e r s e i n t h e cement and w a t e r mix of t h e t e r r a z z o because

i t i s n o t w e t t e d by w a t e r and h a s a v e r y low a p p a r e n t d e n s i t y . The N a t i o n a l T e r r a z z o and Mosaic A s s o c i a t i o n recommends

i s o p r o p y l a l c o h o l as a w e t t i n g a g e n t . T h i s a g e n t was t h e r e - f o r e i n v e s t i g a t e d w i t h r e s u l t s a s f o l l o w s . A number of samples of t e r r a z z o c o n t a i n i n g 2 p e r c e n t a c e t y l e n e b l a c k were p r e p a r e d u s i n g i s o p r o p y l a l c o h o l a s w e t t i n g a g e n t . T h i s w e t t i n g a g e n t was e f f e c t i v e i n a i d i n g t h e d i s p e r s i o n of a c e t y l e n e b l a c k i n t h e wet t e r r a z z o mix.

When a c e t y l e n e c a r b o n b l a c k was added t o cement i n t h e t e r r a z z o mix, more w a t e r was r e q u i r e d t o make t h e mix workable t h a n was needed f o r t e r r a z z o w i t h o u t t h e b l a c k . When i s o p r o p y l a l c o h o l was used as a w e t t i n g a g e n t f o r t h e

b l a c k , s t i l l more w a t e r was needed t o make t h e mix workable. 'l'he compressive s t r e n g t h (jf t h e t h r e e mixes of about t h e

same w o r k a b i l i t y was d e t e r m i n e d and t h e r e s u l t s p r e s e n t e d i n F i g . 1. It w i l l be n o t e d t h a t t h e a d d i t i o n c f 2 p e r c e n t a c e t y l e n e b l a c k by weight of cement r e s u l t e d i n a d e c r e a s e i n t h e s t r e n g t h of t h e t e r r a z z o as would be e x p e c t e d from t h e i n c r e a s e d water-to-ct.n;ent r a t i o , The a d d i t i o n of a w e t t i n g a g e n t f u r t h e r debcreased t h e s t r e n g t h p r o p o r t i o n a l t o t h e i n c r e a s e i n t h e water-to-cement r a t i o . S i n c e t h e t h r e e p o i n t s l i e i n 2 s t r a i g h t l i n e it can be r e a s o n e d t h a t

t h e e f f e c t of i s u p r o p , i l alcohol. a s such upon t h e s t r e n g t h of hardened cement was n e g l i g i b l e ,

Samples made w i t h 2 p e r c e n t a c e t y l e n e b l a c k and i s o p r o p y l a l c o h o l a s w e t t , i n g a g e n t gave r e s u l t s of conduc- t i v i t y q u i t e s i m i l a r t o the samples madn w i t h o u t the

w e t t i n g a g e n t ( T a b l e 11). T t k r i l l . be n o ~ e d t h a t sample A-3

was i n t e n t i o n a l l y overmixed f o r I;, m r i n ~ ~ . L e s . 'The e l e c t r i c a l r e s i s t a n c e of t h i s . sample w a s somewhat hi.gher but i t would a p p e a r t h a t t h e mixing time w a s n o t a c r i t i c a l f a c t o r .

When measuring r e s i s t a n c e of t e r r a z z o c o n t a i n i n g

a c e t y l e n e b l a c k by t h s NFPA method

( 3 )

t h e c o n t a c t r e s i s t a n c e between t h e p o s i t i v e e l e c t r o d e and t h e s u r f a c e i s a b o u t t e n t i m e s t h e volurne r e s i s t a n c e of t h e ma.l;e.rial i t s e l f . (The c o n t a c t r e s i s t a n c e of t h e n e g a t i v e e l e c t r o d e i s u s u a l 1 jr small because of t h e p r o c e s s o f e l e c t r o - o s m o s i s a s s o c i a t e d w i t h d - c . p o t e n t i a l s i n such s y s t e m s , ) It h a s been found t h a t b r a s s f i l i n g s i n t h e s u r f a c e of t e r r a z z o c o n t a i n i n g 2 p e r c e n t a c e t y l e n e b l a c k reduced t h e c o n t a c t r e s i s t a n c e of t h e p o s i t i v e e l e c t r o d e t o t h e s u r f a c e . 'This e f f e c t was l e s s pronounced a s t h e c o n c e n t r a t i o n of a c e t y l e n e b l a c k was reduced

a able

111). The b r a s s f i l i n g s a r e r e q u i r e d j u s t i n t h e s u r f a c e of t h e t e r r a z z o and a n a t t e m p t was made t o

s p r i n k l e t h e b r a s s on t h e s u r f a c e w h i l e t h e mix was b e i n g t r o w e l l e d . T h i s was n o t : ; l ~ ~ - c e s s f " u l because most of t h e b r a s s f i l i n g s were removed i n t h e p r o c e s s of g r i n d i n g t h e t e r r a z z o . Some samples were made by i n c o r p o r a t i n g t h e b r a s s f i l i n g s i n t h e mix. A t l e a s t 2 p e r c e n t of brass f i l i n g s by weight of cement was r e q u i r e d t o have a s e a s o n a b l e c o n c e n t r a t i o n i n t h e s u r f a c e which would produce t h e d e s i r e d effect,, T h i s

a d d i t i o n of b r a s s f i l i n g s t o t e r r a z z o c o n t a i n i n g 2 p e r c e n t a c e t y l e n e b l a c k r e s u l t e d i n v a l u e s of r e s i s t a n c e below t h e lower l i m i t . The e f f e c t , ' . o f b r a s s f i l i n g s was l e s s pronounced a s t h e c o n c e n t r a t i o n of S l a c k was d e c r e a s e d whereas t h e

volume r e s i s t a n c e of t h e s a l ~ l p l e s i n c r e a s e d and became more dependent upon t h e m o i s t u r e c o n t e n t , T e r r a z z o c o n t a i n i f i g 1 p e r c e n t a c e t y l e n e b l a c k and 2 p e r c e n t b r a s s f i l i n g s

might be s u i t a b l e but t h e advantage o v e r t e r r a z z o c o n t a i n i n g 2 p e r c e n t a c e t y l e n e b l a c k a l o n e i s n o t e v i d e n t from t h e r e s u l t s . S i x p r o p r i e t a r y t e r r a z z o s e a l e r s were a p p l i e d on one h a l f of t h e samples of t e r r a z z o c o n t a i n i n g 2 p e r c e n t a c e t y l e n e b l a c k t o observe t h e i r e f f e c t upon e l e c t r i c a l r e s i s t a n c e . These s e a l e r s p e n e t r a t e d i n t o t h e t e r r a z z o and d i d n o t form t h i c k c o a t i n g s on t h e s u r f a c e . In a l l c a s e s t h e s e s e a l e r s caused o n l y a s l i g h t d e c r e a s e i n t h e r e s i s t a n c e of t h e c o n d u c t i v e t e r r a z z o f l o o r i n g . T h i s was c h a r a c t e r i s t i c of t h e s e m a t e r i a l s under a l l c o n d i t i o n s of t e s t i n c l u d i n g d r y i n g t o 220°F. Acetylene c a r b o n b l a c k h a s s o f a r been t h e o n l y c o n d u c t i v e i n g r e d i e n t used i n t e r r a z z o f l o o r s . T h e r e f o r e samples of t e r r a z z o were made c o n t a i n i n g one s p e c i f i c t y p e of t h e s u p e r a b r a s i o n f u r n a c e b l a c k s made by P h i l l i p s Chemical Company. It was found t h a t t h i s b l a c k was s l i g h t l y w e t t a b l e by w a t e r and c o u l d be d i s p e r s e d i n t h e w a t e r and cement mix w i t h o u t much d i f f i c u l t y . The e l e c t r i c a l r e s i s t a n c e s of t h e s e

samples a r e g i v e n i n T a b l e

IV.

It i s a p p a r e n t t h a t t h e f u r n a c e b l a c k s e r v e d a s a n e f f e c t i v e c o n d u c t i n g a g e n t . The compressive s t r e n g t h of one b a t c h of t e r r a z z o c o n t a i n i n g t h e f u r n a c e b l a c k was checked and t h e r e s u l t i n d i c a t e d a d e c r e a s e of s t r e n g t h compared t o t e r r a z z o made w i t h a c e t y l e n e b l a c k . T h i s s h o u l d be checked a g a i n s i n c e t h i s r e s u l t i s based on

o n l y one b a t c h .

Swnmary and Conc l u s i o n s

1. S u c c e s s i v e b a t c h e s of t e r r a z z o w i t h 2 p e r c e n t a c e t y l e n e carbon b l a c k from which samples were made, showed remarkable r e p r o d u c i b i l i t y of e l e c t r i c a l r e s i s t a n c e a s measured by

NFPA method. The r e s i s t a n c e of t h e s e samples remained below 1 megohm even a f t e r d r y i n g i n t h e oven a t 2 2 0 " ~ . ; 2 . I s o p r o p y l a l c o h o l i n c c n c e n t r a t i o n of 1* p e r c e n t i n w a t e r

was found s u i t a b l e a s a w e t t i n g a g e n t f o r a c e t y l e n e carbon b l a c k . T h i s w e t t i n g a g e n t as s u c h d i d n o t a f f e c t t h e

s t r e n g t h of t h e hardened cement. It d i d , however, r e q u i r e more w a t e r t o be used i n t h e mix r e s u l t i n g i n a d e c r e a s e

i n compressive s t r e n g t h of t h e sample;

3 . B r a s s f i l i n g s i n t h e s u r f a c e of t e r r a z ~ o c o n t a i n i n g 2 p e r

c e n t a c e t y l e n e b l a c k d i d reduce t h e c o n t a c t r e s i s t a n c e between t h e e l e c t r o d e and t e r r a z z o s u r f a c e . T e r r a z z o f l o o r i n g h a v i n g a r e s i s t a n c e (NFPA method) l e s s t h a n 10,000 ohms can be o b t a i n e d i n t h i s way. T h i s e f f e c t d e c r e a s e d a s t h e c o n c e n t r a t i o n of b l a c k i n t e r r a z z o was d e c r e a s e d . I n a d d i t i o n when t h e c o n c e n t r a t i o n of a c e t y l e n e

black was decreased i n t h e samples c o n t a i n i n g b r a s s f i l i n g s , t h e r e s i s t a n c e became l e s s s t a b l e . These r e s u l t s could not j u s t i f y t h e use of b r a s s f i l i n g s a l o n g w i t h a c e t y l e n e

carbon black i n t e r r a z z o f l o o r i n g u n l e s s a f l o o r w i t h very low r e s i s t a n c e was d e s i r a b l e ;

4. Terrazzo s e a l e r s of t h e p e n e t r a t i n g type were found t o have no i n j u r i o u s e f f e c t upon t h e e l e c t r i c a l r e s i s t a n c e

of conductive t e r r a z z o f l o o r i n g samples;

5.

I n d i c a t i o n s a r e t h a t super a b r a s i o n f u r n a c e b l a c k s can be used as t h e conductive i n g r e d i e n t i n t e r r a z z o . However, t h e r e i s some evidence t h a t t h e one type t e s t e d had some d e l e t e r i o u s e f f e c t upon t h e s t r e n g t h of t h e hardened cement.

A number of t e r r a z z o f l o o r s , s p e c i f i e d t o c o n t a i n 2 p e r c e n t a c e t y l e n e b l a c k , when i n s t a l l e d i n h o s p i t a l s d i d n o t meet t h e requirements of c o n d u c t i v i t y

.

Present l a b o r a t o r y r e s u l t s i n d i c a t e t h a t t h e c o n d u c t i v i t y of t e r r a z z o is s a t i s - f a c t o r y over a r a t h e r wide range of eoncentsat ions of a c e t y l e n e black. It a p p e a r s , t h e r e f o r e , t h a t t h e d i s p e r s i n g and propor- t i o n i n g of a c e t y l e n e black i n t e r r a z z o on t h e jobs was

p a r t i c u l a r l y poor and t h a t t h e r e were a r e a s of f l o o r i n g c o n t a i n i n g l e s s t h a n 1 p e r c e n t a c e t y l e n e black.

It i s recommended, t h e r e f o r e , t h a t i s o p r o p y l a l c o h o l be used as a w e t t i n g agent t o d i s p e r s e a c e t y l e n e b l a c k i n t h e t e r r a z z o mix and t h a t a l l i n g r e d i e n t s be c a r e f u l l y proportioned and mixed thoroughly. The m i x should be of

such c o n s i s t e n c y t h a t i t could be t r o w e l l e d on t o t h e s u b f l o o r .

References

1. Legget, R.F. and P.J. Seseda. Conductive f l o o r s f o r s a f e t y i n h o s p i t a l s . J o u r n a l , Royal A r c h i t e c t u r a l I n s t i t u t e of Canada, v o l , 31, no. 11, November 1954. ( ~ e p r i n t e d a s NRC 34671,

2 . Sereda, P. J

.

Propert i e a of commercial conductive f l o o r i n g s f o r h o s p i t a l o p e r a t i n g rooms. National Research Council, D i v i s i o n of Building Research. A p r i l

1956.

3. Recommended s a f e s a c t i c e f o r h o s p i t a l o p e r a t i n g rooms. N.F.P.A. No.

5

g

of t h e National F i r e P r o t e c t i o n A s s o c i a t i o n , Boston, 40p.

TABLE I

E l e c t r i c a l R e s i s t a n c e of T e r r a z z o C o n t a i n i n g 2% Acetylene Carbon Black by Weight of Cement ( N O w e t t i n g a g e n t )

*

T h i s h i g h r e s i s t a n c e d e c r e a s e d t o i n i t i a l low v a l u e i n v e r y few minutes a f t e r t h e sample was brought i n t o a room c o n d i t i o n e d t o 5076 R.H. Sample No. 1 2

3

10 11

**

T h i s v a l u e was o b t a i n e d a f t e r sample was l e f t t o d r y f o r two months i n a room c o n d i t i o n e d below 15% R . H .

R e s i s t a n c e ( t h o u s a n d s of ohms) - C o n d i t i o n e r t o

5G$

R . H ,

175

190

130 200 190 Washed w i t h = € e r g e n t s o l u t i o n e v e r y working d a y f o r

3

months 60

55

65

~r iz-Xmy' f o r t e n days 440

*

380

30

**

.

TABLE I1

E l e c t r i c a l R e s i s t a n c e of T e r r a z z o Containing

25

Acetylene Carbon Black Dispersed by Means of I s o p r o p y l Alcohol

*

A - 3 was mixed f o r 1 5 minutes a f t e r t h e carbon p a s t e was added. Other samples were mixed f o r 3 minutes a s recommended i n t h e s p e c i f i c a t i o n of N a t i o n a l Terrazzo and Mosaic A s s o c i a t i o n .

Sample No. A - 1 A - 2 *A-3 B-1

**

T h i s h i g h v a l u e decreased t o 150 a f t e r t h e sample had been i n t h e room c o n d i t i o n e d a t 50% R . H . f o r 20 minutes. R e s i s t a n c e ( t h o u s a n d s of ohms) Dried i n oven a t 2 2 0 ' ~ . f o r 10 days 300 3,000

"*

Conditioned t o

50%

_{R . H .} 100 110 250 150 Washed w i t h d e t e r g e n t s o l u t i o n e v e r y working day f o r 1 month 80 70 90

TABLE 111

E l e c t r i c a l R e s i s t a n c e of Terrazzo Containing Various C o n c e n t r a t i o n s of Acetylene Carbon and Brass F i l i n g s

Brass f i l i n g s $ by w t . of cement i n s u r f a c e I 1 I I I1 1 1 11 0 i n s u r f a c e It I I 11 1 2 Sample No. 4 5 A - 4 A-5 A -6 A - 8 A - 7 A-ll A-12 A - 1 3 A - 1 4 B-2 B-3 1 R e s i s t a n c e ( t h o u s a n d s of ohms) $ Carbon by w t . of cement 2 2 1s 1

4

O O 1% 1* 1

3

1 1 Conditioned t o

50s

R.H. 13 7 10 45 330 2,000 1,500 4 25 35 300 350 325 , Dried a t 220°F. 47 250

5

000 5,000 5,000 8 350 5 000 5,000 5 000

TABLE

IV

E l e c t r i c a l R e s i s t a n c e of T e r r a z z o C o n t a i n i n g V a r i o u s C o n c e n t r a t i o n s of Super Abrasion Furnace B l a c k s and B r a s s F i l i n g s Sample No. C - 1 C - 2

c-3

C - 4 R e s i s t a n c e ( t h o u s a n d s of ohms) Conditioned t o 50% R . H . 147 190 200 120 Cornposit i o n $ b l a c k 2

15

1 2 Dried a t 220°F. 500 900 5,000 710 $ b r a s s 0 0 2 0 Notes W e t t i n g a g e n t W e t t i n g a g e n t W e t t i n g a g e n t N o w e t t i n g a g e n t

WATER T O CEMENT RATIO LEGEND;

X

_{PORTLAND CEMENT TERRAZZO}

0

I fi I I 1 a

+ 2 %

ACETYLENE BLACK

A

I I I I I I

+

2

O l e I I I I

+

WETTING AGENT

V

I I I I 1s

+2'/0

S A F BLACK

FIGURE I

COMPRESSIVE STRENGTH OF TERRAZZO

MIXES

OF ABOUT THE SAME

WORKABILITY