Dimensional changes of brick masonry in relation to "soundness" of mortar materials

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Dimensional changes of brick masonry in relation to "soundness" of mortar materials

NATIONAL RESEARCH COUNCIL

CANADA

D I V I S I O N O F B U I L D I N G RESEARCH

D ~ N S I O N A L

CHANGES

O F B R I C K MASOmRY I N R E L A T I O N TO "SOUNDNESS" O F MORTAR MATERIALS

T. R i t c h i e A N A L Y Z E D I n t e r n a l R e p o r t N o . 212 of the Division o f B u i l d i n g Research OTTAWA D e c e m b e r 1960

PREFACE

Lime has been produced from d o l o m i t i c l i m e s t o n e s i n t h e Toronto a r e a f o r many y e a r s . More r e c e n t l y masonry cements have been made by b l e n d i n g h y d r a t e d l i m e from t h e s e same l i m e s t o n e s w i t h P o r t l a n d cement. Though t h e s e masonry cements a r e shown t o be unsound by t h e a u t o c l a v e t e s t it

i s

m a i n t a i n e d t h a t t h e r e have been no obvious d i f f i c u l t i e s from t h e i r u s e i n t h e f i e l d . !his m a t t e r h a s r e c e n t l y b e e n t h e s u b j e c t o f c o n s i d e r a b l e s t u d y i n c o n n e c t i o n w i t h t h e

p r e p a r a t i o n o f Canadian s p e c i f i c a t i o n s f o r masonry cements. The r e s u l t s o f a l a b o r a t o r y s t u d y o f d i m e n s i o n a l changes i n b r i c k masonry p i e r s made w i t h such cements i s now r e p o r t e d .

The a u t h o r , a r e s e a r c h o f f i c e r w i t h t h e B u i l d i n g M a t e r i a l s S e c t i o n of t h e D i v i s i o n i s i n c h a r g e o f b r i c k masonry

s t u d i e s .

O t t a w a

OF MORWR MATERIALS

T.

R i t c h i e

The c u r r e n t ASTM s p e c i f i c a t i o n f o r masonry cement (1) r e q u i r e s t h a t cement be "soundtt a s determined by t h e amount of expansion r e s u l t i n g from a n a u t o c l a v e t r e a t m e n t of hardened b a r s made of a n e a t p a s t e of t h e cement. This

"soundness" requirement was i n t r o d u c e d i n t o t h e s p e c i f i c a t i o n f o l l o w i n g t h e 1952 r e p o r t of McBurney ( 2 ) t h a t a cause of

c r a c k i n g of b r i c k masonry i s t h e expansion of mortar r e s u l t i n g from t h e delayed h y d r a t i o n of MgO. According t o McBurney

t h e a u t o c l a v e t e s t s e r v e d t o d i s t i n g u i s h between "unsound"

( i . e. expansion-producing) and "sound" cementing m a t e r i a l s f o r m o r t a r , and h e c o n s i d e r e d t h a t a u t o c l a v e expansion g r e a t e r t h a n 1 . 0 p e r c e n t i n d i c a t e d "unsoundness" of t h e cementing m a t e r i a l . A l i m i t of 1 . 0 p e r c e n t was s u b s e q u e n t l y adopted i n t h e ASTM s p e c i f i c a t i o n f o r masonry cement.

A s t u d y made i n 1939 by Welch ( 3 ) of t h e e f f e c t s of

t h e h y d r a t i o n of MgO i n m o r t a r , i n d i c a t e d t h a t f o r t h e m a t e r i a l s h e s t u d i e d , magnesia h y d r a t e d i n t h e m o r t a r j o i n t s w i t h no

n o t i c e a b l e expansion o r harmful e f f e c t s . He c o n s i d e r e d t h a t expansion of m o r t a r i n a n a u t o c l a v e t e s t , which may be

a p p r e c i a b l e , d i d n o t correspond t o i t s dimensional changes under n a t u r a l c o n d i t i o n s of a g i n g .

A s t u d y of dimensional changes of b r i c k masonry i n r e l a t i o n t o t h e a u t o c l a v e expansion p r o p e r t i e s of t h e m o r t a r m a t e r i a l s u s e d was r e p o r t e d i n 1955 by F.O. and J. A .

Anderegg

( 4 ) .

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

m o r t a r m a t e r i a l s and m o r t a r s expanded g r e a t l y i n t h e a u t o c l a v e t e s t b u t brickwork made of them u n d e m e n t l i t t l e expansion and e x h i b i t e d no evidence of unsoundness under n a t u r a l

exposure. I n a d d i t i o n , t h e y found t h a t samples of m o r t a r and c o n c r e t e taken from v e r y o l d s t r u c t u r e s which had shown no i n d i c a t i o n of unsoundness expanded a p p r e c i a b l y when s u b j e c t t o t h e a u t o c l a v e t e s t .

For many y e a r s i n t h e Toronto, O n t a r i o , a r e a t h e

burning of d o l o m i t i c l i m e s t o n e s h a s been c a r r i e d o u t t o o b t a i n lime

( 5 ) .

Slaked quicklime p u t t y and normally h y d r a t e d l i m e prepared from t h e s e d o l o m i t i c l i m e s have been e x t e n s i v e l y used i n m o r t a r f o r masonry c o n s t r u c t i o n . Problems of delayed expansion of masonry made of such l i m e s have n o t been r e p o r t e d , a s f a r a s i s known. I n r e c e n t y e a r s masonry cements made by t h e b l e n d i n g of normally h y d r a t e d lime and p o r t l a n d cement have been produced i n t h e Toronto a r e a . A s shown l a t e r , such masonry

cements would be c o n s i d e r e d "unsoundt' by t h e a u t o c l a v e t e s t . An i n v e s t i g a t i o n t h e r e f o r e w a s made t o determine t h e

r e l a t i o n between t h e i r a u t o c l a v e expansion c h a r a c t e r i s t i c s a n d t h e dimensional changes of b r i c k masonry p i e r s made o f m o r t a r c o n t a i n i n g them. Other t y p e s of cementing m a t e r i a l s were a l s o s t u d i e d f o r comparison.

Mortars of f o u r d i f f e r e n t cementing m a t e r i a l s were s t u d i e d . The f i r s t w a s a masonry cement blended of p o r t l a n d cement and normally h y d r a t e d l i m e i n e q u a l p r o p o r t i o n by volume. llze second w a s a s i m i l a r b l e n d , b u t i n p r o p o r t i o n s by volume of two p a r t s normally h y d r a t e d lime and one p a r t p o r t l a n d cement. The t h i r d was a masonry cement made of i n t e r g r o u n d p o r t l a n d cement and l i m e s t o n e , a n d t h e

l a s t

w a s a m i x t u r e i n e q u a l volumes of p o r t l a n d cement and lime p a s t e o b t a i n e d from t h e s l a k i n g of quicklime. The cementing

m a t e r i a l s mere mixed w i t h a well-graded sand t o make mortar. !be a u t o c l a v e expansions of t h e m a t e r i a l s , i n t h e form of n e a t cement b a r s and m o r t a r b a r s 1 i n c h i n c r o s s - s e c t i o n and 1 0 i n c h e s l o n g , a r e shown i n Table I. The b a r s were demoulded a t 24 h o u r s , s t o r e d i n a humid room f o r a n o t h e r

24 h o u r s , t h e n a u t o c l a v e d f o r 3 h o u r s a t 300 p s i . The cements composed of p o r t l a n d cement and normally h y d r a t e d l i m e

expanded a p p r e c i a b l y , g r e a t l y exceeding t h e 1 . 0 p e r cenk

l i m i t of t h e s p e c i f i c a t i o n , t h e r e f o r e by t h i s t e s t t h e y would be c o n s i d e r e d 'tunsound". The amount of expansion c o u l d n o t be measured by t h e s t a n d a r d comparator, and t h e v a l u e g i v e n i s based on measurements made w i t h a v e r n i e r c a l i p e r . !lhe o t h e r masonry cement and t h e m i x t u r e of p o r t l a n d cement and l i m e p u t t y showed l i t t l e expansion i n t h e t e s t . The r e s u l t s of a t e s t f o r expansion of t h e n e a t cement by steaming i n L e C h a t e l i e r moulds, a s t a n d a r d t e s t i n G r e a t B r i t a i n ( 6 ) and elsewhere f o r soundness of l i m e p r o d u c t s a r e a l s o shown i n ICable I, If i n t h i s t e s t t h e expansion i s l e s s t h a n

1 0 mm, t h e m a t e r i a l i s c o n s i d e r e d t o be "sound". None of t h e m a t e r i a l s t e s t e d expanded enough t o be measured.

A s might be expected, t h e amount of a u t o c l a v e expansion was found t o v a r y w i t h t h e p r o p o r t i o n s of cementing m a t e r i a l t o sand i n t h e m o r t a r . For one m a t e r i a l , a change i n t h e p r o p o r t i o n s of cementing m a t e r i a l t o sand from 1:3 t o 1:l

r e s u l t e d i n a u t o c l a v e expansion 2.5 t i m e s g r e a t e r t h a n t h a t of t h e 1 : 3 mix.

The amount of expansion of m o r t a r may d e c r e a s e on pro- longed s t o r a g e b e f o r e a u t o c l a v i n g , a s t h e s t u d i e s of Welch

( 3 ) , Rogers ( 7 ) , and o t h e r s have i n d i c a t e d . The i n f l u e n c e of s t o r a g e under v a r i o u s humidity c o n d i t i o n s on t h e a u t o c l a v e expansion of m o r t a r b a r s made of t h e two "unsound" masonry cements w a s i n v e s t i g a t e d . Mortar b a r s were removed from t h e moulds a t age 24 h o u r s and s u b s e q u e n t l y were s t o r e d a t 100,

50 and 1 0 p e r c e n t

R.H.,

a t a t e m p e r a t u r e of 73OP, f o r v a r i o u s l e n g t h s of time, when t h e y were a u t o c l a v e d , The r e s u l t s f o r m o r t a r b a r s s t o r e d f o r a y e a r a r e . shown i n Table 11. I n most

c a s e s t h e amount of e x p a n s i o n of t h e b a r s w a s f o r g r e a t e r t h a n c o u l d be measured by t h e s t a n d a r d c o m p a r a t o r , a n d v e r n i e r

c a l i p e r s were u s e d f o r t h e measurements. Itany of t h e b a r s , i n a d d i t i o n , were warped from t h e a u t o c l a v e t r e a t m e n t , h e n c e a t r u e comparison of t h e e x p a n s i o n s was n o t p o s s i b l e . I t i s c l e a r , however, t h a t t h e h u m i d i t y c o n d i t i o n of s t o r a g e

h a d a c o n s i d e r a b l e e f f e c t on t h e amount o f ' a u t o c l a v e e x p a n s i o n . When b a r s of b o t h cements were s t o r e d a t 1 0 0 p e r c e n t R.H.,

t h e r e was a d e c r e a s e i n t h e amount o f a u t o c l a v e e x p a n s i o n w i t h t i m e . S t o r a g e a t 50 p e r c e n t R.H. a l s o r e d u c e d t h e e x p a n s i o n b u t n o t t o t h e same e x t e n t a s s t o r a g e a t 1 0 0 p e r c e n t R.H. When s t o r e d i n t h e 1 0 p e r c e n t R.H. a t m o s p h e r e , however, b a r s of

one of t h e cements h a d i n c r e a s e d a u t o c l a v e e x p a n s i o n a s t h e y a g e d , w h i l e b a r s of t h e o t h e r cement underwent l i t t l e change i n t h e amount of a u t o c l a v e e x p a n s i o n .

DIMENSIONAL CHANGES OF MORTAR BARS I N VARIOUS HUMIDITIES I t w a s o b s e r v e d t h a t a f t e r t h e

f i r s t

measurement of l e n g t h of t h e b a r s , when de-moulded a t 24 h o u r s , t h e b a r s o f t h e v a r i o u s m a t e r i a l s behaved d i f f e r e n t l y , some s h r i n k i n g and o t h e r s e x p a n d i n g , depending on t h e c o n d i t i o n s of s t o r a g e . The l e n g t h changes i n t h e f i r s t 24 h o u r s a f t e r removal from t h e moulds a r e shown i n Table 111. I t

i s

s e e n t h a t a l l n e a t cement b a r s expanded when s t o r e d a t 1 0 0 p e r c e - n t R.H., b u t s h r a n k when s t o r e d a t 50 a n d 10 p e r c e n t R.H. _{Length c h a n g e s} of t h e m o r t a r b a r s were g e n e r a l l y n o t a s g r e a t a s t h o s e of c o r r e s p o n d i n g n e a t cement b a r s . S t o r a g e a t 1 0 0 p e r c e n t R.H. c a u s e d no change i n l e n g t h o f m o r t a r b a r s of one m a t e r i a l , c a u s e d e x p a n s i o n i n b a r s o f a n o t h e r , a n d c a u s e d s h r i n k a g e i n t h e r e m a i n d e r . Vhen s t o r e d a t 50 p e r c e n t R.H. a n d 1 0 p e r c e n t R.H., however, a l l t h e m o r t a r b a r s s h r a n k , t h e amount b e i n g g r e a t e r f o r s t o r a g e a t 1 0 t h a n a t 50 p e r c e n t R.H., a s h a d b e e n t h e c a s e f o r t h e n e a t cement b a r s .

M o r t a r b a r s o f t h e two masonry cements t h a t showed l a r g e e x p a n s i o n s i n t h e a u t o c l a v e t e s t were s t o r e d f o r l o n g p e r i o d s u n d e r t h e h u m i d i t y c o n d i t i o n s d e s c r i b e d . !be

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

3

months a r e shown i n Table I V . Vhen s t o r e d a t 1 0 0 p e r c e n t H.H., t h e m o r t a r b a r s of b o t h cements expanded, w h i l e t h o s e ' s t o r e d a t 50 a n d 1 0 p e r c e n t R.H., s h r a n k . A t

3

months t h e amount of s h r i n k a g e w a s c o n s i d e r a b l y g r e a t e r f o r s t o r a g e a t 50 t h a n a t 1 0 p e r c e n t R.H. BRICK PIERS A s t u d y was made o f t h e d i m e n s i o n a l c h a n g e s of small b r i c k p i e r s , i n which t h e f o u r m o r t a r s d e s c r i b e d p r e v i o u s l y were u s e d . m e p i e r s were made by s t a c k i n g b r i c k s one above a n o t h e r w i t h & - i n c h m o r t a r j o i n t s between

them. I n o r d e r t o magnify t h e i n f l u e n c e o f t h e m o r t a r on movements of t h e p i e r , "Roman" b r i c k s , which a r e s m a l l e r i n h e i g h t t h a n normal b r i c k s , w e r e used. F o r c o n v e n i e n c e , t h e

b r i c k s were c u t i n h a l f , and n i n e such h a l f - b r i c k s were u s e d t o c o n s t r u c t a p i e r , which w a s a b o u t 5 i n c h e s l o n g ,

4

i n c h e s mide, and 18 i n c h e s ,high.

!JMo t y p e s of b r i c k s were used, one made of c l a y and s h a l e , t h e o t h e r of c o n c r e t e . Ihe c l a y b r i c k w a s used w i t h t h e f o u r m o r t a r s s t u d i e d , b u t t h e c o n c r e t e b r i c k was used only w i t h m o r t a r of t h e p o r t l a n d cement and l i m e s t o n e t y p e of masonry cement. IChe average w a t e r a b s o r p t i o n on immersion f o r 24 h o u r s

w a s

10.2 p e r c e n t of t h e dry weight f o r t h e

c l a y b r i c k s and

4.9

p e r c e n t f o r t h e c o n c r e t e b r i c k s . I n making t h e p i e r s a m e t a l mould &-inch h i g h w a s

placed on t h e b r i c k , t h e m o r t a r w a s placed i n

it

and s c r a p e d l e v e l w i t h t h e top. IPhe mould w a s removed and a b r i c k w a s s e t i n t h e m o r t a r bed. Each b r i c k w a s dipped i n w a t e r immediately before l a y i n g t o produce a good bond w i t h t h e m o r t a r , and

was llworked" i n t o t h e m o r t a r by a s l i g h t t w i s t i n g movement. The s u c t i o n of t h e b r i c k s when w e t t e d w a s such t h a t w i t h i n a b o u t 30 seconds a f t e r b e i n g placed i n t h e m o r t a r , s t r o n g adhesion r e s u l t e d .

Ihe t o p and bottom b r i c k s of t h e p i e r p r i o r t o t h e i r u s e i n making t h e p i e r were f i t t e d w i t h s p h e r i c a l l y ended m e t a l p i n s a g a i n s t which measurements were made of changes i n

t h e h e i g h t of t h e p i e r . The first measurement was made w i t h i n

5

minutes a f t e r t h e t o p b r i c k had been s e t i n p l a c e , and f r e q u e n t subsequent r e a d i n g s of t h e h e i g h t were made.

m e measurements were made by t h e device shown i n Fig. 1

which u s e s a micrometer head r e a d i n g t o 0.0001 inch. 'Ihe p i e r s were c o n s t r u c t e d and s t o r e d under t h r e e c o n d i t i o n s . 'One s e t of p i e r s w a s k e p t i n a l a b o r a t o r y w i t h no s p e c i a l c o n t r o l of temperature o r humidity. Another s e t w a s k e p t i n a l a b o r a t o r y maintained

a t

50

p e r c e n t R.H., and 73OF, w h i l e t h e remaining s e t w a s s t o r e d a t 1 0 p e r c e n t R.H. and 73OF. Immediately a panel was completed two b r i c k s were p l a c e d on t o p t o form a "dead l o a d " and remained i n

p l a c e from t h e n on.

HEIGHT CHANGES

'Ihe changes i n t h e v e r t i c a l dimensions of t h e p i e r s , expressed as p e r c e n t of -the o r i g i n a l h e i g h t , a r e shown f o r t h e first y e a r i n Fig. 2. A l l t h e p i e r s shrank f o l l o w i n g t h e i n i t i a l measurement of h e i g h t . m e r e a f t e r t h e r e were d i f f e r e n c e s i n behaviour, w i t h some p i e r s c o n t i n u i n g t o

s h r i n k while o t h e r s , a f t e r t h e i n i t i a l s h r i n k a g e , undergoing expansion, a s d e s c r i b e d i n t h e f o l l o w i n g summary of t h e

Masonry cement of 1:l p o r t l a n d cement : h y d r a t e d lime Ihe p i e r s i n which t h i s m a t e r i a l w a s used had an i n i t i a l s h r i n k a g e which was r e c o v e r e d i n a few days by expaasion. IIhe amount and r a t e of expanston s u b s e q u e n t l y depended on t h e s t o r a g e c o n d i t i o n s . 'The : p i e r s t o r e d

' a t

50 p e r c e n t R.H. c o n t i n u e d t o expanh

graduakw

o v e r t h e firs%

y e a r when

i t

was 0.058 p e r c e n t g r e a t e r i n h e i g h t t h a n o r i g i n a l l y . !he o t h e r two p i e r s had c o n s i d e r a b l y l e s s

movement, and t h a t s t o r e d a t 1 0 p e r c e n t R.H., a f t e r a g r a d u a l expansion f o r a b o u t 6 _{months s t a r t e d t o s h r i n k . This}

s h r i n k a g e continued f o r a b o u t 3 months f o l l o \ v i n g which t h e r e was no a p p r e c i a b l e change i n t h e h e i g h t of t h e p i e r ; a t t h e

end of t h e f i r s t y e a r t h e p i e r was 0.019 p e r c e n t g r e a t e r

i n h e i g h t t h a n o r i g i n a l l y . The p i e r s t o r e d under u n c o n t r o l l e d c o n d i t i o n s underwent s l i g h t g r a d u a l expansion o v e r t h e f i r s t y e a r , a t t h e end of which it was 0.033 p e r c e n t g r e a t e r t h a n t h e o r i g i n a l h e i g h t .

Masonry cement of 1 : 2 p o r t l a n d cement : h y d r a t e d lime Even though t h i s cement w a s t h e most "unsound" of a l l t h e cements a c c o r d i n g t o t h e a u t o c l a v e t e s t , t h e r e w a s

l i t t l e change i n h e i g h t of t h e t h r e e p i e r s i n which

i t

was used. S l i g h t shrinkage of t h e p i e r s o c c u r r e d a f - t e r

c o n s t r u c t i o n b u t i t was r e c o v e r e d a f t e r a b o u t s i x months f o r two of them w h i l e t h e o t h e r r e c o v e r e d a f t e r a b o u t t h r e e weeks.

The p i e r s t o r e d a t 50 p e r c e n t R.H., a f t e r t h e i n i t i a l s h r i n k a g e , underwent s l i g h t g r a d u a l expansion o v e r t h e y e a r . A t t h e end of t h e y e a r

it

w a s 0.004 p e r c e n t g r e a t e r i n h e i g h t t h a n o r i g i n a l l y . The p i e r s t o r e d a t 1 0 p e r c e n t R.H. expanded g r a d u a l l y i n t h e f i r s t s i x ' months b u t

t h e r e a f t e r it g r a d u a l l y shrank and f o r t h e l a s t t h r e e months of t h e y e a r t h e r e w a s l i t t l e change i n h e i g h t . I t s h e i g h t , .

a t t h e end of t h e y e a r was a l s o 0.004 p e r c e n t of t h e

o r i g i n a l . The p i e r s t o r e d i n u n c o n t r o l l e d c o n d i t i o n s s i m i l a r l y undenvent v e r y g r a d u a l and s l i g h t changes i n h e i g h t ; a t t h e

end of t h e y e a r it was 0.006 p e r c e n t g r e a t e r t h a n t h e o r i g i n a l h e i g h t .

Based on t h e n e t movement of t h e p i e r s from t h e o r i g i n a l dimension i n t h e f i r s t y e a r t h e s e t h r e e p i e r s were t h e most s t a b l e of a l l , i n s p i t e of t h e a p p r e c i a b l e

tfunsoundnesstf of t h e m o r t a r as i n d i c a t e d by t h e a u t o c l a v e t e s t .

Masonry cement of 1:l p o r t l a n d cement : l i m e s t o n e

This masonry cement w a s used i n p i e r s of both c l a y b r i c k s and c o n c r e t e b r i c k s . With c l a y b r i c k s t h e r e w a s a

g r a d u a l s h r i n k a g e of t h e p i e r s f o r a b o u t t h r e e months.

T h e r e a f t e r t h e r e w a s l i t t l e change u n t i l a b o u t a g e s i x months when a v e r y s l i g h t and v e r y g r a d u a l expansion o c c u r r e d . A t

t h e e n d o f t h e y e a r t h e p i e r s t o r e d a t 50 p e r c e n t R.H. h a d shrunk 0.014 p e r c e n t from t h e o r i g i n a l , w h i l e t h a t s t o r e d u n d e r u n c o n t r o l l e d c o n d i t i o n s h a d s h r u n k 0.006 p e r c e n t . The p i e r s t o r e d a t 10 p e r c e n t R.H. h a d a n i n t e r m e d i a t e s h r i n k a g e . The s h r i n k a g e s o f t h e p i e r s o f c o n c r e t e b r i c k w i t h t h i s m o r t a r were c o n s i d e r a b l y g r e a t e r t h a n t h o s e of t h e p i e r s of c l a y b r i c k . The p i e r s t o r e d a t 50 p e r c e n t R.H. underwent a p p r e c i a b l e s h r i n k a g e i n t h e f i r s t f o u r months and t h e r e a f t e r remained f a i r l y s t a b l e . A t t h e end of t h e y e a r i t h a d shrunk 0.050 p e r c e n t o f i t s o r i g i n a l h e i g h t . !t!he p i e r s t o r e d a t 10 p e r c e n t

R.H.

_{f o l l o w e d a s i m i l a r p a t t e r n o f s h r i n k a g e b u t} t h e amount o f s h r i n k a g e w a s c o n s i d e r a b l y g r e a t e r . A t a b o u t 10 months, however, i t a p p e a r e d t h a t a s l i g h t expansion was d e v e l o p i n g . A t t h e end of t h e y e a r t h e h e i g h t of t h e p i e r was 0.070 p e r c e n t l e s s t h a n t h e o r i g i n a l . The p a t t e r n o f

s h r i n k a g e o f t h e p i e r s t o r e d u n d e r c n c o n t r o l l e d c o n d i t i o n s w a s s i m i l a r t o t h a t o f t h e p i e r s t o r e d a t 10 p e r c e n t R.H.,

e x c e p t t h a t t h e movements were somewhat e r r a t i c .

mis

p i e r a l s o s t a r t e d t o expand s l i g h t l y a t a b o u t 10 months a n d t h e h e i g h t a t t h e end o f t h e y e a r was 0.069 p e r c e n t l e s s t h a n

t h e o r i g i n a l .

Mixture of 1:l p o r t l a n d cement : l i m e p a s t e

The p i e r s i n which t h i s cementing m a t e r i a l w a s u s e d s h r u n k s l i g h t l y f o r a few months, a f t e r vihich t h e r e w a s

l i t t l e change. The p i e r s t o r e d a t 50 p e r c e n t R.H, remained f a i r l y s t a b l e from a g e trvo months a n d a t t h e end of t h e y e a r i t s h e i g h t w a s 0.025 p e r c e n t l e s s t h a n t h e o r i g i n a l . !The p i e r s s t o r e d a t

. l o

p e r c e n t R.H., a n d u n d e r u n c o n t r o l l e d c o n d i t i o n s , h a d s i m i l a r p a t t e r n s o f movements, b u t a t a b o u t ' 6 months t h e y a p p e a r e d t o undergo a v e r y s l i g h t and v e r y

g r a d u a l e x p a n s i o n . A t t h e end o f t h e y e a r t h e h e i g h t o f b o t h p i e r s w a s 0,029 p e r c e n t l e s s t h a n t h e o r i g i n a l .

It i s e v i d e n t t h a t t h e d i m e n s i o n a l c h a n g e s o f t h e p i e r s depended on t h e cementing m a t e r i a l u s e d i n t h e m o r t a r and on t h e h u m i d i t y c o n d i t i o n s i n which t h e p i e r s were s t o r e d . I n a l l c a s e s t h e r e w a s a n i n i t i a l s h r i n k a g e f o l l o w i n g t h e

c o n s t r u c t i o n of t h e p i e r , p o s s i b l y a s s o c i a t e d i n some d e g r e e w i t h l o s s of m o i s t u r e from t h e m a t e r i a l s , When t h e c l a y

b r i c k w a s u s e d , p i e r s of one o f t h e masonry cements, a f t e r t h e

i n i t i a l s h r i n k a g e , underwent e x p a n s i o n i n t h e first y e a r . P i e r s o f a n o t h e r masonry cement were r e l a t i v e l y s t a b l e , w h i l e p i e r s o f t h e two o t h e r cementing m a t e r i a l s h a d d e f i n i t e

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

p i e r s of t h e c o n c r e t e b r i c k t h a n of t h e c l a y b r i c k . Undoubtedly t h e " d r y i n g s h r i n k a g e " of t h e c o n c r e t e b r i c k s i n f l u e n c e d

t h e movements of t h e p i e r s i n which t h e y were used.

R E L A T I O N S H I P BE'PVE-EN PREDICTED AND OBSZR WD lIOVEAMENTS I N P I E R S !be a u t o c l a v e e x p a n s i o n v a l u e s o f Table I were a p p l i e d t o t h e 4 i n c h e s of m o r t a r i n t h e v e r t i c a l dimension of a

p i e r . Assuming t h a t t h e b r i c k s were s t a b l e , t h e i n c r e a s e

i n

h e i g h t o f t h e p i e r due t o t h e p r e d i c t e d e x p a n s i o n of t h e m o r t a r w a s c a l c u l a t e d . !be v a l u e s a r e shown i n Table V, i n comparison w i t h a c t u a l measured movements which o c c u r r e d

i n

t h e first y e a r . According t o t h e a u t o c l a v e t e s t it would be e x p e c t e d t h a t expansion would t a k e p l a c e i n a l l t h e m o r t a r s . F o r example, t h e masonry cement m o r t a r which was t h e most unsound o f a l l by t h e a u t o c l a v e t e s t would b e e x p e c t e d t o produce, i n t h e p i e r , a n e x p a n s i o n of more t h a n 1 . 0 p e r c e n t . P i e r s c o n t a i n i n g t h i s m o r t a r , however, were q u i t e s t a b l e .

I n o t h e r p i e r s

it

would b e e x p e c t e d from t h e a u t o c l a v e t e s t t h a t a s l i g h t expansion would t a k e p l a c e , whereas s h r i n k a g e s were observed. I t i s c l e a r from t h e r e s u l t s g i v e n i n Table V

t h a t i n t h e f i r s t y e a r a t l e a s t t h e r e was no r e l a t i o n between t h e o b s e r v e d d i m e n s i o n a l changes o f t h e p i e r s a n d t h o s e

p r e d i c t e d on t h e b a s i s of t h e a u t o c l a v e expansion c h a r a c t e r i s t i c s of t h e mor-Lars. !The a u t o c l a v e t e s t t h e r e f o r e vras n o t

u s e f u l a s a means o f p r e d i c t i n g d i m e n s i o n a l changes i n t h e b r i c k masonry p i e r s s t u d i e d .

Dimensional changes i n b r i c k : masonry, as i n o t h e r

b u i l d i n g m a t e r i a l s , may be e x p e c t e d t o t a k e p l s c e a s a r e s u l t o f change i n . t e m p e r a t u r e . An "averager1 v a l u e f o r t h e t h e r m a l expansion of c l a y b r i c k masonry h a s been g i v e n ( 8 ) a s 0 . 4 3 i n c h p e r 1 0 0 f e e t , f o r a t e m p e r a t u r e change o f 100°F, w h i l e t h e c o e f f i c i e n t o f t h e r m a l expansion of c o n c r e t e m a t e r i a l s i s

i n t h e r a n g e

5.5

t o 8 . 0 m i l l i o n t h s

( 9 ) .

Using t h e s e v a l u e s , t h e t h e r m a l movements i n t h e p i e r s f o r 100°F t e m p e r a t u r e

change h a s been shown i n Table V f o r comparison w i t h movements due t o o t h e r c a u s e s .

CAUSES O F DITJIENSIONAL CHANGES I N NiSONRY

The f a c t that m a t e r i z l s expand o r c o n t r a c t from a n i n c r e a s e o r d e c r e a s e i n t e m p e r a t u r e ( f f t h e ~ l movementn )

i s w e l l r e c o g n i z e d . I n a d d i t i o n t o movement from t e m p e r a t u r e changes, many b u i l d i n g m a t e r i a l s s w e l l o r s h r i n k a s t h e i r m o i s t u r e c o n t e n t i n c r e a s e s o r d e c r e a s e s . ll!lhennal movement" a n d " m o i s t u r e movementf1 a r e t h e r e f o r e two p o s s i b l e means o f

d i m e n s i o n a l change

i n

masonry m a t e r i a l s ; t h e r e may be o t h e r s , however, depending on t h e p a r t i c u l a r m a t e r i a l c o n s i d e r e d .

Concrete 1,'lasonry Units

A f t e r a c o n c r e t e u n i t h a s been made,

it

s h r i n k s a s

it

c u r e s and d r i e s . Depending on t h e m a t e r i a l s a n d method of manufacture and on t h e c o n d i t i o n s of c u r i n g t h e u n i t may be p l a c e d i n t h e w a l l w h i l e s t i l l p o s s e s s i n g a l a r g e p o t e n t i a l s h r i n k a g e . !he f i r s t s h r i n k a g e i s p a r t l y i r r e v e r s i b l e i n t h a t when t h e u n i t i s d r i e d and t h e n w e t t e d i t expands, b u t t h e

expansion i s o n l y a f r a c t i o n of t h e amount o f t h e first s h r i n k a g e . The m o i s t u r e movement f o l l o w i n g t h e f i r s t

s h r i n k a g e may be a p p r e c i a b l e i n amount however, b u t i s n o t

as

g r e a t a s t h e f i r s t s h r i n k a g e .

Concrete a b s o r b s carbon d i o x i d e from t h e a i r and t h i s p r o c e s s i s accompanied by s h r i n k a g e ( 1 0 , 11). Concrete u n i t s t h e r e f o r e undergo a g r a d u a l i r r e v e r s i b l e s h r i n k a g e a s a b s o r p t i o n of carbon d i o x i d e t a k e s p l a c e . The r a t e o f a b s o r p t i o n of carbon d i o x i d e and t h u s t h e r a t e o f s h r i n k a g e

i s

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

.

Clay Briclrs

Recent s t u d i e s ( 1 2 , 1 3 ) have shovm t h a t c l a y a n d

s h a l e b r i c k s expand on removal from t h e k i l n due t o a b s o r p t i o n of m o i s t u r e from t h e atmosphere, t h e r a t e and amount of

expansion depending on t h e p a r t i c u l a r m a t e r i a l of t h e b r i c k , t h e t e m p e r a t u r e of f i r i n g , a n d t h e h u m i d i t y c o n d i t i o n s i n which t h e b r i c k i s s u b s e q u e n t l y s t o r e d . I n many c a s e s

t h e expansion i n 6 months i s of t h e o r d e r of 0.05 p e r c e n t of t h e o r i g i n a l 1engt;h and t h e expansion c o n t i n u e s f o r y e a r s , a l t h o u g h n o t a t c o n s t a n t r a t e . The "moisture movement" o f burned c l a y b r i c k s , however, ( t h a t i s , t h e d i m e n s i o n a l change o v e r a s h o r t p e r i o d o f t i m e from t h e d r y t o wet c o n d i t i o n o r t h e r e v e r s e ) i s g e n e r a l l y o n l y a s l i g h t amount, i f t h e

b r i c k s have been w e l l burned. Mortar

Dimensional changes i n m o r t a r may be c o n s i d e r e d a s

due t o s e v e r a l c a u s e s . F r e s h m o r t a r i n newly b u i l t masonry l o s e s m o i s t u r e because of t h e a b s o r p t i o n of t h e u n i t s w i t h

which

i t

i s i n c o n t a c t . On a c c o u n t of t h e d e c r e a s e i n ' m o i s t u r e c o n t e n t , s h r i n k a g e o c c u r s . Another p r o c e s s o f s h r i n k a g e

i s

t h a t a s s o c i a t e d w i t h t h e s e t t i n g of t h e cementing m a t e r i a l s ,

similar t o t h e s h r i n k a g e which t a k e s p l a c e i n newly made c o n c r e t e u n i t s . A d d i t i o n a l s h r i n k a g e due t o c a r b o n a t i o n , similar t o

t h a t o f c o n c r e t e u n i t s , may a l s o a f f e c t m o r t a r . Expansion i n m o r t a r may r e s u l t from t h e h y d r a t i o n o f m a t e r i a l s i n it. Another chemical p r o c e s s which produces expansion i s t h a t of

r e a c t i o n between p o r t l a n d cement i n t h e m o r t a r and s u l p h a t e m a t e r i a l s d e r i v e d from t h e b r i c k ( 9 ) .

I t h a s b e e n , o b s e r v e d ( 1 4 ) t h a t d u r i n g t h e s e t t i n g of p o r t l a n d cement m o r t a r s t h e r e i s a n e a r l y e x p a n s i o n , commencing w i t h i n t h e f i r s t 24 h o u r s a f t e r mixing a n d t h e expansion i s

more pronounced \*{hen m o r t a r s o f r i c h mixes and f i n e s a n d s a r e used. The m o r t a r s~x'osequently s h r i n k s when w a t e r i s l o s t from i t .

It i s c l e a r from t h i s b r i e f review t h a t t h e r e a r e many p o s s i b l e c a u s e s of d i m e n s i o n a l changes i n masonry m a t e r i a l s , Any s t u d y o f f a c t o r s i n v o l v e d i n t h e movements i s f u r t h e r complicated because masonry i s a combination 01 u n i t s and

m o r t a r and t h e components p r o b a b l y have i n t h e m s e l v e s d i f f e r e n t t e n d e n c i e s f o r movemerf.

PmECSS IBLE MOWQIENTS

S i n c e i n a l l normal masonry m a t e r i a l s some d e g r e e of d i m e n s i o n a l change i s t o be e x p e c t e d i n s e r v i c e , t h e

p e r m i s s i b l e magnitude of movement b e f o r e c r a c k i n g o r d i s p l a c e m e n t o f t h e masonry t a k e s p l a c e i s o f i n t e r e s t , D e t e r m i n a t i o n of t h i s v a l u e a p p e a r s t o be t h e b a s i c problem r e g a r d i n g t h e "soundness" of m a t e r i a l s , When masonry i s

f r e e t o move i n a n y d i r e c t i o n w i t h o u t r e s t r a i n t , d i m e n s i o n a l changes a r e p r o b a b l y of no consequence. I n t h e p i e r s

s t u d i e d , f o r example, i n which -there was n e g l i g i b l e r e s t r a i n t imposed, a l l t h e p i e r s a p p e a r e d sound and t h e r e was no

e v i d e n c e of damage from t h e changes i n h e i g h t , e i t h e r from expansion o r s h r i n k a g e .

R e s t r a i n t o f movement of b r i c k masonry, on t h e o t h e r h a n d , s e t s up s t r e s s e s v~liich may be s u f f i c i e n t l y h i g h t o

c r a c k t h e masonry. Bot o n l y t h e amount o f d i m e n s i o n a l change of t h e m a t e r i a l s may be c o n s i d e r e d t o a f f e c t c r a c k i n g i n such a s i t u a % i o n , b u t a l s o t h e a b i l i t y of t h e m a t e r i a l s t h r o u g h p r o p e r t i e s of e l a s t i c i t y , o r f l e x i b i l i t y , t o accommodate t h e movements, Under c e r t a i n c o n d i t i o n s of r e s t r a i n t on b r i c k masonry it may be a r g u e d t h a t a c e r t a i n amount o f s h r i n k a g e a

i s more dangerous t h a n t h e same amount o f e x p a n s i o n s i n c e t e n s i l e s t r e n g t h which h a s t o r e s i s t s h r i n k a g e i s l e s s t h a n c o m p r e s s i v e s t r e n g t h which h a s t o r e s t r a i n e x p a n s i o n .

\ m e r e minimum change i n masonry i s d e s i r a b l e , t h e com- b i n a t i o n o f a s h r i n k a g e - p r o d u c i n g m o r t a r w i t h a n e x p a n s i o n - p r o d u c i n g b r i c k o r a n expansion-producing m o r t a r w i t h a

s h r i n k a g e - p r o d u c i n g b r i c k may b e o f v a l u e . The c o m b i n a t i o n o f t h e c o n c r e t e b r i c k s t u d i e d , f o r example, w i t h t h e masonry cement m o r t a r o f e q u a l p a r t s o f p o r t l a n d cement a n d h y d r a t e d l i m e , may have r e s u l t e d i n a " c a n c e l l i n g - o u t ' ' of movements due t o t h e p r o p e r t i e s o f t h e m a t e r i a l s .

CONCLUSIONS

The a u t o c l a v e e x p a n s i o n c h a r a c t e r i s t i c s o f f o u r m o r t a r s v a r i e d g r e a t l y a n d depended m a i n l y on t h e t y p e o f

cementing m a t e r i a l used. !Ihe a g e a n d s t o r a g e c o n d i t i o n s o f m o r t a r samples b e f o r e a u t o c l a v i n g i n f l u e n c e d t h e amount o f

e x p a n s i o n .

No r e l a t i o n was f o u n d t o e x i s t between t h e d i m e n s i o n a l changes which a c t u a l l y o c c u r r e d i n small b r i c k p i e r s i n one y e a r a f t e r c o n s t r u c t i o n a n d t h o s e d i m e n s i o n a l changes which were p r e d i c t e d on t h e b a s i s of r e s u l t s o f a n a u t o c l a v e

e x p a n s i o n t e s t o f t h e f o u r m o r t a r s . P i e r s u n d e r g o i n g l e a s t change from t h e o r i g i n a l h e i g h t c o n t a i n e d t h e most "unsound" m o r t a r by t h e a u t o c l a v e t e s t . Shrinkage i n i t i a l l y t o o k p l a c e

i n b r i c k p i e r s o f t h e f o u r m o r t a r s s t u d i e d ; t h e r e a f t e r

it

a p p e a r e d t h a t two m o r t a r s i n h e r e n t l y produced e x p a n s i o n i n t h e b r i c k w o r k , w h i l e two o t h e r s produced s h r i n k a g e . ?he t y p e o f b r i c k a n d t h e c o n d i t i o n s o f s t o r a g e , i n a d d i t i o n t o t h e m o r t a r , i n f l u e n c e d t h e d i m e n s i o n a l changes o f t h e p i e r s . The t r u e i n f l u e n c e o f t h e m o r t a r on movements o f t h e p i e r s i s t o some

e x t e n t u n c e r t a i n , p r o b a b l y b e i n g masked by s i m u l t a n e o u s movements i n t h e b r i c k s .

Some c a u s e s of d i m e n s i o n a l changes i n masonry

m a t e r i a l s have been d i s c u s s e d a l o n g w i t h some a s p e c t s o f t h e i m p o r t a n t problem of a l l o w a b l e movements i n b r i c k masonry b e f o r e c r a c k i n g o c c u r s .

REFERENCES

(1 American S o c i e t y f o r T e s t i n g M a t e r i a l s ( P h i l a d e l p h i a , P a ) S p e c i f i c a t i o n C91-56T f o r I~Iasonry Cement.

( 2 ) J . W. McBurney, "Cracking i n Masonry Caused by Expansion of Mortar"; A. S. T.M. P r o c e e d i n g s , 1952.

( 3 )

P.C. Welch, "The H y d r a t i o n o f Magnesian Lime a n d t h e A u t o c l a v e ~ e s t " ; A. S. T.N. Symposium on Lime, 1939.

( 4

) P.O. and J . A . Anderegg, "Some Volume Changes i n M o r t a r s and Concrete"; A. S. T.M. B u l l e t i n No. 210, December 1955. ( 5 ) M. P. Goudge, "Limestone o f Canada, t h e i r o c c u r r e n c e

and c h a r a c t e r i s t i c s , P a r t I V , O n t a r i o " ; Department o f Mines a n d Resources o f Canada, Mines a n d Geology Branch, p u b l i c a t i o n ' No. 781.

( 6 ) B r i t i s h S t a n d a r d S p e c i f i c a t i o n B. S. 890 :1940, " B u i l d i n g Limesft ; B r i t i s h S t a n d a r d s I n s t i t u t i o n , London.

( 7 ) P.L. Rogers, communication t o A.S.T.M. Committee C7 on Lime, m e e t i n g a t P i t t s b u r g h , Penna., Peb.

1959.

(8 ) "112lermal Expansion i n Clay Masonry S t r u c t u r e s 1 ' ; T e c h n i c a l N o t e s on B r i c k and T i l e C o n s t r u c t i o n , Vol. 9 , No.

3,

March 1958, p u b l i s h e d by t h e S t r u c t u r a l Clay P r o d u c t s I n s t i t u t e , Washington, D.C., U. S.A. ( 9 ) " P r i n c i p l e s o f Modern B u i l d i n g " , Vol. 1, 3 r d E d i t i o n , 1959, p u b l i s h e d by t h e Department o f S c i e n t i f i c a n d I n d u s t r i a l R e s e a r c h , B u i l d i n g R e s e a r c h S t a t i o n , G r e a t B r i t a i n .

( 1 0 ) T.C. Poviers, " c a u s e s and C o n t r o l of Volume Change"; J o u r n a l of R e s e a r c h a n d Development L a b o r a t o r i e s , P o r t l a n d Cement A s s o c i a t i o n , S k o k i e , I l l . , U.S.A., Vol. 1, No. 1, Jan. 1959.

(11 ) B. Xi-oone and P.A. B l a k e y , " R e a c t i o n between Carbon Dioxide Gas a n d Mortar"; J o u r n a l , American C o n c r e t e I n s t i t u t e , Vol. 31, No. 6 , Dec. 1959.

( 1 2 ) J.E. Young a n d

W.E.

B r o w n e l l , "Idoisture Expansion o f Clay P r o d u c t s " ; J o u r n a l , American Ceramic S o c i e t y , Vol. 42, No. 1 2 , December 1959.

(13)

E.H. Waters, J . S . Hosking, H. V. Hueber, " T e s t s f o r P o t e n t i a l a n d P a s t Moisture Expansion o f Ceramic B u i l d i n g U n i t s " , A. S.

T.M.

B u l l e t i n , A p r i l , 1960. ( 1 4 ) P. Vaughan, R. H a r r i s o n , A. D i n s d a l e , "Changes i n

S i z e O c c u r r i n g E a r l y i n t h e S e t t i n g o f P o r t l a n d Cement

mortar^'^;

Trans. B r i t . Cer. Soc. Vol. 57, S e p t . 1958.

TABLE I

RESULTS O F EXPANSION

TESTS

Cement l n g M a t e r i a l

(AVERAGE OF TRREE S m L E S )

Autoclave Expansion LeChateller ( p e r cent of l e n g t h ) Expansion (mm) Neat Cement Mortar Neat Cement

Bars Bars Masonry Cement (1 p o r t l a n d cement : 1 limestone) 0.01 0 . 1 0 Masonry Cement ( 1 p o r t l a n d cement: 1 hydrated lime )

5 - 5

2 . 1 0 Masonry Cement ( 1 p o r t l a n d cement: 2 hydrated lime) 10.0

4.7

o

1 p o r t l a n d cement : 1 l h e p a s t e 0.3 0.1 0

Cementing M a t e r i a l

AlJTOCLAVE EXPANSION OF MORTAR BARS AFTER STORAGE UNDER VARIOUS HUh!IDITY CONDITIONS

( AVXRAGE THXEE SAIIIPLES )

S t o r a g e Autoclave Expansion C o n d i t i o n , ( p e r c e n t o f l e n g t h ) a t a g e 73OF a n d 4 8 h o u r s

7

d a y s 3 months 1 y e a r Masonry Cement 100% R,H, 2.1 1 . 3 0 . 5 0.2 (1 p o r t l a n d cement: 50% R.H. 2 . 1

1.7

0.9 1 . 0 1 h y d r a t e d l i m e )

lo$

R.H. 2.2 2.7

3

0 2.6 Masonry Cement 100% R.H,

4.7

3.7

0.7 0 . 2 (1 p o r t l a n d cement: 507; R.H. 4.8 4 . 6 2.2 2.5 2 h y d r a t e d l i m e ) 10% R.H, 5 - 6

5.8

5.6 6.4

LENGTH CHANGES OF NEAT CEMENT ABD 1dORTA.R BARS

IN

24 HOURS A F m R REldOVAL FROM MOULDS (AVERAGE OF THREE SAMPLES)

Cementing M a t e r i a l 1005 R.H. Movement of Bar (<:) ( p e r c e n t of l e n g t h ) s t o r e d a t

730

F and

,So$

R.H. 10% R.H.

NEAT

CE3VIENT B A E Masonry cement (1 p o r t l a n d cement : 1 limestone)

+

.003

-

-056

-

-057 Masonry cement

(1 p o r t l a n d cement : 1 hydrated lime)

+.

012

-

-023 -.032 Masonry cement

(1 p o r t l a n d cemsnt:2 hydrated. l i m e ) + -012

-

-006 -.019

1 p o r t l a n d cement : 1 lime p a s t e

+

. 0 0 ) ~

-

.Oh8

-

-087

MORTAR BARS Mortar cement

( 1 p o r t land cement : 1 limestone

-

-003 Masonry cement

(1 p o r t l a n d cement: 1 hydrated lime) 0 Masonry cement

( 1 p o r t l a n d cemen-t :2 hydrated lime)

+

-002 1 p o r t l a n d cement : 1 l i m o p a s t e

-

-004

TABLE

IV

LENGTH CRABGES O P MORiCAR BARS ON PROLONGED SICORAGE UNDER VARIOUS HUMIDITY C O ~ I TIONS

(AVERAGE

OF TRREE

SAMPLES

1

Cementing

M a t e r i a l Storage Condition Length Change of ( p e r c e n t of l e n g t h ) i n time B a r (*) (73OF) a f t e r de-moulding of

1 day 2 days

7

days 3 month:

Masonry Cement 100% R.H. 0

+.

006 +.011

+.

029 (1 p o r t l a n d cement : 50% R.H.

- .

012

-

0003

-

0069

-

0118

1 hydrated lime) 10% R.H. -.031

-

0025 0.069

-

.095 Masonry Cement +.002 +.004. +.006

+.

024. (1 p o r t l a n d cement :

-

.005 -0004.

-0075

-.

129 2 hydrated lime) 10% R,H. - 0 0 3 2

-

.04l

-

0080

-

0082 ( 3 )

+

i n d i c a t e s expansion

-

i n d i c a t e s shrinkage

9\04 m m m 0 0 0

. . .

000 0-. I k 0

+

u a 0 3 O d d 000 * * a 000 I l l

333

o q o

.

000

+

+

+

999 rn p\ fl\ 000 0 . 0 000 a CPm m r l m 000 0 . 0 000

+ + +

r-er- rlrlrl

m u m

0 . 0 000

+ + +

a 9 9 m c \ m 000 0 . 0 000

s s

₀₀₀ 0 . . 000

+ + +

rlrlrl 9-9 rlrlrl 0 0 . rlrlrl

+ + +

a a

a a

.P

9s

d r l d 43

9 $

0.P k G r l 6 _{0 4 3 k}

5G.g

PEE

u h w

unffi

MICROMETER HEAD

-

I REFERENCE PIN (CEMENTED IN (HALF ROMAN) . ..

.,.

. :..,: ...' , i.:. : ..,.,,,:...' 8 ;:.,,:.. .. ;.. .. :.!1..:...:-::" . ... ... .. ! .,...,. , ,:..,,,.. .::,...l"

-

' :::: .::. . . ..;. .,. a ...,. :. r::. REFERENCE PIN L. (CEMENTED IN SIDE FRONT FIGURE I

INSTRLIMENT FOR MEASUREMENT OF HEIGHT CHANGES OF BRICKWORK PIERS

0.06

-

_{MASONRY CEMENT =}

-

-

_{I HYDRATED LIME : I P O R T L A N D CEMENT}

_-

0.04

-

-

-

_...

_.-

... _-

-

--

...

---_

---

---,--,,,,

----

MASONRY C E M E N T = 2 HYDRATED L I M E : I PORT LAND CEMENT -

-

...

K.

<;',.."...,

-

_{. MASONRY CEMENT=LIMESTONE : P O R T L A N D CEMENT ( C O N C R E T E BRICKS )} ...

---,

-- ----

... _{. . .}

---

-I'-~'-L',.; ;.,,-,,,,,, -

---

-S T O R A G E COEf)ITION

. . .

...

5 0 % RH, 7 3 ' ~

t

UNCONTROLLED 10 % RH, 7 3 ' ~ -

. . .

-,-,,, 0.10 AGE

OF

PIER ( D A Y S )