Masonry field studies, Nova Scotian Hotel extension

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Masonry field studies, Nova Scotian Hotel extension

NATIONAL R E S E A R C H COUNCIL CANADA DIVISION O F BUILDING R E S E A R C H MASONRY F I E L D S T U D I E S NOVA S C O T 1 AN H O T E L E X T E N S I O N by J. I. Davison I n t e r n a l R e p ~ r t No, 2 7 5 of t h e D i v i s i o n of B u i l d i n g R e s e a r c h O T T A W A J u n e 1 9 6 3

MASONRY F I E L D STUDIES NOVA SCOTIAN H O T E L EXTENSION

by

J . I. Davison

T h e c o n s t r u c t i o n of an e x t e n s i o n t o the Nova Scotian Hotel w a s s t a r t e d e a r l y in 1959. In view of r a i n p e n e t r a t i o n p r o b l e m s with the e x i s t i n g building, i t w a s believed t h a t t h e r e would be c o n s i d e r a b l e m e r i t in making s o m e g e n e r a l o b s e r v a t i o n s and r e c o r d i n g i n f o r m a t i o n c o n c e r n i n g m a s o n r y c o n s t r u c t i o n on the new extension. T h e m a t t e r w a s d i s c u s s e d with R. F. Legget when h e visited t h e Atlantic Regional Station e a r l y in S e p t e m b e r 1959, and h e obtained p e r m i s s i o n t o p r o c e e d with t h e study f r o m Chief A r c h i t e c t Gr e e n s i d e of t h e C. N. R.

,

o w n e r s of t h e hotel. T h e m a t t e r w a s a l s o c l e a r e d with M r . A. Sullivan, G e n e r a l M a n a g e r of Foundation M a r i t i m e Ltd.

,

t h e G e n e r a l C o n t r a c t o r s . During an i n i t i a l v i s i t t o t h e c o n s t r u c t i o n s i t e on 23 S e p t e m b e r , p e r m i s s i o n

t o o b s e r v e t h e m a s o n r y c o n s t r u c t i o n w a s a l s o obtained f r o m M r . J . H. G r o s s , Building Superintendent f o r t h e C. N. R . On 14 October c o n t a c t s w e r e

m a d e with M r . B a r n e t t , P r o j e c t Superintendent f o r Foundation M a r i t i m e Ltd.

,

and M r . C a r e y of C a r e y B r o s .

,

t h e m a s o n r y s u b c o n t r a c t o r . F u l l co - o p e r a t i o n w a s obtained f r o m a l l concerned d u r i n g v i s i t s t o t h e

c o n s t r u c t i o n s i t e . T h e s e v i s i t s continued f r o m e a r l y October until the end of D e c e m b e r , at which t i m e t h e e x t e r i o r of t h e new e x t e n s i o n had been c o m p l e t e d with the exception of t h e penthouse and openings t o p e r m i t a c c e s s of v a r i o u s t y p e s , including a c c e s s f r o m t h e h o i s t ( F i g u r e 1).

OLD BUILDING

T h e Nova Scotian Hotel w a s e r e c t e d f o r the Canadian National R a i l w a y in 1930. It adjoins t h e C. N. R . Station and i s l o c a t e d n e a r the w a t e r f r o n t ; i t s south and e a s t w a l l s f a c e H a l i f a x H a r b o u r . It i s a l a r g e building, eight s t o r e y s high and i t r e c e i v e s s e v e r e w e a t h e r e x p o s u r e , p a r t i c u l a r l y on the south and e a s t s i d e s .

T h e o r i g i n a l building i s of s t e e l - f r a m e c o n s t r u c t i o n ; the m a i n floor w a l l s a r e of a r t i f i c i a l stone m a s o n r y ( s i m i l a r t o t h e adjoining r a i l w a y s t a t i o n ) and t h e u p p e r w a l l s a r e of b r i c k m a s o n r y with t r i m and b e l t

c o u r s e s of n a t u r a l stone. T h e b r i c k w a l l s h a v e a 12 -in. t h i c k n e s s of solid b r i c k w o r k backed by t i l e which f o r m s a b a s e f o r p l a s t e r i n g . Roof g a r d e n s on t h e u p p e r f l o o r s a r e e n c l o s e d by p a r a p e t w a l l s .

T h i s i n f o r m a t i o n w a s obtained by T . R i t c h i e of the Division of Building R e s e a r c h d u r i n g a s u r v e y of m a s o n r y in the M a r i t i m e P r o v i n c e s in 1950 (1). At that t i m e it was f u r t h e r esta.blished b y o b s e r v a t i o n and d i s c u s s i o n s with the a u t h o r i t i e s c o n c e r n e d , that t h e r e w e r e s e r i o u s r a i n p e n e t r a t i o n p r o b l e m s in t h e building. Rain p e n e t r a t i o n had s t a r t e d soon a f t e r completion of t h e building and had continued t h r o u g h t h e y e a r s . Among t h e s u g g e s t e d c a u s e s f o r r a i n p e n e t r a t i o n had been ( a ) w a t e r and snow collecting on roof g a r d e n s and e n t e r i n g p a r a p e t w a l l s and ( b ) c o r r o s i o n and d e t e r i o r a t i o n of copper c o v e r i n g s and f l a s h i n g s . T h e r e had a p p a r e n t l y b e e n t r o u b l e with a r t i f i c i a l s t o n e m a s o n r y , a s i t was noted that t h i s p o r t i o n of t h e building had r e c e i v e d a s u r f a c e t r e a t m e n t . F i n e c r a c k s had been noted in individual b r i c k s , and l a r g e r ones throughout the m a s o n r y .

During i n i t i a l d i s c u s s i o n s with M r . G r o s s h e w a s v e r y c r i t i c a l of m a n y a s p e c t s of t h e old building, and s u g g e s t e d two m o r e c a u s e s of r a i n p e n e t r a t i o n : ( a ) i n f e r i o r w o r k m a n s h i p and ( b ) f a i l u r e to f i r e p r o o f s t r u c t u r a l s t e e l which subsequently r u s t e d and s c a l e d , f o r c i n g the b r i c k - w o r k out of p l a c e .

GENERAL

T h e new extension i s eleven s t o r e y s high with an added penthouse t o e n c l o s e s e r v i c e s . It h a s a s t r u c t u r a l s t e e l f r a m e e n c a s e d in c o n c r e t e . B r i c k w a l l s a r e 8 in. thick, e v e r y s i x t h c o u r s e being a row of h e a d e r s . T h e i n s i d e of t h e wall r e c e i v e d a bituminous waterproof coating, then insulation, p l a s t e r , etc. The vapour b a r r i e r provided by t h e waterproof coating w a s n e c e s s i t a t e d by t h e i n s t a l l a t i o n of a i r conditioning. M r . G r o s s told t h e author t h a t h e w a s insisting on completely filled m o r t a r joints

which w e r e t o b e concave-tooled. T h e e x t e r i o r wall a t the m a i n floor l e v e l was f a c e d with l i m e s t o n e ( 4 in. ) which w a s backed up b y an 8-in. b r i c k wall of the s a m e c o n s t r u c t i o n a s d e s c r i b e d above.

The stone m a s o n r y w a s s t a r t e d on 13 J u l y and the b r i c k w o r k on 3 _{August. When r e g u l a r v i s i t s to the s i t e began, b r i c k l a y e r s w e r e}

working a t the s e v e n t h floor l e v e l ; the m a j o r p o r t i o n of the e x t e r i o r s h e l l w a s completed by the end of D e c e m b e r . During this period (August to D e c e m b e r ) t h e r e w a s a n d v e r a g e of 26 to 2 7 brickliryers on the job. _On

(1) R i t c h i e , T . S u r v e y of the p e r f o r m a n c e of m a s o n r y s t r u c t u r e s in the M a r i t i m e P r o v i n c e s . National R e s e a r c h Council, Division of Building R e s e a r c h , I n t e r n a l R e p o r t No. 65, May 1955.

one o c c a s i o n t h e f o r e m a n , M r . Rudolph L e B l a n c , when d i s c u s s i n g productivity, s u g g e s t e d t h a t 400 b r i c k s laid by a b r i c k l a y e r w a s a good d a y ' s w o r k on t h i s t y p e of c o n s t r u c t i o n a s opposed t o 600 t o 700 b r i c k s p e r d a y on " s t r a i g h t " work.

During a p p r o x i m a t e l y 20 v i s i t s f r o m 1 4 October t o 3 1 D e c e m b e r s a m p l e s of m a t e r i a l s w e r e obtained for t e s t s and g e n e r a l o b s e r v a t i o n s of c o n s t r u c t i o n p r a c t i c e s and conditions w e r e o b s e r v e d . NO a t t e m p t w a s m a d e t o c a r r y out a t i m e and motion study.

MATERIALS

T h e l i m e s t o n e u s e d in the l o w e r p o r t i o n of t h e building w a s r e p o r t e d l y obtained f r o m St. M a r k ' s Quebec. C o r e d Chipman b r i c k s w e r e u s e d in the e x t e r i o r w a l l s , with a v a r i e t y of Shaw r e d and buff b r i c k s u s e d a s b a c k - u p m a t e r i a l . T h e Chipman f a c e b r i c k s w e r e r e d and w e r e

s e l e c t e d b e c a u s e of s i m i l a r i t y in colour t o the b r i c k s in the old s e c t i o n of the building. M r . G r o s s w a s c r i t i c a l of t h e b r i c k b e c a u s e of t h e i r

low a b s o r p t i o n and a c h a r a c t e r i s t i c s t r u c t u r a l c r a c k between t h e two c e n t r e c o r e s . T h e a v e r a g e d i m e n s i o n s of five s a m p l e s s e l e c t e d on the job w e r e 7 3/4 by 3 3/4 by 2 1/4 in. Fifteen' s a m p l e s w e r e s e l e c t e d on t h e job and examined in the l a b o r a t o r y for the amount of m o i s t u r e t h e y contained on the j o b - s i t e and the i n i t i a l r a t e of a b s o r p t i o n (I. R. A. ). Six b r i c k s w e r e then c h o s e n a s r e p r e s e n t a t i v e of the suction r a n g e of t h e l o t and a b s o r p t i o n p r o p e r t i e s d e t e r m i n e d . T h e r e s u l t s a r e l i s t e d in T a b l e I . Low-suction and a b s o r p t i o n v a l u e s will b e noted. T h e a v e r a g e suction value w a s 5. 9 gm/min/30 s q in. A _{c h e c k of the m o i s t u r e content of the} b r i c k s a s s t o r e d on the job r e v e a l e d low values. Only b r i c k No. 10 which l o s t 28. 2 gm when d r i e d in t h e l a b o r a t o r y had an a p p r e c i a b l e m o i s t u r e

content (M/c) of 1. 3 p e r c e n t ( a c o m p a r a t i v e l y low l e v e l for a b r i c k with a 24-hr s u b m e r s i o n a b s o r p t i o n of 5. 1 p e r cent). It should, h o w e v e r , b e r e c o r d e d t h a t the s a m p l e s w e r e s e l e c t e d on 20 October d u r i n g a p e r i o d of d r y w e a t h e r . No c o m p r e s s i v e s t r e n g t h t e s t s w e r e c o n s i d e r e d n e c e s s a r y ; t h i s b r i c k c o n s i s t e n t l y h a s c o m p r e s s i v e s t r e n g t h v a l u e s in e x c e s s of

15, 000 p s i and h a s n e v e r failed d u r i n g l a b o r a t o r y f r e e z e -thaw t e s t s .

Two t y p e s of m o r t a r w e r e u s e d on the job, a 1:2+ p a r t s b y volume m i x t u r e of Medusa Stoneset and sand for e x t e r i o r w a l l s and 1: 1:5 p a r t s by volume m i x t u r e of portland c e m e n t with l i m e putty and sand f o r back-up m a s o n r y . T h e p o r t l a n d c e m e n t w a s M a r i t i m e B r a n d m a n u f a c t u r e d b y

Canada C e m e n t Co. ; t h e l i m e putty w a s m a d e by soaking (about 2 d a y s m i n i m u m ) "Limo" h y d r a t e d l i m e , a p r o d u c t of S t a n d a r d L i m e Co. of

on t h e b a g s indicated bag c a p a c i t i e s of 65 l b of Stoneset p e r bag, 50 .Ib of h y d r a t e d l i m e , and 87. 5 .Ib of p o r t l a n d c e m e n t .

T h e sand w a s beach sand f r o m Lawrencetown, commonly used by m a s o n s in t h e a r e a . S a m p l e s w e r e obtained f r o m the s t o c k p i l e on the job on 20 October and 4 D e c e m b e r f o r s t a n d a r d t e s t s and s i e v e a n a l y s e s . T e s t r e s u l t s a r e l i s t e d in T a b l e 11; t h e g r a d i n g c u r v e f o r t h e 20 October s a m p l e i s shown in F i g u r e 2. It will b e noted t h a t sand i s m u c h too fine t o comply with CSA Grading L i m i t s f o r A g g r e g a t e f o r M a s o n r y M o r t a r and t h a t i t h a s a c h a r a c t e r i s t i c a l l y high p e r c e n t a g e of voids. T h e m o i s t u r e

content of the sand in the pile on t h e c o n s t r u c t i o n s i t e w a s f r e q u e n t l y checked during t h e p e r i o d of 16 October t o 2 1 D e c e m b e r ; t h e s e values a r e included i n T a b l e I I . Building R e s e a r c h Station Digest No. 108 ( 2 ) s t a t e s that t h e r e i s a m a x i m u m bulking effect of up t o 30 p e r c e n t for fine s a n d s , with

g r e a t e s t bulking taking p l a c e at m o i s t u r e contents between 5 and 10 p e r cent. On only t h r e e of t h e s e v e n t e e n t e s t d a t e s w e r e the m o i s t u r e content v a l u e s u n d e r 5 p e r c e n t , t h e r e m a i n d e r being in the s u s c e p t i b l e 5 t o 10 p e r cent r a n g e .

M o r t a r

As p r e v i o u s l y noted, t h e r e w e r e two m o r t a r combinations u s e d , one a 1 :2+ p a r t s by volume Medusa Stoneset and sand m i x t u r e (white m o r t a r ) and t h e other a 1:1:5 p a r t s by volume p o r t l a n d c e m e n t , l i m e putty and sand m i x t u r e ( d a r k m o r t a r ) . M r . C h a r l i e Hughes, who w a s in c h a r g e of t h e m a s o n r y for C a r e y B r o s .

,

s t a t e d that s p e c i f i c a t i o n s called f o r a 1:3 S t o n e s e t m o r t a r , but t h e b r i c k l a y e r s had p r o t e s t e d about the h a r s h n e s s of t h i s combination. It w a s t h e n r e d u c e d t o a 1 : 2 $ _{m i x t u r e . M o r t a r -mixing}

0 2 e r a t i o n s w e r e conducted i n a c a n v a s s h e l t e r on t h e ground l e v e l of t h e job. M a t e r i a l s (sand and l i m e p u t t y ) w e r e m e a s u r e d in b u c k e t s , two buckets being equal t o 1 cu ft. T h u s a 1:1:5 c e m e n t - l i m e m o r t a r m i x t u r e contained

1 bag of p o r t l a n d c e m e n t , 2 b u c k e t s of l i m e p u t t y and 10 b u c k e t s of sand. W a t e r w a s added until t h e m i x e r decided t h e m o r t a r had r e a c h e d t h e p r o p e r c o n s i s t e n c y . ( T h e m a n mixing t h e m o r t a r had b e e n doing t h i s w o r k f o r four y e a r s . ) T h e r e w a s only one mixing machlne d u r l n g e a r l y v i s i t s . "White m o r t a r w a s m a c h i n e - m i x e d b e c a u s e of c o n c e n t r a t i o n on o u t s i d e wall; t h e "dark" m o r t a r u s e d f o r back-up w a s mixed by hand. On s e v e r a l o c c a s i o n s when t h i s t r e n d w a s r e v e r s e d and c o n c e n t r a t i o n w a s on back-up and i n t e r i o r p a r t i t i o n s , t h e "dark" m o r t a r w a s m a c h i n e - m i x e d and t h e "white" m o r t a r w a s m i x e d b y hand. On 4 D e c e m b e r t h e r e w e r e two mixing m a c h i n e s on t h e

job ( t h e tempo, slowed by heavy r a i n s in l a t e N o v e m b e r , w a s being stepped up in o r d e r t o c o m p l e t e the o u t s i d e s h e l l b e f o r e t h e w e a t h e r b e c a m e

milch c o l d e r ) . S a m p l e s of m o r t a r w e r e taken on n u m e r o u s o c c a s i o n s and

( 2 ) G r e a t B r i t a i n , D. S. I. R. Building R e s e a r c h Station. Sand for concrete. Digest No. 108, M a r c h 1958, 4p.

r e t u r n e d t o t h e l a b o r a t o r y f o r flow v a l u e d e t e r m i n a t i o n s . T h e v a l u e s l i s t e d in T a b l e I I I , d e t e r m i n e d b y t h e ASTM F l o w T a b l e Method,

i n d i c a t e t h e u s e of high flow m o r t a r s , with a v e r a g e v a l u e s b e i n g h i g h e r f o r S t o n e s e t m o r t a r t h a n f o r t h e m o r e w o r k a b l e c e m e n t - l i m e m o r t a r . M o r t a r s a m p l e s f o r flow d e t e r m i n a t i o n s w e r e g e n e r a l l y t a k e n f r o m t h e m a s o n ' s m o r t a r b o a r d s h o r t l y a f t e r i t w a s p l a c e d t h e r e f r o m t h e w h e e l b a r r o w s . On s e v e r a l o c c a s i o n s o b s e r v a t i o n s of t h e m o r t a r -mixing o p e r a t i o n w e r e m a d e . When m i x i n g white m o r t a r i n t h e m a c h i n e , s o m e w a t e r w a s p u t i n t o t h e m i x e r first, p a r t l y t o w a s h down remwlants f r o m t h e p r e v i o u s m i x and p a r t l y f o r t h e n e w batch. T h e n f o u r b u c k e t s of s a n d w e r e added, t h e m a c h i n e s t a r t e d , and a b a g of S t o n e s e t added. A n o t h e r b u c k e t of s a n d followed with a d d i t i o n a l w a t e r as r e q u i r e d . ( T h e o p e r a t o r e s t i m a t e d t h a t h e u s e d a b u c k e t and a h a l f of w a t e r p e r batch. ) When m i x i n g b y hand, S t o n e s e t and s a n d w e r e m i x e d d r y with a h o e and t h e n w a t e r w a s added. When m i x i n g t h e d a r k m o r t a r b y m a c h i n e , l i m e p u t t y w a s p l a c e d i n t h e m i x e r f i r s t , t h e n s o m e of t h e s a n d , a n d t h e m a c h i n e s t a r t e d . T h e r e m a i n d e r of t h e s a n d w a s added n e x t with s o m e w a t e r

-

-

t h e n a b a g of p o r t l a n d c e m e n t and t h e r e s t of t h e w a t e r (1/2 t o 3/4 bucket p e r m i x ) . M a c h i n e - m i x i n g l a s t e d about 5 m i n and w a s n e v e r h u r r i e d . In view of s e v e r a l f a c t o r s p r e v i o u s l y m e n t i o n e d including ( a ) t h e high p e r c e n t a g e of voids in a g g r e g a t e , ( b ) t h e p o s s i b l e bulking e f f e c t of s a n d (not t a k e n i n t o c o n s i d e r a t i o n in m e a s u r i n g m a t e r i a l s ) , and ( c ) t h e m e t h o d of m e a s u r i n g m a t e r i a l s b y t h e b u c k e t , t h e r e w a s c u r i o s i t y c o n c e r n i n g t h e f i n a l c o m p o s i t i o n of t h e m o r t a r u s e d i n t h e w a l l s . S o m e a t t e m p t s w e r e m a d e t o d e t e r m i n e t h i s i n f o r m a t i o n f o r t h e S t o n e s e t m o r t a r , a s follows. A weighed s a m p l e of f r e s h l y m i x e d m o r t a r w a s p l a c e d on a No. 200 s i e v e and "washed" w i t h d i s t i l l e d w a t e r u n t i l all t h e c e m e n t had a p p a r e n t l y b e e n r e m o v e d f r o m t h e m i x t u r e . S i m u l t a n e o u s l y , m o i s t u r e c o n t e n t d e t e r m i n a t i o n s w e r e conducted on a d d i t i o n a l s a m p l e s of t h e m o r t a r b y t h e o v e n - d r y method. T h e n t h e w a s h e d s a m p l e i n t h e s i e v e w a s d r i e d o v e r n i g h t , weighed, and t h e v a l u e t a k e n t o b e t h e s a n d content of t h e

s a m p l e . T h e d r y weight of t h e s a m p l e w a s d e t e r m i n e d f r o m t h e m o i s t u r e c o n t e n t value, and t h e p e r c e n t a g e of s a n d in t h e m i x t u r e w a s c a l c u l a t e d . T h e v o l u m e r a t i o of S t o n e s e t and s a n d in t h e s a m p l e w a s t h e n d e t e r m i n e d f r o m a g r a p h showing t h e p e r c e n t a g e of s a n d b y weight plotted a g a i n s t t h e v o l u m e of s a n d p e r v o l u m e of Stoneset. T h e r e s u l t s l i s t e d i n T a b l e I V i n d i c a t e a n a v e r a g e m i x of 1:l.

9

_{Stoneset:sand.}

T h e m e t h o d g a v e f a i r l y c o n s i s t e n t r e s u l t s a n d although t h e y should n o t b e c o n s i d e r e d a b s o l u t e , t h e y definitely indicate t h a t v e r y

l l r i c h ' l m o r t a r m i x e s w e r e u s e d and t h a t t h e o p e r a t o r m i x i n g t h e m o r t a r s w a s r e m a r k a b l y c o n s i s t e n t with h i s m i x e s f r o m d a y t o day. R e s u l t s a r e

a l s o l i s t e d f o r d a r k m o r t a r w h e r e an a v e r a g e r e s u l t of 1 : l . 7 c e m e n t i t i o u s m a t e r i a l t o sand w a s obtained. T h e s e v a l u e s have not b e e n c o r r e c t e d for t h e amount of a g g r e g a t e p a s s i n g , o r for the amount of c e m e n t i t i o u s

m a t e r i a l r e t a i n e d on a No. 200 sieve. It was found that 0. 7 p e r cent of a g g r e g a t e p a s s e d through t h e No. 200 s i e v e , while 6 . 5 p e r cent of a Stoneset s a m p l e w a s r e t a i n e d . T h u s i f t h i s c o r r e c t i o n w a s applied, a n even r i c h e r m i x t u r e would r e s u l t . The a c c u r a c y of the e x p e r i m e n t ,

however, m a d e t h e value of a c o r r e c t i o n questionable but r e s u l t s indicate that the method of a n a l y s i s can be u s e d a s a s i m p l e m e a n s of obtaining an indication of the p r o p o r t i o n s of c e m e n t i t i o u s m a t e r i a l and sand i n the m o r t a r .

T h e r i c h m i x e s indicated above a r e typical of m o r t a r s u s e d in m a s o n r y in the a r e a and a r e t h e r e s u l t of s e v e r a l f a c t o r s . ( a ) T h e u s e of fine s a n d s with high p e r c e n t a g e of void s p a c e n e c e s s i t a t e s the u s e of

additional c e m e n t i t i o u s m a t e r i a l beyond t h e u s u a l 1:3 r a t i o . (b) T h e method of m e a s u r i n g m a t e r i a l s i s n e v e r done on a v e r y a c c u r a t e b a s i s and could r e s u l t in a v a r i a t i o n i n m i x e s , p e r h a p s on the " r i c h t t side. R e s u l t s d i s c u s s e d above, however, indicate commendable c o n s i s t e n c y in t h e day-to-day m i x e s . ( c ) P r o b a b l y t h e g r e a t e s t contributor t o

r i c h n e s s of m o r t a r s in t h e a r e a i s t h e f a i l u r e t o allow f o r the sand-bulking effect. It h a s been mentioned t h a t a m a x i m u m bulking effect of 30 p e r cent o c c u r s in fine s a n d s having m o i s t u r e contents between 5 and 10 p e r cent. T h i s i s s e l d o m t a k e n into account when batching sand f o r m o r t a r s . T o i n v e s t i g a t e t h e i m p o r t a n c e of t h i s f a c t o r , a sand s a m p l e w a s obtained f r o m t h e s i t e on 1 D e c e m b e r ( a l / 1 0 - c u ft m e a s u r e w a s filled and

weighed). The sand w a s then allowed t o a i r d r y and w a s r e p l a c e d in t h e m e a s u r e . Shrinkage w a s d e t e r m i n e d by m e a s u r i n g the height of t h e d r y sand in the container and c o m p a r i n g t h i s with t h e o r i g i n a l height. A

bulking value of 32. 4 p e r cent was obtained, o r shrinkage of 24. 5 p e r cent. T h u s , if damp sand w a s u s e d in the p r o p o r t i o n s of 2 1/2 p a r t s t o 1 p a r t of c e m e n t , t h e a c t u a l amount of sand would b e r e d u c e d by 24. 5 p e r cent and t h e m i x would b e c o m e a 1 : l .

₉

_{combination which c o r r e s p o n d s t o t h e} value obtained when f r e s h l y mixed m o r t a r w a s analyzed.

C a r r y i n g t h e calculations f u r t h e r , it can be shown that for a

1:2+ p a r t s b y volume m i x t u r e of Stoneset and damp sand (5. 4 p e r cent on 1 D e c e m b e r ) t h e p e r c e n t a g e of sand t o t o t a l d r y m a t e r i a l s i n the m i x ( c o r r e c t i n g f o r bulking effect and m o i s t u r e content of s a n d ) b e c o m e s 73.2 p e r cent. An a n a l y s i s of f r e s h m o r t a r on 1 December produced a value of 73. 0 p e r cent f o r sand t o d r y m a t e r i a l s . It s e e m s f a i r t o conclude, t h e r e f o r e , t h a t f a i l u r e t o c o r r e c t f o r bulking effect due t o m o i s t u r e content in f i n e s a n d s i s a m a j o r c a u s e of r i c h m o r t a r m i x e s u s e d in the Atlantic a r e a .

O t h e r p r o p e r t i e s of m o r t a r s t h a t w e r e investigated a r e shown in T a b l e V.

P a n e l s

B e s i d e s investigating p r o p e r t i e s of b r i c k s and m o r t a r s , a brief s t u d y of "the m a t e r i a l s in combination" w a s m a d e by a s s e m b l i n g four s m a l l p a n e l s and subjecting t h e m t o l e a k a g e and bond s t r e n g t h t e s t s . T h e r e s u l t s w i l l b e found in ~ a b l k VI

.

T h e f i r s t two p a n e l s w e r e a s s e m b l e d with Chipman r e d c o r e d b r i c k s and "light" and " d a r k t t m o r t a r . M a t e r i a l s w e r e obtained f r o m t h e c o n s t r u c t i o n s i t e and p a n e l s w e r e a s s e m b l e d in t h e l a b o r a t o r y . A 30 - s e c t i m e i n t e r v a l was u s e d with a "heavy" t a p t o a s s u r e contact between

b r i c k and m o r t a r . T h e r e w a s no l e a k a g e o r any indication of m o i s t u r e p e n e t r a t i o n through t h e s e p a n e l s during l e a k a g e t e s t s and the s m a l l a m o u n t s of w a t e r a b s o r b e d d u r i n g t h e t e s t i n d i c a t e e x c e l l e n t r e s i s t a n c e t o m o i s t u r e p e n e t r a t i o n . Bond s t r e n g t h t e s t s r e v e a l e d a good extent of bond. A _{t h i r d p a n e l w a s a s s e m b l e d with buff and r e d b r i c k s , which w e r e}

u s e d f o r back-up m a s o n r y , and t h e " d a r k t f m o r t a r . M a t e r i a l s w e r e a l s o obtained on t h e c o n s t r u c t i o n s i t e and t h e p a n e l w a s a s s e m b l e d i n t h e

l a b o r a t o r y . Again t h e r e w a s no indication of m o i s t u r e p e n e t r a t i o n d u r i n g the t e s t . A higher w a t e r a b s o r p t i o n of 362 gm r e f l e c t e d the h i g h e r

a b s o r p t i o n of the b r i c k s u s e d . T h e r e w e r e good bond s t r e n g t h v a l u e s and a good extent of bond w a s o b s e r v e d . A f o u r t h panel w a s a s s e m b l e d on t h e c o n s t r u c t i o n s i t e b y M r . Rudolph LeBlanc, t h e m a s o n r y f o r e m a n , with the f a c e b r i c k s and "light" m o r t a r . It w a s l e f t t o c u r e on t h e c o n s t r u c t i o n s i t e f o r 24 h o u r s and then r e m o v e d t o the l a b o r a t o r y w h e r e c u r i n g w a s

completed u n d e r controlled conditions. T h e r e w a s n o l e a k a g e d u r i n g the 24-hour t e s t , but a b s o r p t i o n of 518 m l of w a t e r by t h e p a n e l d u r i n g the t e s t i n d i c a t e s that t h i s p a n e l w a s n o t as "tight" a s t h e o t h e r t h r e e . T h i s

o b s e r v a t i o n i s supported by r e s u l t s of the bond s t r e n g t h t e s t , w h e r e l o w e r v a l u e s coupled with a l e s s e r extent of bond a r e self -explanatory.

OBSERVATIONS

Weather

A s u m m a r y of t h e w e a t h e r d u r i n g the p e r i o d f r o m August t o D e c e m b e r 1959, t a k e n f r o m r e p o r t s of t h e H a l i f a x M e t e o r o l o g i c a l Station, w i l l be found i n Appendix A. T h i s s u m m a r y i n d i c a t e s t h a t t h e e x t e r i o r m a s o n r y w a l l s w e r e built d u r i n g a p e r i o d of b e t t e r than a v e r a g e autumn

w e a t h e r . T h e only noteworthy f e a t u r e w a s heavy r a i n f a l l d u r i n g the month of November when the t o t a l p r e c i p i t a t i o n w a s s l i g h t l y m o r e than

11 i n . , 1 0 7 p e r cent above n o r m a l .

Winter Weather P r e c a u t i o n s

A r e a s o n a b l e a t t e m p t w a s m a d e t o p r o t e c t m a s o n r y m a t e r i a l s on the job f r o m t h e w e a t h e r . B r i c k s w e r e c o v e r e d with t a r p a u l i n s , which, while not c o m p l e t e l y effective ( F i g u r e 3) proved adequate a s indicated b y the low m o i s t u r e content of b r i c k s t a k e n f r o m the job. Cement and l i m e w e r e s t o r e d on the m a i n floor of the building w h e r e t h e y w e r e s h e l t e r e d f r o m r a i n and snow.

On 20 October a polyethylene -plywood e n c l o s u r e w a s e r e c t e d on the scaffold on the wall. P i c t u r e s of the enclosed suspended scaffold a r e shown in F i g u r e s 1, 4, and 5. T h e e n c l o s u r e not only provided p r o t e c t i o n f r o m the cold, but a l s o f r o m t h e wind and flying d e b r i s f r o m t h e s l a b , which w a s b o t h e r s o m e a t t i m e s . In t h e c o l d e r w e a t h e r ,

s a l a m a n d e r s w e r e u s e d in t h e c a n v a s m o r t a r e n c l o s u r e , on the enclosed scaffold and in a r e a s w h e r e m a s o n r y w a s being c o n s t r u c t e d without

p r o t e c t i o n . On cold d a y s s t e a m w a s piped into the s a n d p i l e in t h e m o r t a r e n c l o s u r e and s a l a m a n d e r s w e r e placed between m o r t a r b o a r d s on t h e scaffold. On one o c c a s i o n the t e m p e r a t u r e of the m o r t a r on t h e m o r t a r b o a r d w a s found to b e 6 0 ° F ( t h e outside t e m p e r a t u r e a t t h e t i m e w a s

3 5 ° F ) . M o r t a r w a s u s u a l l y moved f r o m the mixing depot to t h e working f a c e in w h e e l b a r r o w s . T h e w h e e l b a r r o w s often r e m a i n e d on t h e floor n e a r the working a r e a for s h o r t p e r i o d s b e f o r e being emptied. It w a s noted t h a t d u r i n g c o l d e r w e a t h e r c a n v a s s h e l t e r s w e r e e r e c t e d on t h e s l a b and w h e e l b a r r o w s full of m o r t a r w e r e placed in the s h e l t e r s until t h e y w e r e r e q u i r e d at t h e working face. T h e m a s o n r y i t s e l f w a s not h e a t e d a f t e r i t had b e e n completed; the enclosed scaffold w a s , in effect, not s e a l e d t o t h e wall, but a p p e a r e d t o b e effective in p r o t e c t i n g newly completed

m a s o n r y f r o m t h e cold. On s e v e r a l o c c a s i o n s , during t h e c o l d e r w e a t h e r , b r i c k w o r k completed d u r i n g the p r e c e d i n g days w a s checked and no evidence of f r o z e n m o r t a r w a s found.

As noted p r e v i o u s l y , t h e r e w e r e s o m e i s o l a t e d a r e a s w h e r e b r i c k w o r k w a s c a r r i e d on d u r i n g cold w e a t h e r without a n y p r o t e c t i o n . E x a m p l e s m a y be s e e n in F i g u r e s 6 and 7. T h e s e s e c t i o n s w e r e p r i m a r i l y a c c e s s a r e a s during t h e m a i n p e r i o d of c o n s t r u c t i o n and w e r e closed in by mid - J a n u a r y d u r i n g r e a s o n a b l y good w e a t h e r .

During t h e b r i c k l a y i n g o p e r a t i o n m a s o n s w e r e o b s e r v e d s t r i n g i n g out m o r t a r b e d s t h e l e n g t h of t h e w a l l b e t w e e n openings f o r windows, a d i s t a n c e a c c o m m o d a t i n g 10 b r i c k s . One of t h e m o r t a r b e d s r e q u i r e d 13 b r i c k s . B e f o r e p l a c i n g , b r i c k s f o r s t r e t c h e r c o u r s e s w e r e b u t t e r e d on one end and "shoved" i n t o p l a c e with a m i n i m u m of t a p p i n g . When l a y i n g h e a d e r b r i c k s , t h e two c o r n e r s w e r e b u t t e r e d , l e a v i n g a n i n c o m p l e t e l y filled v e r t i c a l joint. M o r t a r b e d s w e r e g e n e r a l l y f u r r o w e d . An e x a m p l e of f u r r o w e d m o r t a r b e d s and i n c o m p l e t e l y f i l l e d v e r t i c a l joints c a n b e s e e n in F i g u r e 8 . C o m p l e t e d m o r t a r joints w e r e tooled t o a

s l i g h t l y c o n c a v e s h a p e

.

M e t a l f l a s h i n g w a s o b s e r v e d i n p l a c e b e t w e e n t h e b o t t o m of s t o n e window s i l l s and the top of b r i c k w o r k below. On o c c a s i o n t h e m a s o n s w e r e o b s e r v e d r e t e m p e r i n g m o r t a r on t h e m o r t a r b o a r d , and i t w a s noted t h a t u s u a l l y a l l t h e m o r t a r w a s u s e d within a

2 - t o 3-hour p e r i o d . A f e w o b s e r v a t i o n s on t h e s t o n e w o r k indicated t h a t t h e b a c k of s t o n e s w e r e p a r g e d w i t h w h i t e m o r t a r and l a i d up t o 8 in. of b a c k - u p b r i c k m a s o n r y containing t h e d a r k c e m e n t - l i m e m o r t a r . Any s p a c e b e t w e e n s t o n e and b a c k - u p w a s f i l l e d w i t h m o r t a r . T h e s t o n e - l a y i n g o p e r a t i o n c o n s i s t s of f i r s t p r e p a r i n g a m o r t a r b e d i n w h i c h t i e s w e r e p l a c e d a s w e l l a s wooden s h i m s . T h e s i d e of p r e v i o u s l y p l a c e d s t o n e w a s t h e n b u t t e r e d and t h e n e x t s t o n e w a s p l a c e d , l e v e l l e d , e t c . F i n a l l y t h e m o r t a r joint w a s r a k e d b a c k t o b e pointed l a t e r . CONCLUSIONS O b s e r v a t i o n s of m a s o n r y m a t e r i a l s and p r a c t i c e on new e x t e n s i o n of Nova S c o t i a n H o t e l h a v e b e e n r e c o r d e d . I m p r o v e m e n t s d e s i g n e d t o e l i m i n a t e l e a k a g e p r o b l e m s i n old b u i l d i n g s i n c l u d e p r o p e r f i r e p r o o f i n g of s t r u c t u r a l stee! m e m b e r s and i m p r o v e d w o r k m a n s h i p . M a t e r i a l s u s e d w e r e of good g r a d e w i t h t h e e x c e p t i o n of s a n d w h i c h w a s v e r y fine. E x t e r i o r w a l l s w e r e c o m p l e t e d d u r i n g b e t t e r t h a n a v e r a g e d r y s u m m e r a n d f a l l w e a t h e r . S a t i s f a c t o r y p r e c a u t i o n s w e r e t a k e n t o p r o t e c t m a s o n r y w a l l s d u r i n g u n f a v o u r a b l e c o n s t r u c t i o n w e a t h e r . C e r t a i n a r e a s w e r e , h o w e v e r , not p r o t e c t e d and d e s p i t e e m p h a s i s on good w o r k m a n s h i p t h e r e w a s e v i d e n c e of unfilled m o r t a r joints. T h e s t u d y a l s o i n d i c a t e s t h e u s e of r i c h m o r t a r s , a g e n e r a l p r a c t i c e i n t h e a r e a , found t o be t h e r e s u l t of u s i n g v e r y f i n e s a n d i n a d a m p condition, without p r o p e r m e a n s of m e a s u r i n g and m a k i n g n o a l l o w a n c e f o r bulking e f f e c t .

TABLE I I

PROPERTIES O F SAND OBTAINED FROM CONSTRUCTION SITE

20 October

F i n e n e s s Modulus 1. 33

Unit Weight 99. 8 lb/cu ft Specific G r a v i t y 2. 63

7

0

_{Voids 39. 1} T e s t for O r g a n i c I m p u r i t i e s Neg.

70

P a s s i n g No. 200 Sieve 0 . 7 4 December 1. 42 95. 3 lb/cu ft 2. 60 41. 3 Neg.

- - -

MOISTURE CONTENT O F SAND SAMPLES TAKEN FROM

Date

-

16 Oct 1959 20 Oct 1959 22 Oct 1959 27 Oct 1959 30 Oct 1959 2 Nov 1959 5 Nov 1959 9 Nov 1959 13 Nov 1959 P I L E ON CONSTRUCTION SITE Date

--

17 Nov 1959 20 Nov 1959 26 Nov 1959 1 Dec 1959 4 Dec 1959 16 Dec 1959 18 Dec 1959 2 1 Dec 1959

TABLE I 1 1

FLOW VALUES FOR MORTAR S A M P L E S TAKEN FROM

CONSTRUCTION SITE Date Flow,

70

S t o n e s e t M o r t a r 1:1:5 C e m e n t - L i m e M o r t a r 16 Oct 1959 20 Oct 1959 22 Oct 1959 27 Oct 1959 30 Oct 1959 2 Nov 1959 5 Nov 1959 9 Nov 1959 13 Nov 1959 17 Nov 1959 20 Nov 1959 26 Nov 1959 4 Dec 1959 16 Dec 1959 18 Dec 1959 2 1 Dec 1959

TABLE I V

MORTAR COMPOSITION

-

DETERMINED BY WASHING CEMENTITIOUS MATERIAL FROM FRESHLY MIXED MORTAR

Composition of M o r t a r ( p r o p o r t i o n c e m e n t i t i o u s m a t e r i a l : a g g r e g a t e ) Date

-

20 Oct 1959 22 Oct 1959 27 Oct 1959 30 Oct 1959 2 Nov 1959 5 Nov 1959 9 Nov 1959 13 Nov 1959 17 Nov 1959 20 Nov 1959 26 Nov 1959 1 Dec 1959 4 Dec 1959 16 Dec 1959 18 Dec 1959 21 Dec 1959 Aver a g e Stoneset C e m e n t - L i m e

T A B L E V

O'I'HER P R O P E R T I E S O F MORTAR F R O M CONSTRUCTION S I T E

A i r Content ( S t o n e s e t )

-

11.

6%

C a l c u l a t e d b y m e t h o d outlined i n ASTM S p e c i f i c a t i o n C -9 1. W a t e r R e t e n t i v i t y

-

D a t e S t o n e s e t C e m e n t - L i m e 13 Nov 1959 2 0 Nov 1959 C o m p r e s s i v e S t r e n g t h , p s i S t o n e s e t C e m e n t - L i m e D r y i n g S h r i n k a g e ,

70

S t o n e s e t C e m e n t - L i m e 0. 1 5 0. 12 50 f r e e z e - t h a w c y c l e s ( f r e e z i n g i n air and t h a w i n g in w a t e r ) w e r e c o m p l e t e d on S t o n e s e t m o r t a r c u b e s without f a i l u r e .

0

100

5

0

30

16

8

4

S I E V E S l Z E

G R A D I N G OF S A N D

S A M P L E F R O M N.S.

- H O T E L

E X T E N S I O N

C O N S T R U C T I O N

L l M

_{I T S A}

₈₂

₅₆

_-

_{1 9 5 0}

-

-

S l Z E

P A S S I N G

-

100

2 2

FIGURE

2

GRADING OF SAND SAMPLE TAKEN FROM THE

NOVA SCOT I AN HOTEL E X T E N S

I ON CONSTRUCT I

ON

F i g u r e 3 B r i c k s on construction s i t e c o v e r e d with t a r p a u l i n .

F i g u r e 5 Working a r e a in e n c l o s e d s u s p e n d e d scaffold.

F i g u r e 6 S e t t i n g stone, in f r o n t of building d u r i n g w i n t e r w e a t h e r . No p r o t e c t i o n .

F i g u r e 7 B r i c k l a y i n g at r e a r of building in m i d - J a n u a r y . No p r o t e c t i o n .

APPENDIX A

WEATHER SUMMARY, HALIFAX,

AUGUST T O DECEMBER 1959

(Notes on w e a t h e r taken f r o m monthly s u m m a r i e s of the Halifax M e t e o r o l o g i c a l Station, August - D e c e m b e r 19 59, the p e r i o d of c o n s t r u c t i o n of e x t e r i o r w a l l s of the Nova Scotian Hotel Extension. )

August.

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Mean t e m p e r a t u r e of 64. 1 deg w a s about one-half d e g r e e below n o r m a l . A dull month with f r e q u e n t r a i n f a l l , but t h e a m o u n t s w e r e s m a l l and the t o t a l p r e c i p i t a t i o n of 3. 06 in. w a s 28 p e r c e n t below n o r m a l . T o t a l h o u r s of b r i g h t sunshine w e r e only 35 p e r cent of the p o s s i b l e amount.

Twelve foggy d a y s a l s o contributed t o the d u l l n e s s of the w e a t h e r . T h e p r e v a i l i n g wind w a s f a i r l y evenly divided between e a s t and south and m a x i m u m speed r e c o r d e d for 1 hour w a s 27 m i l e s f r o m t h e n o r t h .

S e p t e m b e r .

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A _{v e r y sunny month, providing s o m e of the b e s t w e a t h e r of}

the y e a r . T o t a l s u n s h i n e c a m e within 36 m i n of being the s u n n i e s t month on r e c o r d . Mean t e m p e r a t u r e of 6 0 . 9 deg w a s 2. 2 deg above n o r m a l . T o t a l p r e c i p i t a t i o n w a s 60 p e r c e n t below n o r m a l a; 1. 83 in. T h e r e w a s fog on 4 days. P r e v a i l i n g wind w a s f r o m t h e w e s t and m a x i m u m s p e e d r e c o r d e d for 1 hour w a s 36 m i l e s f r o m the n o r t h e a s t .

O c t o b e r .

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T h e f i r s t half of t h e month w a s quite w a r m ; t h e r e m a i n d e r w a s much c o l d e r except f o r a f e w w a r m d a y s n e a r t h e end of t h e month. T h e r e s u l t i n g m e a n t e m p e r a t u r e of 49.

9

deg w a s 0 . 6 deg above n o r m a l . T h e r e were m o r e r a i n y d a y s than n o r m a l contributing t o a t o t a l p r e c i p i t a t i o n of 5.99 i n . , 17 p e r cent above n o r m a l . T o t a l s u n s h i n e w a s just below n o r m a l and t h e r e w a s fog on 4 days. T h e r e w e r e no g a l e - f o r c e winds but

g u s t s of 55 mph w e r e r e c o r d e d on t h e 19th. P r e v a i l i n g wind w a s f r o m t h e w e s t and m a x i m u m s p e e d r e c o r d e d for 1 hour w a s 31 m i l e s f r o m t h e south.

November.

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A v e r y dull, m i l d , and exceedingly wet month. T o t a l p r e c i p i t a t i o n of 11. 14 i n . , 107 p e r cent above n o r m a l , h a s only b e e n

exceeded once d u r i n g t h e h i s t o r y of t h e l o c a l w e a t h e r office. P r e c i p i t a t i o n included 4. 1 in. of snow which w a s 52 p e r cent above n o r m a l . T h e sun shone only 27 p e r cent of t h e p o s s i b l e t i m e and t h e r e w a s fog on 5 days. Mean t e m p e r a t u r e a t 43.7 deg w a s 4. 3 d e g above n o r m a l . Minimum t e m p e r a t u r e r e c o r d e d d u r i n g t h e m o n t h w a s 20 deg and the m e a n daily t e m p e r a t u r e w a s 32 deg o r l e s s on f i v e o c c a s i o n s ( t w o of which w e r e on weekends). T h e only "cold snap" affecting t h e working schedule o c c u r r e d

f r o m mid-day on the 18th through t h e 20th and on into t h e weekend. During t h i s period the t e m p e r a t u r e r e m a i n e d between 21 and 33 deg. T h e r e w e r e 6 f r e e z e - t h a w c y c l e s during t h e month. T o define a f r e e z e - thaw cycle i t was a s s u m e d t h a t m o r t a r f r e e z e s when the t e m p e r a t u r e d r o p s t o 3 0 ° F and thaws when it r i s e s t o 3 3 ° F . P r e v a i l i n g wind was f r o m t h e southwest and t h e maximum speed r e c o r d e d for 1 hour was 42 m i l e s f r o m t h e e a s t .

December.

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A mild month but i n a l l other r e s p e c t s the weather was n e a r n o r m a l . Mean t e m p e r a t u r e of 32.8 deg w a s 4. 1 deg above n o r m a l and t h e only cold snap o c c u r r e d f r o m 21 t o 26 December. Rainfall w a s 1 p e r cent above n o r m a l and snowfall 16 p e r cent below n o r m a l r e s u l t i n g in a t o t a l precipitation 3 p e r cent below n o r m a l . T h e r e w e r e heavy downpours on the 7th and 13th which produced new r e c o r d s for v a r i o u s s h o r t - p e r i o d i n t e r v a l s of f r o m 5 m i n t o 1 hour. T h e sun shone 33 p e r cent of t h e p o s s i b l e t i m e , just above n o r m a l . T h e r e w e r e no gales. The p r e v a i l i n g wind w a s f r o m the n o r t h w e s t and t h e m a x i m u m speed r e c o r d e d for 1 hour w a s 36 m i l e s f r o m the e a s t . T h e r e w e r e 12 f r e e z e - t h a w c y c l e s during t h e month.