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Helium flow and density measurement of the hydrated tricalcium
silicate-water system
Feldman, R. F.
https://publications-cnrc.canada.ca/fra/droits
L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.
NRC Publications Record / Notice d'Archives des publications de CNRC:
https://nrc-publications.canada.ca/eng/view/object/?id=6e7c465d-6e8a-40de-bcba-15f15825a546 https://publications-cnrc.canada.ca/fra/voir/objet/?id=6e7c465d-6e8a-40de-bcba-15f15825a546CEMENT and CONCRETE RESEARCH. V o l . 2, pp. 123-136, 1972. Pergamon P r e s s , I n c . P r i n t e d i n t h e U n i t e d S t a t e s .
HELIUM FLOW AND DENSITY MEASUREMENT O F THE HYDRATED
TRICALCIUM SILICATE - WATER SYSTEM
R. F. F e l d m a n
Division of Building R e s e a r c h , National R e s e a r c h Council of Canada Ottawa 7 , O n t a r i o , Canada
(Communicated by P. J. ~ e r e d a )
ABSTRACT
M e a s u r e m e n t s w e r e m a d e on s a m p l e s initially conditioned a t 11% R. H. and d r i e d i n s t a g e s t o t h e d - d r y condition. Helium flow m e a s u r e m e n t s , although l e s s quantitatively, a r e qualitatively s i m i l a r t o t h o s e found f o r h y d r a t e d p o r t l a n d c e m e n t . I t w a s c o n - cluded t h a t t h e n a r r o w s p a c e s into which h e l i u m flowed a r e i n t e r -
l a y e r s p a c e 9 , n o t f i x e d - d i m e n s i o n n a r r o w -necked p o r e s . In t h e
m e a s u r e m e n t of d e n s i t y it was shown t h a t if aqueous solution i s
used on d - d r i e d s a m p l e s , a c c o u n t will have t o b e m a d e f o r t h e
f a c t t h a t r e - e n t r a n c e of i n t e r l a y e r w a t e r o c c u r s . However, if
t h e m a t e r i a l i s d r i e d only to 11% R. H. d e n s i t y c a n b e m e a s u r e d by helium, m e t h a n o l o r aqueous C a ( 0 H ) solution. The v a l u e
2
v a r i e s only f r o m 2.35 t o 2. 37 g m / c c f o r t h e h y d r a t e d C3S.
SOMMAIRE
On a m e s u r d d e s Cchantillons d l a b o r d conditionnCs 'a 11% dlhumiditC r e l a t i v e e t sCchCs p a r Ctapes jusqut'a lt & t a t "d-dry". L e s m e s u r e s d e f l u x dlhClium s o n t s e m b l a b l e s , q u a l i t a t i v e m e n t
-
bien que m o i n s quantitativement, 2 c e l l e s qui c o n c e r n e n t l ec i m e n t p o r t l a n d hydratC. On a c o n c l u que l e s m i n c e s e s p a c e s o'u pCn'etre lthdlium s o n t d e s e s p a c e s i n t e r c o u c h e s e t non d e s p o r e s
d e d i m e n s i o n f i x e e t
B
c o l Ctroit. L e s m e s u r e s d e d e n s i t 6 ontm o n t r g que s i l t o n emploie une solution a q u e u s e p o u r d e s Cchan-
tillons 2 1lCtat I'd-dryt1, il f a u d r a t e n i r c o m p t e d u f a i t que l l e a u
pCn'etre d e nouveau e n t r e l e s couches. Toutefois, s i l f o n n e
s'eche l e m a t d r i a u qut'a une humidit6 r e l a t i v e d e l l % , on peut r e - c o u r i r a u x solutions d'hClium, d e mCthanol ou a q u e u s e d e Ca(OH)2 pour m e s u r e r l a densitC. L a v a l e u r n e v a r i e que d e 2 . 3 5 'a 2.37 g / c c pour l e C3S.
HELIUM FLOW, TRICALCIUM SILICATE, PASTE
I n t r o d u c t i o n
V o l
.
2, No. 1D e n s i t y of t h e p r o d u c t s of h y d r a t i o n of p o r t l a n d c e m e n t and i t s c o n s t i t - u e n t s i s a n i m p o r t a n t b a s i c p r o p e r t y which i s u s e d f o r d e t e r m i n i n g t h e p o - r o s i t y , and t h e r e f o r e the d u r a b i l i t y and s t r e n g t h , of c e m e n t m o r t a r s and c o n - c r e t e . Defining p o r o s i t y h a s a l w a y s b e e n a p r o b l e m b e c a u s e of t h e p r e s e n c e of b o t h p h y s i c a l l y a d s o r b e d a n d h y d r a t e w a t e r ; t h e l a t t e r i s u n s t a b l e only u n d e r m i l d d r y i n g c o n d i t i o n s m a k i n g d i f f e r e n t i a t i o n of t h e t y p e s of w a t e r d i f - f i c u l t . P a r t of t h e w a t e r e v o l v e d d u r i n g d r y i n g s h o u l d b e c o n s i d e r e d a s s o c i - a t e d with t h e s o l i d and p a r t m e r e l y a t t a c h e d t o t h e s u r f a c e ( 1 ) . A n e w e x p e r i m e n t a l t e c h n i q u e h a s b e e n r e c e n t l y d e v i s e d ( 2 ) w h e r e b y t h e c h a n g e s t o t h e s o l i d t h a t r e s u l t f r o m t h e r e m o v a l o r r e p l a c e m e n t of t h e i n t e r l a y e r a n d p h y s i c a l l y a d s o r b e d w a t e r c a n b e followed. T h i s i s t h e h e l i u m f l o w t e c h n i q u e a n d i t w a s a p p l i e d t o h y d r a t e d p o r t l a n d c e m e n t p a s t e s . The l a t t e r w o r k s u p p o r t e d a n d p r o v i d e d m o r e d e t a i l s r e g a r d i n g t h e new m o d e l of h y d r a t e d p o r t l a n d c e m e n t a n d t h e s e q u e n c e of w a t e r r e m o v a l f r o m t h e i n t e r l a y e r s p a c e s a n d s u b s e q u e n t c o l l a p s e of t h e s p a c e s ( 1 ) . The w o r k ( 2 ) s h o w e d c o n c l u s i v e l y t h a t t h e p o r e s w e r e n o t n a r r o w - n e c k e d f i x e d - d i m e n s i o n p o r e s ( i n k - b o t t l e p o r e s ) . T h e h e l i u m f l o w t e c h n i q u e i n v o l v e s t h e u s e of a h e l i u m c o m p a r i s o n p y c n o m e t e r b y which d e n s i t y c a n b e m e a s u r e d . T h e d e n s i t y v a l u e s of h y - d r a t e d p o r t l a n d c e m e n t o b t a i n e d b y t h i s m e t h o d h a v e b e e n c o m p a r e d with t h o s e o b t a i n e d b y n o r m a l p y c n o m e t r y ( 3 ) . I t w a s found t h a t t h e d e n s i t y a n d p o r o s i t y of d - d r i e d h y d r a t e d c e m e n t c a n n o t b e m e a s u r e d with a q u e o u s s o l u t i o n s b e c a u s e r e h y d r a t i o n o c c u r s a n d t h e d e n s i t y v a l u e s b e c o m e t o o high. At t h e 11% R. H. condition, h o w e v e r , t h e d e n s i t y and p o r o s i t y c a n b e m e a s u r e d by h e l i u m , m e t h a n o l o r a q u e o u s C a ( 0 H ) s o l u t i o n i f a p p r o p r i a t e c o r r e c t i o n s a r e a p p l i e d . 2 The p u r p o s e of t h i s w o r k w a s t o a p p l y t h e h e l i u m f l o w a n d d e n s i t y t e c h n i q u e s t o t h e h y d r a t e d C S - w a t e r s y s t e m a n d t o e s t a b l i s h t o w h a t e x t e n t 3 t h e p r o p e r t i e s found f o r h y d r a t e d p o r t l a n d c e m e n t m a y b e a t t r i b u t e d t o c a l - c i u m s i l i c a t e h y d r a t e .
Vol. 2 , No. 1
HELIUM FLOW, TRICALCIUM S I L I C A T E , P A S T E
E x p e r i m e n t a l M a t e r i a l s
T h e C S u s e d w a s p r e p a r e d by c a l c i n a t i o n of CaCO and SiO and was
3 2 3 2' g r o u n d t o a f i n e n e s s of 3 3 10 m / g m B l a i n e . I t c o n t a i n e d 0.470 f r e e CaO a n d w a s 99+0/0 p u r e C S. T h i s m a t e r i a l w a s s u p p l i e d by t h e P o r t l a n d C e m e n t 3 A s s o c i a t i o n , U . S. A. P a s t e s w e r e m i x e d i n v a c u u m in g l a s s t u b e s of 3. 2 c m i n s i d e d i a m e t e r ; t h e t u b e s w e r e p l a c e d h o r i z o n t a l l y on r o t a t i n g r o l l e r s to p r e v e n t a n y s e g r e - g a t i o n b e f o r e s e t o c c u r r e d . S p e c i m e n s w e r e p r e p a r e d a t w a t e r - c e m e n t r a t i o s of 0. 5 and 0. 8 and w e r e allowed t o c u r e in t h e w e t s t a t e i n r u b b e r
m e m b r a n e s f o r 2 . 5 y e a r s . They w e r e t h e n c u t i n d i s c s 3 . 2 c m i n d i a m e t e r and 1 . 2 5 m m t h i c k f o r u s e a s s a m p l e s f o r h e l i u m f l o w a n d d e n s i t y m e a s u r e - m e n t s . T h e h y d r a t e d p r o d u c t c o n t a i n e d 170 CO by w e i g h t of t h e d r i e d m a - 2 t e r i a l . B o t t l e - h y d r a t e d powder w a s p r e p a r e d by r o t a t i n g t h e C S in a b o t t l e a t 3 a w a t e r - s o l i d r a t i o of 5 f o r 18 m o n t h s . The m a t e r i a l w a s f i l t e r e d , d r i e d to
11% R . H. and s c r e e n e d through a 1 0 0 - m e s h s i e v e . L a r g e Ca(OH)2 c r y s t a l s w e r e s e p a r a t e d , g r o u n d and r e m i x e d with t h e p o w d e r . CO c o n t e n t of t h i s
2 m a t e r i a l w a s 1 . 4 % .
S u r f a c e a r e a s w e r e m e a s u r e d by n i t r o g e n a d s o r p t i o n a n d found t o b e 2
5 6 and 67 m / g m f o r p a s t e s with w a t e r - s o l i d r a t i o s of 0. 5 and 0 . 8 r e s p e c - 2 t i v e l y . T h e s u r f a c e a r e a of t h e b o t t l e - h y d r a t e d C S w a s 66 m / g m . 3 P r o c e d u r e s H e l i u m C o m p a r i s o n P y c n o m e t r y and H e l i u m F l o w The a p p a r a t u s and p r o c e d u r e f o r h e l i u m f l o w m e a s u r e m e n t s a r e d e - ' s c r i b e d i n d e t a i l i n p r e v i o u s p a p e r s (2, 3 ) . A t t h e end of 40 h r of h e l i u m flow, t h e d e n s i t y of t h e m a t e r i a l i s m e a s u r e d . T h e t e c h n i q u e u s e s t h e g a s l a w s and i d e a l g a s a s s u m p t i o n to c a l c u l a t e t h e s o l i d v o l u m e of a s a m p l e . S m a l l p o r e s o r i n t e r l a y e r s p a c e s which c a u s e a d e l a y e d f l o w of h e l i u m i n t o t h e s a m p l e a r e i n t h e f i r s t i n s t a n c e r e g a r d e d a s p a r t of t h e s o l i d .
V o l . 2 , No. 1 H E L I U M FLOW, T R I C A L C I U M S I L I C A T E , PASTE G e n e r a l P r o c e d u r e T h e h e l i u m flow and d e n s i t y w e r e m e a s u r e d a t d i f f e r e n t m o i s t u r e c o n - t e n t s , s t a r t i n g f r o m t h e 11% R . H. condition a t which t h e s a m p l e s w e r e o r i g i n a l l y . s t o r e d . Then m o i s t u r e w a s r e m o v e d by e v a c u a t i o n a l o n e a n d f i n a l l y by heating a t i n c r e a s i n g t e m p e r a t u r e s and f o r d i f f e r e n t p e r i o d s of t i m e . T h i s w a s d o n e in a s e p a r a t e v a c u u m v e s s e l a n d t h e s a m p l e w a s then t r a n s f e r r e d to t h e p y c n o m e t e r . H e l i u m w a s a l l o w e d to flow into t h e s a m p l e f o r 40 h r a t 2 a t m . T h e p r e s s u r e w a s r e d u c e d t o 1 a t m and r e c o m p r e s s e d t o 2 a t m . F r o m t h i s t h e I1solid v o l u m e " w a s d e t e r m i n e d f r o m t h e a v e r a g e of f i v e r e a d i n g s . Density D e t e r m i n a t i o n s b y Welds P y c n o m e t e r s M e a s u r e m e n t s w e r e m a d e with b o t h t h e a q u e o u s s a t u r a t e d s o l u t i o n of
C a ( 0 H ) and t h e m e t h a n o l a s f l u i d s . The e x p e r i m e n t w a s done a t 2 4 ° C
+
0. 1,2 a n d t h e f l u i d w a s i n t r o d u c e d into t h e b o t t l e a b o v e t h e s a m p l e under v a c u u m c o n d i t i o n s . This d e n s i t y m e a s u r e m e n t w a s m a d e on b o t t l e - h y d r a t e d C S a t 3 t h e 11% R. H. condition. R e s u l t s P a s t e - H y d r a t e d C S 3 ( a ) Helium F l o w S a m p l e s of C S h y d r a t e d a t w a t e r - s o l i d r a t i o s of 0. 5 and 0. 8 w e r e 3 used i n t h e h e l i u m flow e x p e r i m e n t s . In e a c h c a s e , a s s t a t e d a b o v e , t h e f i r s t h e l i u m flow r u n w a s p e r f o r m e d with t h e s a m p l e s conditioned a t 11%
R. H. S u b s e q u e n t l y , h e l i u m flow m e a s u r e m e n t s w e r e m a d e a t n i n e f u r t h e r
m o i s t u r e conditions f o r both t h e 0. 5 and 0. 8 w a t e r - s o l i d r a t i o p a s t e s . T h e s a m p l e s l o s t i n weight a t o t a l of 7 . 2 0 a n d 7. 13% b a s e d on t h e weight a t 1170
R. H. T h e flow r e s u l t s f o r t h e 0. 5 w a t e r - s o l i d r a t i o p a s t e a r e shown i n
F i g . 1; t h e c u r v e s a r e s i m i l a r q u a l i t a t i v e l y t o t h o s e found f o r h y d r a t e d p o r t l a n d c e m e n t ( 2 ) , a g a i n showing t h r e e t y p e s of c u r v e s . T h e f i r s t , Type I, up t o 2 o r 3% weight l o s s , showed t h a t m o s t of t h e h e l i u m flow o c c u r r e d i n t h e f i r s t h o u r . In t h i s t y p e i t c a n b e a s s u m e d t h a t h e l i u m w a s no l o n g e r flowing into t h e s a m p l e s i n c e t h e r a t e a f t e r 8 - 1 0 h r w a s n o g r e a t e r than t h a t
Vol. 2 , No. 1
127
HELIUM FLOW, TRICALCIUM SILICATE, PASTE
TIME, H O U R S
FIG.
1 H e l i u m f l o w i n t o 0. 5 w a t e r - s o l i d r a t i o C 3 S p a s t e a t d i f f e r e n t w a t e r c o n t e n t s , a s a f u n c t i o n of t i r n e . of t h e b l a n k r u n . T y p e 11 is r e p r c s e n t e d b y t h e c u i - v e s up t o a b o u t 5'10 w e i g h t l o s s w h e r e t h e r a t e i n t h e f i r s t h o u r b e c a m e l e s s t h a n i n t h e p r e v i o u s c o n d i t i o n , b u t t h e r e w a s a n i n c r c a s e i n h e l i u m p c n e t r a t i o n w i t h w e i g h t l o s s1 2 8 V o l . 2 , No. 1
HELIUM FLOW, TRICALCIUM SILICATE, PASTE
a t 4 0 h r . W i t h t h i s t y p e i t a p p e a r s t h a t a t 4 0 h r t h e h e l i u m h a d j u s t p e n e - t r a t e d f u l l y . B e y o n d 570 w e i g h t l o s s , T y p e III, a l o s s i n r a t e a s w e l l a s i n t o t a l h e l i u m f l o w o c c u r r e d a t 4 0 h r . I n d i c a t i o n s a r e t h a t a f t e r 4 0 h r c o m - p l e t e p e n e t r a t i o n h a d n o t o c c u r r e d . F I G . 2 H e l i u m i n f l o w a t 50 m i n a n d 4 0 h r p l o t t e d a s a f u n c t i o n of w e i g h t l o s s f o r 0. 8 a n d 0. 5 w a t e r - s o l i d r a t i o C S p a s t e s . 3 F i g u r e 2 i l l u s t r a t e s h o w t h e h c l i u n ~ f l o w v a r i e s w i t h r n o i s t u r e c o n t e n t ; t h e v o l u m e of h e l i u m t h a t h a d flov.red i n t o t h e s a i n p l e a t 50 m i n a n d a t 4 0 h r i s p l o t t e d a s a f u n c t i o n of n l o i s t u r e c o n t e n t r e l a t i v e t o t h e 1170
R.
H. c o n - d i t i o n . T h e r e s u l t s f o r t h e 0. 5 a n d 0. 8 w a t e r - s o l i d r a t i o p a s t e s a r e e s s e n - t i a l l y t h e s a m e . T h e m a x i m u m i n f l o w a f t e r 50 i n i n w a s a t 3% w e i g h t l o s s a n d a f t e r 4 0 h r a t 4 . 570 w e i g h t l o s s f o r b o t h s a i n p l e s . T h e n l a x i t ~ l u ~ m a m o u n t s of h e l i u n l t o f l o w i n t o t h e s a m p l e s w e r e 2. 5 8 a n d 2 . 4 2 c c / 100 g m f o r 0. 5 a n d 0.8
w a t e r - s o l i d r a t i o s r e s p e c t i v e l y . T h i s c o n t r a s t s w i t h t h e a v e r a g e v a l u e of 3 . 3 c c / 1 0 0 g i n f o r h y d r a t e d p o r t l a n d c e m e n t a t w a t e r - c e m e n t r a t i o s of 0. 6, 0. 8 a n d 1 . 0. I t a g r e e s w i t h t h e e s t i m a t e t h a t 80% ofV o l .
2 , No.
1HELIUM FLOW, TRICALCIUM SILICATE, PASTE
n o r m a l d - d r i e d h y d r a t e d p o r t l a n d c e m e n t i s c o ~ l l p o s e d of l a y e r e d m a t e r i a l c o m p a r e c l w i t h 60% f o r h y d r a t e d C S ( 4 ) . T h e m a x i m a f o r t h e s e c u r v e s oc - 3 c u r a t l o w e r w e i g h t l o s s e s t h a n t h e p r e v i o u s l y r e p o r t e d r e s u l t s f o r h y d r a t e d p o r t l a n d c e m e n t , but t h e c u r v e s h a v e t h e s a m e c h a r a c t e r i s t i c s , i n c l u d i n g t h e s h a r p c l c c r e a s c i n h e l i u m f l o w o b s e r v e d a f t e r 5% w e i g h t l o s s . T h e r e f o r e , t h e s e p r o p e r t i e s r e p o r t c c l f o r h y d r a t e d p o r t l a n d c e ~ n e n t a r e p r o b a b l y d u e t o t h e p r o p e r t i e s of t h e s i l i c a t e . A s d i s c u s s c c l i n t h e experimental s e c t i o n , s o l i d v o l u m e w a s ~ n e a s u r e d a l s o by t h e heliu111 c o t ~ ~ p a r i s o n p y c n o n l e t e r a t t h e d i f f e r e n t r n o i s t u r e c o n t e n t l e v e l s . O n e t h u s o b t a i n s a r e l a t i o n s h i p b e t w e e n c h a n g e i n ' ~ s o l i c l v o l u m e " (AV) a n d w e i g h t l o s s ( t h e w e i g h t l o s s i s d u e t o t h e w a t e r r e n l o v e d i n t h e s t e p - b y - s t e p d r y i n g f r o m t h c 1 lob
R.
H. c o n d i t i o n ) . D e c r e a s e i n v o l u m e g i v e s a n e g a t i v e AV. S i m i l a r l y , one l n a y o b t a i n f r o m t h e r e s u l t s i n F i g . 2, t h e c h a n g e i n " t o t a l h e l i u m i n f l o w , I ' AD, a t 40 h r r e l a t i v e t o t h e 11% R . H. c o n -d i t i o n . An i n c r e a s e i n 11eliur-n inflow i s r e g a r d e d a s a p o s i t i v e AD. T h e p a - r a m e t e r AV - AD i s p l o t t e d a g a i n s t w e i g h t l o s s on F i g . 3 f o r t h e t w o C S 3 p a s t e s . T h i s p a r a m e t e r , a s d i s c u s s e d i n a p r e v i o u s p a p e r ( 2 ) , c a n b e r e - g a r d e d a s t h e s p a c e v a c a t e d by t h e w a t e r . T h e s t r a i g h t l i n e on F i g . 3 , f o u n d b y l i n e a r r e g r e s s i o n a n a l y s i s , i s t h e s a m e a s t h a t p r e s e n t e d i n t h e p r e v i o u s p a p e r f o r s e v e r a l p o r t l a n d c e m e n t p a s t e s . I n addition, b e y o n d 4. 5% w e i g h t l o s s t h e r e i s only a slxlall r a t e of c h a n g e of AV - AD a n d , i n s o m e c a s e s , t h e r e 1s i n f a c t a n i n c r e a s e . F r o m t h e i n v e r s e of t h e s l o p e of t h e s t r a i g h t l i n e , ~ t w a s found p r e v i o u s l y ( 2 ) t h a t t h e a v e r a g e d e n s i t y of t h e w a t e r r e m o v e d w a s 1 . 2 7
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0. 0 8 g r n / c c . I t i s a p p a r e n t t h a t f o r h y d r a t e d C S , a s i t w a s f o r h y d r a t e d c e l l l e n t 3 p a s t e ( 2 ) , r e m o v a l of w a t e r b e y o n d a c e r t a i n p o i n t d o e s n o t i n d i c a t e t h e m e r e r e m o v a l of w a t e r f r o m p o r e s . T h e c o n c l u s i o n s a r e t h e s a i n e a s f o r c e m e n t p a s t e by s i m i l a r r e a s o n i n g , i . e . , h e l l u n l i s f l o w i n g I n t o i n t e r l a y e r s p a c e s , n o t f i x e d - d i m e n s i o n n a r r o w - n e c k e d p o r e s . ( b ) D e n s i t y b y H e l i u m C o m p a r i s o n P y c n o m e t e r T h e d e n s i t i e s of t h e two s e r i e s of C S p a s t e s a r e p r e s e n t e d i n F i g . 4 . 3 T h e s e a r e s h o w n a s a f u n c t i o n of w a t e r l o s s f r o m t h e 11% R . H . c o n d i t i o n a n d d o n o t i n c l u d e t h e v.olume of h e l i u m t h a t m a y h a v e f l o w e d i n a f t e r 40 h r .V o l . 2 , No. 1
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0 . 5 Wl-S C 3 S 0 . 8 W I S C 7 S F I G . 3 P l o t of AV-AD a s a f u n c t i o n of w e i g h t l o s s f o r 0 . 5 a n d 0 . 8 w a t e r - s o l i d C S p a s t e s . 3 . 4 . 0 0 0 0 1 . 0 2 . 0 3 . 0 4 . 0 5 . 0 6 . 0 7 . 0 8 . 0 W E I G H T L O S S , P E R C E N T B o t h c u r v e s s h o w a s l i g h t d e c r e a s e i n d e n s i t y up t o a b o u t 2 t o 3% w e i g h t l o s s , t h e n a s l i g h t i n c r e a s e . T h e v a l u e s v a r y f r o m 2 . 2 4 g m / c c a t 11%
R.
H. t o 2 . 2 7 g m / c c a t 7 . 13% w e i g h t l o s s f o r t h e 0. 8 p a s t e , a n d 2 . 2 5 g m / c c a t 11% R. H. t o 2 . 2 5 g m / c c a t 7.2070 w e i g h t l o s s f o r t h e 0 . 5 p a s t e . T h e s e a r e v a l u e s n o t d i s s i m i l a r t o t h o s e f o u n d p r e v i o u s l y b y t h e s a m e t e c h n i q u e f o r h y d r a t e d p o r t l a n d c e m e n t ( 3 ) . T h e v a l u e s a r e p r e s e n t e d i n T a b l e I. T a b l e I a l s o s h o w s v a l u e s o b t a i n e d by c a l c u l a t i o n s f o r t h e t w o e x t r e m e c o n d i t i o n s . A c o r r e c t i o n i s m a d e o n M o d e l A f o r a d s o r b e d w a t e r a t t h e 11% R. H. c o n d i t i o n b y a s s u m i n g t h e p r e s e n c e of a m o n o l a y e r of w a t e r , t h e q u a n - t i t y of w h i c h is o b t a i n e d f r o m a k n o w l e d g e of t h e s u r f a c e a r e a ( d e t e r m i n e d b y n i t r o g e n a d s o r p t i o n ) . V a l u e s of 2 . 2 8 g m / c c w e r e o b t a i n e d f o r M o d e l B f o r b o t h t h e 0. 5 a n d 0 . 8 p a s t e s a t t h e 11% R. H. c o n d i t i o n . A l s o , a s s u m i n g a C a / S i r a t i o of 1: 5, v a l u e s f o r t h e C - S - H g e l i t s e l f ( p r e s e n t e d a s C - S - H ( B ) w e r e c a l c u l a t e d t o b e 2 . 3 1 g m / c c f o r b o t h t h e 0. 5 a n d 0. 8 p a s t e s . E q u i v a - l e n t c a l c u l a t i o n s a t t h e d r y s t a t e y i e l d e d v a l u e s of 2 . 25 a n d 2 . 2 9 g m / c c r e s p e c t i v e l y . A r e c a l c u l a t i o n of d e n s i t y w a s m a d e b y s u b t r a c t i n g t h e v o l u m e of h e - l i u m t h a t h a d f l o w e d i n a t 40 h r f r o m t h e " s o l i d v o l u m e 1 I o b t a i n e d i n t h e d e n -V o l . 2 , No. 1 H E L I U M FLOW, T R I C A L C I U M S I L I C A T E , PASTE FIG. 4 D e n s i t y v s weight l o s s f o r h y - d r a t e d C3S p a s t e s with w a t e r - s o l i d r a t i o s 0. 5 and 0. 8. 2 . 35 I I I I I I I A 0 . 5 W I C C 3 S W E I G H T L O S S . P E R C E N l s i t y d e t e r m i n a t i o n ; t h e s e r e s u l t s a r e p r e s e n t e d i n F i g . 5 and i n T a b l e I under M o d e l C .
T h e d e n s i t y i n g e n e r a l i n c r e a s e s with w a t e r l o s s up t o about 5% weight
l o s s f o r t h e 0. 5 and 0 , 8 p a s t e s . Beyond 5% weight l o s s t h e d e n s i t y d e c r e a s e s
a b r u p t l y t o 2 . 3 2 and 2 . 3 5 g m / c c r e s p e c t i v e l y a t t h e d - d r y condition. T h e d e c r e a s e i n d e n s i t y i s a m a n i f e s t a t i o n of t h e c o l l a p s e of t h e l a y e r s , which e n c l o s e s s p a c e v a c a t e d by w a t e r t h a t c a n n o t b e p e n e t r a t e d by h e l i u m i n t h e 40 h r . This phenomenon h a s b e e n o b s e r v e d p r e v i o u s l y f o r h y d r a t e d p o r t - land c e m e n t p a s t e ( 3 ) and t h e r e s u l t s h e r e a r e q u a l i t a t i v e l y s i m i l a r . When a c o r r e c t i o n i s m a d e t o t h e d e n s i t y m e a s u r e d a t t h e 1170 R . H. condition, v a l u e s of 2 . 3 6 a n d 2 . 3 5 g m / c c a r e obtained f o r t h e C S p a s t e 3
M o d e l C f o r t h e 0. 5 and 0. 8 w a t e r - s o l i d r a t i o s ' r e s p e c t i v e l y , and 2 . 4 5 and
2 . 4 3 g m / c c f o r C - S - H ( C ) g e l w i t h t h e a d d i t i o n a l c o r r e c t i o n f o r t h e a p p r o x i - m a t e l y 40% C a ( 0 H ) i n h y d r a t e d C S p a s t e . 2 3 The f a c t t h a t t h e l a y e r s d o n o t c o l l a p s e c o m p l e t e l y a n d t h a t s p a c e i s t r a p p e d b e c a m e e v i d e n t f r o m t h e d a t a p r e s e n t e d in F i g s . 3 and 5. However, t h e point f o r t h e 0. 8 w a t e r
-
s o l i d r a t i o p a s t e a t a weight l o s s of 3.7% a p p e a r s t o b e t h e l a s t p o i n t w h e r e h e l i u m h a s fully e n t e r e d a t 40 h r . I n F i g . 3, t h i s point i s p r i o r t o t h e d e v i a t i o n f r o m t h e s t r a i g h t l i n e p l o t and i s n e a r t h e p o i n t of m a x i m u m d e n s i t y i n F i g . 5. Using t h i s point of d e n s i t y , 2. 3 8 g m / c c ,V o l . 2 , No.
1
HELIUM FLOW, TRICALCIUM SILICATE, PASTE
FIG. 5 Density c a l c u l a t e d with h e l i u m f l o w included a s p o r e v o l u m e v s w e i g h t l o s s . W E I G H T L O S S . P E R C E N l i t i s p o s s i b l e t o c a l c u l a t e t h e d e n s i t y excluding t h e i n t e r l a y e r s p a c e s . Another 3 . 4 1 % weight l o s s would give a p p r o x i m a t e l y d - d r y conditions and, a s s u m i n g the d e n s i t y of t h i s w a t e r t o b e a p p r o x i m a t e l y 1.25 g m / c c , t h e d e n - s i t y excluding i n t e r l a y e r s p a c e s i s 2 . 4 6 g m / c c . C o r r e c t i n g f o r C a ( 0 H )
2' a s s u m i n g a C a / S i r a t i o of 1 . 5 f o r the C - S - H gel, g i v e s a v a l u e of 2. 63 g m / c c f o r t h i s m a t e r i a l . If one had a s s u m e d a v a l u e of only 1. 0 g m / c c f o r t h e den-
s i t y of t h e w a t e r , a v a l u e of 2 . 7 4 g m / c c would h a v e b e e n obtained.
( c ) B o t t l e - H y d r a t e d C S
-
Density by Welds Type P y c n o m e t e r s3
B o t t l e - h y d r a t e d C S w a s used in t h e s e m e a s u r e m e n t s a t 11% R. H.
3
Aqueous s a t u r a t e d s o l u t i o n s of C a ( 0 H ) and d r i e d m e t h a n o l w e r e u s e d a s 2
f l u i d s . With the aqueous solution the a v e r a g e d e n s i t y f o r C S was 2 . 38
.*
3
0. 03 g m / c c . A c o r r e c t i o n f o r a d s o r b e d w a t e r was applied h e r e i n the s a m e m a n n e r a s i t w a s applied f o r the h e l i u m p y c n o m e t e r r e s u l t s . Model C a p - p r o x i m a t e s t h i s c o r r e c t i o n . A f u r t h e r c o r r e c t i o n which r e c o g n i z e s t h a t w a t e r would h a v e e n t e r e d s o m e p a r t i a l l y v a c a t e d i n t e r l a y e r s p a c e s with d e n -
s i t y 1. 25 g m / c c b r i n g s t h i s v a l u e t o 2 . 37
+
0. 03 g m / c c ; t h i s c o r r e s p o n d s t oM o d e l C in T a b l e I and i s i l l u s t r a t e d in a p r e v i o u s p a p e r on h y d r a t e d portland c e m e n t ( 3 ) .
The above v a l u e i s t o b e c o m p a r e d with the r e c a l c u l a t e d d e n s i t y o b - tained f r o m h e l i u m p y c n o m e t r y w h e r e h e l i u m flow w a s taken into a c c o u n t .
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HELIUM FLOW, TRICALCIUM SILICATE, PASTE
T A B L E 1 D e n s i t y V a l u e s l o r C S P a s t e s and B o t t l e - H y d r a t e d C S ( g m / c c ) V a l u e s of 2 . 3 6 a n d 2 . 3 5 g m / c c w e r e o b t a i n e d f o r t h e 0 . 5 a n d 0. 8 w a t e r - s o l i d r a t i o C S p a s t e s r e s p e c t i v e l y , a t the 11% R . H. condition ( M o d e l C i n T a b l e I ) . 3 S a m p l e P a s t e C S w / s 0 . 5 " 81 " 0 . 8 01 3 , 0 8 0 . 5 ,! 8 8 " 0 . 8 ' '' " 0 . 5 " " " 0 . 8 " " 81 0 . 5 8 7 " ,t 0 . 8 ' " " 0 . 5 " " " 0 . 8 " 8 , " 0 . 5 1, 8 , 0 3 0 . 8 " " ' I 0 . 5 " " " 0 . 8 " ,! " o , 5 " " " 0 ,
*
" " " 0 . 8 " M O D E L A - No T h e d e n s i t y o b t a i n e d w h e n m e t h a n o l w a s u s e d a s t h e f l u i d w a s 2 . 2 9 5+
H e l i u m A s Fluid M o d e l and C o n d i t i o n 0 . 0 1 5 g m / c c a n d c o r r e s p o n d s t o M o d e l B. An a p p r o x i m a t e c o r r e c t i o n f o r t h e f a c t t h a t m e t h a n o l d o e s n o t f l o w i n t o t h e p a r t i a l l y d e h y d r a t e d i n t e r l a y e r M O D E L B - C o r r e c t i o n i s m a d e o n l y l o r a d s o r b e d w a t e r . D e h y d r a t e d i n t c r 1 ; l y e r s p a c e i s included a s " l i d v o l u m e . C - S - H ( B ) s i g n i ' i e s t h a t C a ( O t l ) 2 c o r r e c t i o n t o t h e v a l u e l o r C 3 S p a s t e h a s b c e n made g ~ v i n g v;glue l o r C - S - H g e l . M O D E L C - D e h y d r a t e d i n t e r l a j e r s p a c e i s n o l o n g e r i n c l u d e d a s s o l i d v o l u m e a s in M o d c l B. T h ~ s s p a c e i s t a k e n a s t h e h e l i u m i n l l o w a t .LO h r . C - S - H ( C ) s i g n i f i e s t h a t C a ( 0 H ) c o r r e c t t o n t o t h i s v : ~ l u e l o r C 3 S p a s t e h a s b e e n m a d e , g i v i n g v;llue l o r C-5-1-1 g e l I I 7 0 R . H . : A A B B C - S - H ( B ) C - S - H (8) C C C - S - H ( C ) C - S - H ( C ) D-Dry: B B C - S - H ( B ) C - S - H ( B ) C C C - S - H ( C ) c o r r e c t i o n i s m a d e s p a c e s c a n b e m a d e f r o m t h e h e l i u m f l o w r e c o r d e d a t 11% R. H. f o r t h e 0 . 8 S a m p l c w a t e r - s o l i d r a t i o p a s t e ; t h i s y i e l d s a v a l u e of 2. 37 g m / c c ( s h o w n a s M o d e l 2. 2 5 2. 2 4 2 . 28 2 . 2 8 2 . 3 1 2 . 31 2. 3 6 2. 3 5 2. 4 5 2. 43 2. 2 5 2. 27 2. 2 5 2. 29 2 . 3 2 2 . 3 5 2. .42 t o t h e C i n T a b l e I). M o d e l :: a n d T h e a g r e e m e n t a m o n g t h e t h r e e d i f f e r e n t r e s u l t s i s s t r i k i n g a s w a s a l s o r e s u l t s f o u n d f o r h y d r a t e d p o r t l a n d c e m e n t ( 3 ) . I t c o n f i r m s t h e i d e a t h a t t h e h i g h e r M e t h a n o l v a l u e g i v e n by w a t e r i n i t i a l l y i s d u e t o i n t e r l a y e r s p a c e s i n t o w h i c h h e l i u m f l o w s f a i r l y r a p i d l y a t 1170 R . H. b u t i n t o which m e t h a n o l c a n n o t p e n e t r a t e . Sarur;gted A q u e o u s C a ( 0 H ) C o n d t t i o n , A s F l u i d D i s c u s s i o n A s ~ l u i j 2. 3 8 2 . 37 B o t t l e - h y d r a t c d7 7 ;
C S1
2 . ,30 T h e h e l i u m f l o w r e s u l t s s h o w a l l t h e f e a t u r e s t h a t w e r e r e p o r t e d f o r h y d r a t e d p o r t l a n d c e m e n t ( 2 ) w h i c h l e d t o t h e c o n c l u s i o n t h a t t h e h e l i u m f l o w for a d s o r b e d w a t c r o r d e h y d r a t e d i n t e r l a y e r s p a c e . C ( a p p r o x ) C 2 . 3 7HELIUM FLOW, TRICALCIUM SILICATE, PASTE
V o l . 2, No. 1
technique e n a b l e s one to o b s e r v e t h e s e q u e n c e of r e m o v a l of w a t e r f r o m t h e i n t e r l a y e r s p a c e s and to what d e g r e e t h e c o l l a p s e of t h e s e s p a c e s o c c u r s . Again of s i g n i f i c a n c e i s t h e f a c t t h a t although c o l l a p s e o c c u r s when i n t e r l a y e r w a t e r i s r e m o v e d , s p a c e s r e m a i n b e t w e e n t h e l a y e r s i n t o which h e l i u m e n t e r s v e r y slowly. I t i s t h u s p o s s i b l e to s t a t e c o n c l u s i v e l y f o r h y d r a t e d C3S ( a s was done f o r h y d r a t e d p o r t l a n d c e m e n t ) t h a t t h e s p a c e s into which h e l i u m i s flowing a r e i n t e r l a y e r s p a c e s , n o t fixed - d i m e n s i o n , n a r r o w - n e c k e d p o r e s a s h a s b e e n s u g g e s t e d ( 5 ) .
The i m p o r t a n c e of the a b o v e points b e c o m e s e v i d e n t when s u c h p r o p e r
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t i e s a s a d s o r p t i o n , d e n s i t y , p o r o s i t y , and s u r f a c e a r e a a r e d e t e r m i n e d b y
u s e of aqueous s o l u t i o n s . In m u c h p r e v i o u s work ( 5
-
11) i t was a s s u m e d that,on d - d r y i n g , l a y e r s c o m p l e t e l y c o l l a p s e and do n o t r e o p e n on r e - e x p o s u r e to w a t e r v a p o u r o r liquid w a t e r . However, r e c e n t w o r k ( 3 ) h a s shown that if aqueous solution i s used i n m e a s u r i n g t h e d e n s i t y and p o r o s i t y of d - d r i e d h y d r a t e d p o r t l a n d c e m e n t one h a s t o a c c o u n t f o r t h e f a c t t h a t r e - e n t r a n c e of i n t e r l a y e r w a t e r o c c u r s . T h i s i s a l s o t r u e f o r h y d r a t e d C S a s s t a t e d in t h e 3 r e s u l t s . The v a l u e s o f d e n s i t i e s r e p o r t e d i n T a b l e I a r e m u c h l o w e r than t h e v a l u e of 2. 86 g m / c c f o r t h e d - d r i e d C - S - H g e l r e p o r t e d by o t h e r w o r k e r s ( 7 ) . However, T a y l o r (12) r e p o r t e d a v a l u e of 2 . 3 8 g m / c c , c a l c u l a t e d f r o m r e -
f r a c t i v e index m e a s u r e m e n t s f o r C S p a s t e , b u t i t i s not c l e a r how t h e
3
s a m p l e was d r i e d . I n a n o t h e r p a p e r ( 1 3 ) v a l u e s of s e v e r a l badly c r y s t a l l i z e d s p e c i m e n s of n a t u r a l t o b e r m o r i t e m i n e r a l s a r e given and none of t h e s e e x - c e e d s 2 . 3 5 g m / c c . T h e high v a l u e of 2. 86 g m / c c mentioned a b o v e s u g g e s t s
t h a t the method used gave t h e d e n s i t y of the l a y e r s t h e m s e l v e s . T h i s w a s
s u b s t a n t i a t e d i n p a r t by the r e s u l t s obtained w h e r e a c o r r e c t i o n f o r i n t e r - l a y e r w a t e r was m a d e t o t h e d e n s i t y obtained by h e l i u m p y c n o m e t e r by a s - s u m i n g a n i n t e r l a y e r w a t e r d e n s i t y of 1. 25 g m / c c and s u b t r a c t i n g t h i s w a t e r in the d e n s i t y c a l c u l a t i o n . In t h e s i t u a t i o n w h e r e c o m p l e t e h e l i u m p e n e t r a t i o n o c c u r r e d , a v a l u e of 2. 63 g m / c c w a s obtained, and if t h e d e n s i t y of t h e i n - t e r l a y e r w a t e r was taken a s 1 . 0 g m / c c ( a s s u m e d in p r e v i o u s w o r k ( 7 ) ) a v a l u e of 2 . 7 4 g m / c c w a s obtained. However, when d e a l i n g with d - d r i e d m a - t e r i a l i t i s obvious t h a t w a t e r c a u s e s c h a n g e s t o t h e m a t e r i a l which a r e n o t c o m p l e t e l y a c c o u n t a b l e .
Vol.
2 ,No. 1
H E L I U M FLOW, T R I C A L C I U M S I L I C A T E , PASTE
I t h a s b e e n shown ( 1 ) t h a t i n t e r l a y e r w a t e r functions a s p a r t of the s o l i d
and t h a t b e c a u s e it i s p r e s e n t i n the n o r m a l s t a t e i n which h y d r a t e d p o r t l a n d
c e m e n t i s used, d e n s i t y and p o r o s i t y should i d e a l l y b e m e a s u r e d with i t p r e s e n t . T h i s w a s done by t h e t h r e e m e t h o d s d e s c r i b e d using t h e t h r e e f l u i d s
with the s a m p l e a t the 11% R . H. condition. The a g r e e m e n t f o r t h e s e t h r e e
w a s excellent, v a r y i n g only f r o m 2 . 3 5 t o 2 . 3 7 g m / c c f o r the C S p a s t e s .
3
However, e v e n in t h e s e e x p e r i m e n t s , with the s a m p l e s d r i e d only t o 11% R . H . , i t i s b e l i e v e d t h a t s o m e of the i n t e r l a y e r w a t e r h a d a l r e a d y b e e n r e - m o v e d ( t h i s w a s m e a s u r e d by h e l i u m flow). I t i s b e l i e v e d t h a t i t would b e i n -
t a c t a t h i g h e r h u m i d i t i e s . T h i s would change t h e s e " h e l i u m flow" modified
v a l u e s to the r a n g e 2 . 3 2
-
2 . 3 5 g m / c c . T h i s p o i n t i s w e l l i l l u s t r a t e d in ap r e v i o u s p a p e r ( 3 ) .
Conclusions
1 . H e l i u m flow m e a s u r e m e n t s on C S p a s t e s a r e q u a l i t a t i v e l y s i m i l a r t o
3
t h o s e found f o r h y d r a t e d p o r t l a n d c e m e n t . The s p a c e i n t o which h e l i u m i s flowing i s i n t e r l a y e r s p a c e , n o t f i x e d - d i m e n s i o n n a r r o w - n e c k e d p o r e s .
2. H e l i u m flow a n d d e n s i t y v a l u e s show t h a t when i n t e r l a y e r w a t e r i s r e -
m o v e d f r o m C S p a s t e s , c o l l a p s e o c c u r s . T h i s c o l l a p s e , h o w e v e r , i s
3
not c o m p l e t e a t d - d r y conditions, leaving v o i d s e n c l o s e d between t h e l a y e r s .
3 . Density and p o r o s i t y of C S p a s t e s d r i e d only t o 11% R. H. c a n b e m e a -
3 s u r e d with a p p r o p r i a t e c o r r e c t i o n s by h e l i u m , m e t h a n o l o r aqueous C a ( 0 H ) A g r e e m e n t i s e x c e l l e n t . 2' 4. M e a s u r e m e n t of p o r o s i t y f o r p r a c t i c a l p u r p o s e s should b e done a t 11% R . H . on s a m p l e s t h a t h a v e n e v e r b e e n d r i e d t o l o w e r l e v e l s of humidity. The u s e of a s a t u r a t e d solution of C a ( 0 H ) a s fluid i s t h e s i m p l e s t
2 m e t h o d .
Acknowledgement
The a u t h o r would l i k e to acknowledge t h e v a l u a b l e a s s i s t a n c e of S. E.
Dods i n p e r f o r m i n g m o s t of the e x p e r i m e n t s .
136 Vol.
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No. 1HELIUM FLOW, TRICALCIUM SILICATE, PASTE
t i o n a l R e s e a r c h C o u n c i l of C a n a d a , a n d i s p u b l i s h e d w i t h t h e a p p r o v a l of t h e D i r e c t o r of t h e D i v i s i o n . R e f e r e n c e s 1 . R . F. F e l d m a n a n d P. J. S e r e d a . M a t e r . C o n s t r . - 1 , No. 6, 509 (1968). 2. R . F . F e l d m a n . C e m e n t C o n c r e t e R e s .
