Cem-FIL GRC Technical Data

7/30/2019 Cem-FIL GRC Technical Data

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Cem-FIL GRC Technical Data

Cem-FIL


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CONDITIONS OF ACCEPTANCE

C o p y r i g h t i n t h e C e m - FI L G R C Te c h n i c a l D a t a p u b l i c at i o n , w h i c hc o n t a in s p r o p r i e t a r y in f o r m a t i o n , b e l o n g s t o C e m - FI LI n t e r n a t i o n a l Li m i t e d * .

1 . T h e p u b l ic at io n a n d in f o rm a ti o n co n t a in e d t h e re in m u sto n l y b e u s ed i n c o n j u n c t i o n w i t h G RC p r o d u c t s m a d e u s in g

C em -FIL A R f ib re .

2 . T h e p u b l ic at io n w i ll n o t b e re p ro d u c e d in w h o l e o r in p a r tw i t h o u t t h e e x p r e ss p e r m i ssi o n o f C e m - FI L I n t e r n a t i o n a lL im i t e d .

3 . T h e in f o rm a t io n c o n t a in e d i n t h e p u b l ic at io n i s g i ve n ing o o d f a it h b u t n o l i ab i l it y i s a c c ep t e d b y C e m - FI LI n t e r n a t i o n a l L i m i t e d o r i t s h o l d i n g c o m p a n y o r a n ysu b si d i a ry o f i t s h o l d i n g c o m p a n y f o r a n y i n j u r y , lo s s o rd a m a g e o f w h a t e ve r n a t u r e an d w h e t h e r c o n se q u e n t i al o ro t h e r w i se , su s t ai n e d b y t h e r e c ip i e n t o r a n y t h i r d p a r t y a s ar e su l t o f u s in g i n f o r m a t i o n c o n t a i n e d t h e r ei n o r a n y a d v i c esu p p l ie d i n c o n n e c t i o n t h e r ew i t h .

4 . N e it h e r C em - FI L I n t er n a t io n a l L im i t ed n o r it s h o l d i n gc o m p a n y o r a n y su b s id i a ry o f i t s h o ld i n g c o m p a n y w a rr an tt h a t t h e u se o f su c h i n f o r m a t i o n d o e s n o t i n f r in g e t h e r ig h t so f t h i r d pa r t i e s .

*Ce m -F IL In te rn a t io n a l L im i te d i s a wh o l l y -o wn e d s u b s id ia r y

o f Ve t ro te x Es p a a SA a n d b o th c o m p a n ie s a re p a r t o f t h e

Sa i n t - G o b a i n G r o u p .

CEM-FIL GRC T E C H N IC A L D A T A

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1. INTRODUCTION

2. RAW MATERIALS

2 .1 C em - FIL A R g l ass f ib r e2 .2 C em en t s2 .3 Fi lle r s2 .4 W at er

2 .5 A d m ix t u res2 .6 Pig m en t s2 .7 H ea lt h asp e ct s o f ra w m at er ia ls

3. MANUFACTURING METHODS

3 .1 Sp ray ed G RC3 .2 Prem i x ed G RC3 .3 M isc el lan e o us p r o ce sses3 .4 C ur in g o f G RC p ro d u ct s

4. PRINCIPLES OF GLASS FIBRE REINFORCEM ENT

4 . 1 T h e ef fe ct o f g l ass f ib r e s o n t h e st r en g t h o f t h e m o r t a rm a t r i x

4 . 2 Te n si le st r ess- st r ai n c u r v es f o r G RC4 .3 C o m pressi ve st r ess-st ra i n cu rves f o r GR C4 .4 B end in g st ress-st ra i n cu rves f o r GR C4 .5 St ra in - t o - f a il u re o f GR C4 .6 T he e f f ec t s o f o r i en t a t i on o f g l ass f i b re4 .7 Shea r st r eng th o f GR C4 .8 Im pac t r esi stance o f GR C4 .9 M od u lus and P o i sson s Ra t i o o f GR C4 . 1 0 Ef f ec t o f ag e i n g o n G R C

4 .11 R e fe rences

5. MECHANICAL PROPERTIES OF GRC

5 .1 T yp i ca l i n i t i a l p ro pe r t y va lues5 . 2 Ef f ec t o f a g e o n t h e in i t i a l p r o p e r t y va lu e s5 . 3 Ef f ec t o f v a r ia t i o n s i n m a n u f a c t u r e a n d co m p o si t i o n

o f G RC5 .4 C reep and st ress- rup tu re beh av iou r o f GR C5 . 5 Fa t i g u e p e r f o r m a n c e5 .6 R e fe rences5 A A p p en d ix - C em -FIL St ar G RC

6. PHYSICAL AND CHEMICAL PROPERTIES OF GRC

6 .1 Sh r in kag e6 .2 Th erm a l ex p an sio n6 .3 C h em ic al r esist an ce6 .4 Freeze-t h aw b eh av io u r6 .5 Th erm al co n d uc t iv it y6 .6 So u n d6 .7 Perm e ab il i t y6 .8 A b rasio n r esist an ce6 .9 D en sit y

6 . 1 0 W a t er ab so r p t io n a n d a p p a re n t p o r o si ty6 .1 1 Po t ab l e w a t er ap p r o va l6 .1 2 U lt ra -v io le t l ig h t6 .1 3 N u c le ar rad i at io n6 .1 4 Re fe re n ce s

7. DESIGN PRINCIPLES

7 .1 M EC H A N IC AL D ESIG N

7 . 1 .1 T h e ap p r o a ch t o m e ch a n ic al d e si g n i n G RC7 . 1 . 2 C h o i c e o f d e si g n st r ess l ev e ls7 .1 .3 D esign st resses7 . 1 . 4 D e s ig n c a lc u l a t io n s

7.2 PHYSICAL D ESIGN

7 . 2 . 1 T h e rm a l m o v e m e n t7 .2 .2 M o ist u re m o vem en t7 . 2 . 3 St r esse s a n d d e fl ec t io n s d u e t o m o i st u r e a n d

t h e rm a l m o v em e n t7 . 2 . 4 T h e r m a l i n su l a t i o n7 .2 .5 I n te r s t i t i al con den sa t i on7 . 2 . 6 Fi r e p e r f o r m a n c e7 . 2 . 7 So u n d r e d u c t io n

7 . 3 I N S TA L LA TI O N C O N SI D ERA TI O N S

7 .3 .1 Fix in g sy st em s7 .3 .2 Jo in t i ng and sea l ing7 . 3 . 3 H a n d l i n g

7 .4 REFEREN C ES

8. DESIGN EXAMPLES

8 .1 Fo rm w ork8 .2 C h an ne l Lin er8 .3 Su nsc reen8 .4 C lad d i n g Pa n el - Sin g l e Sk in8 .5 C lad d i n g Pa n el - Sa n d w i ch C o n st ru c tio n8 .6 Referen ces

9. SURFACE FINISHES

9 .1 In tro d uc t io n9 . 2 S m o o t h9 .3 Ret ard ed9 .4 Sa n d o r A b ra siv e Blast in g9 .5 Fo rm Lin ers9 .6 A c id Et ch ed9 .7 H on ed o r Po lish ed9 .8 V enee r f ac ing m a te r i a ls9 . 9 A p p l i ed C o a t in g s9 .10 R epa i r s

10. QUALITY ASSURANCE

11. STANDARDS AND SPECIFICATIONS


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1. INTRODUCTION

Glass Re in fo r ced C em en t (G RC ) i s a com po si t e m a te r i a lc o n s ist i n g o f a m o r t a r o f h y d r a u l i c c e m e n t a n d f i n e ag g r e g a t ere in fo r ced w i t h C em -FIL al ka li r esi stan t g l ass f i b res. T he G RC m aycon ta in add i t i on a l f i l le r m a te r i a ls, pozzo lan i c m a te r i a ls anda d m i x t u r es. T h e f ib r e c o n t e n t s ar e t y p i ca ll y 3 % t o 5 % b y w e ig h td e p e n d i n g o n p r o d u c t a p p l i c a t i o n a n d p r o d u c t i o n m e t h o de m p l o y e d . T h e p r o p e r t ie s o f G RC d e p e n d o n a w i d e r an g e o fv a r ia b l e s. T h e se i n c lu d e m e t h o d o f m a n u f a c t u r e , m i xf o r m u l at i o n , f ib r e p r o d u c t t y p e , le n g t h a n d o r i en t a t i o n ,a d m i x t u r e s u s ed , e t c . A G R C m a t e r ia l m a y t h e r e f o r e b e t a i lo r e dt o m e e t t h e p a r t ic u l a r re q u i r e m e n t s o f a sp e c i f ic a p p l ic a t io n . T h ei n f o r m a t i o n g i v en i n t h i s p u b l i c at i o n m a in l y r e f er s t o G RCm a t e r ia ls h a v i n g a n a g g r e g a t e : c e m e n t r a t i o o f u p t o 1 : 1 ,i n c o r p o r a t in g C e m - FI L A R g l a ss f i b r e a n d m a d e b y t h e s p r a y a n dp rem ix p ro cesses. T hese GR C m a te r i a ls have b een w ide l y usedfo r m any yea rs and t h e i r p rop e r t i es and cha rac te r i st i c s stud iedextens ive ly .

G R C is a f am i ly o f c o m p o si t e m a t e r ia ls t h a t c o m b i n e t h e h i g hc o m p r e ssi v e st r e n g t h p r o p e r t i e s o f c e m e n t m o r t a r s w i t hsign i f ican t l y i n c reased im p ac t , f le xu ra l and t en si l e st r eng th si m p a r t ed b y t h e f i b r e r ei n f o rc e m e n t .

GR C p ro du c ts a re sa fe , have go od chem ica l r esi stance and w i l ln o t r o t o r c o r r o d e . G RC i s m a d e o f i n o r g a n i c m a t e r ia l s a n d w i lln o t b u r n , h a s n e g l ig i b l e sm o k e e m i ssi o n a n d o f f e r s g o o d f i reresi stance . I n som e c i rcum stances GRC i s m ade con ta in i ngp o l y m e r m a t e r ia ls w h i c h m a y sl ig h t l y a ff e c t so m e f ir ep e r f o r m a n c e p r o p e r t ie s.

GR C i s no rm a l ly o f r e l a t i ve ly t h i n c ross sec t i on , g i v i ng a l owc o m p o n e n t w e ig h t w h i c h a l lo w s sa v in g s i n h a n d l in g , st o r a g e ,t r a n s p o r t a t i o n , a n d i n s t a l l a t i o n c o m p a r e d w i t h t r a d i t o n a lc o n c r e t e p r o d u c t s .

T h e r e a r e t w o m a i n m e t h o d s o f m a n u f a c t u r in g G R C

Spraying o f f i b r e a n d s lu r r y si m u l t a n e o u s ly o n t o a m o u l d ,b y m a n u a l o r m e c h an i c al m e an s.

T y p i c al p r o d u c t s m a d e u s in g t h e s p r a y p r o c e ss in c l u d e

a rch i t ec tu ra l c l add ing pane l s , channe l s , t anks , f acadee le m e n t s, d u c t in g a n d p e rm a n e n t fo r m w o r k .

Premixing t h e f i b r e a n d s lu r r y a n d t h e n p r o c e ssi n g t h em i x t u r e b y v i b r a t i o n c a s t i n g , e x t r u s i o n , i n j e c t i o n m o u l d i n g ,e t c ., t o p r o d u c e t h e e n d p r o d u c t f o r m .

T y p i c al p r o d u c t s m a d e u si n g t h e p r e m i x p r o c e ss a r esun sc reens , p l an te r s , e l ec t r i cal t r an sfo rm e r h ou sing s, s la tesa n d t i l e s , j u n c t i o n b o x e s a n d d r a i n a g e c o m p o n e n t s .


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2. RAW M ATERIALS

2.1 Cem-FIL AR Glass Fibre

Cem -FIL AR Glass F ib re is a con t in uo us f i lam ent , a lka l i resistan tg l a ss f ib r e w i t h h i g h d u r a b i l it y i n c e m e n t . T h e f ib r e c o m p o si t i o nl ie s w i t h i n a c r i t ic a l re g i o n o f t h e N a2 O C a O Z r O 2 SiO 2 sys tem .

Som e t yp i ca l p ro p e r t i es o f C em -FIL A R Fib re a re as f o l l ow s:

Si n g le f il am e n t te n sil e st r en g t h 3 . 5 G N / m 2 3 .5 G N / m 2

St ran d t en si le st re n g th 1 .7 G N / m 2 1 .7 G N / m 2

Yo u n g s M o d u lu s o f Ela st ic it y 7 2 G N / m 2

Sp ec if ic G rav it y 2 .6 8 St r ai n a t b r ea ki n g p o i n t ( st r an d ) 2 . 4 % Fi lam en t d iam et er 1 4 o r 2 0 m

T h e re a re t w o p r o d u c t f o r m s u se d i n c e m e n t r e in f o r c em e n t .T h e se a r e C h o p p e d St r a n d s , f o r u se i n p r e m i x G R C a n d a s are in fo r cem en t i n r end e rs and co nc re tes , and R ov ing s, fo r use i nt h e sp r a y p r o d u c t i o n o f G RC o r f o r c o n t i n u o u s r e in f o r c e m e n t .

C h o p p e d St r a n d s c o n si st o f c o n t i n u o u s st r a n d s c h o p p e d t ou n i f o r m l en g t h w h i le m a in t a i n in g t h e i n t e g r it y o f t h e o r i g i n a lst r an d . T h e y a r e a v ai la b l e i n l en g t h s o f 3 m m t o 3 5 m m .C h o p p e d St r a n d s ar e n o r m a ll y d e si g n a t e d b y l en g t h , b y t h e Te x( m a ss i n g r a m m e s o f a k il o m e t r e le n g t h ) o f t h e in d i v id u a lst r a n d s ( b u n d l e o f f i l am e n t s ) an d b y r e fe r e n c e t o t h e i r si zec o a t i n g . T h e si ze c o a t in g o n C h o p p e d St r a n d p r o d u c t s i sd e s ig n e d t o g i v e r e si st a n c e t o m e c h a n i c al d a m a g e i n p r o c e ssi n go r d e si g n e d t o a l l o w t h e s t r an d s t o d i sp e r se i n t o i n d i v id u a lf il am e n t s o n c o n t a c t w i t h m o i st u r e .

C h o p p e d S t r an d s a r e su p p l i e d p a c k e d e i t h e r i n b o x e s o r b a g s, o ri n b u l k s h i p m e n t s .

A Ro v i n g i s a g r o u p i n g o f i n d i v id u a l p a r al le l st r a n d s w o u n d a s ab u n d l e in t o a c y li n d r i c a l sh a p e d p a c k a g e c o n t a i n i n g t y p i c a l ly 2 0k g o f f ib r e . It m a y b e :

1 ) c h o p p e d i n a g u n a n d sp r a y ed s im u l t an e o u sl y w i t h t h ec e m e n t m a t ri x m a t er ia l t o p r o v id e c o m p o s it e s w h i c h m a y b eo f c o m p l e x p r o f i le .

2 ) c h o p p e d o n - si t e t o r e d u c e t r a n sp o r t c o st s, a n d a l lo w i n gd i r e c t f e ed i n g i n t o p r e m i x p r o c e sse s

Ro v i n g s a r e d e si g n a t e d b y t h e T e x o f t h e w h o l e R o v in g , t h e T e xo f t h e St r a n d a n d t h e n u m b e r o f st r a n d s t h e y c o n t a i n a n d b yre fe rence t o t he i r s i ze coa t i ng .

Ro v i n g s a r e n o r m a ll y sh r i n k - w r a p p e d i n p l ast i c f il m a n d p a c k e di n c a r d b o a r d c a r t o n s .

2.2 Cements

T h e m o s t w i d e l y u s e d c e m e n t s i n G R C m a n u f a c t u r e a r e O r d i n a r yPo r t l an d C e m e n t ( O PC ) a n d Ra p i d H a r d e n i n g P o r t la n d C e m e n t( RH P C ) a n d s h o u l d b e t o t h e r el e va n t N a t i o n a l o r In t e r n a t i o n a lStand a rds . RH P C i s chem ica ll y ve ry sim i l ar t o O P C bu t i s m o re

f i n e ly g r o u n d a n d , b e c au s e o f t h i s , d e v e l o p s st r e n g t h m o r erap id l y a t ea r ly ages . It i s o f t en p re fe r red f o r GR C fo r t h i s r eason .I t sh o u l d b e n o t e d t h a t t h e t e rm r ap i d h a rd e n i n g h a s ad i f fe re n t m e an i n g t o t h e t e rm q u i c k- se t t in g . G R C m a d e w i t hr a p i d - h a r d e n i n g c e m e n t st i f fe n s a n d i n i t i al ly h a r d e n s a t a s im i la rr a t e t o t h a t o f O PC : i t i s a f t er t h e i n i t i a l h a r d e n i n g t h a t t h est reng th i n c reases m o re rap id l y. It sho u ld b e sto red and used i nth e sam e w ay as O P C . RH P C i s sl i gh t l y m o re exp ens ive t h an

O P C .

W h i t e P o r t l a n d c e m e n t i s m a d e f r o m r a w m a t e r i a l s c o n t a i n i n go n l y a v e r y sm a ll q u a n t i t y o f i r o n . I t i s u s ed i n G RC w h e r e aw h i t e o r l i g h t c o l o u r e d f i n i sh i s r e q u i r e d . B ec a u se o f t h i s a n d t h ef a c t t h a t w h i t e c e m e n t c o s t s m o r e t h a n O P C , e x t r a c a r e m u s t b et a k en i n h a n d l in g t h e c e m e n t t o a v o i d c o n t a m i n at i o n , an d i nt h e b a t c h i n g , m i x i n g , a n d t r a n sp o r t a t i o n t o e n s u r e t h a t a l le q u i p m e n t i s k e p t c l e an . I t i s e q u a l l y im p o r t a n t t o m a k e su r et h a t t h e f in i sh e d G R C i s p r o t e c t e d a g a i n s t d i sc o l o r a t io n . T h ese t t i n g a n d st r e n g t h d e v e lo p m e n t p r o p e r t ie s a r e si m i la r t o t h o seo f g rey O P C and , apa r t f r om th e ex t ra ca re necessa ry, t he re i s nod i f f e re n c e i n t h e m e t h o d s o f u s in g i t o r i n st o r a g e .

C a r e sh o u l d b e t a ke n w h e n c u r i n g w h i t e G RC b e c a u se it g e t sd i r t y ve ry easi l y i n t h e ea r l y stag es o f i t s l i f e and i s ve ry d i f f icu l tt o c l ean l a te r.

O t h e r t y p e s o f c e m e n t , s u c h a s H i g h A l u m i n a C e m e n t , S u l p h a t eRe si st a n t a n d Ra p i d S e t t i n g C e m e n t s m a y b e u s ed i n c e r t a ina p p l ic a t i o n s a n d s h o u l d b e t o t h e r e l ev a n t N a t i o n a l St a n d a r d .C a r e sh o u l d b e t a k en t h a t t h e c h o i c e o f c e m e n t i s a p p r o p r i a t ea n d c o m p l i e s w i t h st a t u t o r y r e g u l a t io n s .

I t i s i m p o r t a n t t h a t c e m e n t i s c o r r e c t l y s t o r e d . C e m e n t m u s t b ek e p t d r y , a n d d a m p a i r c an b e a s h a r m f u l a s d i r e c t m o i st u r e .C e m e n t s t o r e d i n b u l k i n a si lo w i ll b e sa t i sf a ct o r y u p t o a b o u t 3m o n t h s. C e m e n t i n n o r m a l 3 - p l y p a p e r b a g s st o r e d u n d e r g o o dc o n d i t i o n s c a n l o se a b o u t 2 0 % o f i t s st r e n g t h a f t e r 4 t o 6 w e e k s.T h e r e fo r e , b a g g e d c e m e n t s h o u l d b e u s e d so o n a f t er d e l i v er y.

2.3 Fi llers

2 . 3 . 1 S a n d

Si l ica sand s t o t h e f o l l ow ing spec i f i ca t i on a re read i l y ava i l ab le i nm o s t c o u n t r i e s o f t h e w o r l d

1 . Al l s a n d s h o u ld b e wa s h e d a n d p re fe ra b ly d r ie d . I t w i ll t h e ncon ta in l ess so lub le m a t te r and f i ne pa r t i c l es, and a l so a l l owe a si e r co n t r o l o f w a t e r :c e m e n t r a t i o .

2 . Par t ic le Shape and Sur face Tex tu re P ar t i c l e shape - r ounded o r i r r egu la r p re fe r red . (F laky and /o re l o n g a t e d s h o u l d b e a v o i d e d )Su r f a c e t e x t u r e - sm o o t h p r e f e r r ed . ( H o n e y c o m b e d s h o u l db e a v o i d e d ) .

3 . C h e m i c a l C o m p o s it i o n ( % )S a n d s o f t h e f o l l o w i n g c o m p o s i t i o n h a v e b e e n u s e d i n t h eU K . a n d h a v e b e e n f o u n d t o b e sa t i sf a ct o r y .


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Sil ica > 9 6M o ist u re < 2So lu b le sal t s ( i .e . a lkal is) < 1Lo ss o n Ig n i t io n < 0 .5O rg an ic m at t e r - m u st n o t af fec t t h e

se t t in g o f t h e c e m e n tSO 3 0 .4 ( 4 0 0 0 p p m ) m ax .

C l 0 .0 6 (6 0 0 p p m ) m ax .

O th e r sand s sho u ld b e sa t i sf ac to r y as l on g as t h ey a re deem edsu i t a b l e fo r g o o d q u a li t y c o n c r e t e .

T he s i l i ca con ten t o f t he sand need no t necessa r i l y be as h igh as9 6 % . T h e re a re g o o d q u a l it y sa n d s w i t h m u c h l o w e r si li c ac o n t e n t t h a t a r e su i t a b l e f o r G RC m a n u f a c t u r e

T h e v a lu e f o r lo s s o n i g n i t i o n c a n b e ac c e p t e d u p t o 3 % ,p r o v i d i n g t h e m a t e r ia l is h a r d , n o n c r u s h a b l e , n o n - r e a ct i v e an do f si m i la r sh a p e a n d g r a d i n g t o t h a t d e sc r ib e d b e l o w .

4 . G r a d i n g

Sprayed GRC

a) Par t ic le s ize

1 . 2 m m m a x . (i .e . 1 0 0 % p a ssi n g B S 1 4 s ie v e , A ST M 1 6si e ve ) f o r sp r a y e d G RC 2 . 4 m m m a x . ( i. e .1 0 0 % p a ssi n gB SS 7 s ieve ) f o r p rem ix G RC

( b ) Fin e f r a c t i o n

M a x .1 0 % p a ssi n g 1 5 0 m m ( BSS1 0 0 , A ST M 1 0 0 si ev e ).

Premix GRC

T h e m a x i m u m p a r t i c le si ze is n o t c r i t ic a l b u t t h e q u a n t i t y o ff i n e s sh o u l d b e l im i t e d b e c au s e o f t h e e f fe c t o n w a t e rd e m a n d a n d h e n c e t h e w a t er :c em e n t r at i o .

2 . 3 . 2 C r u sh e d A g g r e g a t e s

M a n y v a r i et i e s o f a g g r e g a t e s u s ed f o r c o n c r e t e m a y b e c r u s h e dto a su i t ab le g rad ing f o r use in G RC . Exam p les o f sucha g g r e g a t e s a r e m a r b l e , l im e st o n e a n d g r a n i t e .

2 . 3 . 3 Po z z o l a n s

1 : PFA f l y ash i s a po zzo lan i c m a te r i a l and i s t h e ash ex t rac tedf rom f l ue gases o f b o i l e r s f i r ed b y p u l ve r i sed co a l . PFA shou ldbe t o t he re levan t s tanda rd f o r P F A used i n conc re te . B lendedP FA cem en ts su i t ab le fo r con c re te m anu fac tu re a re ava i lab lei n m a n y c o u n t r i e s. Ty p i c a ll y t h e y c o n t a i n 2 5 - 3 5 % PFA .

2 : Si l ica Fum e (o r m ic ro si l ica ) i s a ve ry f ine m a te r i a l and i s ani n d u st r i al b y - p r o d u c t . I t is o f t e n s u p p l ie d i n t h e f o r m o f aw a te r b ased s lu r r y . I t i s usua l ly o n l y u sed i n spec ia l i st m ixdes igns and p rocesses.

3 : C e m - St a r is a p a r t i cu l a r g r a d e o f m e t a k ao l i n w h i c h h a s v e r yh i g h r e a c t i v i t y w i t h h y d r a t i n g c e m e n t . I t p r o v i d e s G R C w i t hv e ry g o o d l o n g t e rm st r e n g t h r e t e n t io n .( Se e Ap p e n d i x A o f C h a p t e r 5 )

2.4 Water

W a t e r sh o u l d b e c l e an a n d f r ee f r o m d e l e t e ri o u s m a t t e r an dsh o u l d m e e t r el ev a n t st a n d a r d s f o r w a t e r u se d t o m a k ec o n c r e t e .

2.5 Admixtures

St a n d a r d c o n c r e t e ad m i x t u r e s o r t h o s e sp e c i a ll y f o r m u l a t e d f o rG R C m a n u f a c t u r e m a y b e u se d a s a p p r o p r i a t e t o t h e p a r t i c u la rp r o c e s s a n d t o o b t a i n t h e r e q u i r e d p r o p e r t i e s o f G R C .A d m i x t u r e s a r e g e n e r a l ly a d d e d t o p r o d u c e t h e f o l lo w i n g e f f e ct s.

I n m a n u f a c t u r e o f G RC

i n cr ea sin g t h e w o r ka b ili ty w i t h o u t i n cr ea si n g t h ew a t er / c e m e n t r a t io

im p ro vin g t he co h esio n r ed u cin g seg reg at io n red u c in g b leed in g r et ar d in g t h e se t ti n g ( st if fe n in g ) p r o c ess a c ce le r at i n g t h e se t t in g ( st i ff en i n g ) p r o c e ss.

On p ro p e r t i e s o f h a rd e n e d GRC

i n cr ea sin g t h e ra t e o f ea rl y st r en g t h d e ve lo p m e n t in cr easin g t h e st ren g t h d e cr easin g t h e p e rm e ab i li t y im p r o vin g f ir e r esist an c e

A d m i x t u r e s a r e a d d e d t o m i x e s i n s m a l l a m o u n t s a n d c a r e m u s tbe exe rc i sed t o ensu re t ha t on l y t he co r rec t dose as spec i f i ed byt h e m a n u f a c t u r e r i s a d d e d .

C a l c iu m c h l o r i d e b a se d a c c e l er a t o r s a r e n o t n o r m a ll y a c c ep t a b l e .

2.6 Pigments

Pi g m e n t s m a y b e u se d t o c o l o u r G RC . Sp e c i a l c a r e is r e q u i r e d t oa c h i ev e u n i f o r m i t y o f c o l o u r a n d t h e st r o n g c o l o u r s a r e n o tu s u a ll y a c h i e v ab l e w i t h o u t s ig n i fi c an t v a r ia t i o n . L o w q u a li t yp i g m e n t s m a y lo se o r c h a n g e c o lo u r w i t h t i m e .

2.7 Health Aspects of Raw M ater ials

2 .7 .1 F ib re

C e m - FI L f ib r e s a t 1 4 a n d 2 0 d i a m e t e r a r e su b s t an t i al ly a b o v ethe range o f r esp i rab le pa r t i c l es . E v idence t o da te has show nt h a t t h e se f ib r e s c a u se n o l o n g t e r m h e a l t h h a z a r d , al t h o u g hso m e t e m p o r a r y sk i n i rr i t at i o n m a y b e e x p e r ie n c e d .

Re f er e n c e : " C o n t i n u o u s Fi la m e n t Fi b r e G l a ss an d H u m a n H e a lt h " .APFE Bru ssels.

2 . 7 . 2 O t h e r C om p o n e n t M a t e ri a ls

Re l ev a n t C o d e s o f Pr a c t ic e a n d m a n u f a c t u r e r s' r ec o m m e n d a t i o n sr e g a r d i n g t h e h a n d l in g a n d u se o f t h e se m a t e r ia l s sh o u l d b ef o l l o w e d .


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3. MANUFACTURING METHODS

3.1 Sprayed GRC

I n t h e m a n u f a c t u r e o f G R C b y t h e sp r a y p r o c e ss, si m u l t a n e o u s

sp r a y s o f c e m e n t / sa n d m o r t a r sl u r r y an d c h o p p e d C e m - FI L A R

g lass f i b r e a re dep os i t ed f r om a sp r ay - h ead i n t o o r on t o a su i t ab l e

m o u l d . T h e sp r a y -h e a d m a y b e h an d h e ld o r m o u n t e d o n a

m a c h i n e . Th e m o r t a r sl u r r y is f e d t o t h e sp r a y g u n f r o m am e t er in g p u m p u n i t a n d i s b r o k e n i n t o d r o p l et s b y c o m p r e sse d

a i r. Cem - FIL AR f i b r e r ov i ng i s f ed t o a g l ass fi b r e ch op per / f eeder ,

m o u n t e d o n t h e sp r a y h e ad w h i c h c h o p s t h e fi b r e t o

p r e d e t e r m i n e d l en g t h s , t y p i c a ll y 2 5 - 4 0 m m a n d i n j e c t s t h e

c h o p p e d s t ra n d s i n t o t h e m o r t a r sp r a y so t h a t a u n i f o r m f e l t o f

f ib r e a n d m o r t a r is d e p o s it e d o n t h e m o u l d . T h e sl u r r y h a s

t y p i c a l ly a sa n d : c e m e n t r a t io o f u p t o 1 : 1 a n d a w a t e r: c em e n t

r a t io o f 0 . 3 3 . T h e w a t e r: c em e n t r a t i o sh o u l d b e k e p t a s l o w a s

p ossi b l e cons i st en t w i t h sa t i sf ac to r y sp r ay and i nco r po r a t i on

char ac te r i st i cs, as i nc r easi ng t h e w a te r : cem ent r a t i o l eads t o a

r e d u c t i o n i n t h e st r e n g t h o f t h e p r o d u c t . A d m i x t u r e s m a y b e u se d

t o o b t a i n t h e r eq u i re d w o r k a b i li t y. T h e p r o p o r t i o n o f f ib r e t o s lu r r yi s ad j us ted so t ha t t h e r esu l t i ng com po si t e con t a i ns t yp i ca ll y 5%

b y w e i g h t o f g l a ss f ib r e . C o m p r e h e n s iv e d e t a i l i s c o n t a in e d i n t h e

" G u i d e t o Sp r a y M a n u f a c t u r e " issu e d b y C e m - FI L.

3 . 1 . 1 M a n u a l Sp r a y M e t h o d

T h e o p e r at o r h o l d s t h e sp r a y - h e a d i n h i s h a n d a n d m o v e s i t t o -a n d - f r o a c r o ss t h e m o u l d , d i r ec t i n g t h e st r e a m o f m a t e r ia lp e r p e n d i c u l a r t o t h e m o u l d su r f a c e, u n t i l t h e r e q u i r e d t h i c kn e sso f G R C h a s b e e n b u i l t u p . R o l le r -c o m p a c t i o n e n su r e s c o m p l i a n c ew i t h t h e m o u l d f a c e , i m p r e g n a t i o n o f t h e f i b r e b y t h e s l u r r y ,r e m o v a l o f t r a p p e d a i r a n d d e v e l o p m e n t o f a d e q u a t e d e n s i t y .T h e r o l l ed su r f a c e m a y b e f i n a l ly t r o w e l le d s m o o t h . T h i c k n e ssc o n t r o l i s a c h i ev e d b y u s e o f p i n - g a u g e s. A t y p i c a l o u t p u t o f asi n g l e h a n d - u n i t i s 1 0 - 1 2 k g o f G RC p e r m i n u t e . T h e p r o c e ssr e su l t s i n o n e su r f a c e o f t h e p r o d u c t h a v i n g a n e x - m o u l d f i n i shand the o the r su r face a ro l l ed o r t r ow e l l ed f i n i sh . P roduc ts a rec o v e r e d w i t h p o l y t h e n e sh e e t a f t er sp r a y i n g a n d n o r m a ll yd e m o u l d e d t h e f o ll o w i n g d a y an d t h e n c u r ed .

T he p rocess i s l abou r i n tens i ve bu t i s capab le o f p roduc ingcom p lex shap es and i s ex t rem e ly ve rsa t i l e . The p rocess i s usedf o r m a n u f ac t u r e o f a w i d e r an g e o f c o m p o n e n t s i n c lu d i n gc l ad d i n g p a n e l s, a g r i c u lt u r a l c o m p o n e n t s , f ac a d e e le m e n t s ,

f o rm w o r k an d d u c t in g .

3 . 1 . 2 M e ch a n i se d Sp r a y M e t h o d

T h e b a si c sp r a y m e t h o d d e sc r ib e d a b o v e i s r ea d i l y m e c h a n i se d .Fo r t h e p r o d u c t i o n o f c o m p o n e n t s w h i c h a re su b st a n t i a ll y fl at o ro f s h a ll o w p r o f il e , m o u l d s ar e p r o p e l le d a l o n g a r o l le r o r f l atc o n v e y o r p a ssi n g b e n e a t h a t r a n sv e r se u n i t o n w h i c h t h e sp r a y -h e a d i s r ec ip r o c a t ed . O u t p u t s a re u p t o 2 5 - 3 0 k g / m i n u t e .Fo rw a rd an d t r ansve rse speed s a re ba lanced an d feed sp rays a rea c c u r at e l y ad j u s t e d t o e n s u r e u n i f o r m l ay d o w n a n d c o r r e c t fi b r ed i s t r i b u t i o n t h r o u g h t h e c o m p o s i t e . T h e f i n i s h e d p r o d u c t h a s a n

e x - m o u l d f i n i sh o n o n e si d e a n d a t r o w e l le d o r r o l l e d f in i sh o nt h e o t h e r.

E q u i p m e n t o f t h i s t y p e i s u s e d i n t h e c o m m e r c i a l p r o d u c t i o n o fsi n g l e - sk i n a n d sa n d w i c h c l a d d i n g a n d f a ca d e e l em e n t s ,

f o r m w o r k a n d s ew e r li n in g s . Fo l d i n g m o u l d s m a y b e u se d i n t h em a n u f a c t u r e o f sh a p e d c o m p o n e n t s su c h a s d u c t s a n d c h a n n e l s.

3 .1 .3 Sp ra y -De wa te r in g P ro c e s s

T h is p rocess u t i l ises t h e p r i n c ip l es o f t he m echan i ca l sp raye q u i p m e n t d e s c r i b e d a b o v e t o f o r m a c o n t i n u o u s G R C f e l tw h i c h i s t h e n d e w a t e r ed t o c o n s o l id a t e i t an d t o g i v e a w o r k a b l e

sh e e t m a t e r ia l w h i c h m a y b e a l lo w e d t o se t i n t h e f la t st a t e :a lt e r n a t i v el y, i t m a y b e f o r m e d w h i l st s t il l in t h e g r e en s t a t e t op r o d u c e c o r r u g a t e d o r p r o f i le d s h e e t s, b o x s e ct i o n s , p i p e s, e t c .W i t h t h e d e w a t e r in g t e c h n i q u e it i s p o ssi b l e t o u t i l ise a m u c hw e t t e r an d m o r e e asi ly sp r a y a b l e m i x , u p t o 0 . 5 w a t e r :c e m e n tr a t io . T h e G R C f e lt i s su b se q u e n t l y d e w a t e r ed t o a b o u t 0 . 2 8w a t e r :c e m e n t r a t i o a n d c a n g i v e a m a t e r ia l o f h i g h e r d e n si t y a n dh i g h e r in i t i a l st r e n g t h t h a n n o n - d e w a t e r ed m a t e r ia l. T h e f in i sh e dp r o d u c t h a s a m a t t t e x t u r e o n o n e si d e . Th e o t h e r si d e m a y b eg i v e n a t r o w e l fi n i sh i f r e q u i r e d . Fo r m i n g o f c o m p l e x sh a p e s isc a r ri ed o u t m a n u a l ly , b u t s t an d a r d c o r r u g a t i o n s o r p r o f i lef o r m i n g m a y b e m e c h an i se d .

3.2 Premixed GRC

A l l p r e m i x p r o c e sse s i n v o l v e t h e b l e n d i n g t o g e t h e r o f t h ec e m e n t , s a n d , w a t e r , a d m i x t u r e s a n d c h o p p e d s t r a n d s o f C e m -FI L f i b r e i n a m i x e r p r i o r t o b e in g f o r m e d .

To p r o d u c e a p r e m i x o f t h e c o r r e ct q u a l it y i t i s n e c e ssa r y t o m i xi n t w o s t a g e s. T h e f i r st s t a g e i s d e s ig n e d t o p r o d u c e a h i g hq u a li t y sl u r r y t o a c h i ev e t h e n e c e ssa r y w o r k a b i l it y a n d a ll o w f o rt h e u n i fo r m i n c o r p o r a t io n o f f i b r e . T h e se c o n d st a g e i s t h eb l e n d i n g o f f ib r e s i n t o t h e sl u r r y a t a r ed u c e d sp e e d .

I t is m o r e c o n v e n i e n t t o c a r r y o u t b o t h st a g e s i n t h e s am e p i e c eo f e q u i p m e n t , b u t s ep a r a t e m i x e r s c a n b e u se d f o r e a c h s t ag e .

T h e ac t u a l m i x f o rm u l at i o n u se d d e p e n d s u p o n t h e t y p e o fp r o d u c t b e i n g m a d e , b u t a t y p i c a l m i x h a s a sa n d : c em e n t r a t ioo f 2 : 3 a n d a w a t e r :c e m e n t r a t i o o f p r e f er a b l y l ess t h a n 0 . 3 5 . I t i sessen t i a l t o keep t he w a te r : cem en t r a t i o as l ow as p ossib lec o n s ist e n t w i t h m a in t a i n i n g w o r k a b i l it y o f t h e m i x , soa d m i x t u r e s a r e u se d .

U p t o 4 % b y w e ig h t o f c h o p p e d st r an d s c an b e in c o r p o r a t e di n t o t h e m i x , b u t t y p i c al fi b r e c o n t e n t i s 3 % . T h e fi b r e le n g t h i s

n o r m a ll y 1 2 m m b e c au se ab o v e t h i s l en g t h t h e m i x b e co m e sd i f f ic u l t t o w o r k . A f i b r e l en g t h o f 2 5 m m i s g e n e r al ly f o u n d t ob e t h e m a x im u m u se ab l e .

A l t h o u g h t h e g l ass f i b r e st r a n d s a re d e si g n e d t o w i t h st a n d t h em i x i n g a c t i o n , i t i s n o r m a l, a s i n d i c a t e d a b o v e , t o a d d t h e f i b r ea t t h e e n d o f t h e m i x in g c y cl e t o m i n im i se f ib r e d a m a g e .C o m p r e h e n s iv e d e t a i l i s c o n t a in e d i n t h e " G u i d e t o P r em i xM a n u f a c t u r e " i ssu e d b y C e m - FI L.

3 . 2 . 1 V ib r a t i o n C a s t i n g

T h is p rocess i s ve ry s im i l ar t o t h e v i b ra t i on cast i ng o f p re - castc o n c r e t e . I t i n v o l v e s p o u r i n g t h e w e t G R C p r e m i x i n t o a n o p e no r d o u b l e -w a ll e d m o u l d a n d v i b r a t i o n e n a b l e s t h e s lu r r y t o f l o wa n d r e m o v e s t r a p p e d a i r. A lt e r n a t i v el y t h e p r e m i x m a y b ep u m p e d t o t h e m o u l d t h r o u g h a h o se u si n g a p e r ist a lt i c p u m p .


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Fo r st a n d a r d p r o d u c t s a t i m e d d i sc h a r g e c a n b e u se d t o p r o d u c ec o n st a n t p r o d u c t w e ig h t s .

T he p rocess i s ex ten si ve l y used t o m ake l arge sun sc reens o rsc r e en w a l li n g p a n e l s u s in g p o l y st y r e n e o r r u b b e r m o u l d s w h i c hhave su f f i c i en t f l e x ib i l i t y t o abso rb t he sm a l l sh r i n kage th a t t akesp l a c e d u r i n g s et t i n g .

O t h e r p r o d u c t s p r o d u c e d b y t h i s p r o c e ss i n c l u d e l it t e r b i n s ,e lec t r i cal t r ans fo rm e r ho us ings , p l an te r s, j un c t i on b ox es andd e c o r a t i v e m o u l d i n g s .

3 .2 .2 Sp ra y e d Pre m ix

T h i s i s a v ar ia t io n o f t h e p r em i x m e t h o d w h e r eb y t h e m i x( i n c l u d i n g c h o p p e d g l a ssf i b r e s) i s b l e n d e d i n a m i x e r an d t h er e su l t i n g m a t e r ia l is t h e n d e l i v er e d b y a su i t a b l e p u m p t o asp e c i a l sp r a y h e a d , w h i c h i s u se d m a n u a l ly t o d e p o s it t h em a t e r i a l i n a n o p e n m o u l d . I n t h i s m e t h o d t h e t h i c k n e s s o fm a t e r ia l is n o r m a ll y d e l iv e r ed i n o n e l a y e r an d n o v i b r a t i o n o ro t h e r co m p a c t i o n i s u s ed . I n c o m p a r i so n w i t h v i b r a t io n c a st i n g ,t h e m o u l d s m a y b e l e ss r o b u st s in c e t h e y a r e n o t s u b j e ct t ov i b r a t i o n a n d a lso a r e o p e n , w i t h o u t c o r e s.

A g l assf ib r e co n t e n t u p t o a m a x im u m 4 % b y w e ig h t c a n b ei n c o r p o r at e d b u t a c o n t e n t o f 3 % , u su a ll y in t h e f o r m o f 1 2 m mchopped s t rands , i s t yp i ca l . T he p rope r t i es o f t he f i n i shedm a t e r ia l ar e si m i la r t o t h o s e o f v i b r at i o n c a st p r e m i x o fequ i va len t g l ass f i b re con ten t .

T h e m e t h o d i s su i t a b l e f o r t h e p r o d u c t i o n o f sm a ll ar c h i t e c t u r alcom po nen ts and d eco ra t i ve f ea tu res such as co rn i ces, co rbe l s,c o l u m n s , w i n d o w si ll s a n d s m a ll c la d d i n g p a n e l s.

3 .2 .3 Press ing

Ra p i d p r o d u c t i o n o f r e l at i v e ly si m p l e sm a l l c o m p o n e n t s e .g .p ro m enad e t i l e s, l id s e t c . i s p ossib le by p ressing t echn iqu es. T hee q u i p m e n t m a y va ry in c o m p l e x it y ac c o r d in g t o t h e o u t p u tr e q u i r e d , w i t h f u l l y a u t o m a t i c sy st e m s b e i n g p o ssi b l e f o r h i g hv o l u m e p r o d u c t i o n , b u t t h e b a si c p r e ssi n g o p e r at i o n i sp e r f o r m e d o n a c h a rg e o f w e t p r em i x G RC w i t h d e w a t er in gt a k in g p l a c e .

3 . 2 . 4 S p r a y m i x

T h i s i s a c o m b i n a t i o n o f p r e m i x a n d sp r a y m e t h o d s a n d u se sn o r m a l sp r a y e q u i p m e n t t o g e t h e r w i t h v ib r a t io n c ast i n g .

A sp ray u n i t d e l ive rs g lass f i b re and sl u r r y o n t o a b a f f le p l a tea b o v e a sl o t i n a d o u b l e -w a ll ed m o u l d o n a v i b r a t in g t a b l e an dt h e v i b r a t i o n e n a b l e s t h e w e t G R C t o sl id e f r o m t h e p l at e i n t ot h e m o u l d . T h i s e l im i n a t e s t h e n e e d t o m i x t h e g l ass f i b r e an dsl u r r y t o g e t h e r in a m i x e r p r i o r t o m o u l d f i ll in g a n d r e d u c e s f i b r ed a m a g e t o a m i n i m u m . N o r m a l c h o p p i n g r o v in g i s u se d r at h e rt h a n t h e c h o p p e d st r a n d s u se d f o r p r e m i x p r o c e sse s.

3.3 Miscellaneous Processes

T h e a p p l i c at i o n o f C e m - FI L f i b r e t o m o r e c o n v e n t i o n a l c e m e n ta n d c o n c r e t e f o r m u l a t io n s is p r e se n t e d i n t h i s se c t i o n , b u t i t

s h o u l d b e n o t e d t h a t t h e p r o p e r t i e s o b t a i n e d i n t h e s ea p p l ic a t i o n s ar e n o t t h o se o f G RC o f t h e t y p e s p r e v i o u sl ydesc r i bed , and a re no t d i scussed subsequen t l y .

3 .3 .1 Renders , F loo r Screeds and Concre te

Fo r m u l at i o n s c o n t a in i n g b e t w e en 0 . 5 % a n d 2 . 5 % b y w e ig h t o fC e m - FI L A R f ib r e h a v e b e e n d e v e lo p e d f o r r e n d e r in g , a p p l i e d b y

e i t h e r sp r a y i n g o r t r o w e ll in g t o a t h i c k n e ss o f 4 - 1 0 m m . T h ef i n i shed rend e r has sup e r i o r r esi stance t o im pac t an d sh r i nkagec r a ck i n g a n d i s l e ss p e r m e a b l e t o w a t e r t h a n n o r m a l sa n d -cem en t r en de r . Fib re re in fo r ced ren de r i s a l so u sed i n d r yb l o c k w a ll c o n st r u c t i o n a n d e x t e r n a l i n su l a t i o n s y st e m s.

O t h e r f o r m u l a t io n s c o n t a in i n g si m i la r q u a n t i t i e s o f f i b r e h a v eb e e n d e v e lo p e d f o r f l o o r sc r e ed s . T h e su p e r io r i m p a c t a n d c r a ckresi stance o f f i b re re i n fo r ced sc reeds enab les t h em to be l a i dm o r e t h i n l y t h a n c o n v e n t i o n a l sc r e ed s . T h e y a lso p r o v i d e a g o o dsu r face f o r t he f i na l f l oo r f i n i sh t r ea tm en t .

3 .3 .2 Sp ra y e d Co n c re te ,Gu n i t i n g a n d Sh o tc re t i n g

C e m - F I L A R f i b r e a t a b o u t 1 % b y w e i g h t o f t o t a l m i x c a n b ea d d e d t o n o r m a l sp r a y e d c o n c r e t e m i x e s, g i v i n g a c r ac k r e si st a n ta n d i m p a c t r e si st a n t l i n i n g f r o m a r el at i v e ly t h i n c o v e r c o m p a r e dw i t h n o r m a l sp r a y ed c o n c r et e . Bo t h d r y g u n i t in g a n d w e tsp rayed con c re te p rocesses can u t i l i se C em -FIL f ib rer e in f o r c em e n t w i t h t h e a d v a n t a g e o f r ed u c e d r e b o u n dc o m p a r e d w i t h s t ee l fi b r e s.

3.4 Curing of GRC Products

T h e h y d r a t io n o f c e m e n t i s a re l at i v e ly s lo w p r o c e ss at a m b i e n tt e m p e r a t u r e s a n d f o r t h i s r e aso n c o n c r e t e p r o d u c t s ar e u su a l lya l l ow ed to hyd ra te o r cu re f o r seve ra l w eeks a f t e r cas t i ng t og i v e f u l l s t r e n g t h d e v e l o p m e n t .

G R C p r o d u c t s ar e n o r m a ll y o f c o m p a r a t i v el y t h i n s ec t i o n ,m a n u f ac t u r ed w i t h a lo w e r w a t e r: ce m e n t r a t io t h a n m o stc o n v e n t i o n a l c o n c r e t e s, a n d a r e p r o n e t o r a p i d d r y i n g . If t h i so c c u r s b e f o r e h y d r a t io n i s c o m p l e t e t h e c e m e n t n e v e r a c h i ev e si t s f u l l s t r eng th and t he p rope r t i es o f t he GR C a re adve rse l ya f f ec ted , so m o re a t t en t i on t o cu r i ng con d i t i ons is necessa ry .

3 . 4 . 1 M o i st C u r i n g o f G RC P ro d u c t s

To ensu re com p le te hy d ra t i o n i t i s essen t i a l t h a t p ro du c t s a rek e p t m o i st i m m e d i at e ly a ft e r m a n u f ac t u r e an d d u r i n g t h e c u r in gpe r i od . Seve ra l m e th od s o f ach iev ing t h i s a re cu r ren t l y i n use ,m a i n l y : s t o r a g e i n a h u m i d i t y c h a m b e r o r f o g r o o m , s e a l i n g i np o l y t h e n e b a g s , o r t o t a l im m e r si o n i n w a t e r.

Fo r a l l p r o d u c t s t h e c u r i n g p e r io d c a n b e d i v i d e d i n t o t h r e epa r t s :

( I ) A p r e - d e m o u l d i n g c u r e t o g i v e su f f i ci e n t st r e n g t h t o t h ep r o d u c t f o r d e m o u l d i n g . T h i s i s i m p o r t a n t a n d i s c a r ri edo u t b y c o v e ri n g t h e c o m p o n e n t c l o se ly w i t h p o l y t h e n e t om i n i m i se a i r f lo w a c r o ss t h e G R C su r f a c e t h u s e n a b l i n g t h ec o m p o n e n t t o r e t a in a s m u c h w a t e r a s p o ssi b l e .


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( i i ) T he m a in cu re as desc r i bed abo ve .

( i ii ) Po s t -c u r i n g d u r i n g w h i c h t h e p r o d u c t is n o r m a li se d t o t h ea m b i e n t c o n d i t i o n s p r i o r t o s t o r a g e o r u se , p a r t i c u la r ly i ne x t r em e h o t o r c o l d c o n d i t io n s .

T h e r a t e o f h y d r a t io n w i ll b e d i f fe r en t i n e a c h o f t h e se p e r i o d s ,b u t a t t h e e n d o f t h e c u r i n g c y c l e t h e G R C sh o u l d h a v e b e e n

b r o u g h t u p t o t h e f i n a l s t r e n g t h r e q u i r e m e n t s . T h e p a r t i c u l a rc u r in g r e g i m e w i l l d e p e n d u p o n t h e p r o d u c t , m a n u f ac t u r in gp r o c e s s a n d m i x d e si g n , a n d m u s t b e su c h t h a t t h e r e q u i r e dleve l o f p ro pe r t i es i s ach ieved .

D u r in g t h e c u r in g p e r io d t h e st r e n g t h o f t h e G R C p r o d u c t s w i llbe b u i l d i n g u p f r om an i n i t i a l l y l ow l eve l and ca re i s necessa ry i nd e m o u l d i n g , h a n d l i n g a n d p a r t ic u l ar ly i n t h e m a in c u r e t oensu re t ha t p roduc t s a re no t ove rs t ressed w h i l s t i n a re l a t i ve l yw e a k s t a t e s i n c e t h e y c o u l d b e p e r m a n e n t l y d e f o r m e d o rsu b j e c t ed t o d a m a g e w h i ch m a y n o t b e v isi b le .

A s w i t h co nc re te , i t i s possib le t o use acce le rated cu r i ngsched u les, e it h e r by t h e use o f chem ica l acce lera to r s o r by ah i g h e r t e m p e r a t u r e c u r e . T h i s m a y b e c o m m e r ci al ly a t t r a c t iv e ,b u t c o n d i t i o n s m u st b e c a re f u l ly c o n t r o l le d t o a c h i ev e c o n s ist e n tand accep tab le s t r eng th l eve l s .

A c o n t r o l l ed p o s t -c u r in g r eg i m e i s i m p o r t a n t w h e r e t h econd i t i ons i n s to rage o r use w i l l be subs tan t i a l l y d i f f e ren t , i ne it h e r t e m p e r at u r e o r h u m i d it y, f ro m t h e m a in c u r e c o n d i t io n s .I n p a r t ic u l ar, t h e c o m b i n a t io n o f d i r ec t su n a n d l o w h u m i d it yc o u l d c a u se p r o b l e m s w i t h d i ff e r en t i a l d r y i n g sh r i n k a g e e v e nt h o u g h t h e G RC s t r en g t h i s h i g h a t t h i s st a g e i n i t s l if e .

A s a g u i d e t o p r a c t ic a l cu r i n g r e g i m e s, C e m - FI L G R C p r o d u c t sw i ll a c h i ev e a su b st a n t i a l p r o p o r t i o n o f t h e i r u l t i m a t e st r e n g t hw h e n t h e m a in c u r e i s c a r ri e d o u t f o r 7 d a y s, in a h u m i d i t y o fg r e at e r t h a n 9 5 % RH , an d w i t h a m i n im u m t e m p e r at u r e o f1 5 C . A su i t a b l e p o s t - c u r in g r e g i m e w i ll a ll o w t h e r e m a in d e r o ft h e s t r en g t h t o b e r e al iz e d .

3 . 4 . 2 A i r Cu r i n g

A n a l t e rn a t i v e m e t h o d o f c u r i n g t h e G RC i s t o i n c o r p o r a t ep o l y m e r i c m a t e r i a l s i n t o t h e G R C m i x . T h e p o l y m e r f o r m u l a t i o nu s e d m u s t b e c a p a b l e o f f o r m i n g a f i l m a r o u n d t h e m i x p a r t i c l e s ,

t h u s a ll o w i n g t h e m o i st u r e i n t h e G R C t o b e r e t a in e d a n dh y d r a t i o n t o c o n t i n u e . T h e p o l y m e r m a t e r i a l s a r e n o r m a l l ya d d e d a t d o s ag e r at e s o f b e t w e en 2 % a n d 1 0 % o f p o l y m e rso l id s t o c e m e n t w e ig h t . A ft e r d e m o u l d i n g t h e G RC p r o d u c t c a nb e a l l o w e d t o c u r e i n a m b i e n t a i r c o n d i t i o n s , b u t c a r e m u s t b et a k e n t o e n s u r e t h a t t h e ai r t em p e r a t u r e is a b o v e t h e m i n i m u mf il m f o r m a t io n t e m p e r at u r e o f t h e p o l y m e r.

T h e p r o p e r t i e s o f G RC c u r e d i n t h i s w a y a r e si m i la r t o t h o s e o ft h e s am e b a si c f o r m u l a t io n ( i .e . sa n d : c e m e n t r a t i o , w a t e r :c e m e n tr at i o a n d g l a ss c o n t e n t ) m a d e w i t h o u t p o l y m e r ad d i t io n s an dm o i st c u r e d a s d e sc r ib e d i n s ec t i o n 3 . 4 . 1 .

H o w e v e r t h e a d d i t i o n o f p o l y m e r m a t e r i a l s t o G R C m a y a f f e c tt h e f i r e p e r f o r m a n c e p r o p e r t ie s.


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4. PRINCIPLES OF GLASS FIBREREINFORCEMENT

4.1 The Eff ect of Glass Fibres on the St rengt h of the

Mortar Matrix

Fi b r o u s m a t e r ia ls h a v e b e e n u se d f o r m a n y t h o u s a n d s o f y e a r s t ostab i l i se m a te r i a ls t h a t a re i nh e ren t l y un re l iab le . St raw i n m udb r i cks and ho rse ha i r p l aste r a re tw o o ld exam p les . A sbes tosf i b r e s i n c e m e n t i s a m o r e m o d e r n e x a m p l e . Th e r o l e o f t h ef i b r o u s m a t e r ia l is t o i n c l u d e s m a ll r e g i o n s o f h i g h st r e n g t hm a t e r ia l w h i c h c o n t r o l t h e p r o p a g a t i o n o f c r a c ks f r o m v o i d s int h e m a t r ix a n d h e n c e g i v e a r el ia b l e t e n si le st r e n g t h t o a no t h e r w i se b r i t t l e m a t e r ia l w i t h a n u n r e li ab l e t e n s il e st r e n g t h a n dp o o r i m p a c t c h a r ac t e r ist i c s

C em -FIL al ka li r esi stan t g l ass fi b res pe r fo rm th i s r o l e i n cem en tbased m a te r i a ls such as m o r t a r s and con c re tes, w h i ch a reinhe ren t l y b r i t t l e and have un re l i ab le t ens i l e s t r eng th . T he f u l lst r e n g t h o f t h e m a t e r ia ls c a n t h u s b e d e v e lo p e d b e c au s e o f t h ep resence o f g l ass f i b res , and i t can be show n (R e fs . 1 and 2 ) t ha tt h e p resence o f su f f i c i en t g l ass f i b res w i l l i n c rease t he m o r ta rst r e n g t h a b o v e t h e e x p e c t e d l ev e ls.

4.2 Tensile Stress-Strain Curves for GRC

W h e n G R C i s t e st e d i n t e n s io n , t h e l o a d e x t e n si o n c u r v ep r o d u c e d t a ke s o n e o f t w o f o r m s, w h i ch a r e sh o w n h e reschem a t i ca ll y.

C u rve T ype A i s r ep resen t a t i ve o f f r esh l y m ade sp rayed G RC o ra g e d C e m - FI L st a r G RC w h i c h e x h i b i t s d u r a b l e b e h a v io u r a n dC u rve Typ e B i s r ep resen t a t i ve o f p rem ix GR C o r o f stand a rda g e d sp r a y e d G RC .

Figure 4.2 (a)

C u r v e T y p e A :Rep resen t a t i ve t ens il e l oad -ex t ens ion d iag ram fo r GR C .

Figure 4.2 (b)

C u r v e T y p e B :Rep resen ta t i ve t ens il e load -ex tens ion d iag ram fo r GR C .

I n b o t h o f t h e se d i a g r a m s, t h e i n i t i a l l in e a r p o r t i o n o f t h e c u r v e ,Re g i o n 1 , is d e t e r m i n e d b y t h e f i b r e s a n d m a t r ix a c t i n g t o g e t h e ras an e last i c com p os it e , t h e st i f f ness and st ress be ing g i ven byt h e a p p r o p r i a t e v er si o n o f t h e La w o f M i x t u r e s . T h u s f o re x a m p l e :

Eq u at io n 1 Ec = k 1k 2k 3EfV f+ Em V man dEq u at io n 2 c = Ec c = ( k 1k 2k 3 EfV f + Em V m ) ci .e.Eq u at io n 3 c = k 1k 2k 3 fV f+ m V m

w h e r eE = Yo u n g s M o d u l u sV = Vo l u m e f r ac t i o n = St ra in = S t ressk = Ef f ic ien cy fac t or

(Fo r a m o re d e ta i l ed t heo re t i ca l ana l ys is see C hap te r 5 o f Re f .1 2 )

T h e su b sc r ip t s c , f a n d m d e n o t e c o m p o si t e , f i b r e an d m a t r ixrespec t i ve l y. T he f ib re p rop e r t y t e rm s i n t h ese equa t i o ns arem o d i fi e d b y e f f ic i en c y f a ct o r s k1 , k 2 , k 3 , w h i c h m a y n o t b eiden t i ca l i n bo th eq ua t i o ns bu t a re usua l l y sim i l ar i n va lue . T heytake accoun t o f t he e f f ec t s o f t he use o f f i b res i n f i n i t e l eng ths(k 1) , i n bund les o r s t r ands ( k 2) a n d o r i en t e d i n d i f f er e n t d i r ec t i o n s(k 3) .

A t a b o u t t h e m o r t a r f a il u r e st r e ss, c r ac k s p r o p a g a t e a r o u n d t h eg l a ss fi b r e s a n d t h e s u b s eq u e n t b e h a v i o u r d e p e n d s u p o nw h e t h e r t h e f i b r e s a r e su f f ic i en t t o c a r r y t h e l o a d ( t y p e A ) o r n o t( t ype B ) . T h i s t r ans i t i ona l po in t o f t he cu rve i s des igna ted t heb e n d - o v e r p o i n t ( B O P ) .


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I n G RC d esign a ted t yp e A , t he g lass f i b res ac t as re in fo r c i nga g e n t s . M o v i n g a w a y f r o m t h e c r a c k f a ce , lo a d i s t r a n sf e rr e db a c k f r o m f i b r e t o m a t r ix , b y sh e a r f o r c es a t t h e f i b r e m a t r ixi n t e r f ac e a n d i n t h e m a t r ix , u n t i l t h e s t r ess an d st r a in i n t h em a t r i x has aga in r i sen t o f a i l u re l eve l and a new c rack is f o rm ed .T h i s con t i nu es un t i l t he m a te r i a l i s t r ave rsed b y an a r ray o f ve ryf i ne c racks - o f t en d i f f i cu l t t o see - a t a spac ing gove rned by t hem a t r i x s t r e n g t h , b o n d s t r e n g t h a n d f i b r e c o n c e n t r a t i o n ( R e g i o n

2 ) . O n f u r t h e r l o a d i n g t h e f ib r e s sl ip a n d t h e e x i st i n g c r a ck sw i d e n ( R eg i o n 3 ) . I n t h e se w a y s r e g i o n s o f c o n si d e r ab l ee x t e n s i o n , a n d h i g h e n e r g y a b s o r p t i o n a r e i n t r o d u c e d .

T he U l t im a te Tens il e St reng th (U T S) a r ises w hen t he b r i d g in gf i b res ac ross one pa r t i cu la r c rack a re e i t he r b roken o r pu l l ed ou to f t h e m a t r ix , a lt h o u g h t h e f ai lu r e i s g r a d u a l ra t h e r t h a n a b r u p t( Re g i o n 4 ) .

T h e c r it e r i o n f o r f i b r e s b r e a k in g o r p u l li n g o u t o f t h e m a t r ixd e p e n d s u p o n t h e l en g t h o f f ib r e em b e d d e d i n t h e m a t ri x an dt h e s t r en g t h o f t h e b o n d . T h e r e i s a c r it i c al l en g t h o f st r a n da b o v e w h i c h t h e s t r an d w i ll a lw a y s b r e a k i f t h e f r ac t u r e p l an e i sa t t h e m i d - p o i n t o f t h e s t r an d , b u t i f t h e st r a n d h a s sh o r t e r t h a nha l f t h i s c r i t i ca l l eng th on e i t he r s i de o f t he f r ac tu re p lane , t hest r a n d w i ll a lw a y s p u l l o u t . T h e c r i t i c al l en g t h i s p r o p o r t i o n a l t ot h e s t r en g t h o f t h e f i b r e s a n d i n v e r se l y p r o p o r t i o n a l t o t h ep h y si c al sh e a r b o n d b e t w e e n t h e f i b r e a n d m a t r ix . I t a lsod e p e n d s u p o n t h e st r an d g e o m e t r y.

I n G R C d e s ig n a t e d t y p e B , t h e U T S o c c u r s sl ig h t l y a b o v e t h el e v el o f t h e B O P, a f t er w h i c h t h e l o a d d r o p s (Re g i o n 2 ) t o a l ev e lw h i ch t he f i b res can sus ta in (R eg ion 3 ) , t he f i b res subsequen t l yb e i n g b r o k e n o r p u l l e d o u t o f t h e m a t r ix . T h e v al u e s f o r l o a d i nRe g i o n 3 w i ll d e p e n d o n t h e a m o u n t , o r ie n t a t io n , l en g t h a n dst r e n g t h o f t h e f i b r e .

P rac t i ca l t est s (Re f . 10 and 11 ) dem on st ra te t h e f eatu res o f t ypesA a n d B u p t o t h e m a x im u m l o ad s , a lt h o u g h t h e t r an si t io nb e t w e e n Re g i o n s 2 a n d 3 o f t h e t y p e A i s o f t e n d i ff i cu l t t ode t ec t . T ype A GR C i s cha rac te r i zed by v i s ib l e m u l t i p l e c rack ingo f t h e sa m p l e w h e r e as t y p e B m a t e r ia l o f t e n h a s o n l y o n e v i si b l ec rack .

M o s t t e st i n g m a c h i n e s a r e u n a b l e t o d e t e c t t h e r e g i o n s a f t er t h eU T S, b u t t h e se c a n b e d e m o n st r a t e d ( Re f . 3 ) b y u si n g sp e c i a lt e st e q u i p m e n t .

4.3 Compressive St ress-St rain Curves for GRC

T he s t ress-st ra i n cu rv e o f GR C w hen tes ted i n com pression i sl in e a r u p t o h i g h st r e sse s a n d i s si m i la r t o t h e c u r v e w h i c h w o u l db e o b t a in e d f r o m t e st i n g t h e m a t ri x w i t h o u t a n y f ib r e .

Figure 4.3

Re p r e se n t a t i v e l o a d - c o m p r e ssi o n d i a g r a m f o r G RC .

T h e e f fe c t o f f ib r e d e p e n d s o n t h e o r i en t a t i o n o f t h e f i b r ere la t i ve t o t h e d i r ec t i on o f t h e com pressi ve st r ess; f ib res runn ingp a r a ll e l t o t h e d i r e c t i o n o f c o m p r e ssi o n c r e at e f r a c t u r e p l a n e sw h i c h c an r e d u c e t h e c o m p r e ssi ve st r e n g t h t o a b o u t 7 0 % o fva lues ob ta ined i n t es t i ng ac ross t h e p lane o f f i b res (Re f . 4 ) . T hecom pressi ve st r eng th o f G RC i s seve ra l t im es t h e t ens i le st r eng th .

4.4 Bending Str ess-Str ain Curves for GRC

C o n si d e r in g a r ec t a n g u l a r G R C b e a m su b j ec t t o b e n d i n g a n da ssu m i n g a l in e a r st r a in d i st r i b u t i o n t h r o u g h t h e b e a m u p t of a il u r e as i n Si m p l e B en d i n g , t h e u p p e r su r f a c e o f t h e b e a m w i llb e i n c o m p r e ssi o n a n d t h e l o w e r su r f a c e in t e n s io n . Fo r a g i v enst ra in , t h e st r esses i n t h e GR C m us t f o l l ow th e t ens i le andco m p ressive st ress-st ra in cu rves .


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Figure 4.4 (a)

Schem at ic st ress-st ra in c urv es fo r G RC

U p to t he t ens i l e B OP s t ra in t he resu l t i ng s t r ess d i s t r i bu t i onrem a ins l i nea r. A bo ve th e B OP st ra in t h e d i st r i bu t i on o f s t r ess onth e t ens i le si de o f t he n eu t ra l ax i s chan ges , and t o sa t i sf y t h e l awo f f o r ce eq u i l i b r i um (To t a l Tens il e Fo rce = T o ta l C o m pressi veFo rce ) t h e neu t ra l ax i s m oves t ow a rds t he com pressi ve si de ,w h i c h a g a i n c a u se s a r e d i st r i b u t i o n o f s t r ess t h r o u g h t h eth ickness .

I f app a ren t st r ess and s t ra i n a re ca l cu la ted f r om sim p le ben d in gtheo ry , t he resu l t i ng bend ing s t ress -s t ra i n cu rve l i e s be tw een thecom pressi ve and t ens i le cu rves. It con ta ins tw o p o in t s o f i n te res t ,t h e e l ast i c li m i t , c o m m o n l y t e r m e d t h e L im i t o f Pr o p o r t i o n a l it y( L O P ) an d t h e h i g h e s t c al c u la t e d s t r ess, t e r m e d t h e M o d u l u s o fRu p t u r e (M O R) .

Figure 4.4 (b)

Schem at ic st ress-st ra in cu rves fo r G RC.

I f t he t ens i le and com pressi ve st r ess-st ra i n cu rves fo r an yp a r t i c u l ar sp e c i m e n o f G R C ar e k n o w n , t h e b e n d i n g c u r v e c anbe es t im a ted (R ef . 3 and 5 ) . (T he reve rse ope ra t i o n can a l so b ep e r f o r m e d , b u t w i t h m o r e d i f f i c u l t y ) . S u c h a n e s t i m a t e o f t h eb e n d i n g c u r v e su g g e st s t h e L O P is si m i la r t o t h e B O P, b u tp r a c t i c al t e st s sh o w t h e L O P t o b e a b o u t 1 . 7 t i m e s t h e B O P.H o w e v e r, b r i t t l e m a t e r ia ls o f t e n sh o w h i g h e r st r e n g t h i n b e n d i n gth an i n t ens ion (R e f. 6 ) so t h i s i s no t su rp r i s ing .

T h e M O R i s f o u n d t o b e ab o u t 2 . 5 t i m e s t h e U T S f o r m o stva r i a t i ons o f GR C com po si t i on an d t h i s has been j u st i f i edth eo re t i ca l ly (R e f . 5 ) .

4.5 Str ain-to-Failure of GRC

T h is m easu re i s usua l ly assoc ia ted w i t h t ens il e o r b end ing t es t s o fG R C a n d i s t h e st r a in a t w h i c h t h e U T S o r M O R i s a c h i ev e d .

4.6 The Eff ects of Orientat ion of Glass Fibre

T he f i b re i s on l y ab le t o p rov ide s t reng th and s t i f f ness i n t hed i r e c t io n o f t h e f i b r e . Fi b r e s w h i c h a r e n o t a l i g n e d w i t h t h ed i rec t i on o f s t r ess ac t i n a l ess e f f i c ien t m ann e r t han t h ose t ha ta r e. H e n c e , a c o m p o si t e w i t h t h e f i b r e s a ll a li g n e d i n o n ed i r e c t io n w i ll p r o v i d e m a x i m u m r e si st a n c e t o s t r e ss i n t h a td i r ec t i on . A pa r t f r o m som e spec ia l i st p rocesses, i t i s no tp rac t i ca l l y feasib le t o m ake use o f t h i s o r i en t a t i on p rop e r t y t o i t sm a x im u m e ff ec t .


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I n t h i n s ec t i o n p r o d u c t s, t h e m a jo r s t r esse s a r e n o r m a ll y i n t h ep l a n e o f t h e s ec t i o n a n d a d v a n t a g e c a n b e t a k en b y u s in gsp r a y ed G RC w h i c h l ay s d o w n t h e f ib r e i n a r an d o m 2 -d i m e n si o n a l a rr a y in t h e p l a n e o f t h e m a t e r ia l. In t h i s w a y t h ee f f i c iency f ac to r k 3 (S ec t i on 4 .2 ) i s abou t tw i ce as h igh as f o rp r e m i x G RC w h e r e t h e f ib r e s a r e r a n d o m l y o r ie n t a t e d i n 3 -d i m e n si o n s an d f o r m G R C w h i c h i s vi r t u a ll y i so t r o p i c . T h e u s e o fC h o p p e d St r a n d M a t s i n p r e m i x G RC e n a b l e s t h e p r o p e r t i e s t o

a p p r o x i m a t e t o t h o s e o f sp r a y e d G RC a s l o n g a s t h e r e i ssu f f ic ien t g lass f ib re present .

A f u r t h e r e f f ec t o f o r i en t a t i o n i s o n t h e q u a n t i t y o f f ib r e t h a t c a nb e i n c o r p o r a t e d i n t o t h e m a t r ix . T h e p a c k in g d e n s it y o f t h e g l assf i b r e st r a n d s i s h i g h e r i f t h e r e is so m e d e g r e e o f a li g n m e n t a n dt h i s sh o w s i n t h e m a n u f ac t u r e o f G RC , w h e r e 5 % b y w e ig h t( 4 . 1 % b y v o l u m e ) is c o m m o n l y u se d i n sp r a y ed G RC , b u t o n l y3 . 5 % b y w e ig h t ( 2 . 9 % b y v o l u m e ) is u se d i n p r e m i x G RC .

T h e e f f ec t o f o r i e n t a t i o n a l so n e e d s t o b e c o n s id e r e d i n aneg a t i ve sense . I f t h e f ib res are assum ed to be rand om lyo r i e n t a t e d ( i n e i t h e r 2 o r 3 d i m e n s i o n s ) , t h e n u n i n t e n t i o n a la l ign m en t o f t he f i b res m ay g i ve r i se t o p lanes o f w eakness. T h i sc a n a r ise i n t h e m a n u f a c t u r e o f p r e m i x G RC i f t h e m i x i s b a d l yp l a c e d . M a c h i n e sp r a y e d G RC , a n d o c c a si o n a l ly h a n d sp r a y e dG R C , c an b e su b j e ct t o p r e f e re n t i a l al ig n m e n t o f t h e f i b r e s a n d i tm a y b e a d v i sa b l e t o m e a su r e p r o p e r t i e s i n t w o d i r ec t i o n s ( Re f .7 ) .

T he m os t obv ious ef f ec t o f o r i en ta t i on a r i ses i n t h e d i f f e ren tshea r p rop e r t i es o f sp rayed G RC .

4.7 Shear Strength of GRC

I f t he shea r st r esses a re con f i n ed t o t he p lane o f t h e GR C , t hem easu red i n -p lane shea r st r eng th i s sim i l ar t o t he U T S. T h i sf o l lo w s lo g i c al ly i f t h e m a t e r ia l is assu m e d o r t h o t r o p i c o ri so t ro p i c , because the shea r st r ess sho u ld equ a l

w h e r e is Poisson 's Rat io

H o w eve r , i f t he re i s a shea r s t r ess ou t o f t h e p lan e o f sp rayedG R C , t h e r e w i ll b e a c o m p l e m e n t a r y i n t e r l am i n a r sh e a r st r e ssw h i c h i s n o t r e si st e d b y a n y c o n t r i b u t i o n f r o m t h e f i b r e s. It c a nb e p o st u l a t e d t h a t t h e i n t e r l am i n a r sh e a r st r e n g t h o f sp r a y e dG R C w i ll b e si m i la r t o t h e m a t r ix s h e ar st r e n g t h o r t o

and p rac t i ca l r esu l t s sup po r t t h i s (Re f . 4 ) .

4.8 Impact Resistance of GRC

I m p a c t l o a d s o n G RC n o r m a ll y i n f li c t d a m a g e o v e r a l o c al iz eda rea . T he p resence o f t he f i b res i n GR C res t r i c t s t he p ropaga t i ono f c racks ou t s ide t h e zone o f s t r essed m a te r i a l. T h i s dam age cano f t e n b e r e p ai re d w i t h n o d e t ri m e n t t o t h e G RC p r o d u c t s.

I m p a c t st r e n g t h o f G R C i s n o r m a ll y m e a su r e d u s in g a m o d i f ie dI zo d t e st m a ch i n e , o n sa m p l e s 2 5 - 5 0 m m w i d e an d 6 - 1 2 m mth i ck . T he va lues ob ta ined i n such a t es t a re o f l i t t l e use excep t

f o r t h e p u r p o s e o f c o m p a r i s o n w i t h s a m p l e s o f G R C a n d o t h e rm a te r i a ls sub jec ted t o t h e sam e test . Such co m pa r i son s sho wt h e i m p a c t st r e n g t h o f G R C t o b e h i g h e r t h a n t h a t o f m a n ysim i l ar m a te r i a ls.

T h e i m p a c t st r e n g t h o f G R C i s h i g h w h e n m a n y l o n g f ib r e s f a ilb y b e i n g p u l l ed o u t o f t h e m a t r ix , t h i s p r o c e s s a b so r b i n g a g r e a td e a l m o r e e n e r g y t h a n f i b r e b r e ak a g e . H o w e v e r, t h i s i m p l i e s

re la t i vel y l ow va lues f o r t h e f ac to r s k1 a n d k 2 i n e q u a t i o n s 1 a n d2 ( S ec t i o n 4 . 2 ) , i n d i c a t i n g t h a t t h e f i b r e s a r e u se d s o m e w h a t l e sse f fi c ie n t l y i n t e r m s o f t h e G R C st r e n g t h .

T h e i m p a c t st r e n g t h o f G RC i s l o w e r w h e n f e w f i b r e s a r e p u l le dou t o f t he GR C . I f t he f i b res have a ve ry sho r t c r i t i ca l l eng th ( seeSe c t i o n 4 . 2 ) t h e G R C m a y e x h i b i t b r i t t l e ch a r a c t er i st i c s u n d e ri m p a c t l o a d s .

4.9 Elast ic M odulus and Poissons Rat io of GRC

T h e El ast i c M o d u l u s o f G RC u su a l ly q u o t e d i s t h e g r a d i e n t o f t h ein i t i a l l inea r p a r t o f t h e t en si l e st r ess-st ra i n cu rve . W h i l e i t shou ldb e p o s si b l e t o o b t a i n v a lu e s f r o m b e n d i n g t e st s, m o stc o m m e r ci al t e st i n g m a c h i n e s a r e t o o so f t t o g i v e a n a c cu r a t ev a lu e w i t h o u t u s in g so m e c o r r e ct i o n f a c t o r .

A l t h o u g h t h e L aw o f M i x t u r e s ( Se c t i o n 4 . 2 ) ap p l ie s, it c a n b esh o w n b y t h e i n se r t io n o f a n y r e a so n a b l e v al u e s i n e q u a t i o n 1t h a t t h e c o m p o si t e m o d u l u s i s n o t si g n i f i ca n t l y d i f f er e n t f r o mt h e m o d u l u s o f t h e m a t r ix . P ra c t ic a ll y m e a su r e d v a l u e s a r e n o t i nd i s a g r e e m e n t w i t h t h i s .

T he sam e reason ing app l i es t o t h e va lue o f P o i sson s Ra t i o w h i chi s a lso s im i la r t o t h a t o f t h e m o r t a r m a t r ix .

4.10 Effect of Ageing on GRC

I n c o m m o n w i t h m a n y m a t er ia ls t h e p r o p e r t ie s o f G R C c an a l t e rw i t h t i m e . Th e d e g r e e t o w h i c h t h e p r o p e r t ie s c a n c h a n g ed e p e n d s u p o n t h e f o r m u l at i o n o f t h e G RC a n d i t s w o r k in ge n v i r o n m e n t .

M o st G R C is m a d e f ro m a c em e n t / sa n d m a t r ix r e in f o r ce d w i t hst r a n d s o f g l a ssf ib r e w h i c h a r e c o m p o se d o f 1 0 0 - 2 0 0 f il a m e n t s .Fresh G RC exh ib i t s a h igh d eg ree o f f l exu ra l t ou gh ness ( Im pac tSt r e n g t h ) . T h i s i s p a r t l y d u e t o t h e f a ct t h a t t h e c e m e n t p a st e i ssu r r o u n d i n g r a t h e r t h a n p e n e t r a t i n g t h e st r a n d . C r a c k en e r g y i sd i ssi p a t e d a t t h e st r a n d - m a t r ix i n t e r f a c e a n d a lso w i t h i n t h est r a n d b u n d l e i t se lf . A s t h e c e m e n t c o n t i n u e s t o h y d r a t e o v e rl o n g p e r i o d s o f t i m e t h e v o i d s b e t w e e n t h e i n d i v i d u a l f i l a m e n t si n t h e st r a n d b e c o m e p r o g r e ssi v e ly f i ll e d w i t h h y d r a t i o np r o d u c t s f r o m t h e f r e e l i m e a n d t h e c o m p o s i t e b e c o m e s l e s scapab le o f abso rb ing c rack ene rgy . T he re i s al so an e f f ec t a r isi ngf r o m t h e r e ac t io n p r o d u c t s b u i l d in g u p o n t h e su r f ac e o f t h ef ib res th em se lves. These c rea te st ress ra isers on th e sur face o f th ef i b r e w h i c h r e su l t s in a r e d u c t i o n i n t h e f i b r e st r e n g t h e v e nt h o u g h t h e r e i s n o si g n i f i c an t r e d u c t i o n i n t h e f i b r e d i a m e t e r.

T h e m i c ro - c r a ck c o n t r o l m e c h a n i sm a s d e sc r ib e d i n Se c t i o n 4 . 1i s r e l at i ve l y una f f ec ted si nce t h e f i b re i s a lw ays m any t im esst r o n g e r t h a n t h e m a t r ix .


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T h e n e t e f fe c t o f a g e i n g o f s t an d a r d s p r a ye d G RC i s so m er e d u c t i o n i n F l e x u r a l a n d I m p a c t S t r e n g t h a c c o m p a n i e d b y a ni n c r e ase i n t h e e la st i c r e g i o n u p t o t h e L i m i t o f P r o p o r t i o n a li t y a st h e b o n d b e t w e e n t h e f i b r e s a n d m a t r ix i n c r e ase s a n d t h ec e m e n t c o n t i n u e s t o h y d r a t e . T h e se c h a n g e s ar e t e m p e r a t u r ea n d m o i st u r e d e p e n d e n t a n d u s e o f t h i s is m a d e i n a c c el e ra t i n gt h e e f f ec t t o d e t e r m i n e l o n g t e r m b e h a v i o u r ( Re f . 9 ) . Re a l t i m ea g e i n g t e st s in a v a r i et y o f e n v i r o n m e n t s d e m o n st r a t e t h a t

m e c h a n i c al p r o p e r t ie s l ev e l o u t e v e n u n d e r t h e m o s t a d v e r sec o n d i t i o n s. T h e l o n g t e r m p r o p e r t i e s a r e st a b l e .

T h e f o r m a t i o n o f h y d r a t io n p r o d u c t s i s d e p e n d a n t o n t h e m a t ri xf o r m u l at i o n . M o d i f y in g t h e m i x d e si g n t o i n c lu d e p o z zo l an i cm a t e r ia ls su c h a s C e m - St a r w h i c h r e a c t w i t h t h e f r ee l im e h a st h e e f f ec t o f r e d u c i n g t h e c h a n g e s i n m e c h a n i c al p r o p e r t i es b yl im i t in g t h e d e v el o p m e n t o f t h e b o n d b e t w e e n h y d r a t io np r o d u c t s a n d f i b r e s. T h e d e g r e e o f im p r o v e m e n t d e p e n d s u p o nt h e a m o u n t a n d r e a c t i v i t y o f t h e p o z z o l a n u s e d .

M a t ri x -d o m i n at e d p r o p e r t ie s d o n o t c h a n g e si g n i fi ca n t l y w i t ht i m e a lt h o u g h c o n d i t i o n s in s e r v ic e c a n a f fe c t p r o p e r t i e s su c h

e l ast i c m o d u l u s a n d L O P w h i c h a r e lo w e r in d r y c o n d i t i o n s t h a ni n w e t c o n d i t i o n s. Th e m i x d e si g n o f m o st G R C fo r m u l a t i o n s i sc h a r a c t e r i s e d b y h i g h e r c e m e n t c o n t e n t s a n d l o w e rw a t er / c e m e n t r at i o s t h a n i s c o m m o n w i t h m o r t a rs a n dc o n c r e t e s. T h e se a re f ac t o r s w h i c h a r e k n o w n t o i m p r o v e t h ed u r a b i li t y o f ce m e n t i t i o u s p r o d u c t s .

T he gene ra l e f f ec t o f age ing on t he s t r ess -s t ra i n behav iou r o fst a n d a r d G R C c a n b e i ll u st r a t e d b y t h e f ig u r e s 4 . 1 0 ( a ) a n d 4 . 1 0( b ) . G R C w h i c h i n i t i a ll y f o l lo w s a t y p e A c u r v e ( sp r a y e d G RC ,h i g h f i b r e c o n t e n t ) w i ll e x h i b i t a g r a d u a l d e c r e ase i n U T S a n ds t ra in - t o - f a i l u re un t i l i t app roaches t he t ype B cu rve . GR C w h ichi n i t i al ly f o l l o w s a t y p e B b e h a v i o u r ( p r e m i x G R C , lo w e r f ib r e

c o n t e n t ) w i ll o n l y e x h i b i t a c h a n g e i n t h e v a l u e o f st r e ss f o r t h et a i l p o r t i o n o f t h e c u r v e .

Figure 4.10 (a)

C u r v e T y p e ARep resen t a t i ve t ens i le l oad -ex t ens ion d iag ram

Figure 4.10 (b)

C u r v e T y p e BRep resen ta t i ve t ens il e load -ex tens ion d iag ram fo r GR C .

T h e f o l l o w i n g t a b l e g i v e s a su m m a r y o f t h e g e n e r a l e f fe c t s o fa g e i n g o n t h e v a r i o u s p r o p e r t ie s o f G R C c o m p o si t e s. Fu r t h e ri n d i c a t i o n s o f t h e m a g n i t u d e o f t h e e f f ec t s a n d r a t e s o f c h a n g ef o r sp e c i f ic f o r m u l a t io n s ar e g i v e n i n C h a p t e r 5 .

Table 4.10

Pr o p e r t i e s o f G R C A g e d i n W e t C o n d i t i o n s an d f o l lo w i n g a nIn i t ia l S t ress-St ra in Curve in Tens ion o f :

Type A Type B

BO P Lit t le C h an g e Lit t le C h an g e

U TS* D ec reases t o st ab le level Lit t le C h an g e

C om pressi ve St reng th L it t l e C hang e L it t l e C hang e

LO P Lit t le C h an g e Lit t le C h an g e

M O R* D ecreases t o st ab le level Lit t le C h an g e

Stra in- t o - fa i lu re* D ecreases sub stan t ia l l y L i t t l e Ch ang e

In -Pl ane Shea r St reng th L it t l e C hang e L it t l e C hang e

In ter lam inar Shear Stren gt h* D ecreases to s tab le leve l Decreases

Im pac t St reng th * D ec reases sub stan t i a l ly L it t l e C hang eM o d u l u s L it t l e C h a n g e L it t l e C h a n g e

Poisson s Rat io L i t t l e Ch ang e L i t t l e Ch ang e

*Th e se ch a n g e s w i l l b e sm a l le r a n d ta k e m u c h lo n g e r to o c c u r w i th

m o d i f i ed m a t r i c e s su c h a s Cem -Sta r GRC.


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4.11 References

1 . A vesto n J. , C oo pe r G.A . , and K e ll y A . , Sing le and M u l t i p l eFrac tu re T he P rop e r t i es o f F ib re C om po si t es, IPC S c iencea n d T e c h n o l o g y Pr e ss, 1 9 7 1 , p p 1 5 - 2 6 .

2 . N a ir N . G . , RI LEM Sy m p o si u m , M e c h a n i c s o f G l a ss Fi b r eRe i n f o r c ed C e m e n t , Fi b r e Re i n f o r ce d C e m e n t & C o n c r e t e ,

T h e C o n st r u c t i o n P r e ss L t d . , 1 9 7 5 , p p 8 1 - 9 3 .

3 . Law s V. and W a l ton , P. L . , RlLEM Sym po sium , T he Tens i le -B end ing Re la t i onsh ip f o r F ib re Re in fo r ced B r i t t l e M a t r i cesTe st i n g a n d T e st M e t h o d s o f Fi b r e C e m e n t C o m p o si t e s, T h eC o n st r u c t i o n Pr e ss LW . , 1 9 7 8 , p p 4 2 9 - 4 3 8 .

4 . O a k le y D . R. , 2 n d I n t e r n a t i o n a l Sy m p o si u m , T h eM echan i ca l P rope r t i es o f G lass Re in fo r ced C em en tC o m p o si t e s , W e i t g e sp a n n t e Fl ac h e n t r a g w e r k e, S FB 6 4 ,1 9 7 9 , p p 1 6 0 - 1 6 7 .

5 . Law s V. , T he Re la t i onsh ip B e tw een Tens il e & B end ingPr o p e r t i e s o f N o n - Li n e a r C o m p o si t e M a t e r ia ls Jo u r n a l o fM a t e r ia ls Sc i en c e , 1 9 8 2 , Vo l . 1 7 , p p 2 9 1 9 - 2 9 2 4 .

6 . Roa rk R.J. , Fo rm u las f o r St ress & St ra in 5 th Ed i t i on ,M c G r aw - H il l I n c ., 1 9 7 5 p p 1 9 8 - 1 9 9 .

7 . B S6 4 3 2 : 1 9 8 4 , B r it i sh St a n d a r d M e t h o d s f o r D e t e r m i n i n gp ro pe r t i es o f g l ass f i b re re in fo r ced cem en t m a te r i a l.

8 . L i t he r l and K .L. , O ak ley D .R. and P roc to r B.A . , T he U se o fA cce le ra ted A ge ing P rocedu res t o P red i c t t he Long T e rmSt r en g t h o f G R C C o m p o s it e s C e m e n t & C o n c r e t eResea rch , Pe rgam on P ress L td . , 198 1 , V o l . 11 , pp 4 55 -46 6 .

9 . G R C A M e t h o d o f t e st fo r st r e n g t h r et e n t i o n o f g l assf i b r e i nc e m e n t s a n d m o r t a r s. T h e G l assf i b r e Re in f o r c e d C e m e n tA sso c i a t io n G R C A S 0 1 0 4 / 0 1 8 4 , Ja n u a r y 1 9 8 4 .

10 . O ak ley D .R. & P roc t o r B .A . , T ens i le St ress St ra in B ehav iou ro f G lassf i b re Re in fo r ced C em en t C om po si t es , RILEMSy m p o si u m , Fi b r e Re i n f o r c ed C e m e n t & C o n c r e t e, Th eC o n st r u c t i o n P r e ss L t d . , 1 9 7 5 , p p 3 4 7 - 3 5 9 .

11 . P roc t o r B .A . , O ak ley D .R. & W ieche rs W. , T ens i leSt ress /S t ra in Charac ter is t ics o f Glass f ib re Re in forcedC e m e n t , C o m p o si t e s - St a n d a r d s Te st i n g & D e s ig n , IPCSc i en c e & Te c h n o l o g y Pr e ss, 1 9 7 4 , p p 1 0 6 - 1 0 7 .

12 . GR C M a jum bd a r A . J. and l aw s V. , G lass f i b re Re in fo r cedC em en t B SP P ro fession a l bo oks , B lackw e l l, 199 1 ISB N 0 -6 3 2 - 0 2 9 0 4 - 8 .

N o te : P as t P roceed ings o f t he b ienn ia l C ong resses o f t heGlassf i b re Re in fo r ced C em en t A ssoc ia t i on a re a usefu l sou rce o fa d d i t i o n a l i n f o rm a t io n .


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5. MECHANICAL PROPERTIES OF GRC( Se e al so C h a p t e r 5 A p p e n d i x A f o r im p r o v e d d u r a b i li t y C e m - FI L St a r G RC )

T h e m e c h an i c al p r o p e r t ie s o f G RC d e p e n d u p o n t h e m i xf o r m u l a t i o n a n d t h e p r o c e ssi n g m e t h o d u s ed . T h i s c h a p t e r g i v e si n i t i al p r o p e r t y v a l u e s f o r a f e w c o m m o n l y u se d f o r m u l a t io n s,sh o w s t h e e f f e ct o f a g e u p o n t h e se p r o p e r t ie s a n d g i v e si n d i c a t i o n s o f t h e e f f e ct o f v a r ia t i o n s i n f o r m u l a t io n u p o n t h ei n i t i al a n d a g e d p r o p e r t i es.

5.1 Typical Initial Property Values

T he rang es o f va r i ous m echan i ca l p ro pe r t i es a re sum m ar i sed i nTab le 5 .1 f o r G RC fo rm u la t i on s sub jec ted t o a sat i sf ac to r y cu r i ngr e g i m e a n d t e st e d a t 2 8 d a y s. I t i s i m p o r t a n t t o r e al ise t h a t G RCis a re la t i ve l y low w / c ra t i o m a te r i a l and because o f it s t h i nse c t i o n , i t c a n , an d w i ll , d r y o u t p r e m a t u r i ly i f it i s n o t k e p t i n ah u m i d en v ir o n m e n t .

A n i d e a l c u r i n g r e g i m e f o r a G R C c o m p o n e n t i s t o c o v e r t h ep r o d u c t in t h e m o u l d i m m e d i at e ly a ft e r m a n u f a c t u r e w i t h ap o l y t h e n e sh e e t u n t i l d e m o u l d i n g a n d t h e n s t o re it i n a h u m i d ,p r e f e r ab l y > 9 5 % RH , e n v i r o n m e n t a t 1 5 - 2 0 C f o r a fu r t h e r 7days .

A l t e rn a t i v e ly , t h e u se o f a i r c u r in g p o l y m e r s, w h i c h w i ll f il m f o r min t h e m ix and sea l i n t h e m o is tu re , w i l l g i ve sim i l ar r esu l t s . A l lm a n u f a c t u r e r s sh o u l d r e g u l ar l y c h e c k t h e i r p r o d u c t s f o rm e c h a n i c al p r o p e r t i e s.

Table 5.1

Typical Initial Mean Property Values of Cem-FIL GRC

T h e v a lu e s sh o w n a r e t h o s e at c o m p l e t i o n o f c u r e an d a r e f o rg u i d a n c e o n l y . Th e y e n c o m p a ss v a r ia b i l it y i n q u a l it y a n d , i n t h ecase o f m ach ine sp rayed GR C , t he an i so t rop y ( i . e. p re fe ren t i a l

o r i e n t a t i o n o f t h e f i b r e i n o n e d i r e c t i o n ) w h i c h m a y o c c u r .

A c h i e v em e n t o f t h e se p r o p e r t i e s i n p r a c t ic e r e q u i r e s a d e q u a t ec a r e , q u a l i t y c o n t r o l a n d c u r i n g d u r i n g m a n u f a c t u r e .

I n fo r m a t io n o n t h e t e st m e t h o d s u se d t o o b t a i n t h e se p r o p e r t yva lues, i n c lud in g som e d i scussion o f t he m e r i t s o f t h e t est s andt h e v a l u e s o b t a i n e d c a n b e f o u n d i n Re f . 1 t o 5 a n d Re f . 1 5 . ( S eea lso C h a p t e r 1 1 . 2 . )

5.2 Effect of Age on the Initial Property Values

T h e l ist o f p r o p e r t y g i v e n i n T ab l e 5 . 1 c a n b e d i v i d e d i n t o t h o se

w h i c h a r e s t r o n g l y l i n k e d t o t h e q u a l i t y o f t h e m a t r i x a n d t h o s ew h i c h a r e st r o n g l y l i n k e d t o t h e g l a ss f i b r e c o n t e n t .

5 . 2 . 1 M a t r i x D e p e n d e n t P ro p e r t ie s

T h o se p r o p e r t i es w h i c h a r e m o r e d e p e n d e n t u p o n t h e m a t ri xa re com pressi ve st r eng th , m od u lus , Po i sson s r a t i o , LOP, B OPa n d t h e i n t e r l a m i n a r sh e a r st r e n g t h .

T h e se p r o p e r t i es v a r y l it t l e w i t h t h e a g e o f t h e G RC , b u t m a yi n c r e ase m a r g i n a ll y in h u m i d e n v i r o n m e n t s a s t h e c e m e n t i n t h em a t r ix c o n t i n u e s t o h y d r a t e .

T h e r e is a m o r e o b v i o u s v ar i at i o n b e t w e e n t h e s e p r o p e r t i esd e p e n d i n g o n t h e m o i st u r e c o n t e n t o f t h e G RC , d r y G R Ce x h i b i t i n g p r o p e r t y v a l u e s l o w e r t h a n w e t G R C .

5 .2 .2 G la s s Fib re De p e n d e n t P ro p er t i e s

T h o s e p r o p e r t i es w h i c h a r e m o r e d e p e n d e n t u p o n t h e g l a ss f i b r ea r e t h e i m p a c t st r e n g t h o f a ll t y p e s o f G R C a n d t h e M O R, U T S,s t ra in - t o - f a i l u re and i n -p lane shea r s t r eng th o f sp rayed GR C .

F i gur e 5 . 2 . 2

T y p i c al Va r ia t i o n w i t h T i m e o f St r e n g t h o f st a n d a r d 5 % C e m - FI L

H a n d Sp r a y G R C a t W a t e r : C e m e n t R at i o 0 . 3 3 - 0 . 3 6 .


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Propert y Unit s Hand Spr ay [st andard Vibrat ion

or Cem-FIL Star ] Cast Premix

D ry b u lk d en sit y ( t / cu . m et re) 1 .9 -2 .1 1 .9 -2 .0

C o m p ressive st ren g t h M Pa 5 0 -8 0 4 0 -6 0

Elast ic M o d u lu s G .Pa 1 0 -2 0 1 0 -2 0

Im pac t St ren g t h kJ/ m 2 1 0 -2 5 1 0 -1 5

Po isso n 's Rat io 0 .2 4 0 .2 4

LO P M Pa 7 -1 1 5 -8

M O R M Pa 2 0 -3 0 1 0 -1 4Direct Tension :

BO P M Pa 5 -7 4 -6

U TS M Pa 8 -1 1 4 -7

St rain t o Fai lu re % 0 .6 -1 .2 0 .2 -0 .6

Shear:

In -p lan e M Pa 8 -1 1 4 -7

In t er lam in ar M Pa 3 -5 N .A.


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T w o c u r v e s a r e sh o w n h e r e , d e p i c t in g t h e e f f ec t o f h o t w a t e rage ing (R e f . 6 ) . T hese cu rves a re show n fo r hand sp ray GR C( Ta b l e 5 . 1 ) a n d a r e sc a le d a c c o r d i n g t o t h e t i m e sp e n t i n h o tw a t e r a n d t h e e q u i v al e n t a g e ( Re f . 6 ) i n U . K . w e a t h e r. T h em e t h o d o f a c ce l er a t in g t h e a g e i n g o f G RC h a s b e e n d e v e lo p e df rom resea rch ove r a p e r i od o f 25 yea rs. I t has been assessed b yc o n t i n u i n g c o r r e l a t i o n w i t h r e a l - t i m e d a t a f r o m G R C e x p o s e d i nm a n y c l i m a t e s a r o u n d t h e w o r l d f o r p e r i o d s u p t o 2 0 y e a r s .

T h e r el at i o n sh i p b e t w e e n d a y s i n h o t w a t er a n d n a t u r alw e at h e r in g d e p e n d s u p o n t h e m e an a n n u a l t em p e r at u r e o f t h ee x p o su r e c o n d i t io n s . W a r m , h u m i d e n v i ro n m e n t s w i ll p r o d u c em o r e r ap i d r e d u c t i o n s in p r o p e r t ie s, le a d i n g t o t h e sa m e lo n gte rm stab le values.

T h e c u r v e s d e p i c t t y p i c a l va r ia t i o n s o f M O R a n d U T S o f t h i ss t a n d a r d f o r m u l a t i o n o f G R C m a d e w i t h C e m - F I L f i b r e .

F o r s tanda rd GR C , t hese cu rves show the p rope r t i es dep i c tedd e c r e a si n g w i t h t i m e t o a st a b l e lo n g t e r m l im i t i n g v a l u e . I t is

o b v i o u s l y i m p o r t a n t i n t e r m s o f d e s i g n a n d c o n f i d e n c e i n G R Ct h a t t h e lo n g - t e r m p r o p e r t i es a r e k n o w n a n d t h i s h a s b e e n t h esub jec t o f m uch i nves t i ga t i on an d d i scussion (R e fs. 6 , 7 , 8 and9 ) . I m p a c t s t r e n g t h , st r a in t o - f a il u r e a n d i n - p l a n e sh e a r st r e n g t ha l so show dec reasing p rop e r t y l eve ls ove r sim i l ar t im e pe r i od s,ach iev ing s tab le va lues a f t e r abou t 150 days i n w a te r a t 50C .A n e st i m a t e o f t h e l o n g t e r m st a b l e p r o p e r t y v a lu e s o f t h e G RCf o r m u l a t i o n s f r o m Ta b l e 5 . 1 i s sh o w n i n Ta b l e 5 . 2 .

Table 5.2

Est im a ted Lon g T e rm Stab le Prop e r t y V alues f o r s tanda rdC em -FIL GRC

T h e r e d u c t i o n i n p r o p e r t i e s i s c o n s id e r a b l y r e d u c e d i n d r ye n v i r o n m e n t s ( le ss t h a n a b o u t 5 0 % RH ) . ( Re f .7 ) a n d a lso b y t h euse o f a C em -FIL Sta r m a t r i x .

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