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U n i t e S t a t e s a t e n t [ 1 9 ] [ 1 1 ] 4 , 2 5 6 , 5 0 4D u n s t a n , J r . [ 4 5 ] M a r . 1 7 ,1 9 8 1

[ 5 4 ] FLY ASH-BASED CEMENT [ 5 6 ] R e f e r e n c e sC i t e d

[ 7 5 ] I n v e n t o r : E d w i nR . D u n s t a n ,J r . , L a k e w o o d , U ~ s ~PATENT DOCUMENTSColo- 2 803 556 8/1957 Carlsson e t a 1 . . . . . . . . . . . . . . . . . . . .. . 106/109

[ 7 3 ] A s s i g n e e : The Uni ted s t a t e s o f America a s 3 , 8 5 4 , 9 6 8 1 2 / 1 9 7 4 M l n n l c ke t a 1 . . . . . . . . . . . . . .. . l 0 6 / D I G . 1

r e p r e s e n t e d b y t h e S e c r et a r y o f t h e P r i m a r yE x a m i n e r J a m e sP o e rI n t e r i o r ,Wa s h i n g t o n ,DC. A t t o r n e y ,A g e n t , o r Firm-William . B r o w n ;D o n a l dA .

G a r d i n e r[ 2 1 ] A p p l . N o . : 8 5 , 4 5 2

_ [ 5 7 ] ABSTRACT

{ 2 2 ] F l l e d : o c t ' 1 6 1 9 7 9 A e m e n tc o m p o s i t i o n c o m p r i s i n ga h i g h c a l c i u m - c o n[ 5 1 ] I n t . C l . 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . C04B 11/10 t e n t ?y a s h and calcium s u l f a t e , and mortar an d con[ 5 2 ] U S . C l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 1 0 6 / 1 0 9 ; 1 0 6 / 1 1 0 ; C r e t e c o m p o s i t i o n sc o n t a i n i n g t h e c e m e n t .

106/DIG. 1[ 5 8 ] F i e l d o f S e a r c h . . . . . . . . . . . . . . . .. . 1 0 6 / 0 9 , D I G . 1 , 1 1 0 5 C l a i m s ,N0 Drawings

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FLY ASH-BASED CEMENT

F l y a s h , t h e r e si d u e c o l l e c te d i n t h e ? u e s o f c o a lb u m i n g p o w e r p l a n t s, h a sb e e n u s e d a s a component o fc o n c r e t e a d m i x t u r e st o r e p l a c e a p o r t i o n e . g . ,a b o u t 1 0

t o 2 5 p e r c e n t , o f t h e c o n v e n t i o n a l l y - e m p l o y e dP o r t l a n dc e m e n t . T h i s c o m b i n a t i o no f f l y a s h a n d P o r t l a n d c ement a f f o r d s a s u b s ta n t i a l r e d u c t i o n i n c o s t s i n c e t h e ?ya s h c o s t s m u c h e s st h a n P o r t l a n d c e m e n t . F u r t h e r m o r e ,P o r t l a n d c e m e n t p r o d u c t i o nr e q u i r e s l a rge a m o u n t so fe n e r g y a n d , c o n s e q u e n t l y , u s eo f ?y a s h r e d u c e s e n e r g ydemand.

I t h a s n o w b e e n f o u n d , a c c o r d i n gt o t h e p r e s e n t i nv e n t i o n , t h a t a cement c o m p r i s i n ga h i g h c a l c i u m - c o nt e n t?y a s h a n d c a l c i u ms u l f a t eh a s s i m i l a r a d v a n t a g e s ,b u t t o a m u c h g r e a t e r d e g r e e s i n c e a l l o f t h e P o r t l a n dc e m e n ti s r e p l a c e d w i t h much l e s se x p e n s i v em a t e r i a l s ,a n d t h e e n e r g y r e q u i r e d t o p r o d u c et h e c o m p o s i t i o n so ft h e i n v e n t i o n i s m i n i m a l .

F l y a s h i s t h e r e s i d u e o f powdered c o a l b u r n e d i np o w e r p l a n t s a t t e m p e r a t u r e s g e n e r a l l y i n e x c e s s o f2 5 0 0 F . The c h e m i c a lmakeup o f t h i sr e s i d u e i s a f u n ct i o no f t h e c o a l b u r n e db y t h e p o w e r p l a n t . I n p a r t i c u l a r ,t h e a m o u n to f c a l c i u mb o u n di n g l a s s p a r t i c l e si n t h e ?ya s h v a r i e s over a w i d e r a n g e . I t has been found a s onea s p e c t o f t h e p r e s e n t i n v e n t i o n , t h a t a c a l c i u m c o n t e n ti n e x c e s s of about 2 0 p e r c e n t , and p r e f e r a b l y i n e x c e s s o f2 6 p e r c e n t , b y w e i g h t o f t h e f l y a s h i s e s s e n t i a lt oa c h i e v e m e n to f t h e n e c e s s a r y c o m p r e s s i v es t r e n g t h t op e r m i t t o t a lr e p l a c e m e n to f P o r t l a n d c e m e n t . C a l c i u mc o n t e n t o f t h e ?y a s h i s r e a d i l y d e t e r m i n e dby convent i o n a l means s u c h a s t h a t o u t l i n e d i n ASTM e s i g n a t i o nC l l 4 , C h e m i c a lA n a l y s i s o f H y d r a u li cC e m e n t ,w i t ht h e r e s u l t su s u a l l y b e i n g r e p o r t e d a s p e r c e n t CaO.

T h e c a l c i u m s u l f a t e ,which c o n s t i t u t e s t h e o t h e r e ss e n t i a li n g r e d i e n t o f t h e c e m e n t c o m p o s i t i o n o ft h ei n v e n t i o n , may b e o f many f o r m s , b u t i s p r e f e r a b l ya n h y d r o u s o r i n t h e f o r m o f t h e h e m i h y d r a t e , i . e . ,CaSO4.H2O p l a s t e ro f p a r i s ) .I t may c o n s i s to f a n h yd r i t e ,a n a t u r a l l y o c c u r r i n g CaSO4 o r i t m a y b e p r ep a r e d b y d e h y d r a t i o no f h y d r a t e d c a l c i u ms u l f a t es u c ha s gypsum. O p t i m u m amounts o f t h e c a l c i u m s u l f a t ew i l ld e p e n do n t h e s p e c i ? c f l y a s h a n d c a l c i u ms u l f a t ee m p l o y e d .S u i t a b l ea m o u n t s , h o w e v e r ,w i l lg e n e r a l l yr a n g e f r o m a b o u t 5 t o 1 5 p e r c e n t by w e i g h t .

S i n c e t h e s e t t i n go f t h i sc e m e n tc o m p o s i t i o n ,i . e . ,t h ec o m b i n a t i o no f h i g h - c a l c i u m?y a s h a n d c a l c i u m s u lf a t e ,i s t o o f a s tf o r m o s t a p p l i c a t i o n s , i t w i l lu s u a l l y b en e c e s s a r y t o a d d a r e t a r d e r a s a t h i r d i n g r e d i e n t of t h ec o m p o s i t i o n . M a t er i a l ss u i t a b l e f o r t h i s p u r p o s e a r et h o s e c o n v e n t i o n a l l ye m p l o y e df o rr e t a r d i n g t h e s e to fconventional cements such a s P o r t l a n d c e m e n t s . One

s u c h r e t a r d e r i s D a r a t a r d 1 7 ,a s o d i u ms a l to f l i g n o s u lf o n i c a c i d p r o d u c e db y W . R . G r a c e Company. S u i ta b l e amounts o f t h e r e t a r d e r w i l l g e n e r a l l y b e c o n s i d e ra b l y, e .g . 3 t o 4 t i m e s , g r e a t e r t h a n t h a t employed w i t hc o n v e n t i o n a l c e m e n t s . a n g e o f a b o u t 9 t o 1 2 ?uido z s . p e r hundred pounds o f cement i s u s u a l l y s a t i s f a ct o r y. Another good r e t a r d e r i s s o d i u mc i t r a t e ,a g r a n ul a r m a t e r i a l , which i s u s e d i n amounts o f a b o u t 0 . 0 5 t o0 . 3p e r c e n t b y w e i g h t o f t h e c e m e n t . L i q u i d r e t a rde r sa r e g e n e r a l l y added w i t h t h e water n s u b s e q u e n t u s eo ft h e c e m e n t , w h i l e g r a n u l a r r e t a r d e r s a r e p r e f e r a b l yadmixed w i t h t h e c a l c i u m s u l f a t e p r i o r t o a d d i t i o n o fwater.

20

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2The c e m e n tc o m p o s i t i o no f t h e i n v e n t i o n i s p r e p a r e d

b y t h o r o u g ha d m i x i n go f t h e f l ya s h a n d c a l c i u ms u l f a t e ,i n ? n e l y d i v i d e d f o r m , by c o n v e n t i o n a l m e a n s . S i n c et h e f l ya s h n o r m a l l yo c c u r s i n ? n e l y d i v i d e d f o r m ,m o s to f t e n c o l l e c t e d e l e c t r o s t a t i c a l l y as a d u s t , f u r t h e r r e d u ct i o n i s u s u a l l y n o t n e c e s s a r y. The c a l c i u m s u l f a t e i s

g e n e r a l l y a v a i l a b l e i n powder f o r m s u i t a b l ef o r a d m i xt u r e w i t h t h e ?y s h .P a r t i c l e s i z eo f t h e c a l c i u ms u l f a t es h o u l dbe s i m i l a r t o t h a t o f P o r t l a n d c e m e n t .Mortar o rc o n c r e t e c o m p o s i t i o n sm a y be p r e p a r e d from t h e c ement o f t h e i n v e n t i o nby a d d i t i o n o f c o n v e n t i o n a lmater i a l s ,i . e . , s a n d o r a combination of s a n d and an aggreg a t e s u c h a sg r a v e l , b r o k e ns t o n e s , p e b b l e s , c i n d e r s , e t c .These m a t e r i a l s , and t h e i r a m o u n t s , a r e e s s e n t i a l l y t h esame a s t h o s e employed with o t h e r r c e m e n t s , such a sPort land cements a n d a r e well known o those versedi n t h e a r t .

Use o f t h e cement a n d c o r r e s p o n d i n gm o r t a r a n dc o n c r e t e c o m p o s i t i o n so f t h e i n v e n t i o n a r e a l s o convent i o n a la n d c o n s i s t s i m p l y o f a d d i t i o n a n d a d m i x t u r e o f

water i n an amoun t s u f f i c i e n t t o form a p a s t e . T h eamount f w a t e r r e q u i r e d i s ,h o w e v e r ,g e n e r a l l y c o n s i de r a b l y l e s st h a n t h a t r e q u i r e d f o r P o r t l a n d cement conc r e t e s .Time r e q u i r e d f o r t h e r e s u l t i n g a d m i x t u r et o s e tu p and harden w i l l depend on t h e t e m p e r a t u r e , amounta n d t y p e o f e t a r d e r ,h a n d l i n g ,e t c .G e n e r a l l y, h o w e v e r ,se t t i m e s w i l l vary from about 1 5 m i n u t e s t o 2 h o u r s .

The i n v e n t i o nw i l l b e more s p e c i ? c a l l y i l l u s t r a t e dbyt h ef o l l o w i n g e x a m p l e .

EXAMPLE

A o r t a r was p r e p a r e dby a d m i x i n g6 7 5 grams o f a?y a s h f r o m Commanche P o w e r p l a n t , P u e b l o , C o l o . ,c o n t a i n i n g 3 2 p e r c e n tc a l c i u m ,w i t h 7 5 g r a m s o f ? n e ly

d i v i d e da n h y d r o u sc a l c i u ms u l f a t e .The l a t t e rwas p r ep a r e d b y d e h y d r a t i o n o ft e c h n i c a lg r a d e C a S O 4 . 2 H 2 Oa t 2 0 0 C . 3 0 2grams o f w a t e r , 3 . 4 cc o f Daratard l 7 ,and2 0 6 2g r a m s o f s i l i c as a n d g r a d e d a c c o r d i n gt o ASTMd e s i g n a t i o n C109 were a d d e d a n d t h o r o u g h l y mixedwith the c e m e n t t o f o r m a mortar w h i c h w a s thenf o r m e di n t o 2 -by 2 - i n c h c u b e s a c c o r d i n gt o t h e ASTMp r o c e d u r e . C o m p r e s s i v es t r e n g t h s o f t h e c u b e s w e r et h e n m e a s u r e d a c c o r d i n g t o t h e p r o c e d u r e o f t h eASTM r o c e d u r e . C o m p r e s s i v es t r e n g t h a t2 8 d a y s , t h emost common e f e r e n c e d s t r e n g t h , was 5770 l b / i n 2 .

By c o m p a r i s o n , c u b e s o fType I I P o r t l a n d c e m e n tmortar prepared and t e s t e d i n t h e same manner s h o w e da c o m p r e s s i v es t r e n g t h o f 5 5 4 0 l b / i n 2 ,w h i l e a m o r t a rc o n s i s t i n ge n t i r e l yo f ? y a s h a n d s a n d ,s i m i l a r l yp r ep a r e d a n d t e s t e d ,showed a c o m p r e s s i v es t r e n g t h o f3970 l b / i n 2 .

I c l a i m :1 . A e m e n tc o m p o s i t i o nc o n s i s t i n g e s s e n t i a l l yo f l )

a m a j o rp r o p o r t i o n o fa ?y a s h h a v i n ga c a l c i u mc o n t e n tgrea t e r t h a n a b o u t 2 0 p e r c e n t b y w e i g h ta n d 2 )a b o u t 5t o 1 5p e r c e n t by w e i g h to f c a l c i u ms u l f a t e .

2 . The c o m p o s i t i o no f c l a i m l . i n which t h e c a l c i u ms u l f a t ei s a n h y d r o u s .

3 . The c o m p o s i t i o n o fc l a i m 2 i n which t h e c a l c i u ms u l f a t ei s a n h y d r i t e .

I t . A o r t a r c o m p o s i t i o n c o m p r i s i n ga m a j o r p r o p o rt i o n o f s a nd and a minor p r o p o r t i o n o ft h e cemen t c o mp o s i t i o n o f c l a i m 1 .

5 . The c o n c r e t e c o m p o s i t i o n c o m p r i s i n ga m a j o rp r o p o r t i o n o f s a n dand an a g g r e g a t e and a minor prop o r t i o n o f t h e c e m e n t c o m p o s i t i o no f c l a i m 1 .

I It 1 1 0 i t