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ABRAMS (1924) - Design of Concrete Mixtures | Construction Aggregate | Concrete

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DESIGN. ”OF CONCRETE MIXTURES’ BY DUFF A. ABRAMS PiWFESSOR IN CHARGE OF LABORATORY The design o~ concrete mixtures is. a subject of vital interest to akl &ineers h.d constructors who have to do with concrete work. The problem involved may be one of the following: 1, 2. 3. 4. W$o;k~ is necessary to produce concrete of proper strength for a given at min. is best .With given materials irnwn cost? what proportions of will givi the best concrete which With different lots of materials suited fo
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  D ES   G N . O F CO N C   E   E   X   U   ES   B Y D U   A . A BR A M S P i   SS OR N C H A RG   O   L A BOR A TOR Y T h ede s i g n o ~ co n c r e t emi x t u r e s i s . a s u b   e c t of v i t a li n t e r e s tt o a k l   i n ee r s h .d co n s t r u c t o r s w h o ha v e t o d o w i t h co n c r e t e w o r k . T h ep r o blemi n v o l v edm a y be o n e of t h e fo ll o w i n g : 1,2.3.4.   o; k ~i s n e c e ss a r y t o p r o d u c e co n c r e t e of p r o pe r s t r e n g t h fo r a g i v e n .   i t h g i v e n m a t e r i a l s w ha t p r o p o r t i o n s w ill g i v i t h ebe s t co n c r e t e a t mi n .i r n w n co s t ?   i t h di ff e r e n t l o t s of m a t e r i a l s of di ff e r e n t c ha r a c t e r i s t i c s w h i c h i s be s t s u i t ed fo r t bep u r p o s e ?   ha t ~ s t h ee ff e c t O . s t r e n g t h ofco n c r e t e f mm c han g e s i n m ix , c . o ns i~ t e n q o   s u x an d g r a di n g of a gg r e g a t e ? P mp O ~ t i O ? i n g co n c r e t e f r eq u e n t l y ,i n v o l v e s   e c t i   of m a t e r i a l s a S~ c] l   t h ei r co mbm ah o n . In g e n e r a l, t h eq u e s t i o n of r e Ia t l v e co s t s i s a l s o p r e s e n t . T h e t e r m “ D e s i g r l ” ii u s edi n t h e. t i t le of t h i s a r t i c le a s di s t i n g u i s h ed f r o m “ p r o p o r t i o n i n g ” s i n c ei t i s t h ei n t e n t i o n t o impl y t ha t e a c h eleme n t of t h ep r o blemi s a pp r o a c h ed w i t h   delibe r a t ep u r p o s ei n v ie ww h ~ c bi s g u ided h y a r a t i o na lme t h o d of a cco mpli s bmm t , “ ___ T h ede s i g n ofco n c r e t emi x t u r e s , w i t ha v ie w t o p r o dll c ill g a g i v e n r e s u l t i n t l,em o s t e co n o mi c m ann e r ,i n v o l v e s m an y co mpli c a t i o n s   w bi c b ha v e h e r e t ofo r ede f ied ana l y s i s . M an y di ff e r e n t me t h o d s of p r o p o r t i o n i n g h p v ebee n s u gg e s t ed ; t h em o s t im.p o r t an t o n e s m a y be c ha r a c t e r i z ed a s fo ll o w s : 1.2.3.4.5. A r h i t m r y s ele c t i o n , w c ha s 1 : 2 ; 4mi x , w i t h o u t r e f e r e n c e t o t h e s i z em g r a di n g of t h e t i n e an d co a r s e a gg r e g a t e ; D e n s i t y of a gg r e g a t e s i n w h i c h t h ee n de a v o r i s m a de t o s e c u r e ana gg r e g a t e of m a x im u mde n s i t y ; D e n s i t y ofco n c r e t ei n w Y , c h t be a tt emp t i s m a de t o s e c u r e co n c r e t e of m a x im u mde n s i t y ; Sie v e ana l y s i s ,i n w h i c h t h e g r a di n g of t h e a gg r e g a t e s i s m a de t o a pp r o x - im a t e s o mep r ede t e r mi n ed s ie v e ana l y s i s c u r v e w h i c h i s co n s ide r ed t o g i v e t h ebe s t r e s u l t s ; s u r f a c e a r e a of a gg r e g a t e s . I t i s a m a tt e r ofco mm o n e x pe r ie n c e t ha tt h eme t h dd of a r h i t m r y s ele c t i o n i n , w h i c h f i x edq uan t i t ie s off i n e a “ d co a r s e a gg r e g a t e s a r emi x ed w i t h o u t r e g a r d t o t h e s i z e an d g r a di n g of t h ei n di v id ua lm a t e r i a l s ,   f a r f r o m s a t i s f a c t o r y ., O u r e x pe r i - me n t s ha v e s h o w n t ha tt h e o t h e r me t h o d s me nh o n ed a b o v e a m a l s o s u b   e c tt o s e r m u s limi t a t i o n s .   e ha w fo un d t ha tt h em a x im u m s t r e n g t h ofcc m c r e t ed o e s n o t depe n dmei t h e r m a gg r e g a t e of ,m a x im u mde n s i t y o r a co n c r e t e of , nu yz i n mmde n s i t y , an d t ha tt h eme t h o d s w h , c hha v ebee n s u gg e s t ed fo r p r o p o r t l o m n g co n c r e t eb y s ie v em a l y s i s of a gg r e g a t e s a r eb a s ed o n me rr o n e o u s t h e o r y . A ll of t h eme t h o d s of p r o p o r t i c x g cc m. r e t e w h i c hha v eb : . ” p r o p o s ~di n t bepm Ih , a v e f a iled t o g i v ep r o pe r , a tt e n t l o n . t o t be   w a t e r co n t e n t o   t h emm. O u r e x pe r m x m t a .1 w o r k b a s emp ha s i z ed t h e nn p c m t an c e of t h e w a t e r q co n c r e t emm t u r e s , an d, s h p w n , t b a tt h e w a t e r i s ,i n f a c t , t h em ? s t imp o r t an t   n q r ed g . t , s i n c e v e r y s m a ll v a r m t m n s m. y . t . r co n t e n t p r o d c w em o r e t mp o r t an t vM m t mmm t h e s t r e n g t han d o t h e r p r o pe r t ie s ofco n c r e t e t han s imil a r c han g e s i n t h e o t h e r i n g r edie n t s .   R .   i . t . d f   o m M i nu t e s o f t h e A .. u a l   ee t i n go f t h e Po   t l an d C eme n t A ss o c i a t io n,h e l d i n N e w ?   k , D ecem b e   , 1918.  2STRUCTUR A L M A T   R I A LSR   S   A RC H L A B O R A r O R Y N e w S f . d ie s of C o .. r e t . ML r t u r .. D u r i n g t h e p as ~ t h r ee y e a r sa l a r g e nu m be r of i n v e s t i g a t i o nsha ” ebee nun d e r w a y a tt h eS t r u c tt i r a l M a t e r i a l s Re s e a r c h L a b o r a t o r y ,Le w i sIns t i t u t e,C h i c a g o , w h i c h t h r o w co ns i d e r a ble n e w li g h t o n t h e su b J e c t of p r o p o ~ t l o .i n g co . c r e t  T h e s ei m e s t i g a t i o nsa r ebei n g c a rr   e d o u tt h r o u g h t h e coo p e r a t m n of t h e Ins t d n t e an d t h e P o r t l an d Ce m e n t A ss oc i a t i o n .T h e s e s t u d ie sha v e co v e r e d an i n v e s t i g a t i o n of t h ei n t e r - r el a t i o n of t h e fo ll o w i n g f a c t o r s : 1.T h e co ns i s t e n c y   q uan t i t y of m i x i n gw a t e r ) .2,T h e s ize an d g r a d i n g of a gg r e g a t e s .,3.Tbe m i x   p r o p o r t i o n ofc e m e n t ) . A n y co mp r ebe. s i y e s t u d y of p r o p o r t i o n i n g co n c r e t e m us tt ak ei n t o a cco un t a ll of t h e s e f a c t o r s . D u r i n g t h   s p e r   o d a b o u t 50,0   X l t e s t sha v ebee n c a rr ie d o u t w h i c hha v e a be a r i n g o n t h i ssu b   e c t .T h e s e t e s t sha v ebee : l a r g el y co n f i n e d t oco mp r e ss i o n t e s t s ofco n c r e t e an dm o r t a r   .T h e s e m v e s t , g a t l o? sha v e gw mm an e w i ns i g h t i n t o t h e f a c t o , r s w h i c hun d e r be t h e co rr e c t p r o p o r t i o n i n g ofco n c r e t e m i x t u r e san d sh o w t h eli m , t a t i o m ofo l d e r m e t h o d s .Ce r t a i n p has e s of t h e s ei n v e s t i g a t i o nsa r e s t a ll un d e r w a y ,T h e fo ll o w i n g m a y be m e n t i o n e d asa m o n g t h e m o s t i mp o r t an t p r i n c i p le s   w h i c hha v ebee n e s t a bli sh e d w i t h r e f e r e ?c e t o t h e d e s i g n of . co n c r e t e m i x t u r e s .1 “ a b r ie f r e p o r t of t h m k i n d i t i s i mp r a c t i c a ble t o p r e s e n t m o r e t hanan o u t li n e of t h e m e t h o d s of a pp l y i n g ~be p r i n c i p le ? t o p . r a c t l c a l P r o ble m s . In o nh   a f e w i ns t an c e s ... - a r ee x p e r i m e n t a l d a t a g   v e n o n w h i c h t h e s e co n c l us m nsa r eb as e d .1.   i t h g l v   e n co n c r e t e m a t e r i a l san d co n d i t i o ns of t e s tt h eq uan t i t y of m i x i ? gw a t e r us e dd e t e r mm e s t h e s t r e n g t h of t h e co n c r e t e, s o l o n g as t h e mm n of a w o r ka ble p l as t i c i t y .2.T h e s ie v e ana l y s i s f u r n i sh e s t h e o n l y co rr e c t b as i s fo r p r o p o r t i o n i n g a ~ g r e g a t e s m co n c r e t e m i x t u r e s .3. A s i mp le m e t h o d of m e asu r i n g t h ee cc t i v ,e s ize an d g ~ a d i n g of ana g - g r e g a t e has bee n d e v el o p e d .T h i s gw e s r , s e t o a f un c t i o nkn o w nas t h e~ “ f i n e n e ss m o d u l us ” of t be a m z r e x a t e. . 4.Tbe f i n e n e ss m o d u l us of t be a gg r   g a t e f u r n i sh e sa r a t i o na l m e t h o d fo r co m bi n i n g m a t e r i a l s of d i ff e r e n t s ize fo r co n c r e t e m i x t u r e s .5.Tbe s ie v e ana l y ~i s c u r v ~ of t h e a gg r e g a t e m a y be w i d el y d i ff e r e n t i n fo r m w i t h o u t e x e r t nu ? an y u d h c n c e o n t h e co n c r e t e s t r e n ii t h .6. A gg r e g a t e of eq u ~ v a l~q t co n c r e t e - m ak i n g c i ua l~ t ie s m a ; b. p r o d u c e d b y an m f i m t e nu m be r of d , ff . r e n t g r a d i n g s of a gw e n m a t e r ] a l.7. A gg r e g a t e s of eq u i v a le n t co n c r e~e - m ak i n g q ua li t ie s m a y be p r o d u c e d f r o mm a t e r i a l s of w , d el y d i ff e r e n t s ,ze an d g r a d i n g .8. In g e n e r a l, f i n   an d . co a r s e a gg r e g a t e s of w i d el y d i ff? r : n t s ize o r g r a d i n g c an be co m b m e dm su c ha m ann e r as t o p r o d u c e s m n b m r e su l t s i n m “ - .   e t e . 9.T h e ? gg , -c g a t e g pd i,, gw bi, c h p r o d u c e s t f ie s t r o n g e s t co n c r e t ei s “ d t ha t g   v ? n g t h eq =x l m u md   n ~   t y   l Ow e s t vO , d s ) .. A g r a d i n g co a r s e r t han t ha t w   , m g m a x , m u l n d e ns , t y ,, n e c e ssa r y f O r h i g h e s t co n c r e t e t r e n g t h .10.T h e r i c h e r t h e m i x ,T h e co a r s e r t h e g r a d i n g sh o dd be fo r ana gg r e g a t e of  i~e n m a x   m u m s , = ; h e n c   , t h e g r e a t e r t h e d i s c r e p an c y be t w ee n m a x - i m u md e ns i t y an d be s t g r a d i n g 11. A mmp ~e t e ana l~ s ,i s of t h e w a t e~ - r eq~i r c m c n t s ofco n c r e t e sh o w s t ha tt h eq uan t , t y of m , x m gw a t e rr eq m r e d , s g o v e r n e d b y t be fo ll o w ; n g f a c t o r s :  a ) T h e co n d i t i o n of “ p l as t i c i t y ” m “ w e, - ka bili t y ” ofco n c r e t e w h i c h m us t be us e d - t h e r el a t i v e co ns i s t e n c y ;  b ) T h e, n o r m a l co ns i s t e n c y of t h e c e m e n t ; c) T h e s ize an d g r a d i n g of t h e a gg r e g a t e ;
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