ABSTRACT
Abstract It h a s been rep o r ted th a t su ita b le q u a n tity of the v is c o s ity a g en t W elan gu m , a kind of n atu ra l w ater so lu b le p o ly sa cch a r id e , is very e f f e c t i v e f o r s t a b i l i z i n g th e r h e o l o g i c a l p r o p e r t y o f s e l f - c o n so lid a t in g co n cr e te . In th is rep ort, we have ju st stu d ied b a sic properties of Welan gum exp erim en tally and effects of Welan gum for fresh con crete such as se lf - co n so lid a tin g p rop erty . A s a resu lt, we understand that v iscosity of Welan g u m ’s w ater sol. is not affected by ca lc iu m co n cen tra tio n and pH, excep t for a litt le b it h igh v isc o s ity in a l k a l i n e s o l u t i o n . A n d w e le a r n e d th a t it s t a b i l i z e s th e r h e o l o g i c a l p r o p e r t y a n d m o b i l i t y in s m a l l s p a c e o f s e l f - c o n so lid a t in g con crete to apply su ita b le q u an tity of W elan gum for co n crete , in a d d itio n , the product p rov id es lo n g - te r m s ta b ility and im proves se lf - con solidatin g property in wide range of s lu m p -flo w . Wfe m ade clear p artia lly how the product provides these effects. Keywords: p o ly sa cc h a r id e , rh eo lo g ica l p rop erty , se lf - co n so lid a tin g concrete, s lu m p -flo w , welan gum
1 Introduction
Self - co n so lid a tin g concrete has been stud ied and developed in lo ts of lab oratory in stitu tio n s, since it w as advocated by P ro fessor O kam ura at T okyo U n iv ers ity in J a p a n [ l] . N ow th is con crete is ap p lied for n ot o n ly g e n e r a l c o n s tr u c t s b u t h u g e s c a le c o n s tr u c t s and very im p ortan t co n stru c ts . T h is se lf - con so lid a tin g concrete is defined as
a con crete, w hich h as ex ce llen t se lf - c o n so lid a tin g and tra n sfig u r in g p ro p ertie s , w hich can be ca st in to every nock and corn er in fo rm s w ith o u t u s in g v ib r a to r s , w h ich is e a s y to a vo id d e fe c ts su ch as shrinkage at the tim e of hardening at e a r ly -a g e step, and which has a lo n g -te r m d urab ility . The report by D r.K .O zaw a in dicates that these p roperties can be estim ated through two tests , slum p flow test and V type fu n n el te s t [2 ] .
