Homework about reading an article and write summary
( h ttp ://w ww.a cce ssscie nce .c o m .e zp ro xy2 .lib ra ry .d re xe l. e du/) H id e A pplic a tio n o f m ic ro bio lo gy in g eote ch nic a l e ngin eerin g A rtic le b y:
C hu, J ia n D epartm ent o f C iv il, C onstr u ctio n a nd E nvir o nm enta l E ngin eerin g, Io w a S ta te U niv e rs ity , A m es, Io w a. I v anov, V olo dym yr S ch ool o f C iv il a nd E nvir o nm enta l E ngin eerin g, N anya ng T e ch nolo gic a l U niv e rs ity , S in gapore . H e, J ia S ch ool o f C iv il a nd E nvir o nm enta l E ngin eerin g, N anya ng T e ch nolo gic a l U niv e rs ity , S in gapore . L ast u pdate d: 2 013 D OI: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l.e du/1 0.1 036/1 0978 542.Y B130098 ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l.e du/1 0.1 036/1 097 8 542.Y B130098) C onte nt E nhancin g s hear s tr e ngth o f s and o r to m ake a s tr o ng g ro und M it ig atio n o f s oil liq uefa ctio n d urin g e arth quakes b y u sin g b io gas S eepage a nd e ro sio n c ontr o l o r c onstr u ctio n o f a w ate r p ond in a d esert O utlo ok L in ks to P rim ary L it e ra tu re H ave y o u e ve r w ondere d h ow a h ig hris e b uild in g c a n b e c o nstr u cte d o n s o ft g ro und? T he a nsw er is th at th e s o ft s o il c a n b e im pro ve d b efo re th e c o nstr u ctio n o f th e h ig hris e b uild in g. In fa ct, b acte ria , c a n b e u se d to im pro ve th e e ngin eerin g p ro pertie s o f s o il. In th is a rtic le , th e a pplic a tio n o f th is m ic ro bia l a ppro ach to g eote ch nic a l e ngin eerin g, a d is cip lin e th at d eals w it h s o ils a nd fo undatio ns, is d is cu sse d.
T here a re a n um ber o f w ays to s tr e ngth en s o ft o r w eak s o il. O ne o f th e c o m mon o nes is to u se c e m ent o r c h em ic a ls to i n cre ase th e lo adb earin g c a pacit y o r th e s o c a lle d s h ear s tr e ngth o f th e s o il. T he s a m e p ro ce ss c a n b e u se d to r e duce th e w ate r c o nductiv it y o f s o il o r th e r a te o f w ate r flo w in s o il. T his is n ece ssa ry w hen th ere is a n eed to p re ve nt w ate r fr o m f lo w in g in th e g ro und, fo r e xa m ple , to c u t o ff th e flo w o f c o nta m in ate d g ro undw ate r. In th is c a se , c e m ent o r c h em ic a ls a re u se d a s b in ders a nd m ix e d w it h s o il to e it h er in cre ase th e s h ear s tr e ngth o r r e duce th e w ate r c o nductiv it y o f th e s o il.
H ow eve r, th e u se o f c e m ent o r c h em ic a ls fo r s o il im pro ve m ent is n ot s u sta in able in th e lo ng r u n, b eca use c e m ent a nd c h em ic a l p ro ductio n r e quir e a c o nsid era ble a m ount o f n atu ra l r e so urc e ( fo r e xa m ple , lim esto ne) a nd e nerg y. T he p ro ductio n p ro ce ss a ls o g enera te s c a rb on d io xid e, d ust, a nd p ossib ly o th er to xic s u bsta nce s a nd th us is n ot e nvir o nm enta lly fr ie ndly . T he u se o f c e m ent o r c h em ic a ls fo r s o il im pro ve m ent is a ls o e xp ensiv e a nd tim ec o nsu m in g.
T here is a n u rg ent n eed to d eve lo p n ew a nd s u sta in able c o nstr u ctio n m ate ria ls th at c a n r e duce th e n eed to u se c e m ent o r c h em ic a ls fo r g eote ch nic a l a pplic a tio ns.
U sin g th e la te st m ic ro bia l b io te ch nolo gy, a n ew ty p e o f c o nstr u ctio n m ate ria l, c a lle d b io ce m ent, h as b een d eve lo ped a s a n a lt e rn ativ e to c e m ent o r c h em ic a ls . B io ce m ent is m ade b y n atu ra lly o ccu rrin g m ic ro org anis m s a t a m bie nt te m pera tu re a nd t h us r e quir e s m uch le ss e nerg y to p ro duce . It is s u sta in able , b eca use m ic ro org anis m s a re a bundant in n atu re a nd c a n b e r e pro duce d e asily a t lo w c o st. T he m ic ro org anis m s th at a re s u it a ble fo r m akin g b io ce m ent a re n onpath ogenic a nd e nvir o nm enta lly fr ie ndly . F urth erm ore , u nlik e th e u se o f c e m ent, s o ils c a n b e tr e ate d w it h out d is tu rb in g th e g ro und o r th e e nvir o nm ent, b eca use m ic ro org anis m s c a n p enetr a te a nd r e pro duce th em se lv e s in s o il. H arn essin g th is n atu ra l a nd i n exh austib le r e so urc e m ay r e su lt in a n e ntir e ly n ew a ppro ach to g eote ch nic a l o r e nvir o nm enta l e ngin eerin g p ro ble m s a nd b rin g e norm ous e co nom ic b enefit to th e c o nstr u ctio n in dustr ie s. T he a pplic a tio n o f m ic ro bia l te ch nolo gy to c o nstr u ctio n w ill a ls o s im plif y s o m e e xis tin g c o nstr u ctio n p ro ce sse s. F or e xa m ple , th e b io ce m ent c a n b e in e it h er s o lid o r liq uid fo rm . In l iq uid fo rm , th e b io gro ut h as m uch lo w er v is co sit y a nd c a n flo w lik e w ate r. T hus, th e d eliv e ry o f b io ce m ent in to s o il is m uch e asie r c o m pare d w it h th at o f c e m ent o r c h em ic a ls . F urth erm ore , w hen c e m ent is u se d, o ne h as to w ait fo r 2 8 d ays fo r th e f u ll s tr e ngth to b e d eve lo ped, w here as w hen b io ce m ent is u se d, th e r e actio n tim e c a n b e m uch r e duce d o r c o ntr o lle d if r e quir e d.
T he p rin cip le o f m ic ro bia l tr e atm ent is to u se m ic ro bia lly in duce d p re cip it a tio n o f c a lc iu m c a rb onate o r o th er a ppro ach es to p ro duce b ondin g a nd c e m enta tio n in s o il s o a s to in cre ase th e s tr e ngth a nd r e duce th e w ate r c o nductiv it y o f th e s o il. A n um ber o f s tu die s h ave b een d one in r e ce nt y e ars . P re se ntly , m uch o f th e w ork is a t th e e xp erim enta l s ta ge. H ow eve r, th e s ca le o f tr e atm ent h as in cre ase d r a pid ly w it h tim e a nd h as r e ach ed 1 00 m in r e ce nt y e ars . T he m ic ro bio lo gic a l p ro ce sse s in duce c a lc iu m c a rb onate c ry sta ls , o th er m in era ls , o r s lim es, a s s h ow n b y M . V a n d er R uyt a nd W . v a n d er Z on ( 2 009), L . A . V a n P aasse n a nd c o lle agues ( 2 010), a nd J . C hu a nd c o lle agues ( 2 012). T hose m in era ls o r s lim es a ct a s c e m entin g a gents b etw een s o il g ra in s to in cre ase th e s h ear s tr e ngth o f s o il a nd/o r to fill in th e p ore s in s o il t o r e duce th e w ate r c o nductiv it y , a s s h ow n in F ig . 1 . T he tw o p ro ce sse s to in cre ase s tr e ngth a nd r e duce c o nductiv it y h ave b een c a lle d b io ce m enta tio n a nd b io clo ggin g, r e sp ectiv e ly . T he p ro ce ss to d eliv e r th e b io ce m ent in s it u to a ch ie ve b io ce m enta tio n o r b io clo ggin g is c a lle d b io gro utin g. In th e tr e atm ent o f s a ndy s o il, b eca use th e v is co sit y o f b io ce m ent g ro ut i s lo w , it is p ossib le to p um p it in to th e g ro und w it h out m ix in g. T his w ill e nable th e c o nstr u ctio n p ro ce ss to b e s im plif ie d. T he s tu die s s o fa r s h ow th at th e b io ce m ent m eth od is e ff e ctiv e in b oth in cre asin g th e s h ear s tr e ngth a nd r e ducin g th e w ate r c o nductiv it y o f s o il. S om e p ote ntia l a pplic a tio ns o f b io ce m ent a re d is cu sse d in th e fo llo w in g. 3 F ig . 1 S chem atic o f t h e b io cem enta tio n a nd b io clo ggin g p ro cesses. E nhan cin g s h ear s tr e n gth o f s an d o r t o m ake a s tr o ng g ro und B y u sin g th e m ic ro bia lly in duce d c a lc iu m c a rb onate p re cip it a tio n m eth od, th e s h ear s tr e ngth o f s o il c a n b e in cre ase d. W e k n ow fr o m o ur c h ild hood e xp erie nce b uild in g s a nd c a stle s o n th e b each th at d ry s a nd w ill n ot s ta nd. H ow eve r, w hen d ry s a nd is tr e ate d w it h b io ce m ent, it n ot o nly c a n s ta nd a s a c o lu m n, it c a n a ls o s u sta in a lo t o f w eig ht, a s s h ow n in F ig . 2 . W hen c e m ent o r c h em ic a ls a re u se d to tr e at s o il, th e a m ount o f im pro ve m ent in th e s h ear s tr e ngth o f th e s o il d epends o n t h e a m ount o f c e m ent o r c h em ic a l u se d. S im ila rly , w hen b io ce m ent is u se d, th e s h ear s tr e ngth o f th e s o il is a ff e cte d b y th e a m ount o f m eta l p re cip it a tio n. O ne w ay to m easu re th e s h ear s tr e ngth o f s o il is s im ply to c o m pre ss a s o il c o lu m n b etw een t w o r ig id p la te s, th e s o c a lle d u nia xia l c o m pre ssio n te st. T he s h ear s tr e ngth m easu re d b y th is m eth od is c a lle d th e u nia xia l c o m pre ssiv e s tr e ngth ( U CS). In a s tu dy b y M . V a n d er R uyt a nd W . v a n d er Z on ( 2 009), th e U CS o f b io ce m ent tr e ate d s a nd w as m easu re d fo r s p ecim ens h avin g d if f e re nt c a lc iu m c a rb onate c o nte nts . T he r e su lt s a re s h ow n in F ig . 3 . It c a n b e s e en th at th e U CS s tr e ngth in cre ase s w it h in cre asin g c a lc iu m c a rb onate c o nte nt. T he h ig hest U CS o bta in ed w as 2 7 M Pa.
F or n orm al a pplic a tio ns, th e U CS s tr e ngth r e quir e d is le ss th an 3 M Pa. T his w ill o nly r e quir e a c a lc iu m c o nte nt o f 1 00 to 2 00 k g /m . T o a ch ie ve th e s a m e U CS s tr e ngth fo r s a nd u sin g c e m ent g ro utin g, th e a m ount o f c e m ent r e quir e d w ould b e b etw een 2 50 a nd 3 00 k g /m . B eca use th e p ro ductio n o f b io ce m ent c a n b e c h eaper, th e o ve ra ll c o st fo r b io ce m ent g ro utin g c a n b e p ote ntia lly lo w er. 3 3 F ig . 2 S and c olu m n t r e ate d u sin g b io cem ent. M it ig atio n o f s o il liq uefa ctio n d urin g e arth quakes b y u sin g b io gas S oil liq uefa ctio n r e fe rs to a p henom enon in w hic h a s o il is tr a nsfo rm ed in to a s u bsta nce th at a cts lik e a liq uid in r e sp onse to a n e xte rn al a ctio n s u ch a s a n e arth quake . W hen liq uefa ctio n o ccu rs , th e g ro und c o m ple te ly lo se s it s b earin g c a pacit y a nd u nderg oes la rg e d efo rm atio n. S oil liq uefa ctio n n orm ally o ccu rs in s a tu ra te d s a nd d eposit s d urin g e arth quake s. T he g ro und s h akin g c a use s th e w ate r p re ssu re in th e s o il— th e p ore w ate r p re ssu re — to b uild u p. W hen th e p ore w ate r p re ssu re h as i n cre ase d to a c e rta in p oin t, s o il liq uefa ctio n o ccu rs . S oil liq uefa ctio n h as b een o ne o f th e m ajo r c a use s o f e arth quake r e la te d d is a ste rs . L iq uefa ctio n w as la rg ely r e sp onsib le fo r th e e xte nsiv e d am age to p orts a nd r e sid entia l p ro pertie s in th e e arth quake s in N ew Z eala nd a nd J a pan in 2 010 a nd 2 011 .
C om mon m eth ods th at c a n b e a dopte d fo r m it ig atio n o f s o il liq uefa ctio n in clu de d ensif ic a tio n a nd g ro und m odif ic a tio n u sin g c e m ent o r c h em ic a ls . A n ew a ppro ach th at is b ein g d eve lo ped is c a lle d th e b io gas m eth od. In th is m eth od, tin y g as b ubble s a re g enera te d in s it u in s a tu ra te d s a nd w here liq uefa ctio n m ay o ccu r. W hen s a tu ra te d s a nd is m ade s lig htly u nsa tu ra te d b y t h e in clu sio n o f g as b ubble s, th e a m ount o f p ore w ate rp re ssu re g enera tio n in th e s a nd u nder a d yn am ic lo ad is g re atly r e duce d. A cco rd in g to r e se arc h , if o nly a bout 5 % o f th e w ate r b y v o lu m e is r e pla ce d b y g as, th e liq uefa ctio n r e sis ta nce o f l o ose s a nd c a n b e in cre ase d b y m ore th an 2 tim es.
H ow eve r, it is n ot e asy to in tr o duce g as in to th e g ro und. P um pin g c a n b e u se d. H ow eve r, th e d is tr ib utio n o f g as b ubble s i n tr o duce d b y p um pin g w ill n ot b e e ve n. F urth erm ore , th e g as p um ped in to g ro und te nds to b e p re se nt in th e fo rm o f a ggre gate d g as p ocke ts r a th er th an in div id ual b ubble s. A s a r e su lt , th e g as te nds to e sca pe fr o m th e g ro und. O ne o f th e m ost e ff e ctiv e w ays to in tr o duce tin y g as b ubble s in s it u is to u se m ic ro org anis m s. T his m eth od h as th e fo llo w in g th re e a dva nta ges o ve r e xis tin g m eth ods. ( 1 ) B io ce m ent c a n flo w e asily in s a nd, m uch lik e w ate r. G ase s c a n b e g enera te d e asily b y b acte ria a nyw here u nderg ro und u sin g o nly a s m all a m ount o f e nerg y. T hus th e b io gas m eth od w ill b e m uch m ore c o st e ff e ctiv e th an a ny o th er m eth od. T he s ca le o f tr e atm ent fo r liq uefa ctio n is n orm ally v e ry la rg e, s o th e p ote ntia l e co nom ic b enefit is s ig nif ic a nt. ( 2 ) T he g as b ubble s g enera te d b y b acte ria c a n b e d is tr ib ute d m ore e ve nly th an b y o th er m eans. T his i s b eca use th e g as b ubble s a re g enera te d in s it u r a th er th an p um ped. ( 3 ) T he g as b ubble s g enera te d b y b acte ria a re tin y a nd le ss p ro ne to e sca pin g fr o m th e g ro und.
S om e m odel te sts u sin g a s h ake ta ble to g enera te g ro und m otio n w ere d one b y o ur r e se arc h g ro up. A c o m paris o n o f g ro und s e ttle m ent fo r a fu lly s a tu ra te d s a nd la ye r a nd a s a nd la ye r tr e ate d w it h b io gas is s h ow n in F ig . 4 . T he s e ttle m ent is e xp re sse d a s a s e ttle m ent r a tio , w it h th e s e ttle m ent fo r fu lly s a tu ra te d s a nd b ein g 1 00% . It c a n b e s e en fr o m F ig . 4 th at F ig . 3 U nconfin ed c om pre ssio n s tr e ngth ( U CS) v ers us c alc iu m c arb onate c onte nt f o r b io cem enttr e ate d s and. ( A fte r M . V an d er R uyt a nd W . v an d er Z on, 2 009 ) 2 w it h o nly 5 % g as r e pla ce m ent, th e g ro und s e ttle m ent g enera te d b y g ro und s h akin g w it h a n a cce le ra tio n o f 1 .5 m /s c a n b e r e duce d b y m ore th an 9 0% . T hus, th e b io gas m eth od is e ff e ctiv e in p re ve ntin g th e o ccu rre nce o f s o il liq uefa ctio n o r r e ducin g th e d am age c a use d b y liq uefa ctio n.
S eep ag e a n d e ro sio n c o ntr o l o r c o nstr u ctio n o f a w ate r p ond in a d esert B io ce m ent c a n a ls o b e u se d to r e duce th e w ate r c o nductiv it y o f s a nd th ro ugh th e b io clo ggin g m ech anis m , a s s h ow n in F ig . 2 . O ne m eth od th at h as b een d eve lo ped b y o ur r e se arc h g ro up is to u se u re are ducin g b acte ria to p re cip it a te a la ye r o f c a lc iu m c a rb onate o n to p o f s a nd, a s s h ow n in F ig . 5 . T his h ard la ye r o f c ru st h as a w ate r c o nductiv it y o f le ss th an 1 0 m /s a nd th us c a n b e u se d a s a n im perv io us la ye r fo r w ate r s to ra ge. T his m eans w e n ow h ave a m eth od fo r b uild in g a w ate r p ond in th e d ese rt. T he s a m e m eth od c a n a ls o b e u se d fo r e ro sio n c o ntr o l o f a b each o r r iv e rb ank. A s th e la ye r o f t r e atm ent is r a th er th in , th e a m ount o f b io gro ut u se d is s m all. T hus th e m eth od c a n b e m ore e co nom ic a l th an c o nve ntio nal m eth ods.
O utlo ok 2 F ig . 4 C om paris on o f g ro und s ettle m ent in duced b y g ro und s hakin g u nder a n a ccele ra tio n o f 1 .5 m /s f o r a s atu ra te d s and l a yer a nd a s and la yer w it h 5 % g as r e pla cem ent. 2 − 7 F ig . 5 F orm atio n o f ( a ) a t h in im perv io us la yer o n t o p o f s and u sin g t h e b io cem ent m eth od a nd ( b ) a w ate r p ond m odel b uilt u sin g t h is m eth od in s and. T he n ew c o nstr u ctio n m ate ria l, b io ce m ent, h as a n um ber o f a dva nta ges o ve r c e m ent o r c h em ic a ls fo r g eote ch nic a l a pplic a tio ns. S eve ra l p ote ntia l a pplic a tio ns e xis t fo r g ro und s tr e ngth enin g, m it ig atio n o f liq uefa ctio n, a nd s e epage o r e ro sio n c o ntr o l. T he n ew m ic ro bia l te ch nolo gy p ro vid es a m ore c o st e ff e ctiv e , s u sta in able , a nd e nvir o nm enta lly fr ie ndly s o lu tio n to g ro und im pro ve m ent. H ow eve r, a lo t o f r e se arc h s tu die s s till n eed to b e d one b efo re th is n ew a ppro ach c a n b e d eve lo ped in to c o m mon p ra ctic e .
S ee a ls o : B acte ria ( /c o nte n t/b acte ria /0 68100) ; C em en t ( /c o nte n t/c em en t/1 1 8400) ; E ngin eerin g g eo lo gy ( /c o nte n t/e n gin eerin gg eo lo gy/2 34000) ; F oundatio ns ( /c o nte n t/f o undatio ns/2 70400) ; G ro ut ( /c o nte n t/g ro ut/3 01600) ; M ic ro bio lo gy ( /c o nte n t/m ic ro bio lo gy/4 22200) ; S an d ( /c o nte n t/s an d/6 00600) ; S oil ( /c o nte n t/s o il/6 31500) ; S oil m ech an ic s ( /c o nte n t/s o il m ech an ic s/6 31900) J ia n C hu V olo dym yr Iv anov J ia H e L in ks t o P rim ary L it e ra tu re J . C hu, V . S ta bnik o v, a nd V . Iv a nov, M ic ro bia lly in duce d c a lc iu m c a rb onate p re cip it a tio n o n s u rfa ce o r in th e b ulk o f s o il, G eom ic ro bio l. J . , 2 9(6 ):5 44–549, 2 012 D O I: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 080/0 1490451.2 011 .5 92929 ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 080/0 1490451.2 011 .5 92929) V . Iv a nov a nd J . C hu, A pplic a tio ns o f m ic ro org anis m s to g eote ch nic a l e ngin eerin g fo r b io clo ggin g a nd b io ce m enta tio n o f s o il in s it u , R ev. E nvir o n. S ci. B io te ch nol. , 7 (2 ):1 39–153, 2 008 D O I: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 007/s 111 570 079 1263 ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 007/s 111 57 0 079 1263 ) J . K . M it c h ell a nd J . C . S anta m arin a, B io lo gic a l c o nsid era tio ns in g eote ch nic a l e ngin eerin g, J . G eote ch . G eoenvir o n. E ng. , 1 31(1 0):1 222–1233, 2 005 D O I: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 061/( A SC E)1 0900 241(2 005)1 31:1 0(1 222) ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 061/( A SC E)1 0900 241(2 005)1 31:1 0(1 222)) M . V a n d er R uyt a nd W . v a n d er Z on, B io lo gic a l in s it u r e in fo rc e m ent o f s a nd in n ears h ore a re as, G eote ch . E ng. , 1 62(1 ):8 1–83, 2 009 D O I: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 680/g eng.2 009.1 62.1 .8 1 ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 680/g eng.2 009.1 62.1 .8 1) L . A . v a n P aasse n e t a l. , Q uantif y in g b io m edia te d g ro und im pro ve m ent b y u re oly sis : L arg es ca le b io gro ut e xp erim ent, J . G eote ch . G eoenvir o n. E ng. , 1 36(1 2):1 721–1728, 2 010 D O I: h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 061/( A SC E)G T.1 9435 606.0 000382 ( h ttp s://d oi o rg .e zp ro xy2 .lib ra ry .d re xe l. e du/1 0.1 061/( A SC E)G T.1 9435 606.0 000382)