K H O A HOC-CdNG N G H £
Ctfofng do chiu n e n cua be tong
sijf dung sgfi poly-propylene va silica fiime
• TS. PHAN DLirC HUNG
Tradng D$i hgc Sif pham Ky thu$t TP. Ho Chi Minh
• TS. LE ANH TUAN
Trudng D^i hgc Bdch khoa TP. HS Chi Minh
Tom tdt: Bdi bdo xem xdt anh hadng cOa sgi poiy-propyiene vd silica fume din cadng dg chju ndn cOa bi tdng. Cdc cap phoi kit hgp sur dt/ng sgi poly-propylene vdi hdm iagng 0,5 va 1%
theo the tich vd silica fume thay thi xi mdng vdi ty lg 5, 10 vd 15% theo khoi iagng vd cip phoi dii chang. Nghi§n cau chi ra vi$c sijt dgng phg phim nha silica fume thay thi tUSdin 10% khii iagng xl mdng glOp cdi thi$n cadng d^ chju ndn cua bd tdng. Ngodi ra, kit qud cho thiy cadng dg chiu ndn gidm tU 5 din 12% khi thdm tU 0,5 din i% sgi poly-propylene. Tuy nhldn, kit qua thi nghidm cung cho thiy vi$c sijr dgng 5 ho0c 10% silica fume kit hgp vdi hdm iagng sgi 0,5%
theo the tich cho cadng dg chju ndn cao hdn so vdi mau dil chang.
Tfl khda: Sgi poly-propylene, silica fume, be tdng, cadng d0 chju ndn.
Abstract: The paper considers the effect of poly-propylene fibers and silica fume on compressive strength of concrete. Many mixes have been studied by combination between poly-propylene fibers with the fractions of 0.5 and 1% by volume and silica fume with cement replacement of 5, 10 and 15% by weight in addition to reference mix. The study revealed that the use of waste material like silica fume improved the compressive strength of concrete as a partial replacement of cement about 5-10%
by weight. Besides, the results showed that the compressive strength decreases by about 5-12% when adding 0,5-1% polypropylene fibers.
However, results show that the use of 5% or 10%
silica fume combined with 0,5% fiber volume fraction results in higher compressive strength of concrete comparing to reference mix.
Keywords: Poiy-propylene fiber, silica fume, concrete, compressive strength.
1. Gidl thigu
Sfl phdt triln cua n i n kinh t l ddi hdi sfl phdt triln ding bO ciia ed sd hg tdng, trong dd be tbng sfl dyng eho cac cdng trlnh edn cd tfnh nang eao nhfl khd ndng chiu keo, va ddp, chju tdi trpng ddng, hgn c h l khe nflt... Be tdng truyln thing cb cfldng db chju nen tdt nhflng khd ndng chju keo vd khd ndng chong va dap kdm. Vide sfl dyng spi gia cfldng giiip tang khd ndng chju lflc va nang eao tuli thp kd't edu thdng qua khd ndng ehju uln vd chju keo td't hdn be tdng thdng thfldng. Do db, be tdng cdt sdi dflpc flng dyng nhilu trong Ifnh vflc xdy dflng nhfl: Mat dfldng d td, mat dfldng sdn bay, bdn mat cau dfldng ham, gifl on djnh mdi ddc, san nha edng nghidp, k i t cau chju tdi trpng ddng... Tfnh ddo eua sdi gia cfldng phg thude vdo ddc tfnh bdc cdu khi v i t nflt xult hi^n vd khd ndng biln dgng ciia spi [1]. Vai trb chfnh cCia spi trong bd tdng Id kilm soat v i t nflt, tdng cfldng khd nang chju kdo, dd cflng va bien dgng, tuy nhidn ehiing cdn phy thubc vdo logi spi sfl dyng. [2] Trong cae logi spi, spi poly-propylene khdng phdn flng vdi cdc chdt hdg hpc nen khi cd sfl tac dbng cua cdc chat hda hpc, be tdng lubn bj phd hogi trflde spi.
Khi kit hdp vdi eac phy gig khoang nhfl tro bay, silica fume, x? hat Id cao- bd tdng spt eb khd ndng tgo ndn vat lidu rdt phii hpp vdi tlnh hlnh Vidt Nam, giiip gia tang higu qud kinh t l , han chl gdy d nhilm mdi trfldng. Murahari vd Rao [3] da nghien cflu dnh hudng cua sdi poly-propylene trong bd tdng tro bay vdi ham Iflpng spi thap kit ludn cfldng dp ehju nen tdng ldn vdi hdm Iflpng spi 0,15% den 0,3%.
Bai bdo nghidn eflu dnh hfldng cOa hdm Iflpng spi poly-propylene trong bd tdng sit dung silica fume thay t h l mdt phdn xi mdng, tfl dd tim ra logi, hdm Ifldng spi va silica fume thfch hpp vd tfnh chdt eiia bd tbng nay.
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KHOA HOC - C O N G N G H £ —
2. Nguyen vat li$u va phadng phap thi nghidm
2.1. Nguyin v$tli$u 2.1.1. CStiiSu
Cdt li$u nh6 suf dgng cat tii nhien sgch. co khfii lUdng riSng 2,67g/cm', I(h6i li/sng t h l tich 1,7g/cm', thanh phan hat l h i hiSn trong Bing 2.1.
Bing2.1. Thanh pliin h^t cua cit
C A t ^ C m m ) Ll^Dg sdt ritee bift (M)
5 0
Z J 4 2
l^i 483
0,63 6 3 0
0,3 IS
«'
0,14 2 1 0
D i y i t e g 105
Cdt Hdu thd sfl dung dd sgch, cd khdi Iflpng ridng 2,78g/em^ khdi Iflpng t h l tieh 1,5g/cm^
Dmax bang 15mm.
2.1.2. Ximdng
Sfl dyng xi mang poociang PC40 vdi thanh phan hda hpc, dd min phdi phCi hdp vdi cdc tieu chudn TCVN 2682-91 vd TCVN 2682-89 vdi cde d|ic tinh cd ly ciia xi mang nhfl khdi Iflpng rieng 3,1g/cm3.
2.1.3. Silica fume
Silica fume sfl dyng trong bd tdng nhdm tdng cfldng khd nang chju Iflc, gidm dp tham nflde cd ddc tinh dflpc the hien trong Bdng 2.2.
Bang 2.2. Thdnh phan hda hgc cua silicafume
l U n i I u 9 i i g S i O ] ( H )
> 8 5
B f ^ ( K )
< 3
LuvDg n i i l khi nung (%)
<6
Tydi*n{m!/E) IS-30
2.1.4. sgi
Trong nghidn eflu nay, sfl dgng logi spi tong hdp poly-propylene (PP) cd i^ le chieu dai tren dfldng kfnh sdi (l/d) Id 150 vd ede thdng sd ky thudt theo nhd sdn xud't dflpe trinh bdy trong Bdng 2.3.
Bang 2.3. Cdc chf tieu ky thu$tcua sgi polymer
Babas
0,3 ELrtCog
0,9 M A - d u n U n
bbl(OPa) 3,S
Cubng d 4 dija ldo (OPa) (0,SS^1,76)
D f d a o d i i t u m g a o i p t ) 1S-2S
Khlnekifaii.
m u i i . u l t C « .
Hinh 2.1: Sgi poly-propylene gia cudng trong bi tdng
2.2. Cip phii
Cac cdp phdi bd tdng ed sfl dgng sdi poly- propylene vdi hdm Iflpng thay d l i Id 0, 0,5, 1% vd
So 10/2015 silica fume vdi ham Iflpng thay d l i la 0, 5,10,15%.
Cap phli vd cfldng dp chju nen d 28 ngdy tuli dflpc trlnh bay trong Bdng 2.4.
Bing 2.4. Cap phii vd cadng d0 chju ndn (Mf^)
STT
S l S2 Si S 4 S i SA S7 SH S9 SIO S I I S12
N u o c
» B t o J ) 172 172 172 172 172 172 172 172 172 172 172 172
(kgfln^
3 8 2 ^ 3 8 2 , 2 3 £ 2 ^ 3 6 4 364 3 6 4 3 4 4 3 4 4 3 4 4 324,B 324.9 324,9
1042 1D42 1042 1042 1042 1042 1042 1 0 4 2 1042 1042 1042 1042
C i t (fceW)
S40,6 S72,B BS9,4 831,2 819,7 806,4 823,6 812 J 798,9
BIB B04,7 791.3
Silica ibme H 0 0 0 s 5 3 10 10 ID 15 15 IS
Itgftt^
0,0 0 ^ 0,0 19,2 19,2 1 9 ^ 3 8 , 2 3 8 , 2 3 8 , 2 5 7 J 5 7 3 57,3
SQX
H 0 0,3
1 0
»,5 1 0 0,3
1 0 0 4 1
iffln?
0 4,73 9,S 0 4,75 9,5 0 4,73
9.S 0 4,T5
»,3 (MPa)
3 S . 0 3 3 , 2 30f MA 3 5 , 7 3 2 4 364»
36,3 3XZ 3 6 , 1 3 4 , 0 3 1 , 0
3. Ket qud thi nghi$m
3.1. Anh hadng cua ham lugng silica fume den cudng dg chju ndn
1 . 3&0
4
3 6 . 4
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—
36.1
-
Him \itqmts\\ica fume |%)
Hinh 3.1: Mii quan h$ giOa cUdng d^ chiu ndn vd hdm lugng silica fume
Kit qud bilu diln trdn Hinh 3.1 cho thdy sfl dnh hfldng ciia phy gia khodng silica fume den cfldng dd ehju nen eiia bd tbng vdi hdm Ifldng thay d l l tfl 0 d i n 15%, Cfldng dp chju nen ciia be tdng diu eb khuynh hfldng tdng khi sfl dung phg gia khodngsilica fume vdi ham Iflpng tfl 5 d i n 10%. So vdi mdu d l i chflng, mflc tdng cfldng dd tfldng flng Id 4 va 5,4% khi thay t h l xi mdng bang silica fume vdi ham Iflpng tfldng flng Id 5 vd 10%.
Tuy nhidn, khi ham Iflpng silica fume tdng ldn 15%
thi cfldng dp chju ndn cCia cdp phdi bd tdng ndy lai gidm xudng 2,2% so vdi cap phdi stjf dyng hdm Iflpng silica fume 10%.
Theo Shanmugavalli [4], cap phli sfl dung 10% silica fume thay t h l xi mang se cdi thidn dang k l khd ndng chju nen ciia bd tdng do cd hdm Iflpng pozzolanie tfl nhien cao, giup phdn flng vdi calcium hydroxide de hlnh thanh the gel calcium hydroxide hydrate tdng cfldng cd tfnh cho be tdng.
• y / SJlNBT^O-CHUJfHMVC-THVCTHI 27
KHOA H p c - C O N G NGHE
3.2. Xdc djnh anh hudng ctia hdm iagng sgi din cudng d0 chju nen
S f l dnh hfldng eua spi poly-propylene va phy gia khodng silica fume den cfldng d d ehju nen cua be t b n g dflpc trinh bdy trong Hinh 3.2.
—OKsfl - « - - 0 5 X 5 9 ! . . - * . . I X t ? !
[••^^ x ^
S , 3 l<-
-4—UXSIICBlunit
Hinh 3.2: Mii quan h$ giffa hdm lugng sgi, hdm iagng silica fume vd cadng dg chju ndn
H}nh 3.2 eho thdy, khi k i t hpp sfl d y n g sdi poly-propylene thi cfldng db ehju nen cua be tbng cb sfl dung phu gia khodng silica fume cb xu hfldng thay d l i cfldng dd gdn gidng nhau. Cfldng dp ehju nen cang gidm khi ham Iflpng spi sfl d y n g cang tang, so vdl mdu khdng sfl dung spi (hdm Iflpng spt 0% - mdu 81) cudng dp chju nen gidm 5 , 1 % vd 12% tfldng flng vdi edp phdi chfla 0,5%
va 1 % hdm Ifldng spi poly-propylene.
Trong nghien eflu ciia minh, Zinkaah [5] cung chf ra sfl gidm cfldng dd ehju nen khi sfl d y n g spi poly-propylene trong be t d n g . Tuy nhien, k i t qud thf nghidm eung eho thay, khi k i t hpp sfl d y n g spi vd phu gia khodng vdi mbt ham Iflpng nhat djnh trong bd tdng cd khd nang lam tang cudng db chju nen eho bd tdng so vdi mdu ddi chflng khbng cd sdi vd phu gia khoang. Cy t h l , khi sfl dgng ham Iflpng spi 0,5%, nen ket hPp vdl vide thay t h l 5 hode 10% xi mang bang silica fume se cho gid trj cfldng do chju nen tang tfldng flng Id 2,0 va 3,7% so vdi m d u dd'i chflng. K i t qud c h y p SEIVI (scanning electron microscope) mdu be tbng geopolymer spi poly-propylene t h l hidn trong Hlnh 3.3.
4. Ket ludn
Nghien cflu sfl d g n g eac logi phy pham cdng nghiep nhfl silica fume de che tgo bd t d n g c d khd ndng edi thidn cd tinh cua be t d n g . K i t hpp vdl viec sfl d y n g sdi poly-propylene, mbt vai k i t ludn ed the rut ra tfl ket qua thf nghidm nhfl sau:
- Cb the sfl d g n g silica fume thay the tfl 5 de'n 10% hdm tfldng xi m a n g , cfldng dd ehju nen dat gia trj eao flng vdi ham Iflpng 10%.
- Cfldng db ehju nen c u a be tdng cd khuynh hfldng gidm khi ehi t h d m sdi poly-propylene vao edp phdi, gidm khodng t f l 5 d i n 12% so vdi cap phdi khbng gia cfldng spi. Tuy nhien, neu k i t hpp vdi ham Iflpng nhdt djnh phu gia khodng silica fume thay the xi m a n g v d n c d t h l ddm bdo gia tang ve cfldng dp chju nen •
Tdi li#u tham khdo
[1]. Madhavi T.C, Raju L.S., Mathur D. (2014), Polypropylene Fiber Reinforced Concrete-A Review, International Journal of Emerging Technology and Advanced Engineering, V o l . 4(4), pp.114-119.
[2]. Don Wimpenny et al (2010), The use of steel and synthetic fibres In concrete under extreme conditions. Science Agenda Investment Fund.
[3]. M u r a h a r i K., Rao R.M ( 2 0 1 3 ) , Effects of Polypropylene fibres on the strength properties of fly ash based concrete. International Journal of Engineering S c i e n c e Invention, Vol.2(5), p p . 1 3 - 1 9 .
[4]. Raj l.R.l, Shanmugavalli B. (2015), A study on the effect of silica fume on the properties of recycled aggregate concrete, Journal of Mechanical And Civil Engineering, Vol.2(3), pp.5-15.
[5]. Othman Hameed Zinkaah (2014), Effect of hybrid micro steel-polypropylene fibers on high strength concrete with micro silica fume. Journal for Engineering Sciences, Vol.3(1), pp.90-102.
Ngdy n h | n b d i : 22/8/2015 N g a y c h a p n h | n d a n g : 9/9/2015 Ngfldi phdn bign: TS. Ld A n h T h a n g
T S . Nguydn M a n h Tu^n
Hinh 3.3: Sgi poly-propylene trong mau be tdng geopolymer
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