Nghiên cứu góp phần hoàn thiện công nghệ sản xuất phụ gia tro trấu ở Việt Nam

NGHIEM CLTU GOP P H A N HOAN THIEN CONG NGHE<br /> SAN X U A T PHU GIA TRO TRAU 6 VIET NAM<br /> <br /> <br /> <br /> TS. DAO VAN DONG<br /> Vien Khoa hgc & Cdng nghe XDGT<br /> Tru&ng Dgi hpc Giao thdng Viin tdi<br /> <br /> <br /> <br /> <br /> Tdm tdt: Bdi bdo trinh bdy tdm tdt cdng nghi di san xudt phu gia tro trdu vdi quy md thir<br /> nghiim trong diiu kiin Viet Nam. Vo trdu duge ddt cd khdng chi trong Id thu nghiim, ddm<br /> bao nhiit do dot lir 500 din 700°C. Qud trinh dot dam bao khdng khi dugc tudn hodn di tgo<br /> diiu kiin cho phdn img chdy xay ra triit di. Tro trdu sau khi dot dugc nghiin a 3 chi do,<br /> gdm: a) nghiin nude bdng mdy nghiin md: b) nghien khd bdng may nghien hi 3000 vdng: vd<br /> c) nghiin khd bdng mdy nghiin bi 6000 vdng. Kil qua thi nghiim cdc chi lieu ly - hod cua san<br /> phdm thu dugc cho thdy logi tro trdu san xudt thu nghiim hodn todn ddp irng dugc cdc yeu<br /> cdu ky thudt ddi vdi phu gia pozzolan hogt tinh dimg cho be Idng xi mdng. Ket qud nghien ciru<br /> cho phip di xudt cdng nghi ddi phu hgp cho cdc nhd mdy nliiil diin chgy Irdii r/ Viet Nam di<br /> tir do vira ldn dung dugc nhiit lugng phuc vu cho cdc ngdnh cdng nghiip khac, vira ldn thu<br /> dugc tro trdu ddm hao chdt lugng nhdm thay thi cho cdc phu gia khodng hogt iinh nhdp ngogi<br /> ddi liin. Ddng thdi. ddy ciing Id ca sa di giam lliiiu d nhiim mdi Irudng do vo trdu gdy ra.<br /> <br /> Summary: This paper presents briefly a technical process to manufacture rice husk ash<br /> in a pilot scale in condition of Vietnam. Rice husk was burned in controlled condition in an<br /> experimental combustion furnace at a temperature range from 500 to 700"C The burning<br /> process also maintains air circulating lo support fully burning reactions. Rice husk ash after<br /> burning was ground in three regimes, namely: a) water grinding: b) ball milling of 3000<br /> revolutions: and c) ball milling of 6000 revolutions. Experimental results of physical-chemical<br /> properties shown that the rice husk ash product satisfied requirements of a reactive pozzolanic<br /> admixture for cementituos concretes. The results also alow suggesting a suitable burning<br /> technology to rice husk power plants in Vietnam to utilise both released energy and high<br /> performance rice husk ash to replace for costly imported pozzolanic admixtures. In addition,<br /> this is a fundamental approach to reduce environmental pollution due lo rice husk waste.<br /> <br /> Tir khod: RH.4: phu gia khodng hogt tinh: nhiit diin chgy trdu.<br /> <br /> <br /> <br /> <br /> I. GIOI THIFl<br /> <br /> Liia dugc trdng d hau het cac chau luc va chiem tren 1% dien tich be mat trai dat 6k tao ra<br /> ngudn lugng thuc nudi sdng hang ty ngudi. chi dirng sau liia mi ca vl dien tich va san lugng [11.<br /> <br /> <br /> 150 Tap chi KHOA HQC GIAO THONG VAN TAI So 29 - 03/2010<br /> Nganh ndng nghiep trdng liia the gidi trong nhung nam gin day da dat dugc nhiJng tiln bd vugt<br /> bac trong viec ap dung cdng nghe sinh hgc nham nang cao nang suit gdp phin tao ra tdng san<br /> lugng Ilia toan cau udc tinh 640 trieu tan nam 2007 [2], 0 Viet Nam, thanh tuu nay cdn ndi bat<br /> hon vdi tdng san lugng lua hang nam dat 36 trieu tin va du kiln din nam 2020 con so nay se<br /> tang len 40 trieu tan nam [3].<br /> <br /> Khi che bien, cu mdi tan liia tao ra khoang 200 kg vd trau va lugng vd triu nay sau khi ddt<br /> tao ra khoang 40 kg tro [4], Nhu vay, trung binh hang nam thi gidi tao ra khang 130 trieu tin vd<br /> trau. Hien tai, hau het lugng vd trau tao ra chua dirge tan dung ma bj vut bd nhu la mdt dang<br /> chat thai ndng nghiep. Chat thai nay tap trung pho biln d cac quoc gia ndng nghiep, Rieng Viet<br /> Nam, khdi lugng chat thai vd trau trung binh la 8 tneu tin nam. Do chua cd giai phap xu ly hieu<br /> qua nen vd trau sau khi bj thai thang ra mdi trudng da gay hau qua nghiem trgng vl d nhiem<br /> mdi trudng, nhat la ngudn nude va cac ngudn Igi gan liln vdi ngudn nude [5, 6],<br /> <br /> Trau da dugc tan dung lam nhien lieu dot tro cac nha may phat dien, phat nhiet nhd, hay<br /> ddt de say khd thdc nhu d An Do, Thai Lan, Inddnesia va Viet Nam [7], Dong thdi, viec tan<br /> dung tro ddt tir vd trau da dugc xem xet tir dau nhii-ng nam 1970 [8], Ke tii- dd, nhieu nghien cuu<br /> ve quy trinh san xuat, bao gdm cdng nghe dot va nghien, da dugc tien hanh nham tao ra cac loai<br /> tro trau cd chat lugng cao. Tro trau (Rice Husk Ash - RHA) da dugc su dung cd hieu qua trong<br /> cac nganh cdng nghiep nhu: cdng nghiep thep de san xuat cac loai thep tam chat lugng cao va<br /> de san xuat cac vat lieu each nhiet [7], Mdt sd loai RHA chat lugng cao da dugc san xuat thanh<br /> cdng d An Do, Thai Lan de lam phu gia hoat tinh nham nang cao chat lugng cho be tdng xi<br /> mang [9, 10, 11, 12], RHA cung da dugc san xuat thir nghiem d Viet Nam trong nhirng nam gan<br /> day [13], Tuy nhien, mdi chi cd mdt nha san xuat cd the cung cap RHA d mirc do san pham<br /> tliirong mai, Hon nua, chat lugng ciia RHA nay van cdn can dugc xem xet,<br /> <br /> Viet Nam dang trien khai xay dung nha may Dudng Hai d Can Tho- sir dung viec ddt vd<br /> trau de ddng thai phat nhiet va dien vdi quy md tu-oiig irng 20 tan hai/gid va 70 MW dien, Mdt<br /> sd du an nha may nhiet dien, hoi khac sir dung trau dang dugc du kien xay dung d cac tinh Can<br /> Tho-, A(i Giang va Kien Giang,<br /> <br /> Tuy nhien. nhung nha may chay trau ca tren the gidi va d Viet Nam, mdi chi quan tam den<br /> hieu qua tan thu nguon nhiet khi ddt trau. Viec dieu chinh che do ddt de vira tan dung dugc<br /> nhiet lugng khi dot triu vira thu dugc RHA cd boat tinh pozzolan cao van chua dugc quan tam,<br /> <br /> Bai bao trinh bay tdm tit ca sd khoa bgc ciia cdng nghe san xuat RHA va ca che cac loai Id<br /> dot triu, Tir dd xay dung Id ddt triu quy md thir nghiem de san xuat RHA dam bao chat lugng<br /> ciia phii gia khoang boat tinh dimg cho be tdng xi mang, Ddng thdi kien nghj cdng nghe ddt phii hgp<br /> cho cac nha may nhiet dien chay triu d Viet Nam de thu dugc phu gia RHA pozzolan boat tinh.<br /> <br /> II. CO SO KHOA HOC CUA CONG NGHE SAN XUAT TRO TRAU<br /> <br /> Vd trau cd kich thude trung binh khoang 8 - 1 0 mm dai, 2 - 3 mm rdng va 0.2 mm day,<br /> Khoi lugng the tich ciia vd triu khi nen trong bao dirng khoang 122 kg/m^ [14], Thanh phan boa<br /> <br /> <br /> r^p chi KHOA HQC GIAO THONG Vi\N TAI So 29 - 03/2010 151<br /> hgc ciia vd trau tliay ddi theo loai thdc, miia vu canh tac, dieu kien khi hau va dac trung viing<br /> mien, Tuy nhien, hau bet cac loai vd trau cd thanh phin huu ca chiem tren 90% theo khdi<br /> lugng, Cac hgp chat chinh cd cau true xdp dang cellulo va lignin [15], Nhung hop chat nay khi<br /> chay se chuyen boa thanh tro chira chu yeu Si02 va cac khi CO2, CO thoat ra mdi trudng.<br /> <br /> Bdng 1. Thdnh phdn hint ca cua vo trdu fl5]<br /> Thanh phan chu yeu Ty le theo khdi lirong (%)<br /> oc-cellulose 43.30<br /> Lignin 22.00<br /> D-xylose 17.52<br /> I-arabinose 6,53<br /> Methylglucuronic axit 3,27<br /> D-galactose 2,37<br /> Tdng cdng 94.99<br /> Tdng san lugng thdc la kha dn djnh tren toan cau nham duy tri luong thuc cho nhan loai.<br /> Do vay, vd trau cd the dugc xem la mdt ngudn sinh khdi quan trgng, kha on djnh va cd tinh tai<br /> tao tren the gidi. Khi ddt vd trau tao ra nhiet lugng khoang 15 MJ/kg [7]. Nhu vay, vdi tdng<br /> khdi lugng vd trau toan cau la 130 trieu tan thi hang nam ngudn sinh khdi nay cd the tao ra xap<br /> xi 2xl0'' GJ nang lugng (tuong dirong 556x10* MWh), Ddi vdi Viet Nam, con sd nay tuang<br /> irng se la 0,12x10'' GJ nang lugng (tuang duang 33x10*^ MWh),<br /> <br /> Neu su dung vd trau lam nguyen lieu cho cac nha may dien (ndng - dien) thi cii' vdi cdng<br /> suat ciia nha may la 1 MW yeu cau 10000 tan trau nam, Nhu vay, vdi khdi lugng trau hang nam<br /> ciia Viet Nam xap xi 8 trieu tan nam cho phep tan dung lam nguyen lieu cho cac nha may dien<br /> vdi cdng suat gan 800 MW, tuong diro-ng vdi cdng suat ciia 8 nha may nhiet dien Ninh Binh<br /> hien tai.<br /> <br /> Cac qua trinh dot triu thanh tro dugc thuc hien bang nhieu cdng nghe khac nhau va tao ra<br /> san pham RHA cd chat lugng khac nhau, Tuy nhien, dien hinh nhat hien nay la mdt trong sd<br /> nhdng phuong phap sau [7];<br /> <br /> • Ddt til- do: vd trau dugc dd thanh ddng va ddt tu do ngoai khdng khi, Phuong phap<br /> nay khdng dieu chinh dugc nhiet do va sir ddi luu ciia khdng khi nen khdng quan ly dugc chat<br /> lugng ciia tro,<br /> <br /> • Ddt khong tan thu ndng luang: vd trau dugc ddt trong cac loai Id cd khong ehl nhiet<br /> do nhung khdng thiet ke cac bd phan de tan thu nhiet nang, Phuang phap nay thu dugc san<br /> phim RHA cd chit lugng dam bao nhirng nhiet nang bj phat tan ra mdi trudng,<br /> <br /> • Ddt sir dung cho Id hoi: nhiet thu dugc tir qua trinh ddt trau dugc tan dung dl dun<br /> ndng nude trong cac Id hai, Cac loai Id nay hien nay chua quan tam den cdng nghe ddt dl dat<br /> dirge RHA dam bao chat lugng ma mdi chi quan tam den viec tan dung nhiet lugng,<br /> <br /> • Ddt trong Id dot tdng sdi: day la loai Id ddt cd dieu khien nhiet cho phep chuyin hoa<br /> <br /> Tap chi KHOA HQC GIAO THONG V^^N TAI S6 29 - 03/2010<br /> 152<br /> nhanh \d trau thanh nhiet lugng \a tro d dilu kien nhiet do khdng ddi djnh trudc, Trong qua<br /> tnnh boat ddng. hdn hgp khdng khi va nhien lieu dot dugc thdi ap luc \ao budng ddt cua Id,<br /> Dudi tac ddng cua nhiet do va luu toe ddng khi. trau dugc ddt chay dl chuyin boa thanh nhiet<br /> va tro, Sau dd. nhiet nang va tro nhe se dugc thu theo nhung thilt bj dugc thiet kl trudc,<br /> <br /> • Ddt trong Id dot hod hoi: triu nhien lieu dugc dot d chi do nhiet cao (tren 700°C) de<br /> chuyen hda thanh cac nhien lieu khi thuong mai nhu CO; H, va metan, Tuy nhien, do phai dot d<br /> nhiet do cao nen RHA thu dugc khdng dat dugc chit lugng pozzolan mong mudn<br /> <br /> <br /> <br /> ?r<br /> <br /> <br /> <br /> <br /> x2e 0427 ISkV Za» 8361° 2eKU X I , 600 19Mm UD23<br /> Hinh 1. Cdu triic xdp cua vo trdu fl5] Hinh 2. Tro trdu (RH.4) fl6]<br /> Tir nhung phan tich neu tren cho thay. Id ddt tang sdi la kieu Id phii hgp nhit cho viec dot<br /> trau, Kieu Id nay mdt mat vira thu dugc nang lugng khi dot triu phuc vu cho cac muc dich cdng<br /> nghiep. mdt mat dam bao dugc chat lugng cua RHA thu dirge,<br /> <br /> Khi trau dugc ddt d dieu kien khdng che nhiet, Si02 vd djnh hinh vdi do boat tinh cao, kich<br /> cd hat mjn va ty dien tich be mat Idn cd the dugc tao ra, Nhu vay, cac ylu td anh hudng din<br /> chat lugng ciia san pham RHA sau khi ddt bao gdm: a) tdc do tang nhiet do trong qua trinh dot;<br /> b) nhiet do cao nhat trong qua trinh ddt; c) thdi gian duy tri nhiet do cao nhat khi ddt; va d) mirc<br /> do cung cap oxy (khdng khi) cho phan img cbiiv khi ddt, Nhirng yen td nay anh hudng den chit<br /> lugng ciia RI IA thdng qua nhirng co- che sau;<br /> <br /> • Tdc dp tdng nhiet d() trong qud trinh dot: Yeu td nay quyet djnh den qua trinh oxy<br /> hoa cacbon, Khi chay vdi tdc do nhanh, qua trinh oxy hoa cacbon khd xay ra do sir chay be mat<br /> dien ra trudc, dan den ham lugng cac cac hat mau den tang len. Khi dd lugng MKN se cao,<br /> Ngugc lai, neu trau chay vdi tdc do chain thi qua trinh oxy boa cacbon dien ra trudc khi sir chay<br /> be mat ciia SiOi, lam giam dang ke ham lugng cac hat man den, ddng thdi se kich thich qua<br /> trinh oxy hoa cacbon xay ra de giai phdng khi COn,<br /> <br /> • Nhiet d() cao nhdt trong qud trinh dot: Da\ la _\eu td quan trgng nhat trong qua trinh<br /> dot. Neu nhiet do ddt thap se lam cho trau khdng cha\' triet de va dan den ham lugng cacbon tdn<br /> lai trong tro ldn. tuong ung \di lugng MKN cao, Ngugc lai. neu nhiet do chay qua cao se hinh<br /> thanh Si02 dang tinh the, lam cho do boat tinh pozzolan ciia RHA thap, Cac nghien ciru da chi<br /> ra nhiet do phu hgp de phan irng chay dien ra triet de va hinh thanh RHA cd ham lugng Si02 vd<br /> djnh hinh cao nhat lii \ iinu nhicl lir 500 den 700"C,<br /> <br /> <br /> <br /> . 9p chi KHOA HQC GIAO THONG VAN TAI So 29 - 03/2010 153<br />  • Thoi gian duy tri nhiet do cao nhat: La ylu to dam bao su oxy haa triet de ciia cac<br /> phan ung chay ciia vd trau. Neu thdi gian ngin, mgt phin \ d triu chua chay hit se de lai lugng<br /> MKN ldn. Ngugc lai, khi duy tri thdi gian chay dai se lam cho hieu suit ciia chu trinh dot thap.<br /> <br /> • Su- luu thdng ciia khong khi: Day la mgt ylu td quan trgng dl dam baa ty le oxy hoa<br /> cac thanh phan vd trau. Neu lugng oxy khdng dii cho cac phan ii-ng oxy boa khi chay se lam cho<br /> ham lugng ca.cban trong tra Idn. Ngugc lai. khi cung cip dii oxy trong qua trinh chay thi toan bd<br /> cac thanh phan hoa hgc trong vd trau cd the oxy boa dl tach phin cacbon \^a chuyen hoa thanh<br /> khi CO2 thoat ra klidi Id dot.<br /> <br /> III. SAN XUAT TRO TRAU 6 QUY M O THU NGHIEM<br /> Dua tren ket qua phan tich ca sd khoa hgc ciia qua trinh ddt trau va cac phirong phap dot<br /> (loai Id dot) de san xuat RHA cd chat lugng phii hgp lam phu gia boat tinh pozzolan nhu da neu<br /> d muc 2, mdt loai Id quy md thu nghiem da dugc xay dung (hinh 3), Loai Id thu nghiem dua<br /> tren nguyen ly ciia Id dot tang sdi d nhung diem sau:<br /> <br /> Khdng che nhiet do trong qua trinh ddt dam bao vimg nhiet do trong khoang 500 den<br /> 700°C;<br /> <br /> • Dam bao su luu thdng khdng khi trong qua trinh ddt vdi dien tich tiep xiic giua trau va<br /> khdng khi la ldn nhat, Yeu td nay ddng thai cung dam bao dugc thdi gian ddt phii hgp de o.xy<br /> boa triet de trau;<br /> <br /> • Ld dot phai de dang xay dung va sir dung cac vat lieu, thiet bj san cd trong nude.<br /> <br /> Qua nhieu lan thir nghiem, hieu chinh dua tren ket qua thuc nghiem hien trudng, mgt loai<br /> Id quy md thir nghiem da dugc tdi irii vdi cac dac diem sau:<br /> <br /> ••• Vat lieu: sir dung tdn dot Id loai inox day 1,5 mm, chju nhiet, khdng ri. Dudng kinh Id<br /> dot 2inni (dam bao vd trau khdng bj Igt), Mat do 4 ld/cm~,<br /> <br /> • Kich thuirc: cau tao va kich thude ciia Id ddt dugc the hien nlur hinh 1, Vdi quy md Id<br /> nhu tren, moi me ddt su dung khoang 100 kg trau va san xuat dirge khoang 20 kg RHA.<br /> <br /> •:• Ddm hdo nuic dp cung cdp khdng khi cho phdn itng chdy: De dam bao luu thdng<br /> khdng khi trong qua trinh dot, trau dugc dd vao Id ddt va khdng nen, Ddng thdi chieu day ciia<br /> moi ldp trill theo phuang ngang nen khdng Idn hon 500 mm,<br /> <br /> ••• Qud trinh (tot trdu: Tdc do tang nhiet trung binh khoang 5"C7phut, Sau khoang 2 gid,<br /> nhiet do Id dot dat tir 550 din 650"C, Nhiet do cue trj nay duy tri trong khoang 4 gid, sau do<br /> ngudi din vl nhiet do mdi trirdng,<br /> <br /> •:• Dieu chinh nhiet trong qud trinh d('>t: Xung quanh Id ddt dugc quay bat dl dilu clunh<br /> tdc do gid thdi vao Id va toe do toa nhiet ra mdi trudng, Tir do gdp phan khdng che \a dicu<br /> chinh tdc do thay doi nhiet ciia trau khi ddt. Qua trinh nay cd the ket hgp vdi viec day/mo nap<br /> dinh Id.<br /> <br /> <br /> Tap chi KHOA HQC GIAO THONG VAN TAI So 29 - 03/2010<br /> 154<br />  • Cdc lu-uy khac: Trong qua trinh ddt, cin chuin bj vat lieu che chin dl dl phdng gid<br /> va mua.<br /> <br /> Sau khi ddt hoan chinh, tro trau dugc de<br /> ngudi tu nhien. Sau khoang 4 din 6 gid thi tien<br /> hanh thu san pham va luu gitr trong cac bao<br /> nildng dam bao each am, Khoi lugng tro triu thu<br /> dugc trong nghien ciru dat khoang 50 kg. Chiing<br /> dugc nghien thir nghiem d 3 che do nghiin va dan<br /> nhan tuong irng, gdm; a) nghien nude bang may<br /> nghien ma (RHA3,1); b) nghiin khd bing may<br /> nghien bi 3000 vdng (tuong irng vdi thdi gian<br /> nghien clanke de san xuat xi mang podclarig<br /> (XMP) PC30 truyln thdng) (RHA3.2); va c)<br /> nghien khd bang may nghiin bi 6000 vdng (tuong<br /> ung vdi thdi gian nghien clanke dl san xuit XMP<br /> PC50) (RHA3,3), Sau khi nghiin, RHA tilp tuc<br /> dugc luu giu- trong cac bao nildng each am cho<br /> Hinh 3. Ld dot trdu quy md thu nghiim<br /> den khi thi nghiem hoac sii- dung.<br /> (kich thude mm)<br /> <br /> <br /> IV. CAC CHI TIEU KY THUAT CUA TRO TRAU SAN XUAT THI NGHIEM<br /> Sau khi dirge nghien d 3 che do nhu da neu d muc 3. cac miu RHA dugc tiln hanh phan<br /> tich cac cbi tieu ky thuat ddi vdi mgt phu gia pozzolan cho be tdng xi mang theo cac tieu chuin<br /> TCXDVN 311 [17] va ASTM C6I8 [18], Cac chi tieu ky thuat bao gom: a) nhdm cac chi tieu<br /> vat ly; va b) nhdm cac chi tieu hda hgc, San pham RHA san xuit thu nghiem dugc ky hieu la<br /> RHA3 (gom RHA3.1; RHA3,2; va RHA3.3). Kit qua thi nghiem dirge ddi chirng vdi 2 loai<br /> RHA thuong mai, mdt loai do Viet Nam san xuat (RHAl) va mdt loai do An Do san xuit<br /> (RHA2); va so sanh vdi yen can ky thuat ciia phu gia tro trau dimg cho be tdng va vQ-a theo<br /> TCXDVN 311 [17], Ket qua thi nghiem dugc the hien trong bang 2.<br /> <br /> Mail ciia RHA phan anh thanh phan boa hgc ciia tro. Vdi tro mau trang, la mau phan anh<br /> cho khoang silica, chimg td loai tro dd cd chira ham lugng Si02 ldn. Ngugc lai, tro cd mau den,<br /> mau dac trung ciia cacbon, phan anh loai tro dd cd chira nhieu thanh phan cacbon chua chay hit.<br /> Mau sac cua 3 loai RHAl; RHA2 va RHA3 dirge the hien d hinh 4, RHAl ciia Viet Nam cd<br /> mau den, chirng td ham lugng cac bon trong tro ldn, Dieu nay cung phii hgp vdi ham lugng<br /> Si02 thap (ca d trang thai tinh the va vd djnh hinh), Ngugc lai, cac loai RHA2 ciia An Do va<br /> RHA3 thu dugc tu san xuat thu nghiem cd mau tii- trang xam cho ket qua ham lugng SiOi cao.<br /> dac biet ham lugng Si02 a trang thai vd dinh hinh cao (tren 85%) va lugng MKN thap (dudi<br /> 2%) (bang 2), Chi tieu nay thoa man yeu cau cho loai phu gia pozzolan hoat tinh.<br /> <br /> <br /> <br /> Tapjchi KHOA HQC GIAO THONG V^N TAI S6 29 - 03/2ai 0 155<br />  • • ' Hinh 4. Mdu sdc cua RH.4<br /> a) RHAl: b) RHA2: c) RHA3<br /> Xet ve do mjn ciia san pham cho thiy ca hai loai RHA2 va RHA3 deu tdt hon so vdi<br /> RHAl. Ket qua nay cung phii hgp vdi chi tieu vl chi so boat tinh doi vdi XMP d 7 ngay tudi,<br /> Dieu nay chung td rang do mjn cao se tang hieu qua pozzolan boa va gdp phan tao ra cudng do<br /> cung nhu tdc do phat triln cudng do khi sir dung dl thay thi cha XMP,<br /> <br /> Cac ket qua th i nghiem ddi vdi cac mau RHA cho thay loai RHA san xuat thu nghiem dap<br /> ung tdt cac yeu cau ky thuat ciia mdt phu gia pozzolan cho be tdng xi mang.<br /> Bdng 2. Cdc tinh elicit cua RHA<br /> RHA3 (tro trau san xuat thir nghiem)<br /> TCXD RHA2 RHA3,1 RHA3.2 RHA3,3<br /> Cac tinh chat RHAl<br /> VN311 -2004 (An Do) (nghien (nghien kho (nghien kho<br /> (Viet Nam)<br /> nuoc) 3000 vong) 6000 vong)<br /> Cdc linh elicit<br /> vdl ly:<br /> Khoi lirong<br /> the tich xop<br /> (g/cmA 0.60 0.46 0.45 0.50 0,48<br /> Thanh phan hat<br /> (%): 76 100 100 91 100<br /> Lot sang 45 f.im 40 82 80 42 65<br /> Lot sang 20 |jm 16 53 49 19 41 •<br /> Lot sang 10 |.im 7 22 18 8 16<br /> Lot sang 5 |.im 6.23 1.56 1.92 1,96 1,95<br /> Lupng mat khi den trang xam trang xam trang xam trang xam<br /> nung (%) 85<br /> 0,80 0,30 0.53 0,40 0.43<br /> - Chi so hoat tinh, 1.43 0,89 1,12 1,09 1.00<br /> 7 ngay 2,80 0,10 0.60 0,60 0.50<br /> ALOj 0,90 0,96 0.86 0.90 0.88<br /> Fe,0,<br /> CaO<br /> KO<br /> \4gO<br /> <br /> V. KET LUAN<br /> Tren ca sd ciia nhiing phan tich va cac ket qua da dugc trinh bay. bai bao rut ra nhung kit<br /> <br /> <br /> <br /> 156 T9P chi KHOA HQC GIAO THONG V^N TAI So 29 - 03/2010<br /> luan sau;<br /> • Chat thai vd trau la ngudn sinh khoi sach, tai tao diy tilm nang d Viet Nam, Day ddng<br /> thdi ciing la ngudn nguyen lieu phong phii dl san xuit ra RHA cho cac irng dung xay dung.<br /> Quan trgng hon, viec tan dung vd trau se giam thilu dugc d nbilm mdi trudng, •' V<br /> <br /> • Che do ddt khdng che nhiet va khdng khi la co sd dl cd the san xuat dugc RHA chat<br /> lugng dam bao, Dua vao ca che nay, mdt loai Id ddt trau quy md tbii' nghiem da dugc xay dirng,<br /> RHA ddt bang Id nay sau khi dugc nghien bang cac ehl do nghiin tuong tu nhu nghien XMP<br /> truyen thdng da dap ung dugc cac yeu cau ky thuat cua mdt loai phu gia khoang pozzolan boat<br /> dnh.<br /> <br /> • Viec ket hgp co- che ddt tang sdi vao cac nha may nhiet dien chay trau d Viet Nam la<br /> hoan toan cd the thuc hien dugc thdng qua viec khdng che nhiet do dot trong khoang 500 den<br /> 700°C va thdi gid tuan hoan, Dieu nay mdt mat van tan dung dugc nhiet khi ddt trau, mdt mat<br /> tan thu dugc RHA cd chat lugng dam bao ve do boat tinh pozzolan nham thay the cho cac phu<br /> gia khoang boat tinh nhap ngoai dat tien,<br /> <br /> • Mdt ca che phii hgp cho cac nha dau tu nham khuyen khich ddi mdi cdng nghe de xay<br /> dung cac nha may nhiet dien chay trau va tan thu RHA can dugc sdm thuc hien d Viet Nam,<br /> Day se la tien de de nang cao ban nua gia trj hat liia cho ngudi ndng dan.<br /> <br /> <br /> <br /> <br /> Till lieu tham khao<br /> <br /> [1], FAQ statistical database. (2002). http://apps.fao.org,<br /> [2], Calpe C (2007), Review of the rice market situation in 2007, FAG,<br /> http://www.fao,org/dociep/fao/010/a 141 Ot/a 141 OtO 1 .pdf<br /> [3], http://-www.vnagency,com,vn,<br /> [4], Mehia, P. K. (1986). StrucUire, Properties and Materials, Englewood Cliffs, NJ: Prentice-Hall.<br /> [5], http://ww\v.nioitre,com,vri/Tianyoa'lndex.aspx?ArticleID=131231&ChanrielID=3.<br /> [6]. Ddo Vdn Ddng (2008). Anh hirdng cua phu gia tro trau den cac tinh chat ciia be long cudng dp cao.<br /> Tap chi ciu Dudng Viet nam, so 9-i-10, tr. 26-32.<br /> [7]. Bronzeoak Ltd., (2003). Rice husk ash market study. Crown copyright,<br /> [8], Mehta. P.K (1994). Rice-husk Ash - A unique Supplementary Cementing Material, Advances in<br /> Concrete Technology, MSL Report 94-1 (R). CANMET 1994, ed. Malhotra, V.M., pp. 419-444.<br /> [9], Chindaprasirl P., et al. (2008). Resistance to chloride peneuation of blended Portland cement mortar<br /> containing palm oil fuel ash. rice husk ash and fly ash. Con. & Bml. Materials Journal. Vol. 22, pp. 932-<br /> 938.<br /> [10]. Deepa G. N., et al. (2008). A structural investigation relating to the pozzolanic activity of rice husk<br /> ashes. Cement and concrete research. Vol, 38. pp, 861-869.<br /> [11], Columna, V. B. (1974). The effect of nee hull ash in cement and concrete mixes. M. Eng. Thesis.<br /> Asian Institute of Technology,<br /> [12], Hamad, M.A., Khattab, LA. (1981), Effect of the combustion process on the stmcture of nee hull<br /> <br /> <br /> .>p Chi KHOA HQC GIAO THONG VAN TAI So 29 - 03/2010 157<br /> silica, Thermochim:..a Acta Vol, 48. pp. 343-349.<br /> [13], Bui D. D.. et al. (2005). Particle size effect on the strength of rice husk ash blended gap-graded<br /> Portland cement concrete. Cement & concrete composites. Vol, 27, pp, 357-366,<br /> [14], Fang M.. et al. (2004). Experimental study on rice husk combustion in a circulating fluidized bed.<br /> Fuel processing technology. Vol, 85. pp, 1273-1282,<br /> [15], Chandrasekhar K.G., et al. (2003), Processing, properties and application of reacdve silica from rice<br /> husk ash - an overview. Materials Science Journal, Vol, 38, pp, 3159-3168,<br /> [16], Bouzoubad N. and Fournier B. (2001), Concrete incorporating rice husk ash: Compressive strength<br /> and chloride ion penetrability. MTL 2001-5 (TR),<br /> [17], TCXDVN 311 (2004). Phu gia khoang hoat tinh cao dimg cho be long va vira: Silicafume va tro trau<br /> nghien mjn, Tuyen tap Tieu chuan xay dung Viet Nam,<br /> [18], ASTM C618 (2003), Standard Specification for Coal Fly Ash and Raw or Calcined Natural<br /> Pozzolan for Use in Concrete, Annual book of ASTM standards*<br /> <br /> <br /> <br /> DIA MOI TRl/ONG<br /> (Tiip theo trang 69)<br /> <br /> III. KET L l AN<br /> <br /> Khi giai quyet nhung van de lien quan khai tbac va su dung khdng gian ngam tai Ha Ndi,<br /> khdng chi tinh den cac dac diem ve dieu kien dja chat hien tai ma can xem xet nhii-ng dien bien<br /> dja mdi trudng theo khdng gian va thai gian, nham lira chgn giai phap thi cdng, ket cau va vat<br /> lieu xay dung phii hgp, dam bao an toan va dn djnh lau dai cho cdng trinh,<br /> <br /> Vai trd cua cac chat vd ca, huu ca, dac biet la vi sinh vat tir nhung ngudn d nhiem khac<br /> nhau tbirdng chi dugc xem xet trong cac cdng trinh nghien ciru d nhiem nude ngam phuc vu<br /> sinh boat, cdn anh hudng ciia chung den sir bien ddi mdi trudng dat can phai dugc nghien cuu,<br /> nham khai tbac an toan va hieu qua khdng gian ngam theo muc dich xay dung tai Ha Ngi,<br /> <br /> <br /> <br /> <br /> T i i lieu tham khiio<br /> <br /> [1], Nguyin Dire Dgi vd NNK. Bao cao dieu tra dja chat do thj thanh pho Ha Npi, thupc "chuang trinh dia<br /> chat do thi Viet Nam". Tong Cue dia chat Viet Nam, Ha Npi, 1996,<br /> [2], Nguyin Huy Phuang vd NNK. Thu thap, kiem chimg cac tai lieu da co, nghien ciru bl sung lap ban<br /> do phan vimg dat yeu Ha Npi phuc vu phat trien ben vung Thii do, bao cao de tai trong dilm thanh phi<br /> Ha Npi, DH Mo - Dia chit, Ha Npi. 2005.<br /> [3], Vil Cdng Ngii' vd NNK. Nghien ciiu danh gia bo sung dieu kien dat nen viing Ha Noi va vimg phu can<br /> \-a giai phap nen mong cong trinli, bao cao khoa hpc long ket de tai. Lien hiep khoa hpc san xuit dia chit<br /> xay dung va cap nude, Ha Npi, 2007.<br /> [4], Terzaghi K., Peck R.B., Mesri G. Soil Mechanics in Engineering Prentice Hall. New Jersy, 1996.<br /> [5]. HavMHbie PCHOBBI o6ecneMeHiia 6e3onacHOCTH >KH3Hefle5iTejibH0CTH MeranojincoB. OTMCT O uayMHO-<br /> iiccjienoBaTejibCKon paoore. HayHHbiii pvKOBO/iHTejib pa5oT npo(().. ii,T,H,, TpvuiKo B,J1,, OTB<br /> Hcno,nHHTe.nb npocj).. ii,r,-M,H„flauiKOP.3„ CaHKr-flexepdypr, 2002 r. (oHflbi CnrFM)*<br /> <br /> <br /> 158 Tap chi KHOA HQC GIAO THONG VAN TAI So 29 - 03/2010<br />