KHOA HOC ^ E S 3 ! B i m
NGHIEN ClTU TO HOfP PHU GIA SIEU DEO DA TINH NANG - KHOANG HOAT TINH - POLYMER DE NANG CAO C H O N G THAM
CHO BE TONG D A M LAN DAP TRONG LlTC
ThS. Nguyen Quang Binh Vien Thuy cong
Tom tat: Ndng cao chdng thdm cho be tong ddm lan (BTDL) la mot yeu cdu cdp thiet ddi vdi cdng trinh dap hodn todn BTDL. Bdi bdo ndy trinh bdy ket qud nghien cuu to hgp phu gia sieu deo cao chdm ddng ket, khodng hogt tinh vd polymer de gidm ti le nudc/chdt ket dinh, thay ddi cdu trdc be tdng de ndng cao chong thdm cho BTDL.
Summary: The improvement of waterproofing for roller compacted concrete (RCC) is a critical requirement for the completely RCC dam. This paper presents the results of studies combining high superplasticizer and slow settings, active mineral and polymer materials to reduce a ratio ofwater/binder, concrete structural changes to improve waterproofing RCC.
1. M O DAU
Co sd nang cao cbdng tham cho BTDL la tang do dac cbac bang su dung td hop phu gia, trong do phu gia sieu deo cao giam thieu lugng nude trdn, phu gia khoang boat tinh giam vdi trong qua trinh thuy boa xi mang va giam luong dung xi mang, phu gia polymer lam nhd dudng kinh va cat dut lien thdng cac Id mao quan trong da xi mang.
Tbeo [3], viec giam ty le N/CKD lam tang cudng do nen do ben chdng tham) cua be tdng binh bay d binh 1, su cd mat cua phu gia sieu deo cao cham ddng ket giam toi da N/CKD van dam bao tinh cdng tac (Vc) va thdi gian ddng ket Tjk cua BTDL.
Khi sii dung polymer trong BTDL, cac tieu phan nhu polymer phan tan trong nude cd kich thudc 500 - 5000A° [6], Co che bien tinh xi mang cua polymer tan trong nudc[7, 8] dugc giai thich do cac phan tu polymer hap phu tren be mat hat xi mang, trong qua trinh thuy boa mach polymer
ddng ran phan bd tren be mat cac pha mdi binh thanh cua da xi mang va cd kha nang xuyen sau vao vung tiep xuc giua cac tinh the. Phan bd trong cau true da xi mang d dang vi mang lam giam dudng kinh cac Id rdng Idn va giam lugng rdng thdng nhau, ngan can nude di chuyen, tang kha nang cbdng tham cho BTDL.
Ngudi phan bien: PGS.TS Le Minh Ngay nhan bai: 22/9/2014 Ngay thdng qua phan bien: 10/10/2014 Ngay duyet dang: 13/10/2014
Hinh 1: Do chdng thdm vd N/CKD Phu gia khoang tro bay cd tac dung bo sung thanh phan hat min, tac dung boat tinh ddi vdi Ca(0H)2 trong xi mang thuy boa, giam lugng dung nude trong BTDL.
- Trong BTDL lugng diing xi mang thuong it hoac rat it, lugng dung nude cQng it, nen kbdng du de nbet day cac khe ke giGa cac bat cdt lieu. Vi vay, phai diing them tro bay dk
KHOA
Hocill^Es&^BSI
tang lugng chit bgt min dam bao dii de nhet ke trong be tong. Theo tai lieu [4], vi$e nhet ke dugc thS hien blng hai he s6 du ho a va du viia p, theo nhiSu kgt qua nghien ciiu ten the gioi thi he s6 a=l,l - 1,3 con he so p=l,3-l,5 la phu hgp cho san xuat BTDL.
- Trong thanh phin ciia tro bay co cac thanh phin SiOz v6 dinh hinh, AI2O3 va FejOs boat tinh. Cac chit nay se phan ling vol thanh phan CO hai Ca(0H)2 tao ra trong qiia trinh thuy hoa ciia xi mang tao thanh cac khoang co cuong do, lam tang cuong do, do die chae va chong thim ciia BTDL.
Tro bay con lam giam lugng dimg nuoc nho hieu ling 6 bi. Khi thay thS xi mang bang tro bay, do cac hat tro bay co dang hinh cau nen chung CO tac dung boi iron lam tang tinh cong tac cho hon hgp be tong hoac de dat dugc cimg tinh cong tac thi hSn hgp be tong sir dung tro bay se ein lugng nuoc trgn it ban so voi hon hgp khong su dung tro bay. Diiu nay dong nghia vol viec giam lugng nugc du trong BTDL, tang do dac chSc, tang cucmg do BTDL va kha nang ehong thim.
Nhu vay, viec su dung to hgp phu gia sieu deo da tinh nang, phu gia khoang tro bay, phu gia polymer se dat hieu qua chong tham cao cho BTDL.
2.Vat Ueu si dyng va phinmg phap nghiSn cuu Cac loai vat lieu su dung nhu sau: Xi mang Biit Son PC40 co chit lugng dat cac tieu chuin TCVN 4030-2003 va TCVN 6017- 1995; phu gia khoang boat tinh tro bay Pha Lai dat loai F theo ASTM C618; Cat nghik Son La dat chit lugng theo TCVN 9205:2012; da dam Son La dat chit lugng theo TCVN 7570:2006, phu gia cham dong kit complastR hang Fosroe loai B theo TCVN 8816:2011;
phu gia cham dong kit GPI01 hang Grace loai B theo TCVN 8816:2011, phii gia ADVA 181 sieu deo thi he moi loai F theo TCVN 8816, phu gia polymer DM200 hang Schooll - Diic.
Trong di tai nay tiin hanh nghien cihi che tsio BTDL c6 cuong do nen dat 20MPa va dp ching thim din W12 blng t i hgp phu gia sieu deo da chiic nang S (pha trgn giira ADVA-181 va GP 101), tro bay Pha Lai va polymer DM200 ciia Diic. Trong nghien cim co sii dung quy hoach thuc nghiem.
3. Bo tri quy hoach thwc nghiem 3.1. Chon thanh phan hat cot lieu Trong nghien ciru sir dung cot lieu co thanh phin hat theo Yeu cau ky thuat ciia cong trinh thiiy dien Son La [2], nhu trong bang 1 va hinh 2.
Bang 1. Thanh phan hat ciia cot tieu
Cd hat. mm
% lot sang tiieo trong lugng
Yen can Ket qua
63 100 100
50 100 100
38 87-100
98.6 25 72-85I
83.8 20 63-79
72.6 12.5 50-64 58.7
10 43-59
50 6 5 29-42
38.2 2.4 21-32
27.3 1.2 14-24
19 0.6 10-19
12.9 0.3 8-15 9.5
0.15 6-12 7.4
0.075 5-10 6.0
Hinh 2. Duang thdnh phdn hgt cug cot lieu
3.2. Tinh thanh phan cap phoi cho quy hoach thirc nghif m
De xay dung mo hinh toan hoc bieu thi anh huong cua lugng dimg phu gia sieu deo ch|ni dong ket thi he mdi (S), ham lugng tro bay pha Lai (T) va ham lugng phu gia polymer (P) din cuong do va do chong thim, sir dung phuong phap quy hoach thuc nghiem bac II, 3 biin tam xoay.
50 TAP CHl KHOA HOC VA CONG NGHE T H O Y LOI S 6 23 - 2014
KHOAHOC M H H l ' I ' l l ' H i l ^ - S: lugng dimg phu gia sieu deo trong Im^ dien Son La lam cap phdi co sd (CPCS) nhu BTDL, lit. trong bang 2 de tinh toan cac cap phdi tai cac di^m trong ma tran quy hoach thuc nghiem.
Viec tinh toan cac cap phdi BTDL trong quy - P: lugng dung phu gia polymer trong Im^ hoach tbeo nguyen tac:
BTDL, kg.
- T: lugng dung tro bay trong 1 m BTDL, kg.
Tuong ling voi cac bien thuc noi tren la cac bi6n ma Xi, X2, X3. Vung biin tbien cua cac biSn la:
S = 2.0-3.4, T = 1 2 0 - 1 6 0 , ? = 0.93-3.47.
Lira chpn cap phdi BTDL da dung cho thuy
- Cd dinb tdng lugng chat ket dinh nhu CPCS (220kg);
- Gin nguyen thanh phan cap phdi hat cua bdn hgp cdt lieu (Cd dinb ty le C/(C+D) tbeo kbdi lugng nhu cua CPCS);
- Thay ddi lugng nude de BTDL dat tinh cdng tac.
Bang 2. Thanh phan CPCS SIT
1
Trang thai VL Kho
XM (kg) 60
TB(kg) 160
Cat (kg) 850
Da dam (kg) 1396
CDK, lit Nu6c, lit 140
Ting 2589
N/CKD 0,64 Ghi chu: cap phdi co sd cd cudng dp nen 20Mpa, do chdng t h ^ dat W6.
Ket qua tinh toan thanh pbSn cap phdi tai 19 diem cua ma tran quy hoach thuc nghiem nhu trong bang 3.
Bang 3. Thanh phan cap phoi BTDL trong quy hoach
STT 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
X , k g 2 60 60 100 100 60 60 100 100 80 80 45 115
80 80 80
T , k g 3 160 160 120 120 160 160 120 120 140 140 175 105 140 140 140
P , k g 4 3.47 3.47 3.47 3.47 0.93 0.93 0.93 0.93 2.2 2.2 2.2 2.2 4.4 0.00
2.2 S,lit
J 3.4 2.0 3.4 2.0 3.4 2.0 3.4 2.0 3.91 1.49 2.7 2.7 2.7 2.7 2.7
C , K g 6 891 865 895 870 893 867 897 872 903 860 877 885 879 883 881
D , k g 5-12,5
7 418 408 420 410 420 410 421 411 423 406 413 416 414 416 415
12,5-25 8 560 546 562 548 561 548 563 550 567 543 553 556 553 556 555
25-50 P 465 454 466 455 466 455 467 456 470 450 459 462 459 461 460
N, lit 10 85.4 108.4 85.1 108.0
85.4 108.4 85.1 108.0
77.0 116.3 97.0 96.4 96.7 96.7 96.7
N/CKD
11 0.39 0.49 0.39 0.49 0.39 0.49 0.39 0.49 0.35 0.53 0.44 0.44 0.44 0.44 0.44
KHOAHOC ~ ^ E ! ! 3 ! B i l ^ l
4. KET QUA VA BINH LUAN cua 19 diim trong ma tran ki hoach thuc ,,; , , . . . . , ,. , i,', „„ I,-, n r n i nghiem duac trinh bay trong bang 4.
Ket qua thi nghiem cac tmh chat CO ly BIDL o . . j e = Biing 4. Tinh chat cff ly BTDL tai cac diem quy hoach
Diem TN
1 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 17 18 19
Vc,s
18 20 22 20 20 19 20 20 17 20 23 20 20 21 20 23 20 20 20
Thai gian dong ket, gio. phut Bat dau
17.00 16.50 17.10 18.00 18.10 17.50 17.40 17.00 16.55 18.25 18.05 17.00 17.25 18.00 17.40 17.20 18.20 17.00 17.15
Kit thuc 71.25 71.15 70.00 71.35 71.15 70.55 71.05 72.15 7105 71.55 72.35 70.45 71.00 71.30 71.55 72.00 71.45 72.35 70.55
Khoi lugng the tich, kg/m' Hon hgp
2649 2603 2651 2614 2641 2616 2653 2623 2663 2608 2627 2646 2622 2637 2632 2635 2632 2636 2637
Tuii 90 ngay (kho gi6)
2645 2597 2648 2608 2639 2610 2650 2618 2661 2600 2623 2643 2619 2632 2628 2631 2618 2633 2634
Cuong do nen tuoi 90 ngay, daN/cm^
308.4 241.4 472.9 368.9 309.9 242.6 471.6 369.2 437.5 281.5 216.6 466.9 343.4 336.8 339.1 340.1 342.2 341.6 343.1
He s i thim, K/10-'°,
cm/s 7.82 61.22 5.95 45.3 10.42 102.86 4.60 45.71 10.76 120.0 36.42 10.15 10.66 20.14 11.71 9.14 12.81 10.820 10.180
Do chong thim B,
atm B12 B4 B14 86 B12 B4 B14 B6 B12 B4 B6 812 B12 810 B12 812 B12 B12 812 - Tir ket qua thanh phin cac cip phii BTDL
bang 3, ti le N/CKD = 0,35-0,53. Nhu vay voi su CO mat ciia phu gia S thi he moi thi ti le N/CKD nho nhit ciia BTDL nghien citu thip hon ti le N/CKD nho nhit cua BTDL Trung Quoc sir dung cho dap trong luc (N/CKD=0,43) [1], ti le nay cimg nho hon ti le N/CKD nho nhit cua BTDL da thi cong cac dap trong lire o Viet Nam (N/CKD=0,48) [2].
Tinh cong tac ciia BTDL trong quy hoach, Vc
= 17+23 s, nim trong khoang phu hgp di thi cong; thoi gian BTDK xip xi 18 gid, KTDK xip xi 72 gio; khii lugng thi tich h6n hop BTDL, 2579*2685 kg/m'; khii lugng thi ticli BTDL (kho gio) tuii 90 ngay, 2566*2676 kg/m'; cucmg do nen tuii 90 ngay dat til 216.6*472.9 daN/cm^ he s6 tham tuii 90 ngay dat tir 120 xlO-'^-^ 4.61 xlO'»cm/s c5p
52 TAP CHl KHOA HOC VA CONG NGHE T H O Y LOI 5(5 23 - 2014
KHOA HOC ^ E S B I B U B
chdng th4m dat tu B4^B14.
4.1. Anh hvdng cua to horp phu gia S-T-P den cirtmg do nen BTDL
Phuong trinh bdi quy cua cudng do nen tudi 90 ngay theo bien ma:
R90 = 341.4+ 43.6 Xi - 72.4X2 - 9.0 X1X2 + 6.2 Xi^ (4) Nbu vay, cudng do nen BTDL tudi 90 ngay kbdng chiu su anh hudng cua bam lugng
polymer sit dung trong be tdng (khdng cd bien X3 trong phuong trinh). Dieu nay cd the dugc giai tbicb do polymer khi tan trong nude khdng phan ung vdi cac thanh phan khac trong be tdng d^ tao chat mdi va cung khdng cd tac dung giam nude hoac lam hieu suat phan ung cua CKD.
Be mat bilu diin cua phuong trinh cudng do nen BTDL tudi 90 ngay nhu hinh 3.
Hinh 3. Be mat bieu hien vd duong ddng mice cua hdm muc tieu R90 theo Xj vd X2 - Tir hinh 3. ta cd the dl dang nban thay sir anh
hudng den cudng do nen BTDL tudi 90 ngay kha rd cua ca 2 yeu td la lugng diing phu gia S (Xi) va lugng dung tro bay T (X2): Cudng do nen BTDL tudi 90 ngay ty le tbu^ vdi S va T.
+ Khi phu gia S tang tbi ti le N/CKD giam di tinh cdng tac Vc kbdng thay ddi, lam giam lugng nude tu do trong BTDL anh hudng den cdu ttuc BTDL tang dp dac cbac va cudng do nen va ngugc Iai.
+ Khi lugng dung T tang anh hudng ro ret den cSu true cua BTDL, tang do rdng do lugng nude du khdng tham gia vao phan ung thuy
boa xi mang bay boi va phan ung puzzolanic cua xi mang vol tro bay cung giam lam giam dp dac cbac va cudng dp nen va ngugc lal.
4.2. Anh hu-dng ciia to hop phu gia S-T-P den dac tinh tham cua BTDL
Phuong trinh bdi quy cua be sd tham tudi 90 ngay theo bien ma:
K90 = (10.8 - 29.7Xi +9.0X2 - 4.3X3 -8.2 X1X2 +5.1X1X3-5.7X2X3+18.3X1^+4.3X2^
+1.6X3^)10-'°cm/s. (5) Be mat bieu tbi phuong trinh bdi quy he sd
tham Ciia BTDL khi cd dinh bien X3 nbu trong binh 4.
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Hinh 4. Be mat bieu dien vd dudng ddng mirc cuahdm muc tieu K90 theo Xi vd X2 - Bi mat biiu thi phuong trinh hoi quy he so thim cua BTDL khi c6 dinh biin X2 nhu trong hinh 5.
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Hmh 5: Be mat bleu hien vd duang ddng mice cua hdm muc tieu K,o theo X, vd X3
Be mat bieu thi phuong trinh hii quy he s6 thim cua BTDL khi c6 dinh biin X, nhu trone
hinh 6. ^
54 TAP CHl KHOA HOC VA CONG NGHE T H O Y LOI S 6 23 - 2014
KHOAHOC M H - | l ' H l ' H i | - M
Hinh 6. Be mat bieu hien vd duang ddng mice cua hdm muc tieu K^o theo X2 vd X3 Nhan xet: Tu binh 4, 5, 6 ta cd the nhan th4y
lugng dung phu gia S (Xi) va lugng P (X3) ti le nghich vdi he sd tham BTDL tudi 90 ngay, lugng diing T (X2) ti 1^ thuSn vdi be sd thdm BTDL tudi 90 ngay.
Khi lugng phu gia S tang thi he sd tham BTDL tudi 90 ngay giam manh. Dieu nay cd the dugc giai thich nhu sau: Khi phu gia S tang (N/CKD giam) thi lugng nude tu do trong BTDL giam nen ham lugng xdp rong giam lam cho he sd tham cua BTDL giam manh.
- Khi lugng dung P tang tbi be sd tham cua BTDL tudi 90 ngay nhin chung giam, tuy nhien vol cap phdi cd lugng dung S cao (ty le N/CKD thap) tbi khi tang ham lugng P be sd tham cua BTDL gan nhu khdng thay ddi.
Nguyen nhan ciia bien tugng nay la do P tao ra vi mang tren ranb gidi cau true da xi mang va trong be mat cac lo xdp dan den giam dudng kinh Id xdp va cau tnic khdng.lien tuc lam tang do ben chdng tham BTDL. Vdi cap phdi be tdng cd ty le N/CKD nhd thi ban than be tdng da CO cau tnic dac cbac (the tich xdp va dudng kinh Id xdp nhd) nen dp cbdng thim tdt. Trong trudng hgp nay tac dung nang cao dp ben tham be tong ciia P khdng dang kl.
- Khi lugng dung T tang thi be sd tham cua BTDL tudi 90 ngay tang, dieu nay dugc giai tbicb: Khi lugng tro bay tang khdng chi anh hudng den dp ben co, ddng tbdi cdn anh hudng ro ret den cau tnic ciia be tdng, tang dp rdng do lugng nuoc du kbdng tham gia vao phan ling thiiy hda xi mang bay hoi va phan ung puzzolanic cua xi mang vdd tro bay ciing giam lam tang he sd tham BTDL.
5. KET LUAN
Ket qua nghien ciiu cho thay su dung td hgp phu gia hda-kboang-poljoner cd the nang cao ro ret kha nang chdng tham BTDL, cu the la:
1. Cac tinh chat ciia bdn hgp BTDL phu hgp vdi dieu kien thi cdng bien nay d Viet Nam:
Tinh cdng tac BTDL Vc=17-23 giay; tbdi gian bat diu ddng ket dat 16h50^18h; thdi gian kit thiic ddng kit dat 70h00^72b35.
2. Giam manh lugng nude trgn yeu cau trong BTDL, ti le N/CKD trong BTDL cd tbi giam tdi N/CKD = 0,35
3. Cudng dp nen BTDL tudi 90 ngay dat M20H-M40.
4. BTDL cd the dat dugc dp chdng tbira cao
TAP CHI KHOA HOC VA C O N G N G H E T H O Y LOl S6 23 - 2014 55
I KHOA H'OC ^ E S 3 ! B ! I ^ B
toi 14 atm (cap phoi so 3, 7 bang 3). co the giam lugng dimg xi mang 15kg/m (cap 5. Di dat cuimg do va do ching thim CPCS P^°' ' ' ' ' ^ 8 ^'•
TAI LIEU THAM KHAO
[1] Cong ty tu vin xay dung thtiy lgi, Quy pham thiet ke dap be tong dam lan. (Dich tir tiing Trung tieu chuan SL 314- 2004 cua Trung Quoc. Nguoi dich Nguyin Nggc Bach, 1/2005.
[2] Lugng Van Dai, Bao cao tdm tit tinh hinh xiiy dung dap be tong dam lan tren the gioi va 6 Viet Nam hien nay. (Trong tuyen tap bao cao Hgi nghi Cong nghe be tong dam lan trong thi cong dap thuy dien cua Viet Nam, EVN, Ha Ngi,4/ 2004.
[31 B. Sharp, Concrete V.30 (4), pl2-15, (1996).
[4] CIRIA-Report 135. Concreting deep lifts and large volimie pours. London, 1995, 84p.
[5] BhushanL., Karihaloo. Fracture mechanics structural concrete. Longman S&T, 1995, 330p.;
[6] V.R. Riley, I. Razl. Polymer additive for cement composites, Composites, 1974, V5 (1), p.27-33.
[7] Y. Malier, Les Beton a hautes performances; Press, de I'ecold national de ponts et chausses 1992, p. 3-416.
[8] S. Chandra and P. Flodin. Interactions of polymenrs and organic admixture on Portland cement hydration, Cem. Conor, res., 1987, V.17, p. 875-890.
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