PIEW BAN KHOA HOC C 6 N G NGHfe
ANH Hl/dNG CUA SOl POLY-PROPYLENE DEN UfNG XUf CHIU U 6 N QUA DAM BE TONG GEOPOLYMER C 6 T THEP SUf DUNG TRO BAY
EFFECT OF POLY-PROPYLENE FIBERS TO FLEXURAL BEHAVIOR OF REINFORCED FLY ASH-BASED GEOPOLYMER CONCRETE BEAMS P H A N O O C H U N G , D l / d N G V A N D U N G - AH Si/pham KJ thult TRHCM.
L E A N H T U A N - Khoa Ky thuat Xay di/ng, OH Bdch Khoa Tp.HCM.
T 6 M TAT:
Ckc tinh chdt cd hpc cfla be tong geopolymer da di/gc chiing minh ti/dng ttf nhi/ be tdng truyin thong vk thS hign tfnii l/u vi§t cfla mOt loai vat lieu xanh vi khdng can siJ dung xi mang. Ngoat ra, tinh gion cua bfi tflng geopolymer cfl khS nang di/Oc kh4c phuc bSng cac loai sdi nhU sdi th6p va spi poly-propylene. Trong bk\ bSo nay, c^c loai sdi poly-propylene c6 ctiieu ddi 19mm va 25mm dUdc bi sung vfli ham lupng sdi 0.5% vk 1.0% theo th^ tfch 3e 6knh gik knh hi/flng cOa spi ilu
\ihk nkng chm uon cua cau kien d ^ b§ tflng geopolymer. Ket qu3 ttii nghiem cho ttiSy, be tflng geopolymer n^n si dung spi poly-prapylene vdi hkm li/png 0.5% cai ttiien tflt aidng dfl chju nfin va uon nhi/ng chi cki thi§n ci/flng dfl chju u6n ktii h^m lu^ng spi 1%. Tuy nhien, clp phfli be tflng svi dung sdi cfl t^ te chieu dai - di/dng kinh sdi \k 380 vdi hkm lUQng s^i 0.5% cfl khd n^ng chiu uon tot nhk khi lam viec trong ciu kien dim.
W khda: Sdi poly-propylene. be tong geopolymer, Qng xd chiu udn. dam.
ABSTRACT
The mechanical properties of geopolymer concretes had been proven to be similar to traditional concrete. Previous stud- ies also demonstrated ttieir superiority as a green matenal because of without using cement. In addition, the brittleness of geopolymer concrete can be overcome by using fibers such as steel or poly-propylene fibers. In this paper, poly-propylene fibers of 19mm and 25mm in length are supplemented with content of 0.5% and 1.0% by volume in order to improve the bending resistance of geopolymer concrete beams. Experimental results show that geopolymer concrete using poly-propy- lene fibers with content of 0.5% improves its compressive and flexural strengtti, but just improves the flexural strength wiQi content of 1 %. However, concrete mixture with ratio of lengtti to diameter of fiber by 380 and 0.5% fiber content has the best bending resistance.
Keywords: Poly-propylene fiber, geopolymer concrete, flexural behavior, beam. ^
L G l d l l THIEU
NgSy nay, viec nghien cOru mang tfnh ung dung cac lo^i v&t ll^u xay dLmg m6i ngky cang dL/ote trien khai mgnh me, dac bi§t 1^ cSc logi vat lieu xanh, than thien vflfi moi trLftfng nhlim hgn ch§ tiieu Cmg nha kfnh. Vat li^u b§ t6ng geopolymer da va dang diidc nghien cOru da chiJng minh dirpc su phii hop vert cac tinh chdt cof hpc tuong ttr nhu be tong truySn thdng va t h ^ hien tfnh ou viSt cCia mpt loai v | t lieu xanh vi khong c4n sit dung xi mang. Ngoai ra, loai vat ligu nay con giup xit ly duoc trO" lupng Idm phu pti^m cua nganh cong nghidp nhiet di&n {tro bay). C6ng nghe geopolymer da dope giko su Joseph Davidovits gidi thieu vao nhOng nam 1970. [ 1 , 2] Quy trinh tong hpp polymer til ckc khoang chdt b§ng each trpn cac loai vat li§u cd chijra hkm lupng Ipn hpp chdt silie v^ nhom vko dung djch alkaline silicate co n6ng dp ki6m cao nhkm tao ra mpt hpp chdt 6 dang gel va dupc gpi la geopolymer. Tuong t l / nhtr be tdng t r u y i n thdng, tinh gion ciJa be tdng geopolymer c6 kha nang dupc khke phuc biing cac logi spi nhu spi thep va sgi poly-propylene, han chd cdc tAc dpng ciJa cac hiSn tupng ttr bidn, co ngot, mdi,... cung nhir chju tdc dpng cua tai trpng va sir xam t h y t cua moi tru6ng l^m kha nang chiu luc cac kdt cdu cdng trinh be tdng cdt thdp bi suy giam. [3,4,5] Tuy
nhien, sti Ikm vl§c ci!ia bk tdng geopolymer c6 gia cu&ng c6t spi phan tan trong cdu kien cdn dUi?c nghien cOfu de tCr do cd t h ^ xdc djnh loai spi, hkm lupng spi phfj hpp voi cdp phdi, \km tang nhQng d$c tinh c6 lpi, hgn chd cac nhupc d i l m cua bfi t6ng geopolymer, dac bigt khi sOr dpng cdc loai vdt li^u dja phuong vd tro bay tU cdc nhd mdy nhi#t di§n trong nudc.
Bai bdo xdc djnh anh hu&ng cua sgi poly-pro|:^
lene ddn kha nang chju udn cua cdu kign ddm bfl tAng geopolymer sO dung tro bay thu dupc tii ckc nhd miy nhiet didn trong nuPc. Sgi poly-propylene vdrt hai logi cd chidu dai 19mm vd 25mm dupc sCrdung vdi h&m lupng spi Id 0.5% va 1 % theo the tich ptidn bd nglu nhien trong qud trinh nhdo trdn bd tdng geopolymer.
2. NGUYEN VAT LIEU v X PHUONG PHAP THI NGHIEM
2 . 1 . N g u y g n v a t lieu 2.1.1. Cdt lidu '
Bd tdng sCr dung dd dam cd hrnh dang trdn. It hai det vd ft gdc canh, dupc rCia sach, phoi khd. Cdc chi tieu va cdp phdi thanh phdn hat cua dd dam du^c trinh bay ldn lupt trong Bang 1 vd Hinh 2.
Cat vdng dupc siHr dyng Id cdt sdng, riia sach, phrt khd, sang Ipc bdt hdm lupng hat nhd. Cdc chl tidu vi N G U d l XAY DUNG SO T H A N G 3 & 4 < 2 0 1 6
ANH HUflNG COA Sdi POLY-PROPYLENE BEN l?NG Xljf CHIU UON...
B a n g 1 , Cac chi tieu cda da dam C h i M u t h l n g h M m
Dmax Kt]6j luung rigng Kh6i li/dng M bch d trang
Ml khe
Kh6llij^gth€tich Strang thai bao hO(l {)Qhdtnt/i3c Kh6i luong Ihi bch x6p BQ r6ng gida cdc hat
Phddng phip Ihi nghigm T(WN 7572-2:2006 TC™ 7572-4:2006 TCVN 7572-4:2006 TCVN 7572-4:2006 TCVN 7572-4:2006 TCVN 7572-6:2006 TCVN 7572-6:2006
Kh qua Ihi nghigm 2.20 cm 2.78 g/cm*
2.61 s/cm' 2.67 g/cm"
2.5%
1415 kg/m' 45.8%
Hlnh 2. Bieu do Oiinh phhn hat cda di dim Bang 2. Cac chi tidu ca /y cda cat siy dung Cht sgu thi nghigm
MO dun do ldn Kh6i IUdng rigng KhA luung Dig tfch avang thilkhO
M l luong thg tich a trang M l bio hoi SObiitnillic Khii liUigtiig tich xip Og ling gioa Cilc hat
PhUdng phip fhi nghigm TCVN 7672-2:2006 TCVN 7572-4:2006 TCVN 7572-4:2006 TCVN 7572-4:2006 TCVN 7572-4:2006 TCVN 7572-2:2006 TCVN 7572-2:2006
Kit qui thi nghigm 2.5 mm 2.60 g/cm' 2.43 g/cm' 2.49 g/cm' 2.9%
1545 kg/m' 36.4%
'Dirtnig bao vung c h u ^ I Iheo TCVN 7572-23006 -A-Oirirng bilu diin thSnh
phin hgt cOa cat I Kich i h t r ^ A sing (mm)
Hlnh 3. Bleu dS thanh phin hat cit sif dung ip phdi thdnh phdn hat cua dd dam dupc trinh bdy n lupt trong Bang 2 va Hinh 3.
2.1.2. Tro bay
Tro bay loai F sft dung co ngudn gdc ti^ nha mdy nhiet di$n, khdi lupng ridng 2500 kg/m^ dp mjn 94%
lupng Ipt qua sang co cdf sdng Id 0.08 mm.
Bang 3. Thinh phan hoa hoc cua tro bay Ttianh
phan hca hoc
% k h i i luong
SiO,
51.7
Mfi,
31.9 M l
3.48 CaO
1.21 K20
+ Na,0 1.02
MgO
0.81 SO,
0.25 MKNC)
9.63 (') MKN; mat khi nung 2.1.3. Dung djch ho^t hda
Dung dich hoat hda la s u kdt hpp giOa sodium hydroxide va sodium silicate. Dung djch sodium hydroxide mdu trdng duo co dp tinh khidt tren 90% vd khdi lupng rieng la 2130kg/m^ Bi tao dung djch sodi- um hydroxide, NaOH dang vay ran dupc hda tan vdo nudc theo ndng dp 16mol/l cho trudc. Dung djch sodi- um silicate sir dung vpi hdm lupng Na^O vd S i O j dao dpng ti:r 36 ddn 38 %, ty trong i .42±0.01 g/ml.
2.1.4. Spi
Hinh 4. Sdi poly-propylene
Scrt poly-propylene dupc dCing de chd tao mau cd cdc dac ti'nh:
- Oudng kinh: 0,05 mm - Chidu ddi: 19mm va 25mm.
- Op ddn ddi ddt: 15 - 20%
- Ktidi lupng ridng: 0,91 g/cm^
- Dp bdn keo: 700MPa
- Mifc dd chju axit vd kidm: mdc cao.
2.2. d p p h d i
Cac cdp phdi be tdng geopolymer (GPC) sir dyng Bang 4. Miu cip phdi cho cau kien dim
Miu
M1 M2 MS M4
Chilu dil SSI (mm) 19 25
T f l i tren sd 1%) 0.5 1.0 05 1.0
Hi (kg) 1073 1068 1073 1068
Cil (kg) 590 587 590 587
Tro (kg) 416 413 416 413
m
(kg)
78.75 82.5 78.75 82.5
NaOH (kg)
194.25 203.5 192.25 203.5
Kh6l IUdng sdi (ko) 4.55 9,1 4.55 9.1
Mdi
IGM leM 16M 16M
PHUCHUNG A •flS N G U d l X A Y D I M C SO T H A N G 3 & 4 - 2 0 1 6
spi poly-propylene cd cac ty le c h i l u ddi - duPng kfnh klidc nhau vdi ham lupng la 0.5 va 1.0% theo the tich.
Cdp phdi be tdng geopolymer ndn dupc trinh bay trong Banc| 4.
Cdc ddm cd kich thudc 200x300x3300mm dupc due d l xac dinh khd ndng chju udn. Ddm dupc duSng
ANH HUdNG CUA Sdi POLY-PROPYLENE PEN LfNG XOf CHIU UOM
Hinh 6. Dddng ho nhiet cho ciu kien
II 1 1 1 1 M l 1 II
y L ^ \
Hinh 7. Cau tao dam be long cot thep 1 ^ 1
U
iirt^-
j - j .1 ^ ™ » ^
Pi 1 . C - t
n
1 II II II I,„.1,J1 II i| ! II, i , , ! „ i Wmt\i.Sdd6thinghi$m
Hinh 9. Chuh bi thi nghiem u6n dam
hd nhiet 6 90^0 trong 10 gicf.
2.3. Phu'cng phap t h i n g h i g m
Ddm_ be tdng cdt thep cd chidu ddi 3300mm, ti#t didn mdu (200x300)mm. SiJr dung thep 5i^14mm v^
2(til2mm lam cdt dpc va it>6a150mm Idm cdt dai. Clu- tao ddm bd tong c6t thep vd so dd thi nghidm dupc Vnl hien or Hinh 7, 8 va 9.
Ddm dupc chdt tdi giiJa nhjp bdng khung thir u6n 50 tdn. Hinh 9 md td stf dd thi nghidm, bidn dang tjii mat day or giQa ddm va chuyen vj tai giua ddm va tai 1/4 nhjp ddm dupc duoc thu nhan theo butSc tang tai cho ddn khi phd hoai ddm.
3. K I T QUA THI NGHIEM
3 . 1 . C i r d n g d o c h j u n e n , u d n c u a m l u Kdt qua thi nghiem cuPng dp n6n udn cua cdc c4p phdi be tdng GPC dupc trinh bdy trong Bang 5.
Bang 5. Kit qua thi nghidm miu Kv
hieu GPC M1 M2 M3 M4
T } l i (l/d) 0 380 380 500 500
Ham luting soi (%)
0.0 0.5 10 0.5 1.0
CUSng Hi chju nin (MPa)
32 61 35.77 34.34 35.08 32.29
Cudng 6i diju uin (MPa)
3.7 6.30 7.17 6.27 6.69 So vdi mau khdng gia cuPng spi thi khi dupt gia cuPng spj mdu cd kha ndng dupc cai thien vd cuftng dp chju nen, udn. Trong dd, cac cdp phdi cd h^m lupng spi 0.5% cho kdt qua cuPng dp chju ndn Idn iifln khodng 10% so vdi mdu khdng gia cudng spi GPC, Khi tang ty Id spi tii 0.5% Idn 1.0% thi cuPng dO chju nen ciJa to m l u giam. So vdi cudng dp chju ndn thi cuPng do chiu udn cua mau vupt trpi hon khi gia cuPng cdt spi va cd xu hudng tang khi ham lupng soi tdng, tiJ" 70% ddn 90% so vdi cdp phdi GPC. Oilu n^y dupc giai thich la vat lieu s d phat huy tdt vai trd bic cdu khi hidn tupng ndt xay ra. Vc^ cung hdm lucmg sol sir dung thi ty le chidu dai - duPng kinh scri bang 380 la hpp \y, cho kdt qua tdt hon.
3.2. A n h h t r d n g cua s o i d i n c h u y i n vj cOa dim Kdt qua do chuyen vj tCrthuc nghidm cho thdy, Jpi tri dp vdng cua cd bdn cdp phdi khi tdi trpng dat din 90kN la tuong dUtfng nhau trong khodng 15mm. Mra quan he giOa tai trpng tdc ddng vd chuyen vj trong giai doan ndy la tuydn tfnh. Khi tai trpng Idn hon thi moi quan he nay Id phi tuydn vd khi tai trpng ldn htfn 10OkN thi cac duPng bieu didn mdi quan he ndy cd sii phan tan Idn. Ddm si!r dung hai cdp phdi M1 vk M3 (ung vdi hdm lupng spi la 0.5%) cd kha nang chju lire tdt hon, tuy nhidn tfnh deo cua hai cdp phdi M3 vS M4 cung da dupc cai thidn hon, chuydn vj giiJa ddm I * hon (Kmh 11a.). So vdi kdt qud thf nghidm trdn dilm cd cung cdu tao vd cdp phdi bd tdng geopolymer khdng trdn them spi (Hlnh l i b . ) , kha ndnp chju tai cfia cdc ddm sir dung bd tdng geopolymer cdt spi tdt hem.
Didu nay cho thdy vai tro cua spi trong qud trinh 1 ^ N G l / d l XAY D U N G SO T H A N G 3 & 4 • 2 0 1 6 I
ANH HlfCiNG CUA SOl POLY-PROPYLENE flEN iJNG XUf CHIU UON...
Chuyin vj L/2 (mm)
a. Kit qui thi nghiSm cic cip phdi GPC sdt popy-propylene
ChuySn v| t/2 (mm)
b. Ket qui thi nghiem cic ckp phoi GPC khdng sdi [6]
Hinh 11. Quan h6 gida tii trong va chuyen vi tai vi tri gida nhip
Chuyin vfL/4 (mm)
a. Kit qui thi nghidm cic cip phoi GPC sdi popy-propylene
Chuyin vit^L/4 (mm)
b. Kit qua thinghiem cic cip phdi GPC khdng sdi [6]
Hinh 12. Ouan hi giOa tai trong va chuyen vi tai vi tri 1/4 nhip dim
4000 6000 8000 10000 12000 eWndtni(lii)
a. Kit qui thi nghiim cic cip phoi GPC sdi popy-pmpylene
3O0O 40)0 5000 GOOO 7000 Bl6i dfng (fie)
b. Kit qui thf nghidm cic cip phdi GPC khdng sdi [6]
Hlnh 13 Quan hi gida tii trong va bl§n dang tai vi tri gida nhip vide cua cdu kidn, khi ddm bidn dang vd hinh thanh
vdt ndt, s u lien kdt giOa cdc sol va vat lidu ndn kim ham s u phdt trien vdt ndt, han chd chuydn vi cua dkm. K i t qud tucffig t u khi xet mdi quan he giiJa Iut va chuyen vj tai vj trf 1/4 nhjp ddm (Hinh 12).
3.3. a n h h i r d n g ci^a s o i d i n bidn d ^ n g Mdi quan hd tai trpng tdc ddng va bidn dang d mat ddy giQa ddm cho thdy bidn dang cua cdu kidn cd xu hudng tang ddn theo cdp dd tdi trpng, tdng tuydn tfnh trong giai doan ddu vd phdn tdn Cmg vdi tdi trpng Idn {Hinh 13a.). S u d n h hudng cua spi cd ty Id l/d Idn (dng V(M spi c d chidu dai ldn hon, 25mm) cd s u 6 n dinh hon trong giai doan ddu tdng luc do dnh hudng ctia ydu td chidu dai, tang khd ndng bdc cdu. Vdi cung mdt cdp phdi, so vdi ddm GPC khdng spi thi gia trj bidn dang
cung cd xu hudng nhd hon 6 ti!mg cap tai trpng. Bidu ndy chdng minh dupc khd nang han chd bidn dang cua spi poly-propylene.
3.4. Sir h m h t h a n h vdt n i i i khi t a n g tai Ben canh dd, sol poly-prpylene la loai spi sidu manh ndn trong qua trinh nhdo trpn Idm gidm dp ddo ban ddu cua hdn hgp vd trd ndn khd nhdo trdn hon do mdt phdn dung djch long bdm Idn bd mat soi. Trong qud trinh tang tai, cac vdt ndt dung gida ddm xudt hidn ddu tien va phdt tri^n len phia mat trdn ddm cung vdi s u xudt hien cdc vdt ndt xidn vd phfa hai ben gdi ti/a.
So vdi cdu kien cung cdp phdi vd cdu tao, dupc dudng hp 6 90°C trong 12 gid cd tdi trpng phd hoai khodng 104kN, cdu kidn vdt iidu ndn dupc gia cuOng spi, vdt nut hinh thdnh d cdp tai trpng 50kN vd phd huy cdu
N G U O I X A Y D U N G SO T H A N G 3 ft 4 - 2 0 1 6
ANH HUaNG CUft Sdi POLY-PROPYLENE flEN UfNG XUf CHIU UON
Hinh 14 Vet ndt cua dam
kidn d cdp tai trpng khoang tCr 102 ddn 130kN. Tai trong pha hoai cua cdu kidn ddm cho thdy cac mdu M l , M3 vdi ham lupng spi la 0.5% cho khd ndng chju udn tdt hon cdc mdu M2, M4 cd ham lupng spi la 1.0%.
4. K i T LUAN
Bai bao nghien citu thyc nghidm vd kha nang chiu tdi ciJa ddm bd tdng geopolymer su'dung tro bay, dupc gia cudng them spi poly - propylene hdm lupng 0.5%
va 1.0% va so sanh vdi cdu kien ddm geopolyrner c d ciing cdp phdi va khdng gia cudng spi. Mpt so kdt ludn dupc rut ra n h u s a u ;
- Cdu kien dupc gia cUPng spi cho khd nang chju tdi trpng ldn hon len ddn 25% so vdi cdu kien cung cdp phdi;
- Cdp phdi bd tdng geopolymer cd hdm lupng spi 0.5% the tich giup cai thidn kha nang chiu nen v d udn cua be tdng ndn. Khi s i r d u n g ham lupng spi 1 % thi sgi chidm mdt the tfch bd tdng ndn Idn ldm cho mdt di tfnh ddng nhdt trong hon hpp bd tong va gidm kha nang chju luc nen trong khi kha nang chiu udn van t a n g . l y
le chidu ddi - dudng kfnh spi khdng anh hucng ntiiSu ddn kha nang chju nen, udn cua bd tdng ndn, tuy nhien ty Id nay bdng 380 cho kdt qua tdt hon;
- Khi sir dung cac cdp phdi be tdng geopolymer ^ cuOng cdt spi cho cdu kidn d d m , cdp phoi sit 6 i ^ hdm luong spi 0.5% cho kdt qua kha nang chju tdi p hon vd tdt nhdt dng vdi ty Id l/d la 380. dng xiir chju u f i cua cdu kidn sir dung be tdng geopolymer pia cudrig cdt spi poly-propylene cung tuong t u n h u cau kien sDf dung be tdng geopolymer hoac bd tdng truydn th6fg, Ti'nh bdc cdu cua spi trong b d tdng giup han c h i sy m d rdng vdt ndt, giam c h u y i n vj va bidn dang, tang kha nang chju tai cho d d m . Q
TAI LIEU THAM KHAO:
1. D. Hardiito and B.V. Rangan (2005), "Development and prop- erties of low-calcium fly ash-based geopolymer concrete". Research Report GC1 Faculty of Engineering Curtn University of Technology Perth, Australia.
2. J. Davidovits (2011), Geopolymer Chemistry and Application.
3rd edition. Geopolymer Instrtute.
3 Zu-hua Zhang et al. (2009), "Preparation and mechanic^
properties of poly-propylene fiber reinforced calcined kaolin-lt/ asft based geopolymer"., vol.16(1), pp.49-52.
4 K Vi)ai,R KumuthaandB.G.Vishnuram(2012). "P/upe/fieso^
glass fibre reinforced geopolymer Concrete composites", Asian Journal of Civil Engineering (Building and Housing), vol13(4), pp.511-520.
5. Don Wimpenny et ai. (2010), 'The use of Steel and Synthetic Fibres in Concrete under Extreme Conditions". Science Agenda Investment Fund.
6. DH. Phan and DH. Nguyen (2015), f/ewra/fieftawor o^re/n- forced geopolymer concrete beams. Tap chi Xay dung, s6 570(09);166-168. ISSN 0866 - 0762.
CAC DANG Ht/ HONG VA BIEN PHAP SUfA C H Q A L C P BAG VE...
(Tiip theo trang 74)
ta chl tiet cdc gidi phdp cong nghd sita chOa ddi vdi cac dang h u hdng ndu tren. Day Id can c d khoa hpc quan trgng di c o quan quan ly xem xet dtra vao quy trinh qudn ly van hdnh, duy tu bdo du&ng de bien sir dung van lidu hdn hop asphalt trong tuong lai.Q
TAI LIEU THAM KHAO
1. Vien Kfioa hoc Thuy Idi, Quy trinh cong nghe thiet ki cic dang ldp gia cd de bien sd dung vit lieu hin hdp. Ha Noi 2013.
2. Vien Khoa hoc Thuy Idi, Quy trinh cong nghi thi cdng cAc dang Idp gia c6 dd biin sddung vit lieu hdn hdp. Hh Noi 2013
3. Thflng t i / so 10/2010/TT-BGTVT ciia Bfl Giao thflng van tai quy
dinh ve q u i n ly va bao tri dudng bd, 2010.
4. Keri<hoven, R. E., Underwater Bed Protection using hot asphalt mixes, Koninklijke Stiell Laboratorium, Amsterdam.
5. Rijkswaterstaat Communications. The use of asphalt in hydeaulic engineering, The Nederiands, 2007.
6. Brouns, P, Application of asphalt mastic, open stone asphalt, lean sand asphalt and bihiminous watertight revetments. Symposiim recente evolutie in de oeverbescherming van de waterwegen, Technologisch Instituut-K.VIV, Gent, 27-28 lanuari 1981.
7. Mulders. G., R. Termaat R Ruijgrok en R 0. PetschI, Application of lean asphalt in the construction of the land heads of the SVKO.
Voorlopige nota, 12 DALA-IPROBU N 8 4 4 , Deltadienst, Rijl(swaters1aat, augustus 1980
8. Sipkema, J. S., Lean sand asphalt, Cursus asfalt in de water- bouw 1969-1970, Stichting Pos-tdoctora^ Onderaijs in de Civiele Techniek, Delft University of Technology.
9. Barends, F. B J.. Dynamics of elastic plates on a flexible su^^
soil. LGM-Mededelingen, deel 12, no. 2, June 1980, Delft Soil Mechanics Laboratory.
10. Krystan W. Pilarczyk Dimensioning Aspects of Coastal pro- tection structrues dikes and revetments. Appendix B Unification of the stability criteria for revetinents. The Netiielands, 1988.
N G U d l X A Y D U N G SO T H A N G 3 & 4 • 2 0 1 6