VietnamJournalofMechanics,VAST,Vol.30,No.2(2008),pp.99 - 111
RESEARCHONMANUFACTURINGDRYMIXED CEMENT MORTAR WITHHIGHCOMPRESSIVE
STRENGTH,HIGHFLEXURALSTRENGTH,LOW SHRINKAGEANDHIGHWATERTIGHTNESSFOR
RESTORATIONOFDAMAGEDHYDRAULIC STRUCTURESINVIETNAM
NguyenQuangPhu112,HoangPhoUyen3,JiangLinHua1,LiuJiaping4 1
Collegeof MaterialsScienceandEngineering,
HohaiUniversity,Nanjing,P.R.China(210098) 2 Facultyof
HydraulicEngineeringofWaterResourcesUniversity,Vietnam 3 Researchof
BuildingMaterialScienceDepartment, Instituteof
WaterResourcesResearch,Vi etnam 4 JiangsuResearchInstituteof
BuildingScience,Nanjing210008,China. Abstract.Usi
ngnormalmaterialstomanufacturethemixedmortarisnecessaryfor
restoration of hydrauli c structuresinViet nam. It will salvagethe
materials and decreases thecostpriceof
themortar.Inthisresearch,weusedcementmadeinVietnam(Chinfon -
Haiphongcement),natural sand(LoRiversand),polymeracrylic
andhighrangewater reducing(of SIKA company)' with proportion1 : 3:
0.03: 0.003by weight.Thewat erto
cementratiois0.5,whichalwaysensuret hecompressivestrengthof
mortarmoret han
40MPaandsmallshrinkage,goodwatertightness,andhighadhesion.Thatissuitable
fortherestoration of concrete structuresingeneral and hydraulic
structuresinparticular
ofVietnam.Thedrymixedmortarismanufacturedandinbagof150.5 kgweight.
Keywords: dry mixed cement mortar , compressive strength,
shrinkage, flexural strength, adhesion, watertightness, high range
water reducing admixt ure(HRWR),polymeracrylic. 1.INTRODUCTION
After fiftyyears, many hydraulic structures in Vietnam were damaged
and downgraded thatwhyitisnecessarytorepairthemforcontinuing
operated.Herethemostimportant hydraulic structuresare madeof
concrete and reinforcedconcrete,that whenrepairing has
requiredthesamematerialshavingthesamefundamentalproperties.Inordertorepair
thosestructures,themort
arfromcementwithhighcompressivestrength,noshrinkage, andhighwatert
ightnessisused[1].
Themixedmortarshavegoodpropertiesofsomeoverseascompaniesareavail
able
inVietnam,buttheyareveryexpensive,sotheyarenotsuitableforVietnamsituation.
Actually,the materials neededto manufacture these mortars are
available in Vietnam and wecan usethemto make akindof mixedmortar
usingtorepairthe damage of structures ingeneral ,hydraulicstruct
uresinparticular.Toproducethismixedmortarwecanuse usualmaterials
Vietnam's. 100NguyenQuangPhu,HoangPhoUyen,JiangLinHua,LiuJiaping
2.RESEARCHOBJECTIVES The objective isto manufacture the mixed
cement mortar whichhashighcompressive
strength,highflexuralstrength,lowshrinkageandhighwatertightnessinordertorepair
hydraulicconcretestructuresandreinforcedconcretestructures.Themortar
shouldhave followingproperties: + Highwatertightness +
Goodslumpforapplication + Thegoodadhesionwiththeparent
concreteandmortar + Highcompressive 2:40MPa). 3.MATERIALS
3.1.Cement Chinfon Portland
cementPC40madeinHaiPhong,Vietnam.Itsphysicalproperties
areshowninTable1 Table1.Physicalpropertiesof
PortlandcementPC40Chinfon - Haiphong N o ItemUnitResult
1Compressive strength,28daysMPa42 2Flexuralstrength,28daysMP a6.0
3Setting time:Initial;Finalminute113;190
4Specificgravity(g/cm0)3.10 3.2.Fineaggregate(sand)
Inthisresearch,weusedthestandardsandandthecrushsiliconsand.Theresults
wereverygood,butthecostpricewasveryhigh,thereforewehavetakentheriversand
forexperiments[2].Namely,weusedLoRiversandwhichhassomepropertiesasshown
inTable2. Table2.Propertiesof fineaggregate(sand) No ItemUnitResult
1Bulk specificgravity onoven-drybasis(g/cm0)2.65
2Apparentspecificgravity(g/cm0)1.45 3SSD*Absorption%0.4
4Finenessmodulus2.54 SSD*:Saturatedsurface-dry
Thesandissievedtorejectthegrainssize>5mm.Thenitwasdriedbytheoven
intemperature of 100-150Cforfivehoursuntilthehumidity of
sandequalzeropercent. The sandwaspackedandkeptinthedrycondition.
3.3.Polymer Polymeracrylicisadmixtureinformof.
powder,dry,whitecolor,odorless.Itiseasy to dissolve inthe water.The
chemicalfunctionof Polymeracrylicasshown following[3]:
Researchonmanufacturing drymixedcement mortar... (-CH2-CH-)n I COOH
3.4.Highrangewaterreducingadmixture(HRWR) 101
Highrangewaterreducingadmixturehasthebrandname~ f Mighty[3].Themain
componentof Mighty
isnaphthaleneformaldehydesulphonated.Thisadmixtureisbeing
soldinVietnam. 4.MIXTUREPROPORTION
4.1.Designpreliminaryproportionmortar
Themortarusinginconcretestructuresandreinforcedstructuresmusthavehigh
compressivestrength(thecompressivestrengthofmortarandthecompressivestrength
ofmortarmatrixinoldconcrete
isequivalent).However,thepolymermortarhasnot strength
function;inresearchwedesignedtheproportion mortar
wasusedincompliance with14T ~ 80-2001andTCXD2000-
Buildingstandard[4,5]. Thecompressivestrength of mortar
iscalculatedbyfollowingEq.(1) II(c) fv=A.JcW- 0.8,(1)
where:Aexpressesmaterialsquality,A=l.05formaterialsofgoodquality,A=0.90for
materialsofnormalquality,anrlA=O. 75formaterialsof lowquality.f ~
istherequired compressivestrengthofmortar,f ~
isthecompressivestrengthof cement,CandWare respectivelytheamountof
cementandwater in1m3 of themortar. The
cementcontentiscalculatedbyEq.(2) c =1000(2) 1Wn -+-+-PcCPs
where:Pc,Psarerespectivelythebulkspecificgravityonoven-drybasisofcementand
sand,nisthesandtocementratiobyweight,n=(Cf
S);Sisthesandcontentin1m3
mortar,(C/S)canbechoseningraphofappendixA.2ofthestandardbranch14TCN
80-2001. Thenwecancalculate the.proportionof mortar asfollows: 1:
S/C: W/C =1: 3.0:0.50 Inother hand,the high range water
reducingadmixture and polymer acrylic are usedwith theamountof
0.2-0.33and2-33,respectively. 4.2.Theexperimental schememethod In
thisproject,weusedtheexperimental schememethodwiththe orthogonal
central
turnoftwolevelsandtwofactorstoaimbuildingthestatisticalmathematicsmodel,
basedonthattoaccesstheeffectsoffactorsonthepropertiesofmortar;suchasthe
plasticity,compressive strength,flexuralstrength,adhesionbetween
the oldconcreteand
newmortar,saturatedabsorption;thencefindingtheoptimalpercentofpolymerand
HRWR.of realvariablesandcodedvariablesarepresentedinTable3.
102NguyenQuangPhu,HoangPhoUyen,JiangLin Hua,LiuJiaping Table3.The
experimentalscheme No CodedvariablesRealvariables X1X2~ l (3)6(3)
11-10.301 2-1-10.201 3-110.203 4110.303 5000.252 61.41400.372
70-1.4140.250.6 8-1.41400.182 901.4140.253.6 10000.252 11000.252
12000.252 X2 (9)+ 1.4 t4 0) +I p, p, .1 G) C!:i) +I -1. 5 mm Oven
dry Cooling Container silo Dosage Cement PC-40 Container silo
Determine the amount Polymer acrylic Container silo Dosage (2%-3%
cement) Mixing and package Storage II HRWR Container silo Dosage
(0.2%-0.3% cement) 6.2.Mainconclusions 1.Thepresenceof
polymerandhighrange waterreducingadmixture withresearched range
don'taffectthesetting timeandworkability of mortar. 2. With water
to cementratio W/C=0.5, the compressive strength of mortar ismore
than 40MPa. It issuitable forhigh strength mortar forrestoration of
hydraulic structures. 3.The presence of polymer and high range
water reducing,exercises small the influence
toflexuralstrength,thecompressiveof mortar onthecompacted
sub-grade.
4.Themortarwithpolymerandhighrangewaterreducingadmixtureincreasethe
adhesionstrengthandwatertightness of mortar. REFERENCES 1.Duong Due
Tin,LeMinh,Researchto manufacture and usepoly-molecule materials
sprayfor therestorationof
hydraulicstructures;aprojectofBuildingMaterialScienceDepartment,
Instituteof WaterResourcesResearch,1996. Researchonmanufacturing
drymixedcementmortar...111
2.ProceedingofVietnamConstructionStandards,BuildingStandards1770.BuildingSand-TechnicalRequirements,ConstructionPublisher,Hanoi1997.
3.Ministryof AgricultureandRuralDevelopment:Standardbranch14 TCN
80,Hydraulic Mor-tar-
TechnicalRequirementsandTestingMethod,CentralInformationofAgricultureand
RuralDevelopment Publisher,Hanoi2002.
4.ProceedingofVietnamConstructionStandards,BuildingStandards2000.Drycementmor-t
arnoshrinkage-
TechnicalrequirementsandTestingmethod,MinistryofConstruction,
ConstructionPublisher,Hanoi2000. 5.V. I.Malin,Proportionsof
drymortarforconstruction,Doctordissertation,1986.
6.AmericanSocietyforTesting
andMaterials(ASTM)CommitteeC09,2003b.Standards Test
MethodforLengthChangeofHardenedHydraulic-CementMortarandConcrete(ASTMC
157 /C157M-03) , WestConshohocken:ASTMInternational. 7.L. Czarnecki
and P.Lukowski,Optimization of Polymer cement concret es,
Optimization meth-ods formaterial design of
cement-basedcomposites(ed.A.M.Brandt) , Modern Concret e
Tech-nology7,E&FNSpon,LondonandNewYork,1998, pp.231-250.
8.E.SakaiandJ.Sugita,CompositeMechanismofPolymerModifiedCement,Cementand
ConcreteResearch25(1)(1995)127-135.
9.S.Chandra,PolymerCementComposite-
aCriticalReview,AdvancedinCementandCon-crete,AmericanSocietyof
CivilEngineers,1994,pp.15-36. ReceivedJuly29,2008 NGHIENcuu sAN
xuAT vDA KHOTRQNSANc6 cu'dNGDQNENv.A. cVdNGDQuoN CAO,co NG6T
TRAPvACHONGTHAMTOTDUNG TRONGsDACHUAHu'HONGcAc CONGTRINH
THUYLQICUAVlTNAM Slidungcac th6ngthuongdsanxuitvli'atronsanlari tch
thitchosl:tachli'a caccongtrlnhthuyl
