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