ISSN: 2617-2070 (Print) ournal o Advanced Sciences and ...jaset.isnra.org/wp-content/uploads/sites/12/2019/12/...2007/02/01 · depending on BS8110:Part1:1985, O.P.C. Sand and cursed

Aziz I. Abdulla et al. / Journal of Advanced Sciences and Engineering Technologies 1- 89 68

ISSN:2617-2070(Print)

JournalofAdvancedSciencesandEngineeringTechnologies

availableonlineat:http://www.jaset.isnra.org

AzizI.Abdulla*

OthmanMajeedAbdullah

DepartmentofCivilEngineering,CollegeofEngineering,TikritUniversity,Iraq

Keywords:Compositebeam

Ferrocement

Skeletalbar

WireMesh

A R T I C L E I N F O

Articlehistory:Received01Oct.2019Accepted25Nov.2019Availableonline25Dec.2019DOI:http://doi.org/10.32441/jaset.02.01.07

Copyright © 2018 by author(s) and Thiswork is licensed under the CreativeCommons Attribution InternationalLicense(CCBY4.0).

http://creativecommons.org/licenses/by/4.0

JournalofAdvancedSciencesandEngineeringTechnologiesJournalofAdvancedSciencesandEngineeringTechnologiesJournalofAdvancedInvest

BEHAVIOR OF COMPOSITE FERROCEMENT REINFORCED CONCRETE BEAMS

A B S T R A C T

The Ferrocement is a type of thin reinforcement concretemadeofcement-sandmortarmixturewithcloselyspacedofrelativelysmalldiameterwiremesheswithorwithoutbarsofsmalldiametercalledskeletalbar.Thepurposeofthecurrentstudyistoidentifythebehaviorofthecompositefibrocementand reinforced concrete beams. The main variables of thecurrent study are the number of layers of wire mesh, thecastingtimeforthesecondlayer(Normalconcrete),andtheeffect of the presence or absence of the skeletal bars. Thecurrent study included the casting of two reference beamswith a different reinforcing ratio (2φ8mm), and (3φ8mm).Thestudyalsoincludedthecastingofeightcompositebeamsoffibrocementandreinforcedconcrete.Theresultsshowthatthe use of fibrocement layer, with (4,6,8) layers of wiremeshes,skeletalbar,andthefirstcastingperiod(1.5hr)leadsto increase the ultimate load by (17.142%, 21.42%,and22.85%) also the cracking load increased by (31.57%,47.36%,and 68.42%). The results show that the use offibrocementlayer,with(4,6,8)layersofwiremeshes,skeletalbar ,andthesecondcastingperiod(24hr) leadstoincreasethe ultimate load by (32.85%, 40%,and 42.85%) also thecracking load increased by (36.84%, 84.21%,and89.47%).Whenusingthefibrocement layercontainingontheskeletalbarthemaximumloadincreased(6.96%,17.64%)forthe first and second casting, respectively, also for crackingload, it increasedby(6.67%,16.12%)respectively,this isdueto that the skeletal bar leads to increase reinforcement areaand increase restriction in comparedwith ferrocement layerwithouttheskeletalbar.

© 2019 JASET, International Scholars and ResearchersAssociation

*CorrespondingAuthor:AzizIbrahimAbdulla,E-mail:[email protected]

OpenAccess

Journal of Advanced Sciences and Engineering Technologies (2019) Vol.2, No.2, 68-22 69

Introduction

Ferrocement is a type of thin-wall reinforcedconcrete. It is commonly constructed ofhydraulic cement mortar reinforced withclosely spaced layers of continuous andrelatively small size wire mesh. The mesh ismade of metallic or other suitable materials[1].Ferrocement has taken a noteworthyposition among segments utilized forconstruction development. It has strength,durability, and little thickness,whichmakes itis a segment appropriate for building somelightweight structures [2]. Over the past fewdecades, there has been a growing interest inresearch and studies for the development ofconstruction materials. Many attempts havebeen made to succeed and improve theproperties of concrete mix and increase theeffectiveness of steel used in the reinforcedparts, and suchattempts led to theemergenceof syntheticmaterialwhich has good qualitiesin terms of tensile strength and resistance tocracking this material has been called theferrocement[3].

MahmoudandKimio[4],presentedthedetailsof an experimental study conducted forstudying the characteristics of 24 samples ofsimply supported ferrocement compositeelements of (520*40*10mm) and loaded withtwo symmetrical point loads, the parametersconsidered in their investigation were, theeffect of different types of reinforcementmeshes, number of mesh laminates anddifferentmeshdiameterwithopeningsizealsodifferenttypesofmortarmaterials.Fortesting,theUniversalmachineof capacity500kNwasused. the authors observed that the used ofstainless steel meshes as reinforcement leadsto the improvement of bending characteristicsfrom where of bending stiffness, fractureenergy, ductility, and crack pattern also thebending properties of the thin compositeelements of ferrocement made of differentmortar materials show similar behavior, in

spite of using different number of meshlaminatesorreinforcementmeshes.

P.Paramasivam [5] presented a study on theflexural behavior of reinforced T- beamsstrengthened with ferrocement layers. Testswere conducted on 12 specimens simplysupportedand loadedwithconcentrated loadsat mid-span. These beams were designeddepending on BS8110:Part1:1985, O.P.C. Sandandcursedcoarseaggregateswithamaximumsize of 20mm were used the mix withproportions of (1:2.8:3.5) by weight. Thewater/cement ratio was 0.6. The mainparametersconsideredwerethevolumeofthefraction, the spacing of the shear connectorsandmethodof preparationof the surface.Theperformance of beams also compared with afocus on cracking patterns, ultimate strength,andmid-spandeflection.Loadsof500kNwereapplied by a hydraulic jack at increments of5kNuntiltheappearanceofthefirstcrack.Thisstudyshowedthatwhentheferrocementlayerwas added to the soffit face ( tension face), itledtoimprovedperformanceofthebeamsandincreased the rigidity of the strengthenedbeams.Italsoledtoanincreaseintheflexuralcapacity, which depended on the amount ofadditionalreinforcement.

Hani andHusam [6],present the details of anexperimentalstudyconductedforstudyingthebehavior of 24 composite beams under two-point loading system until the failure. Allspecimens’ dimensions were(152*152*914mm). Ferrocement layerthicknesswas25.4mmwithsteelwiremeshasa reinforcement (welded and hexagonal) withdifferent layers (4, 6, and 8). The compositebeam is classified into two groups. Group 1possessesfourbeams,threebeamshaving(4,6,and 8) welded layers of wire meshes in 12.7mm thick ferrocement laminate and onecontrol beam. Group 2 possesses four beams


three beams having ( 4,6, and 8 ) hexagonallayers of wire meshes in 12.7 mm thickferrocement laminate, and one control beam.Different types of studs are used as shearconnectors. From the results, the authorsobserved that the load-deflection curve goesthrough three stages, a linear to yield, acontinuous yield stage, and a stage of fullplastic deformation until the point of failure.Also from the result, the first crack loading ofcomposite beam increased by 81.716% incompared with the control beam, and theultimate load also increased by 25% incomparedwiththecontrolbeam.

EhsanAhmed[7],experimentalinvestigationof2 Grad 30 concrete beams, one beam wasstrengthened with ferrocement layers intension zone while the other was withoutferrocement layer.Everyoneof thespecimenswas tested under four-point flexural loadingoverarangeof1400mmandinstrumentedforthe estimation of the quarter and mid-lengthredirections. It is empiric from the curves thatthe load-deflectioncurveat the first stagewaslinearandwithincreasingload,thebehavioroftheload-deflectioncurvegoestothenon-linearbehavior until the final failure of the beam.From theexperimental investigation, it is seenthat the ultimate load was increased by 21%compared with that of the control beam. Thestrengthening effectwas additionallypowerfulindeferring thedevelopmentof the first crackandthecrackingloadwasincreasedby65%forthebeamstrengthenedwithferrocementlayer.Also, the three layers of wire mesh used inferrocementlayerinsoffitlayerofthebeamledto improvement of the first crack loading andincreased the flexural stiffness and load-carryingcapacityofthestrengthenedbeam.

AlaaAbdwlTawab[8]presentedthedetailsofan experimental study conducted for studyingthe characteristics of three control reinforcedconcretebeamsofdimensions(300,150,2000mm ) and eighteen beamswith dimensions of

(300,150 ,2000mm),consistingofreinforcedconcretecorescastin25mmU-shapedprecastferrocement laminates. The control beam wasreinforced with two steel bars of 12 mmdiameteratthetopandbottomofthebeamandstirrupsof10mmdiameterplacedat200mm.parameters were the types of mesh layers(wovenwiremesh, expandedwiremesh). Thesingle and double layers of each type of thesteel mesh were utilized. All the beams wereexamined under three-point flexural loadings.The results showed that the ultimate load,crack resistance control, and good energyabsorption properties were achieved by usingthe ferrocement layers. The increase in theultimateloadforthebeamscouldbeattributedto the presence of larger area of steel, steelmesh,andsteelbars,onthetensionfaceofthebeamsascomparedtothecontrolbeamswhichhad steel bars only, The energy absorption ofthe beams incorporating the ferrocementpermanent formswassignificantlyhigherthanthat of the control beams. The level ofincrementof the energy absorption relative tothe control beamswas around (15.6%,37.6%,and 1.6%) when a single layer of steel meshwas utilized and( 46.7%, 66.4%, and 44.4%)whenadoublelayerofsteelmeshwasutilizedforwovenwiremesh,andexpandedwiremesh,respectively.

Hamza Al Saadi [9], studied four elements of(100*150*750mm)materialsusedinthisstudywere O.P.C, sand, coarse aggregate, and wateralso steel mesh and rebars as reinforcement.The mix proportional was (1, 2.03, 2.492)basedonBScode[10],andw/cratiowas0.45.The elements tested under two-point loads byusing 100T (U T M). This study includes thetheoreticalanalysisandexperimentalstudyonthe flexural strengthening of reinforcedconcrete beams by using steel mesh. Fromexperimental study and theoretical analysis,theauthorsobservedthattheuseofwiremeshleadstoenhance loadcarrycapacity.Fromtheexperimentalstudy,thefailureloadofelement


strengthenedwithwiremeshwasincreasedby(18.3%) and from theoretical analysis, failureloadwasincreasedby(5.14kN)comparedwiththecontrolelement.

Wen-Jie Ge [11], studied the flexural behaviorof ECC – concrete composite beam. Theparameters of the study were thereinforcementratio,ECCthickness.Theresultsof these study show that in the case of tensilefailure increasing reinforcement ratio and

increasingEECratioledtoincreasingyieldandultimatemoment. Incompressive failurewhenincreasing ECC replacement ratio andreinforcement ratio led to decreasing theductility also the curvature and energydissipation increasing in case of tensile failurebut decreased in the case of compressivefailure.

Table(1)Materialsproportionsandcompressivestrengthofthecubesamples

Trail Mix No W⁄C C⁄S S.P (Mega

flow 500)%

fcu Compressive

Strength (MPa)

7days

fcu Compressive

Strength ( Mpa) at

28 day

Trail -n-1 0.32 1:1.5 1.5 37.194 51.7

Trail -n-2 0.32 1:1.5 1.25 37.6 52.2

Trail-n-3 0.3 1:2 1.5 37.88 53.9

Trail -n-4 0.3 1:1.5 1.25 39.1 55.8

Trail -n-5 0.28 1:1.5 1.25 41.6 57.34

Trail -n-6 0.28 1:1.5 1.5 42.41 60.03

TheAimofStudy

Thechoiceofthestudy(BehaviorofCompositeFerrocementReinforcedConcreteBeams)istopresent the effect of the fibrocement layer onthetensilezoneoftheconcretebeams.This study includes the casting of compositebeams of concrete and fibrocement, these areexamined under static loads and comparedwith normal beams and reinforced withdifferentpercentagesofreinforcing.

3.MaterialsCement , sand and coarse aggregates are usedto get a suitable concrete mixture The mixproportional was (1:2.13:2.41) and with w/c

ratio ( 0.505). Also the mortar mixtureproportion for fibrocement was as shown intablebelow.Thehighest compressive strengthwasforthetrailmixnamed(Trail–n-6),whichwas 42.41Mpa at the age of 7 days and 60.03Mpaattheageof28days.

Cement

For casting Samples during the experimentalprogram, Ordinary Portland cement usedlocally known (MASS). Bogue,s equations areused to calculate. The chemical compositionand physical properties of cement areconformed the Iraqi Specification No.5/1984[12].


Table(2)Physicalpropertiesofcement

PhysicalProperties TestResults Limit of Iraqi specification No.(5/1984)

Settingtimeby,(Vicatapparatus)

Theinitialsetting,(hrs:min)

Thefinalsetting,(hrs:min)

1:30

7:10

Notlessthan45min

Notmorethan10hrs

Compressivestrength(MPa)

For3day

For7day

34.2

36.15

15MPalowerlimit

23MPalowerlimit

(*)TestswerecarriedoutatCivilEngineeringLabatUniversityofTikrit.

CoarseAggregates

ThenaturalgravelobtainedfromtheALzwyahcity at the north of Tikrit was used to castingspecimen.Themaximumnominalsizewas12.5

mm.The coarse aggregates were cleaned withwater.The classification of rough aggregatescorresponds to the requirements of (IraqiClassificationNo.45/1984)[13].

Table(3)Gradingofcoarseaggregate

*ConductedatCivilEngineeringDepartmentlaboratory/TikritUniversity

Sievesize Pass% Iraqiclassification

(No.45/1984withtheadjustment,No.20/2010)

20 100% 100%

14 100% 90%-100%

10 70% 50%-85%

5 0.2% 0%-10%

2.36 - 0%


Table(4)Physicalpropertiesofcoarseaggregate

3.3.FineAggregate

AsfineaggregateriversandfromALzwyahcityatthenorthofTikritwasusedtocasting

specimen.BasedontheIraqistandard,(I.Q.S.,No.45-1984)[13]

Table(5)Sieveanalysisoffineaggregates

Sievesize Cumulativepassing(%) Limit of IQS No. 45/1984 - zoneNo.(2)

4.75mm(No.4) 100 90–100

2.36mm(No.8) 81 75–100

1.18mm(No.16) 67.6 55–90

600μm(No.30) 54.8 35–59

300μm(No.50) 24.7 8–30

150μm(No.100) 4.7 0–10


Table(6)Physicalandchemicalpropertiesofsand

Properties Testresult Specification

Specificgravity 2.59 ASTMC127-88

Absorption% 0.45% ASTMC127-88

Oven-drydensity 1600kg/m3 ASTMC29/C29M

Moisturecontent 0.3% ASTMC566-97


Properties Specification TestResults Limitsofspecification

Specificgravity ASTMC128-01\04 2.69 -

Absorption(%) ASTMC128-01\04 1% -

Finessmodulus ASTMC33-01 2.17

Drylooseunitweight(kg/m3)

ASTMC29/C29M-10 1565 -

Sulfate content (asSO3)(%)

(IQS)No.45-84 0.028 0.5(max.value)

Gypsummaterial% (IQS)No.45-84 0.06 < 𝟎 ∙ 𝟓

Solublesalts% (IQS)No.45-84 0.13 < 𝟎 ∙ 𝟓

Material finer than0.075mm(%)

(IQS)No.45-84 1.3 5(max.value)


Water

Inallmixturesandcuringtapwaterwasused.

Reinforcement

WeldedWireMesh

In the reinforcement, the square-welded wiremesh,knownlocallyasthechickenwiremesh,was used. These meshes are produced in theformof1.25mwidthrolls.Thewiremeshwascutintheformofstripsof11cmwidth,and96cm length to suit the measurement of molds.The average diameter of the grids is 0.5 mmandthesizeofthehole12.7mmismountedonthe skeletal bar according to the number of

layers required. The yield stress, final tensilestrength, and elasticity modulus weremeasured by the direct tensile strength of thesample.The testwasperformed inaccordancewith ACI 549[14]. Table(7) shows the yieldstrength, theabsolute tensilestrength,and theelasticcoefficient.

SkeletalBar

TheSkeletalbar ismadeusingsteelgridswithadiameterof4mmandadistancebetween60mmbars.Thewiremeshwasinstalledwiththeskeletal bar. Direct tensile testing of the steelbarswasperformedinaccordancewith(ASTMA 615 / A615M-09)[13] and the results areshowninTable(7).

ShearReinforcement

The shearing reinforcement was used with adiameter of 6mmand a circumferenceof 640mm. The shear designed depending on (ACICode 318) [14]. The direct tensile test wasperformedand theresultsareshown inTable(7).

FlexuralReinforcement

The flexural reinforcement was used with adiameterof8mmandalengthof940mm.Theflexuraldesigndependson(ACIcode318).[14].At some beams, reinforced with (2 ϕ 8 mm)and in the other reinforced (3 ϕ 8 mm) bydesign, the direct tensile test was performed.ResultsareshowninTable(1).


Table(7)Testresultsofwiremeshandsteelbarreinforcement.Error!Notavalidlink.(*)Tests were carried out at MechanicalEngineeringLabatTikritUniversity

(**) Tests were carried out at MechanicalEngineeringLabatBaghdadUniversity.

Superplasticizers

Asasuperplasticizer,MegaFlow500wasused.Themainpurposeofusingthisadmixturewas

to improve theworkability of themixture andto get high strength of the concrete mixture.MegaFlow500dependedon(ASTMC494)[15]

4.BeamsDetails

The dimensions of the composite beam lengthwere1000mm, the effective span of the beamwas900mm, thewidthwas150mm, and thedepthofthebeamwas200mm,Fig.(1),andFig(2)Shownthedetailsofreinforcement

Fig.(1):NormalConcreteBeamsReinforcement


Fig.(2):CompositeBeamReinforcement

Table (8) Details of study models


Name of beam Number of wire mesh

layers

Rebar The thickness of Ferrocement layers (mm)

Beam dimensions (mm)

B1 …….. 2ϕ8mm …….. ( 150*200*1000)

B2 …….. 3ϕ8mm …….. ( 150*200*1000)

BCW4SD1 4 2ϕ8mm 50 ( 150*200*1000)

BCW4SD2 4 2ϕ8mm 50 ( 150*200*1000)

BCW6SD1 6 2ϕ8mm 50 ( 150*200*1000)

BCW6SD2 6 2ϕ8mm 50 ( 150*200*1000)

BCW8SD1 8 2ϕ8mm 50 ( 150*200*1000)

BCW8SD2 8 2ϕ8mm 50 ( 150*200*1000)

BCW8D1 8 2ϕ8mm 50 ( 150*200*1000)

BCW8D2 8 2ϕ8mm 50 ( 150*200*1000)

*Wire mesh type: welded wire mesh with (12.7mm spacing and 0.5mm diameter)

Where:-

B1:- Control Beam Number 1 with (2ϕ8mm),

B2:- Control Beam Number 2 with (3ϕ8mm),

C:- Composite symbol, W:- Wire Mesh symbol,

S:- Skeletal bar symbol, D:- Duration symbol

ExperimentalProgram

The main purpose of the study is to investigate

the behavior of the composite beams of the

ferrocement and concrete under static loads.

The current study examines the effect of the

number of layers of the wire meshes, the

casting period as well as the skeletal bar effect

on the properties of the beams such as flexural

strength, toughness, ductility, and stiffness, as

discussed and compared to the control beams.

The results of the tests were obtained on the

basis of the load-deflection in the center of the

beam, the crack pattern, the failure loads. The

following parameters were adopted this study

in:-

1- The number of wire meshes layers.

2- Duration of casting the second layer.

3- Presence or absence of skeletal bar.

StagesofMoldingandProcessingofUsedModels.

The Samples used in the study were poured and

processed by following these steps as shown in

Fig (3, A-D) and described below:-

1. Preparing and cutting the wire meshes

according to the required dimensions, and then


cutting the skeletal bar in the required

dimensions, as appropriate to the dimensions of

the mold.

2. After cutting the wire mesh and skeletal bar,

they are installed and linked together

3. Preparing the metal mold, and lubrication of

the inner surface using motor oil to facilitate the

lifting of the model from the mold when

opened.

4. Installation of the layers of reinforcement in

the casting mold; and according to the details of

each model, to allow the provision of concrete

cover for the layers of reinforcement.

5. Mixing the cement mortar and putting it in

the lower part of the mold (tensile area), with a

thickness of 50 mm.

6. After finishing the casting of the ferrocement

layer, the normal concrete layer is poured

according to the time periods specified in the

study (1.5 and 24 hr).

Fig ( 3- A): Slicing the skeletal bar

Fig ( 3- B): Connecting the wired meshes with the skeletal bar

Fig ( 3-C): Connecting the ferrocement reinforcement with the flexural reinforcement


7- The quality control samples (cubes and

prisms) are poured from the mixture of

ferrocement and normal concrete and then

opened after 24 hours and put in the curing

basin with water for 7, and 28 days.

8. After the casting process, the samples are left

for 24 hours and then opened and transported to

the treatment basins and treated with immersion

in the treatment basins for 28 days.

9. After the processing has finished, the

samples are uplifted from the treatment basins

and are prepared for testing.

TestedBeams

All composite beams are cured for 28 days, and

after this period beams coated by using white

color. The beams were tested using a universal

testing machine under static loads until failure.

Adial gauge of 0.001mm was used at mid-span

to measured deflection in beams. Beams with

effective span ( 900mm) tested under one point

load at center. Fig (4)

Fig. (4): Beams Under Testing

ResultsandDiscussion

CrackLoad


The results show the effect of the ferrocement layer on the first crack. Where it was noted that by increasing the number of wire mesh layers leads to an increase in the cracking load as shown in Fig.5. Also, the cracks have been confined to the loading area and decreased the number of cracks. As for the effect of the casting period, the results show that the beams that were cast at the second casting period have a higher crack load than the beams that were

poured in the first period and due to the cohesion of the ferrocement layer after 24 hours was greater. Also for the effect of containing or not containing the composite beam on the skeletal bar. The beams containing on the skeletal bar have a higher crack load than the beams without the skeletal bar. The reason for this because the beams that possess skeletal bar are more restricted than beams that do not contain a skeletal bar.

UltimateLoad

As shown in Fig. 6 the ultimate load of thecompositebeamhasincreasedbytheratioof(17.142 %, 21.42 %, and 22.85%) whenusing4,6,and8 layersofwiremeshes,andwith the first duration. Also, the ultimateloadofthecompositebeamhasincreasedbythe ratio of (32.857 %, 40%, and 42.85%)whenusing4,6,and8layersofwiremeshes,

andwiththesecondduration.Thecompositebeams that possess skeletal bar have anultimate load more than composite beamswithout skeletal bar by a ratio of (17.64%).This is due to the fact that the compositebeamswithskeletalbarhavereinforcementarea higher than composite beam withouttheskeletalbar.

38

60

5052

56

7064

72

60 62

0

10

20

30

40

50

60

70

80

B1 B2 D1 D2 D1 D2 D1 D2 D1 D2

Crackload

(kN

)

4layerswithskeletal

6ayerswithskeletal.8layerswithskeletal.

8layerswithoutskeletal.

Controlbeam.1

Controlbeam.2

D1:-FirstDuraMonD2:-SecondDuraMon

Fig. (5): Crack Load With Different Types of Beams


7.2.1EffectofSecondLayerCastingDuration

In this study, two different periodswere adopted,forthecastingofthesecondlayer(normalconcretelayer),whichis(1.5hrand24hr).Theresultsofthesecond casting period are the best with thedifferent numbers of the layers of wire meshes.Wheretheresultsofthecompositebeamthatwerepouredafter24hrhavethehighestultimateload.

The reason for this because the ferrocment layerafter the first casting period 1.5 hr is fresh.Whencasting the second layer of concrete effect onferrocement layer. It depends on the number ofwiremesh layers in thebeam.Where the increaseofwiremesh layers led to increasedultimate loadby(17.14%–42.85%)asshowninFig.7.

EffectofSkeletalbar

Controlbeam1

Controlbeam2

4Layerswithskeletal

6Layerswithskeletal

8LayersWithskeletal

D1:-FirstdurationD2:-Secondduration

Fig.(7):TheEffectofCastingDuration


In this study, the effect of containing or notcontaining the composite beam on skeletal bar,where the beams were carried out on modelswiththereinforcingof8layersofwiremesh,wasfoundbystudyingtheeffectoftheskeletalbaronthe ultimate load, as the ultimate load of thebeam with the skeletal bar was higher than

ultimate load of the beam without the skeletalbarwithan increaseof (17.64%).This isdue tothe fact that the composite beamswith skeletalbar have reinforcement area higher thancomposite beam without the skeletal bar asshowninFig.8.

Fig.(8):EffectofSkeletalbars

TheStiffness Taking the load at 45% of the yield load, andintersecting it on the load-deflection curve takethendeflectionatthispoint,andbydividingtheloadat45%tothisdeflection,thestiffnesscanbecalculated. The effect of the number of wiremesheswasclearlyrelatedtotheskeletalbaraswell as the castingperiod. It hasbeenobservedthatbyincreasingwiremeshfrom(4to6and8),stiffness increased. Due to the increase in the

wiremeshlayersledtoanincreaseintherateofvolume fraction and thus an increase in therestriction of the beam and this led to anincrease in stiffness.Also, thebeams cast at thesecond duration has higher stiffness comparedwithbeamsthatcastatfirstduration.Thereasonforthisisthattheferrocementlayerafter1.5hrisfreshandaffectedbythecastingofthesecondlayer(normalconcrete)asshowninFig.9.

8Layerswithskeletal8Layerswithoutskeletal

D1:-FirstdurationD2:-Secondduration


Fig.(9):TheStiffnessofTestedBeams

Ductility

The ductility is the result of the division thedeflectionattheultimateloadtodeflectionattheyielding load. The effect of the number of wiremesheswasclearlyrelatedtothetypeofskeletalbar aswell as the casting period. In the case oftheuseof4 layersofwiremeshwith a skeletalbarandthefirstcasting,periodledtoanincreaseof theductility by (13.89%) for the first castingperiodanddecreaseby(21.24%)forthesecondcastingperiod.Thereason for that isdue to thefirst period for casting with skeletal bar led toless restrictive for the composite beam, whichledtoincreaseductility,asshowninFig.10.

Asfortheincreaseinthenumberofwiremeshesfrom 4 to 6 and 8 and in the same period ofcasting seconddurationand the second skeletalled toadecreaseof theductilityand thereasonforthisisduetotheincreasethenumberofwiremeshes led to a decrease in the cohesionbetweenthemortarandthewiremeshes.Asforthe effect of the presence and absence of theskeletal bar on theductility,where theductilityof the beams that do not contain a skeletal barincreased and the reason in this is due to thepresence of the skeletal bar increases therestriction of the beams in compared with thebeamsthatdonotcontaintheskeletalbar.

𝜇=∆𝒖∆𝒚

Where: µ:ductilityindex ∆u:ultimateloaddeflection ∆y:yieldingloaddeflection.


Toughness Toughness is the resistance of the material tobreakwhen exposed to the stresses and knownas the amount of energy that the material canabsorb before refraction and its equal the areaunder the load-deflectioncurve.The test resultsshowedthatincreasingthenumberofwiremeshincreasedthetoughnessatfirstcracklayersfrom4 to 6and 8 and that because of the increase inthe ratio of volume fraction. The test resultsshowthatthetoughnessatyieldloadat4layersofwiremeshwasdecreasedbecauseofthewiremesh is yield to relatively little load. Buttoughness at first crack increases by increasingwire mesh from 6 to 8. And the test resultsshowed that the toughnessatultimate loadwasdecreasedbecauseoftheincreaseinthenumber

of wire mesh layers led to increasing therestriction of the composite beam so that thetoughness decrease. As for the effect of thepresence andabsenceof the skeletal baron thetoughness, The toughness at first crack and atyield load of the beams that do not contain askeletal bar decreased and the reason in this isthebeamswithoutaskeletalbar it'syieldingbythe relative little load. The toughness at theultimate load of beam possesses skeletal bardecreased. The reason in this is due to thepresence of the skeletal bar increases therestriction of the beams in compared with thebeams that do not contain the skeletal bar, asshowninFig.11.

ModesofFailure Fig.(11):TheToughness(kN.mm)


All the composite beams tested underconcentrated load show a similar failure mode.Also,thecracksconcentratedintheloadingarea.Also,theirnumberdecreasedasitwasnotedthattheincreaseinthenumberofwiremeshesledto

adecreaseinthenumberofcracks.andconfinedin the loading area. Due to the increase ofwiremeshes, the restriction of the cracks hasincreased, reducing their number and confiningthemtotheloadingarea,asshowninFig.12.

Crack pattern

Crack pattern Crack pattern

A- ControlBeamB1

B- Control beam B2

C- BCWSD1


(f)BCW6SD2

E-BCW6SD1

F-BCW6SD2

H-BCW8SD1


Conclusions

Fromtheexperimentalstudycarriedoutduringthis research, the following conclusions can becalculated:

1. The ultimate load of the composite beamhas increased by the ratio of (17.142 %,21.42%,and22.85%)whenusing4,6,and8 layers of wiremeshes, skeletal bar, andwith the first duration. Also, the ultimateload of the composite beam has increasedby the ratio of (32.857 %, 40%, and42.85%) when using 4,6, and 8 layers ofwiremeshes,skeletalbarNo.2,andwiththesecondduration.

2. By increasing the number of wire meshlayers, a load of cracks is increased by aratioof(31.57%,47.36%,and68.42),whenusing 4,6, and 8 layers of wire meshes,skeletalbar.Also,a loadofcracks increasedbyaratioof(36.84%,84.21%,and89.47%)when using 4,6, and 8 layers of wiremeshes, skeletal bar No.2, and with thesecondcastingduration.

3. Thestiffnessofcompositebeams increasedbyaratio(226.4%-436.58%)iscomparedwiththecontrolbeam.Thisisduetothefactthat the ferrocement layer increases therestrictionofbeams.

4. The ductility of composite beam with 4layers ofwiremesh, skeletal bar, andwith

I-BCW8D1

H-BCW8SD2

J-BCW8D2 Fig.(12):TheModeofFailureandCrackPatternofbeams


thefirstdurationwasincreasedbyaratioof( 13.89%)while the same beam casting inthe second duration the ductility wasdecreasedbyaratio(21.24%).Thisisduetothefactthatthecompositebeamwiththesecond poured duration was restrictedmore than composite beam with firstpouredduration.

5. By increasing the number of wire meshlayersfrom(4to6)layerswithskeletal,andthe first duration. The ductility increase (13.89% - 52.07% ), while the same beamcasting in the secondduration theductilitywas decreased by a ratio ( 21.24% -56.38%). This is due to the fact that thecomposite beams with the second pouredduration were restricted more thancompositebeamwithfirstpouredduration.Alsobyincreasingthenumberofwiremeshlayersfrom(6to8),theductilitydecreasedby a ratio ( 7.82%) is compared with thecontrolbeam.Thisisduetothefactthattheincreasing number of wire meshes layersfrom(6to8)leadtoadecreaseincohesionbetweenthewiremeshandmortar.

6. The composite beam without skeletal barhas ductility more than composite beamwithskeletalbarbyaratioof(93.93%)iscompared with a composite beam withskeletalbar, andbya ratioof (78.75%and115.65% ) is comparedwith control beam.This is due to the fact that the compositebeamswiththeskeletalbarwererestrictedmore than composite beam without theskeletalbar.

7. The toughness of the composite beam hasdecreasedbyaratio (4.81%- 6292%).Depending on the number of wire mesheslayers, skeletal type, and duration of thecasting. This is due to the fact that theferrocement layer leads to increases therestriction of the composite beam so thatthetoughnessdecrease

References

[1] International Ferrocement Society (IFS 10-01). (2001). Ferrocement Model Code.

International Ferrocement Information Center,Thailand,pp.1.2.

[2] ACI 549R-97. State-of-the-Art Report onFerrocement.Part5,pp.1-26.[3] Naaman, A. E. (2000).Ferrocement andlaminated cementitious composites(Vol. 3000,No.1).AnnArbor:Technopress.

[4] Wafa, M. A., & Fukuzawa, K. (2010).Characteristics of ferrocement thin compositeelementsusingvariousreinforcementmeshesinflexure. Journal of Reinforced Plastics andComposites,29(23),3530-3539.

[5]Paramasivam,P.,Ong,K.C.G.,&Lim,C.T.E.(1994).FerrocementlaminatesforstrengtheningRC T-beams.Cement and ConcreteComposites,16(2),143-152.

[6]Nassif,H.H.,&Najm,H.(2004).Experimentaland analytical investigation of ferrocement–concretecompositebeams.CementandConcreteComposites,26(7),787-796. [7]Ahmed,E.,Sobuz,H.R.,&Lee, J.B.H.(2011).Flexuralandcrackingperformanceofreinforcedconcrete beam strengthened with ferrocementlaminates.[8] Tawab, A. A., Fahmy, E. H., & Shaheen, Y. B.(2012).Useofpermanentferrocementformsforconcrete beam construction.Materials andStructures,45(9),1319-1329. [9] Al Saadi, H. S. M., Mohandas, H. P., &Namasivayam,A.(2017).AnExperimentalStudyon Strengthening of Reinforced ConcreteFlexuralMembersusingSteelWireMesh.Curvedandlayeredstructures,4(1),31-37[10] British DOE (Department of Environment)Method, (1988). Design of normal concretemixes.BSI,ChiswickHighRoad,London.

[11]Ge,W.J.,Ashour,A.F.,Ji,X.,Cai,C.,&Cao,D.F. (2018). Flexural behavior of ECC-concretecomposite beams reinforced with steelbars.Construction and Building Materials,159,175-188.


[12]Meikandaan T, HemapriyaM.(2017). Studyof damaged RC beams repaired by bonding ofCFRP laminates. International Journal of PureandAppliedMathematics

[13] Iraqi classification (No.45 / 1984 with theadjustment, No.20 / 2010).Aggregate fromnatural sources for concrete and buildingconstruction.

[14] ACI Committee 549- 93. (1993). Guide forthe design construction, and repair offerrocement.ACI549–93,inmanualofconcretepractice,Americanconcreteinstitute,27pages.

[15] ASTMA615/615M-09.(2010).Standard testmethodfordeformedandplaincarbonsteelbarsforconcretereinforcement.

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