Engineering, Technology & Applied Science Research Vol. 8, No. 2, 2018, 2741-2744 2741 www.etasr.com Ali et al.: Comparison of Mechanical Properties of Lightweight and Normal Weight Concretes … Comparison of Mechanical Properties of Lightweight and Normal Weight Concretes Reinforced with Steel Fibers Ahsan Ali Department of Civil Engineering Quaid-e-Awam University of Engineering, Science & Technology Larkana, Pakistan ahsanone@gmail.com Zuhairuddin Soomro Department of Civil Engineering Quaid-e-Awam University of Engineering, Science & Technology Larkana, Pakistan zuhairuddin@quest.edu.pk Shahid Iqbal Department of Civil Engineering CECOS University Peshawar, Pakistan shahid.iqbalmce@gmail.com Nadeem-ul-Karim Bhatti Department of Civil Engineering Quaid-e-Awam University of Engineering, Science & Technology Larkana, Pakistan knadeem_b@yahoo.com Ahmed Faraz Abro Department of Civil Engineering, Quaid-e-Awam University of Engineering, Science & Technology Larkana, Pakistan a.faraz.abro@outlook.com Abstract-Compared to conventional concrete, lightweight concrete is more brittle in nature however, in many situations its application is advantageous due to its lower weight. The associated brittleness issue can be, to some extent, addressed by incorporation of discrete fibers. It is now established that fibers modify some fresh and hardened concrete properties. However, evaluation of those properties for lightweight fiber-reinforced concrete (LWFC) against conventional/normal weight concrete of similar strength class has not been done before. Current study not only discusses the change in these properties for lightweight concrete after the addition of steel fibers, but also presents a comparison of these properties with conventional concrete with and without fibers. Both the lightweight and conventional concrete were reinforced with similar types and quantity of fibers. Hooked end steel fibers were added in the quantities of 0, 20, 40 and 60kg/m3. For similar compressive strength class, results indicate that compared to normal weight fiber-reinforced concrete (NWFC), lightweight fiber-reinforced concrete (LWFC) has better fresh concrete properties, but performs poorly when tested for hardened concrete properties. Keywords-lightweight; steel fibers; density; elastic modulus; ductility I. INTRODUCTION Structural lightweight concrete is defined as the one with minimum 28-days compressive strength of 17MPa and equilibrium density between 1120 and 1920kg/m3[1], whereas a cubic meter of conventional concrete weighs around 2300kg. Compared to conventional concrete, structural lightweight concrete generally weighs 25% to 35% less [2]. This reduced weight not only imparts favorable effects on foundations, but also lowers the seismic inertial mass [3]. Wide acceptance of the lightweight concrete by the construction industry in the past has been hindered by multiple factors including the lower strength of lightweight aggregates, the aggregate availability, the extra attention required during designing and making of lightweight concrete due to its higher water absorption and most importantly due to its higher brittleness associated with the material compared to the conventional concrete. Nevertheless, current consumption trends show that structural lightweight concrete is getting momentum [4], as an increasing number of industrial plants have been set up for production of artificial aggregates addressing the aggregates’ availability issue. Design engineers now have the choice of selecting among varieties of artificial aggregates such as expanded clay and expanded shale etc. Moreover, development of mineral and chemical admixtures and improvement in particle strength of the artificial aggregates over the years have made it possible to produce lightweight aggregate concrete with better mechanical and rheological properties. As for the concerned brittleness issue, studies suggest that discrete fibers can be used to make concrete a more ductile material. Use of fibers in concrete has been found to affect the properties of fresh and hardened concrete [5-7]. This effect so far has been quantified mostly for the conventional concrete and its test results have been made part of different committee reports and code sections[8, 9]. Our understanding, however, regarding the influence of fibers on fresh and hardened lig in des con [10 is gu con exp and inc A. com con B. 1 den AS 12 wo wa exa wo sta non C. ela Engineering www.etasr ghtweight conc initial stage, sign of memb ncrete, wherea 0] is available therefore esse idelines that ncrete is fir perimental pro d hardened corporation of Materials Us One of the mpressive str ncrete, therefo Exp H Experimenta 1) Fresh Tested fresh nsity. Fresh STM method 350-5 [13] orkability of a as chosen ove ample, it beco orkability usin andard, the sam n-fibrous conc Fig. 1. Mix Hardened Co All hardene astic modulus g, Technology & r.com crete propertie for example ers produced u as a compreh for normal w ential for the the behavior rstly well un ogram was de lightweight f steel fibers. II. EXPERIM sed major objec rength for bot ore ordinary P Type P panded clay Gravel Sand Shape Hooked-end al Tests Concrete Tes concrete prop concrete dens [12]. Germa were follow all the used mi er other meth omes easy to q ng German DI me DIN stand crete mixes. (a) xes at the end of sl oncrete Tests ed concrete t and splitting t & Applied Scien Ali e s and the mate there are no c using lightwei ensive commi weight fiber rei development r of lightweig nderstood. Co evised for the concrete pro MENTAL PROG tives was to th lightweigh Portland ceme Particle size range 2-10 2-8 0-2 fl [mm] 35 ts perties include sity test wer an standard g wed for the ixes (Figure 1 hods due to quantify the ef IN standard, s dard can be u lump flow test (a) tests, i.e. com tensile strengt nce Research et al.: Compari erial behavior code guidelin ight fiber-reinf ittee report by inforced concr of any such d ght fiber-reinf onsidering th evaluation of operties after GRAM attain comp ht and conven ent (CEM-1/4 TABLE I. e [mm] Bulk d ed workability e performed guidelines DIN determinatio 1). This test m its simplicity ffect of fibers o since unlike A used for fibrou (b) ) NWFC (b) LWF mpressive str th tests were c Vol ison of Mechan is still nes for forced y ACI rete. It design forced his an f fresh r the arable ntional 42.5N) was san part 257 mo con was rou to 1 of t Gra NW to 8 sele hoo asp PROPERTIES OF Aggregates density [kg/m3] 650 1474 1604 Fibers fd [mm] 0.55 y, and using N EN on of method y. For on the ASTM us and FC ength, carried out cap add side serv spe wer stre elas 200 the calc pro A. han coa stro Han con agg wei con was spe con an whe l. 8, No. 2, 2018 nical Properties s used as the b nd for both co ticle size in t 70kg/m3. AST isture conten ncrete mixing s used as a co und and regula 10mm.These l their weight w avels were us WFC. These ag 8mm. Steel fib ected as reinfo oked-end in sh pect ratio . F THE MATERIALS Particle density 1190 2520 2573 Fiber dosage 0, 20, 40, in the similar pacity of 50 ditional steel p es of the test ved the purpos ecimens. Cub re used for b ength tests. C stic modulus, 0mm.A mecha measurement culation. The ocessing unit v I Fresh Concre During mea ndling, it was arse aggregate ong influence ndling of lig nventional con gregates used ight than gra ncrete density s 21% heavie ecific gravity, ncrete density. increase of 6. ereas for NWF 8, 2741-2744 s of Lightweigh binding ingred oncretes was u the range of TM procedure nt determinati stage. For ligh oarse aggregat ar in shape and lightweight ag when kept imm sed as coarse ggregates had bers 35mm lo orcement for f hape, with a t Other materia S USED y [kg/m3] Wa [kg/m3] Te , 60 r testing machi 00kN. For plates were u t specimens a se of directing bes of dimen both compres Cylinders were these had dia anical jig was t of vertical recorded disp via data cables II. RESULTS ete Density asuring concr observed tha es, particle d on workabil ghtweight con ncrete at all f in the mixes avels and ha test results sh r than LWFC they have t At maximum 7% in density FC this increas ht and Normal W dient for both used as a fine 0–2mm and e [11]was use ion and was htweight conc te material, th d had particle ggregates abso mersed under w e aggregates particle size r ong with 0.55m fibrous mixes. tensile strength al details are g ater absorption (24 14.36 1.48 1.02 ensile strength [M 1100 ine with maxim splitting tens used, placed o as shown in F g the load alon nsions 150mm ssive strength e used for th ameter of 100 attached to th displacement placement was as shown in F S AND DISCUSS rete properti at parameters density and fi lity and fresh ncrete was e fiber content s making wer ad regular ro how that on a C. Since steel the tendency m fiber dosage y values of LW se was only 2. 2742 Weight Concre concretes. Na e aggregate, ha particle densi ed for aggreg s adjusted d crete expanded he aggregates size between orbed water at water for 24 h for productio ranging from mm diameter . These fibers h of 1100MPa given in Table 4 h)% MPa] mum load app sile strength on top and bo Figure 2(b). P ng the center li mx150mmx15 h and split te he measureme 0mm and heig hese specimen needed for s s transferred t Figure 2(c). SION ies and con like the shap iber quantity h concrete den easy compare levels becaus re twice light ound shape. F an average NW fibers have h of increasing level i.e. 60k WFC was reco 2%. etes … atural aving ity of gates’ during d clay were 2mm 14% hours. on of 2mm were were a and I. plying test, ottom Plates ine of 50mm ensile ent of ght of ns for strain to the ncrete pe of have nsity. ed to e the ter in Fresh WFC higher g the kg/m3, orded, B. lig add jol rea fib nor con the wh ma C. the con con fai fai num con com 40k thi 21 con fro str po wh loa D. of Engineerin www.etasr Workability Compared to ghtweight conc dition. The m lting of table h ason conventio bers. Also, the rmal weight ntent of 40kg e workability hereas for ligh aximum fiber c Compressiv A number of e compressive ncretes. The ntent levels w ir evaluation o iled in a brittl mber of crack ntent, the widt mpressive stre kg/m3 as sho is quantity of .1% for spe ncretes respec om 40kg/m3 t ength of bot ssibly due to hich resulted i ads. Splitting Ten Splitting tens the compressi ng, Technology r.com Fig o conventiona crete was mo mechanism of helps the grav onal concrete i effect of fiber concrete was g/m3. When m of normal we htweight conc content level. ve Strength f mix trials we e strength of difference be as brought to of properties. le fashion an ks before fail th of cracks w ength value w own in Figure f fibers was f ecimens of n ctively. Furthe to 60kg/m3 c th lightweight the difficulty in voids whic nsile Strength sile strength is ive strength fo y & Applied Sci Ali e (b) g. 2. Test setu al concrete’s, ore affected a flow table te vitational fall o is less affected rs in reducing not observed measured in ter eight concrete crete this decr ere performed lightweight a etween the str less than 5MP Specimens c d those with lure. Also, wi was observed t was recorded e 3. The comp found to incr normal weigh er increase in caused reducti t and normal of achieving ch led specime s noted to be o or all mixes o ience Research et al.: Compari up (a) compressiv the workabil as a result of est is such th of concrete, fo d by the presen g the slump flo d even up to rms of slump e reduced by rease was 12.5 d for bringing and normal w rengths at all Pa (see Figure ontaining no fibers develo ith increasing to decrease. H at fiber dosa pressive stren rease by 7.7% ht and lightw n fiber quantit ion in compr l weight con proper comp ens to fail at on an average f LWFC, whil V ison of Mechan (a) e strength (b) spli lity of f fiber hat the or this nce of ow for fiber flow, 6.4%, 5% at closer weight fiber 3) for fibers oped a g fiber Highest age of gth at % and weight ty i.e. essive ncretes action lower e 6.6% le this per fail con due at sho of f find imp viab stre Fig. add in[1 tens of s 14% kg/ an i Vol. 8, No. 2, 20 nical Properties itting tensile stren rcentage range led with sing ntent level, wh e to transverse center due to own in Figure fiber volume b dings indicate pact on concre ble option to ength through 3. Dependen Enhancement dition was mo 14] reported s sile strength w steel fibers. Re % for NWFC /m3.For this fib increase of 19 18, 2741-2744 s of Lightweigh (c) ngth (c) elastic mo s from 6.41% le major crac hile, at highes e compressive o uniform ten 3, variation o but follows the e that compr ete splitting ten bring improv addition of ste nce of splitting ten t in splitting ore distinct in similar observ was of no great esults show ma and LWFC re ber volume (40 9% in splitting ht and Normal W odulus to 6.88% for N ck in two ha st fiber dosage stresses and c nsile stresses of tensile stren e compressive ressive streng nsile strength a vement in fir eel fibers. nsile strength on c tensile stren LWFC than i ations. Enhan ter significanc aximum impro espectively at 0kg/m3), autho g tensile streng 2743 Weight Concre NWFC. Speci alves at zero e, crushing at compound crac was observed ngth is indepen e test results. T gth has signif and it may not rst cracking te compressive stren ngth due to in NWFC. Au ncement in spl ce after the add ovement of 9% fiber volume ors in [15] rep gth of high-stre etes … imens fiber ends cking d. As ndent These ficant t be a ensile ngth fiber uthors litting dition % and of40 ported ength fib con E. 4 a som the red sim cre res ela rel ela ela com lig 14 of str com vo int cre com con ran and com com res firs bee usi exp lite 2% Ho str Engineerin www.etasr ber-reinforced ncrete [16] rep Elastic Modu Results of m as a function o me reduction e fiber volume duction is abou milar trends. T eated by stee sulting in les asticity. Test lation betwee asticity i.e. any astic modulu mpressive st ghtweight conc GPa lower tha expanded clay Fig. 4. M No obvious ength of NW mpressive str lume. Howev take. The ma eated by fibe mpaction by ncrete’s comp nge of fiber vo d NWFC is mpressive str mpressive str sults. Also for st cracking ten en reported in ing larger fibe perience gain erature sugges % for differe owever, there ength as a resu ng, Technology r.com concrete. For ports 11% incr ulus modulus of elas of fiber conten in elastic mo e increases and ut 5.86%.Auth This behavior el fibers in c ss denser ma results of N en compressi y change in co us exponenti trength class crete at all fi an NWFC val y compared to Modulus of elasti IV. CO divergence w WFC with max rength of LW er it begins to ain reason for ers which re the concrete. pressive streng olume. Tensile on an avera rengths. Depe rength is pro r the quantity nsile strength n[19] that thi er volume fra ned from curr st the limiting ent reasons l e is some m ult of fiber add y & Applied Sci Ali e r normal stren rease. sticity test are nt. It can be se odulus of light d at the highe hors in [17, 18 r is probably concrete’s con aterial with WFC follow ive strength ompressive stre ally. Despite , elastic m fiber dosages lues due to low gravel. city as a function ONCLUSIONS was noticed o ximizing volu WFC rises up o lower down r this change esults in fail It is, therefo gth does not v e strength gain ge of 6.7% endence of t oved by curre y of fibers use was least affe is property ca action (>2% o rent lab testi of fiber volum like economy minimal enhan dition and it is ience Research et al.: Compari gth fiber-reinf illustrated in F een that that th tweight concr st fiber volum ] have also rep due to hindr nsolidation pr lower modulu a well-estab and modulu ength will affe e having s odulus value had an avera wer specific g n of fiber content on the compr ume, given th to 40Kg/m3 n at maximum e is the disru lure to attain ore, established vary for the se ned by both L of their resp tensile strengt ent laboratory ed in current ected. Though an be improv of volume frac ing and revie me maximum y and practic ncement in t s more noticea V ison of Mechan forced Figure here is rete as me this ported rances rocess us of blished us of ect the similar es of age of gravity essive hat the fiber m fiber uption n full d that elected LWFC pective th on y test study, it has ed by ction), ew of up to cality. tensile able in ligh bec stee mo com sub [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] Vol. 8, No. 2, 20 nical Properties htweight conc cause of the gr el fiber volum dulus of elast mpressive str bstantial impac ACI Committe Concrete (ACI American Conc A. Kumar R., P by Blending Innovative Res 48–52, 2015 C. Shi, Y. Lightweight Co K. Holschema lightweight con Structural Engi Group: London S. Iqbal, A. Ali of steel fiber concrete (SHLS 325–333, 2015 A. A. Shah, Y concrete”, Mate M. 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