International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, I...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volu...
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Effect of sulfate on the properties of self compacting concrete 2

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Effect of sulfate on the properties of self compacting concrete 2

  1. 1. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME270EFFECT OF SULFATE ON THE PROPERTIES OF SELFCOMPACTING CONCRETE REINFORCED BY STEEL FIBERAbbas S. Al-Ameeri1, Rawaa H. Issa 21(Civil, Engineering/ University of Babylon, Babylon City, Iraq)2(Civil, Engineering/University of Babylon, Al-Najaf Al-Ashraf, Iraq)ABSTRACTThe Internal sulfate attack is considered as very important problem of concretemanufacture in Iraq and Middle East countries. Sulfate drastically influence the propertiesof concrete. This experimental study is aimed at investigating the effect of internal sulfates onfresh and some of the hardened properties of self compacting concrete (SCC) made fromlocally available materials and reinforced by steel fibers. Tests were conducted on fifteenmixes, three varied steel fiber contents (0, 0.75 and1.5) (%by Vol.) with five SO3 levels (3.9,5, 6, 7 and 8) (% by wt. of cement). The last four SO3 levels are outside the limits of the Iraqispecifications (IQS NO.45/1984). The results indicated that sulfate passively influenced thefresh and hardened properties of the plain and the reinforced SCC. However, regarding theeffect on the hardened properties, the SCC reinforced with steel fiber showed similar to bettersulfate resistance over plain SCC, the resistance enhanced with increasing steel fiber content.The results of the present study refer to that there might be a possibility of using reinforcedSCC with unacceptable SO3 (with regard to Iraqi specifications) if high steel fiber content andlong curing period are employed and if the SO3 is limited to 6 (% by wt. of cement).Keywords: Self compacting concrete, Steel fiber, Steel fiber reinforced concrete, Steel fiberreinforced self compacting concrete, Sulfate attack, Internal sulfate attack.1. INTRODUCTIONSelf compacting concrete (SCC) is a concrete which has the ability to flow by its ownweight and achieve good compaction without external vibration. In addition, SCC has goodresistance to segregation and bleeding because of its cohesive properties [1]. SCC, like anyother concrete, is known to be brittle and can easily crack under low levels of tensile force.This inherent shortcoming, which limits the application of this material, can be overcome byINTERNATIONAL JOURNAL OF CIVIL ENGINEERING ANDTECHNOLOGY (IJCIET)ISSN 0976 – 6308 (Print)ISSN 0976 – 6316(Online)Volume 4, Issue 2, March - April (2013), pp. 270-287© IAEME: www.iaeme.com/ijciet.aspJournal Impact Factor (2013): 5.3277 (Calculated by GISI)www.jifactor.comIJCIET© IAEME
  2. 2. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME271the inclusion of fibers. The steel fiber is the most common fiber type in the building industry.The mechanical properties of SCC reinforced with steel fibers have been the pivot ofnumerous research programs, whereas its durability has not been investigated to the sameextent. One of the durability problems which may encounter the concrete during its servicelife is the internal sulfate attack; internal sulfate attack is the major culprit of causing thedeterioration to concretes in middle east countries, particularly in Iraq.Internal sulfate attack results from the reaction between sulfates in concreteingredients ( water , cement , sand , gravel ) and cement paste, which had calcium aluminates,and water to form high calcium sulfoaluminate (ettringite). One of the main sources ofinternal sulfates that cause damage of concrete structures is the sand used. In the central andsouthern regions of Iraq, most sands are contaminated with sulfates mainly in the form ofgypsum. About 95% of the sulfates in sand are in the form of calcium sulfates [2]. Gypsum isalso normally added to cement to retard early hydration, prevent quickset and increase theefficiency of clinker grinding. The total sulfate in concrete may, therefore, be high enough tocause internal sulfate attack. This may lead to deterioration and possibly cracking and failureof concrete structure[3].Therefore, an attempt has been made to study the behavior of self compactingconcrete reinforced by steel fiber in the fresh and in the hardened state, in case of exposure tointernal sulfate attack. To shed some light on the potential of the exposure to this kind ofproblem in such a concrete is highly requisite, it may illustrate to what extent internal sulfatescan affect the properties of this type of concrete and to what extent can this concrete resist thesulfate attack.2. Materials Used2.1 CementOrdinary Portland cement, which has specific gravity of 3.15 and the SO3 of 2.51, wasused in this investigation. It is conforming to IQS:5 -19842.2 Coarse aggregateRounded shape aggregate of size of 10 mm was used and it has the following properties:Specific gravity of 2.61 and the SO3 of 0.042.3 Fine aggregateNatural sand conforming to zone III of IQS: 45 – 1984 was used and its properties arefound as follows: Specific gravity 2.56 and the SO3 of 0.372.4 Water &Super-plasticizerThe drinking tap water has been used for both mixing and curing of concrete. A chemicaladmixture based on modified polycarboxylic ether, which is known commercially (Glenium51) was used in producing SCC as a superplasticizer admixture.2.5 Lime stone powder (LSP)This material was used to increase the amount of powder (cement + filler). It has SO3 of 1.9and its specific gravity was 2.7.
  3. 3. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2722.6 GypsumGypsum was added to the fine aggregate to obtain the required SO3 content in concrete.The added gypsum was natural gypsum rock .It was crushed and ground by hammer to obtainnearly the same gradation set of fine aggregate used in the mixes. This gypsum was used as apartial replacement by weight of fine aggregate with limited percentages. The followingequation has been used to control the SO3 contents in the used sand:( )NSRw%37.0−= …………. (1)Where:‫ݓ‬ : the weight of natural gypsum needed to be added to fine aggregate.ܴ : the percentage of SO3 desired in fine aggregate.ܵ : the weight of fine aggregate in mix.N: the percentage of SO3 in the used natural gypsum (34.9%).2.7 FibersIn this work, type of steel fiber having geometry of cylindrical with hooked ends was used.The characteristics of the steel fiber ; length, diameter ,tensile strength, specific gravity were30mm , 0.5 mm,1100 MPa and 7000 Kg/m3respectively.3. METHODOLOGYIn order to cover a broad range of SO3 levels ( 3.9 which is within the limits ofIraqi specifications[4] and, 5,6,7and 8 which are outside the limits)% by weight of cement inconcrete, a total of fifteen mixes were made. The mixture was designed according to [5]. Addinggypsum as a partial replacement of sand was the adopted procedure to obtain the required SO3level in concrete. Fibers were added in quantities ranging from 0 to 1.5 % by volume of the totalmixture. Moist curing was adopted , the curing time was for four ages (7, 28, 90 and 180) days.Table (1) shows the proportions of reference plain mixture.Table (1) Proportions of reference plain mixtureCement(kg/m3)Sand(kg/m3)Gravel(kg/m3)LSP(kg/m3)SP(L/m3)w/c w/p425 870 600 129.2 3.35 0.52 0.44.FRESH CONCRETE TESTSThe fresh properties of plain SCC and SCC reinforced by steel fiber were tested by theprocedures of (European Guidelines for self compacting concrete). In this work three testswere used slump flow test, L-box test and V-funnel test.5. HARDENED CONCRETE TESTSThe mechanical properties studied are compressive strength, splitting tensile strength,flexural strength and static modulus of elasticity. Furthermore, the non-destructive test methods,length change test, ultra-sonic pulse velocity test and Schmidt hammer test are used. The
  4. 4. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, Marchcompressive strength test was performed in accordance with IQS:348cube specimens. The splitting tensile strength test was carried out according to IQS:283[7] using Ø100 × 200 mm cylinder specimens. The test procedure given in IQS:291was used to determine the flexural strength using 100 × 100 × 400 mm prisms. The stamodulus of elasticity was performed according to IQS:370Ø150×300 mm. According to IQS:54used to measure the changing in length due to sulfate action. The UPV antests were conducted according to IQS:3006. Results of Tests6.1 Fresh Concrete Properties6.1.1 Slump Flow TestTable (2) and Fig. (1) show the results of slump flow tests . The vthe maximum spread (slump flow final diameter), while the values of T50 represent the timerequired for the concrete flow to reach a circle with 50 cm diameter. The results of the slumpflow range between (486-750) mm, the results ofshown in Fig. (2). The results indicate that increasing sulfate decrease the slump flow diameterand increase the time required to reach the diameter of 50 cm (T50), This can be accounted for,during very early stages of hydration, ettringite forms in relatively increased quantities withincreased sulfates content, as a result, relatively large amount of water would be consumed forthe reaction forming ettringite, beside, the roughness of gypsum particles could bereason. Therefore, concrete mixtures tending to be cohesivevalue might be increased causing the reduced flowability. Significant decrease in slump flowdiameter and increase in T50 have been observed with incoradding steel fibers increases the resistance to flow and reduces the flowability due to increasingthe interlocking and friction between fibers and aggregateFig.(1): Slump flow diameter D (mm6.1.2 L-Box TestThe L-Box with 2 bars was used in this study to assessmixes. The Blocking Ratios results (BR=Hplotted in Fig. (3). The results of the BR ranged between01002003004005006007008003.9 5 6 7 8Slumpflowdiameter(mm)Total SO3 (% by wt. of cement)International Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM273compressive strength test was performed in accordance with IQS:348-1992 [6]. The splitting tensile strength test was carried out according to IQS:283using Ø100 × 200 mm cylinder specimens. The test procedure given in IQS:291was used to determine the flexural strength using 100 × 100 × 400 mm prisms. The stamodulus of elasticity was performed according to IQS:370-1993 [9] by using test cylinders ofØ150×300 mm. According to IQS:54-1989 [10] prisms of (75×75×285) mm of concrete wasused to measure the changing in length due to sulfate action. The UPV and Schmidt hammertests were conducted according to IQS:300-1993 [11] and IQS:325-1993 [12] respectively.Table (2) and Fig. (1) show the results of slump flow tests . The values of (D) representthe maximum spread (slump flow final diameter), while the values of T50 represent the timerequired for the concrete flow to reach a circle with 50 cm diameter. The results of the slump750) mm, the results of T50 cm range between (2.1shown in Fig. (2). The results indicate that increasing sulfate decrease the slump flow diameterand increase the time required to reach the diameter of 50 cm (T50), This can be accounted for,ages of hydration, ettringite forms in relatively increased quantities withincreased sulfates content, as a result, relatively large amount of water would be consumed forthe reaction forming ettringite, beside, the roughness of gypsum particles could bereason. Therefore, concrete mixtures tending to be cohesive [13]. Accordingly, the yield stressvalue might be increased causing the reduced flowability. Significant decrease in slump flowdiameter and increase in T50 have been observed with incorporating steel fibers in SCC mixes,adding steel fibers increases the resistance to flow and reduces the flowability due to increasingthe interlocking and friction between fibers and aggregate [14].Fig.(1): Slump flow diameter D (mm) Fig.(2):Time required to reach a circlewith50diaBox with 2 bars was used in this study to assess the passing ability of themixes. The Blocking Ratios results (BR=H2/H1) of the tests are summarized in Table (2) &The results of the BR ranged between (0.58-1). According toVf%=0Vf%=0.75Vf%=1.501234563.9 5 6 7 8T50(sec)Total SO3 (% by wt. of cement)International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEME[6] using 150 mm. The splitting tensile strength test was carried out according to IQS:283-1995using Ø100 × 200 mm cylinder specimens. The test procedure given in IQS:291-1991 [8]was used to determine the flexural strength using 100 × 100 × 400 mm prisms. The staticby using test cylinders ofprisms of (75×75×285) mm of concrete wasd Schmidt hammerrespectively.alues of (D) representthe maximum spread (slump flow final diameter), while the values of T50 represent the timerequired for the concrete flow to reach a circle with 50 cm diameter. The results of the slumpcm range between (2.1-5.7) seconds asshown in Fig. (2). The results indicate that increasing sulfate decrease the slump flow diameterand increase the time required to reach the diameter of 50 cm (T50), This can be accounted for,ages of hydration, ettringite forms in relatively increased quantities withincreased sulfates content, as a result, relatively large amount of water would be consumed forthe reaction forming ettringite, beside, the roughness of gypsum particles could be another. Accordingly, the yield stressvalue might be increased causing the reduced flowability. Significant decrease in slump flowporating steel fibers in SCC mixes,adding steel fibers increases the resistance to flow and reduces the flowability due to increasingFig.(2):Time required to reach a circlethe passing ability of the) of the tests are summarized in Table (2) &1). According to [5], a8Vf%=0Vf%=0.75Vf%=1.5
  5. 5. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, Marchblocking ratio (H2/H1) of more than or equal to 0.mixtures had a good passing ability with BRhad BR less than 0.8.The results show that the BR decreased with increasing sulfates inconcrete. This decrease is likely due to increased yield stress and viscosity with theincreasing in sulfates.Fig.(3): Blocking Ratios for L6.1.3 V-Funnel TestThe V-funnel test is used to assess the viscosity and filling ability of selfconcrete [5] . Table (2) shows the results of V(6.57-12.3). It is clear from the results that the Vincreasing SO3 content in the mixes, confirming that raising sulfate contentviscosity of the mixtures. V-Funnel flow time also increased by incorporating steel fibers inmixes. Similar behavior was observed in the T50 testcontent, the more the flow-time increased. This can be ascricontent leads to increase the friction between the fibers and aggregates and the friction of thefibers with each other which could extend the required time to empty the VFig.(4): V02468101214Tv(sec)00.20.40.60.811.2BRInternational Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM274blocking ratio (H2/H1) of more than or equal to 0.8 represents good passing ability. Allmixtures had a good passing ability with BR ≥ 0.8 except the mixtures (S4F3 and S5F3)had BR less than 0.8.The results show that the BR decreased with increasing sulfates inse is likely due to increased yield stress and viscosity with theFig.(3): Blocking Ratios for L-box testsfunnel test is used to assess the viscosity and filling ability of selfTable (2) shows the results of V-funnel test. The Tv values ranged between12.3). It is clear from the results that the V-funnel flow time increased with thecontent in the mixes, confirming that raising sulfate contentFunnel flow time also increased by incorporating steel fibers inSimilar behavior was observed in the T50 test. Besides, the higher the steel fibertime increased. This can be ascribed to, the increasing in fibercontent leads to increase the friction between the fibers and aggregates and the friction of thefibers with each other which could extend the required time to empty the V-funnelFig.(4): V-funnel flow time Tv (sec)3.9 5 6 7 8Total SO3 (% by wt. of cement)Vf%=0Vf%=0.75Vf%=1.53.9 5 6 7 8Total SO3 (% by wt. of cement)Vf%=0Vf%=0.75Vf%=1.5International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEME8 represents good passing ability. All0.8 except the mixtures (S4F3 and S5F3)had BR less than 0.8.The results show that the BR decreased with increasing sulfates inse is likely due to increased yield stress and viscosity with thefunnel test is used to assess the viscosity and filling ability of self-compactingvalues ranged betweenfunnel flow time increased with thecontent in the mixes, confirming that raising sulfate content increasesFunnel flow time also increased by incorporating steel fibers in. Besides, the higher the steel fiberbed to, the increasing in fibercontent leads to increase the friction between the fibers and aggregates and the friction of thefunnel
  6. 6. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME275Table (2) Results of fresh concrete testsMix SO3 (%bywt. ofcement)Steel Fiber(% by Vol.)D (mm) T50 (Sec) Blocking Ratio(BR)Tv (sec)S1F1 3.9 0 750 2.1 1 6.57S1F2 0.75 681 2.95 0.95 7.68S1F3 1.5 584 4.25 0.84 9.23S2F150 745 2.18 1 6.69S2F2 0.75 675 3.1 0.93 7.86S2F3 1.5 573 4.53 0.82 9.46S3F160 729 2.35 0.98 6.8S3F2 0.75 658 3.37 0.91 8.27S3F3 1.5 555 5 0.79 10.27S4F170 699 2.55 0.96 7.22S4F2 0.75 625 3.71 0.88 8.9S4F3 1.5 518 5.7 0.71 11.53S5F180 685 2.73 0.93 7.51S5F2 0.75 595 4.12 0.83 9.36S5F3 1.5 486 N.a* 0. 58 12.3*N.a: not applicable6.2 Hardened Concrete properties6.2.1 Compressive StrengthTable (3) and Fig.(5) refer to that there is an optimum SO3 content at which the compressivestrength is maximum. The data in table (5) indicate that the optimum SO3 content for these mixes isabout (5) (% by wt. of cement), beyond this optimum value the compressive strength decreased withthe increase of sulfates content for all SCCs the plain and the reinforced ones, at all ages oftest. at age of 180 days, the percentages of change (increase or decrease) in compressive strength forSCCs having 5 %, 6 % ,7% and 8 % SO3 content in concrete, were (4.36%, -10.89%,-25.66% and-36.14%) relative to corresponding reference SCC. While, for SCC reinforced with 0.75 (%by Vol.)the percentages of change were (5.10%, -5.92%,-23.02% and -33.39%) and for SCC reinforced with1.5 (% by Vol.), the percentages of change were (4.66%, -3.39%,-19.49% and -29.26%) relative totheir corresponding reference SCC reinforced with 0.75 and 1.5 (%by Vol.) respectively.Adding steel fibers decreased compressive strength at low sulfate contents at (3.9 and 5)%.while, at high sulfate contents(6,7 and 8)% the compressive strength was increased by adding steelfibers. at age180 days, the percentages of change in compressive strength for SCCs having3.9%,5%,6%,7% and 8% percent SO3 content in SCC reinforced with 0.75 and 1.5 steel fibercontents (% by Vol.), were (-2.97%, -2.28%, 2.44%, 0.48%, 1.21%) and (-6.53%, -6.26%, 1.33%,1.23%, 3.53%) respectively relative to corresponding plain SCC. The improvement in strength referto the control of cracking and the mode of failure by means of post cracking ductility as indicated byAL-Musawee [14].While, the decrease in strength refer to entraining air with incorporating steelfibers [15]. Moreover, the steel fiber indirectly would contribute to the increment of strength throughdelaying the deterioration due to the sulfate action while, the corresponding plain SCC continue todeteriorate, therefore, there would be a definite difference between plain and reinforced SCC.
  7. 7. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, MarchFig.(5):Effect of increasing SOdays (b) 28 days (c) 90 days (d) 180 days6.2.2 Splitting Tensile StrengthTable (3) shows the average of the results of splitting tensile strength test at 7, 28, 90 and180 days gained from cylinders. Table (3) and Fig.(6), show the optimthe splitting tensile strength is maximum. Further increase in SOstrength. at age of 180 days, the percentages of change in splitting tensile strength for SCCshaving 5 %, 6 % ,7 and 8 % SO-33.33%) relative to reference SCC. While, for SCC reinforced with 0.75 (%by Vol.) thepercentages of change were (3.05%,1.5 (% by Vol.) the percentages of change were (8.97%,their corresponding SCCs reinforced with 0.75 and 1.5 (%by Vol.)that both the plain and the reinforced SCC suffered reduction in splitting tensile strenincreased SO3 beyond the optimum value. However, in general, the reinforced SCC showedbetter performance than SCC. This reduction can be ascribed to, with high sulfates contents andcontinued exposure to water, more ettringite would be formed, coincreased, inducing high tensile stresses and causing decrease in ultimate strength. The existenceof steel fibers restricts the expansion and hence, delays the failure process. The SCC reinforcedwith steel fibers and contained 6tolerable limits.By contrast to the compressive strength, the results of the splitting tensile strength tests,indicated in Table (3), clearly showed the benefit of steel fibers. Splittingindicated significant increase in strength due to the inclusion of steel fibers. The percent of1520253035403.5 4 4.5 5 5.5 6 6.5 7 7.5 8Fcu(MPa)Total SO3 (% by wt. of cement)253035404550553.5 4 4.5 5 5.5 6 6.5 7 7.5 8Fcu(MPa)Total SO3 (% by wt. of cement)cInternational Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM276Fig.(5):Effect of increasing SO3 content in concrete on compressive strengtdays (b) 28 days (c) 90 days (d) 180 daysTable (3) shows the average of the results of splitting tensile strength test at 7, 28, 90 and180 days gained from cylinders. Table (3) and Fig.(6), show the optimum SO3 content at whichthe splitting tensile strength is maximum. Further increase in SO3 content caused decreasing instrength. at age of 180 days, the percentages of change in splitting tensile strength for SCCshaving 5 %, 6 % ,7 and 8 % SO3 content in concrete ,were (4.95%, -12.90%,33.33%) relative to reference SCC. While, for SCC reinforced with 0.75 (%by Vol.) thepercentages of change were (3.05%, -10.00%,-31.3%and -36.49%) and for SCC reinforced withercentages of change were (8.97%,-2.21%,-23.72% and -31.86%) relative totheir corresponding SCCs reinforced with 0.75 and 1.5 (%by Vol.) respectively. It can be seen,that both the plain and the reinforced SCC suffered reduction in splitting tensile strenbeyond the optimum value. However, in general, the reinforced SCC showedbetter performance than SCC. This reduction can be ascribed to, with high sulfates contents andcontinued exposure to water, more ettringite would be formed, consequently the expansionincreased, inducing high tensile stresses and causing decrease in ultimate strength. The existenceof steel fibers restricts the expansion and hence, delays the failure process. The SCC reinforcedwith steel fibers and contained 6 % (by wt. of cement) suffered losses at later ages within aBy contrast to the compressive strength, the results of the splitting tensile strength tests,indicated in Table (3), clearly showed the benefit of steel fibers. Splitting tensile strengthindicated significant increase in strength due to the inclusion of steel fibers. The percent ofVf%=0Vf%=0.75Vf%=1.5202530354045503.5 4 4.5 5 5.5 6 6.5 7 7.5 8Fcu(MPa)Total SO3 (% by wt. of cement)Vf%=0Vf%=0.75Vf%=1.53035404550553.5 4 4.5 5 5.5 6 6.5 7 7.5 8Fcu(MPa)Total SO3 (% by wt. of cement)dInternational Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMEcontent in concrete on compressive strength at (a) 7Table (3) shows the average of the results of splitting tensile strength test at 7, 28, 90 andcontent at whichcontent caused decreasing instrength. at age of 180 days, the percentages of change in splitting tensile strength for SCCs12.90%, -26.88% and33.33%) relative to reference SCC. While, for SCC reinforced with 0.75 (%by Vol.) the36.49%) and for SCC reinforced with31.86%) relative torespectively. It can be seen,that both the plain and the reinforced SCC suffered reduction in splitting tensile strength withbeyond the optimum value. However, in general, the reinforced SCC showedbetter performance than SCC. This reduction can be ascribed to, with high sulfates contents andnsequently the expansionincreased, inducing high tensile stresses and causing decrease in ultimate strength. The existenceof steel fibers restricts the expansion and hence, delays the failure process. The SCC reinforced% (by wt. of cement) suffered losses at later ages within aBy contrast to the compressive strength, the results of the splitting tensile strength tests,tensile strengthindicated significant increase in strength due to the inclusion of steel fibers. The percent ofVf%=0Vf%=0.75Vf%=1.5Vf%=0Vf%=0.75Vf%=1.5
  8. 8. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, Marchincrease in splitting tensile strength was found to be increase with the increase in steel fiberscontent for all mixes. at age180 days, the peSCCs having 3.9%, 5%, 6%, 7% and 8% SOfiber contents (% by Vol.) were (40.86%, 38.32%, 45.56%, 32.35% and 34.19%) and(55.9%,61.89%,75.06%, 62.65% and 59.35%) respectively relative to corresponding plain SCC.Fig.(6):Effect of increasing SOdays (b) 28 days (c) 90 days (d) 180 days6.2.3 Flexural StrengthThe flexural strength results for the plain and the reinforced SCC mixes are listed inTable (3). The optimum SO3 content at which the flexural strength is maximum has beenrecognized, Fig.(7). The flexural strength decreased with increasing SOoptimum value. at age of 180 days, the percentages of change in flexural strength for SCCshaving 5 % 6 % ,7 and 8 % SO36.17%) relative to reference SCC. While, for SCC reinforcedpercentages of change were (4.97%,with 1.5 (% by Vol.) the percentages of change were (3.91%,relative to their corresponding SCC reinforced with 0.75 aThe fine voids developed over the aggregate surface represent structural breaks in thecontinuity and are, at the same time, an opportunity for the accumulation of ettringite,aaaa1.52.53.54.55.53.5 4 4.5 5 5.5 6 6.5 7 7.5 8ft(MPa)Total SO3 (% by wt. of cement)2.53.54.55.56.57.58.53.5 4 4.5 5 5.5 6 6.5 7 7.5 8ft(MPa)Total SO3 (% by wt. of cement)cInternational Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM277increase in splitting tensile strength was found to be increase with the increase in steel fibersat age180 days, the percentages of increase in splitting tensile strength forSCCs having 3.9%, 5%, 6%, 7% and 8% SO3 content in SCC reinforced with 0.75 and 1.5 steelfiber contents (% by Vol.) were (40.86%, 38.32%, 45.56%, 32.35% and 34.19%) and% and 59.35%) respectively relative to corresponding plain SCC.Fig.(6):Effect of increasing SO3 content in concrete on splitting tensile strength at (a) 7days (b) 28 days (c) 90 days (d) 180 daysThe flexural strength results for the plain and the reinforced SCC mixes are listed incontent at which the flexural strength is maximum has beenrecognized, Fig.(7). The flexural strength decreased with increasing SO3 content beyond theat age of 180 days, the percentages of change in flexural strength for SCCshaving 5 % 6 % ,7 and 8 % SO3 content in concrete ,were (15.60%,-7.80%,-36.17%) relative to reference SCC. While, for SCC reinforced with 0.75 (%by Vol.) thepercentages of change were (4.97%,-7.18%,-25.97% and -38.12%) and for SCC reinforcedwith 1.5 (% by Vol.) the percentages of change were (3.91%,-7.24%,-23.11% andrelative to their corresponding SCC reinforced with 0.75 and 1.5 (%by Vol.) respectively.The fine voids developed over the aggregate surface represent structural breaks in thecontinuity and are, at the same time, an opportunity for the accumulation of ettringite,bbbbVf%=0Vf%=0.75Vf%=1.51.52.53.54.55.56.53.5 4 4.5 5 5.5 6 6.5 7 7.5 8ft(MPa)Total SO3 (% by wt. of cement)Vf%=0Vf%=0.75Vf%=1.52.53.54.55.56.57.58.53.5 4 4.5 5 5.5 6 6.5 7 7.5 8ft(MPa)Total SO3 (% by wt. of cement)dInternational Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMEincrease in splitting tensile strength was found to be increase with the increase in steel fibersrcentages of increase in splitting tensile strength forcontent in SCC reinforced with 0.75 and 1.5 steelfiber contents (% by Vol.) were (40.86%, 38.32%, 45.56%, 32.35% and 34.19%) and% and 59.35%) respectively relative to corresponding plain SCC.content in concrete on splitting tensile strength at (a) 7The flexural strength results for the plain and the reinforced SCC mixes are listed incontent at which the flexural strength is maximum has beenent beyond theat age of 180 days, the percentages of change in flexural strength for SCCs-24.65% and -with 0.75 (%by Vol.) the38.12%) and for SCC reinforced23.11% and -32.47%)respectively.The fine voids developed over the aggregate surface represent structural breaks in thecontinuity and are, at the same time, an opportunity for the accumulation of ettringite,Vf%=0Vf%=0.75Vf%=1.5Vf%=0Vf%=0.75Vf%=1.5
  9. 9. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, Marchettringite forms in voids and microcpaste [16]. It has been observed by many researchersthat the ettringite crystals are usually present in cracks, voids, and transition zone at theaggregate-binder interface, if concrete is submitted to expansion due to ettringite, fact whichleads to an additional stress on the aggregateBeside, ettringite formed in microcracks, due to expansion pressure will widen thesemicrocracks. These processes will result in debonding of aggregates/matrix under low appliedstresses, giving rise to prompt failure. The presence of steel fibers will delay these wholeprocesses by restricting the widening and arresting any new microcracnegative effect of sulfates on concrete.Concrete mixes reinforced with steel fibers showed significant improvement inflexural strength at all ages relative to their corresponding plain concretes.percentages of increase for SCCs having 3.9%,5%,6%,7% and 8% SOreinforced with 0.75 and 1.5 steel fiber contents (% by Vol.) , were (60.46%, 45.71%,61.54%, 57.65% and 55.56%) and (117.91%, 95.86%, 119.23%, 122.35% and 130.56%)respectively relative to corresponding plain SCC. This is mainly due to the increase in crackresistance of the composite and to the ability of fibers to resist forces after the concrete matrixhas failed. The SCC reinforced with 1.5 % steel fiber and contain 6% (by wt. ofsuffered losses within tolerable limits.Fig.(7):Effect of increasing SO28 days (c) 90 days (d) 180 days246810123.5 4 4.5 5 5.5 6 6.5 7 7.5 8fr(MPa)Total SO3(% by wt. of cement)aaaacccc1357911133.5 4 4.5 5 5.5 6 6.5 7 7.5 8fr(MPa)Total SO3(% by wt. of cement)International Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM278ettringite forms in voids and microcracks requires less surface energy than forming in bulk. It has been observed by many researchers [16], [17], [18] in damaged concretes,that the ettringite crystals are usually present in cracks, voids, and transition zone at theer interface, if concrete is submitted to expansion due to ettringite, fact whichleads to an additional stress on the aggregate-matrix interface and hence to microcracks.Beside, ettringite formed in microcracks, due to expansion pressure will widen theseThese processes will result in debonding of aggregates/matrix under low appliedstresses, giving rise to prompt failure. The presence of steel fibers will delay these wholeprocesses by restricting the widening and arresting any new microcracks. Thus, reducing thenegative effect of sulfates on concrete.Concrete mixes reinforced with steel fibers showed significant improvement inflexural strength at all ages relative to their corresponding plain concretes. at age180 days, theges of increase for SCCs having 3.9%,5%,6%,7% and 8% SO3 content in SCCreinforced with 0.75 and 1.5 steel fiber contents (% by Vol.) , were (60.46%, 45.71%,61.54%, 57.65% and 55.56%) and (117.91%, 95.86%, 119.23%, 122.35% and 130.56%)ive to corresponding plain SCC. This is mainly due to the increase in crackresistance of the composite and to the ability of fibers to resist forces after the concrete matrixhas failed. The SCC reinforced with 1.5 % steel fiber and contain 6% (by wt. ofsuffered losses within tolerable limits.Fig.(7):Effect of increasing SO3 content in concrete on flexural strength at (a) 7 days (b)28 days (c) 90 days (d) 180 days8Vf%=0Vf%=0.75Vf%=1.5bbbbdddd24681012143.5 4 4.5 5 5.5 6 6.5 7 7.5 8fr(MPa)Total SO3(% by wt. of cement)1357911133.5 4 4.5 5 5.5 6 6.5 7 7.5 8fr(MPa)Total SO3(% by wt. of cement)8Vf%=0Vf%=0.75Vf%=1.5International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMEracks requires less surface energy than forming in bulkin damaged concretes,that the ettringite crystals are usually present in cracks, voids, and transition zone at theer interface, if concrete is submitted to expansion due to ettringite, fact whichmatrix interface and hence to microcracks.Beside, ettringite formed in microcracks, due to expansion pressure will widen theseThese processes will result in debonding of aggregates/matrix under low appliedstresses, giving rise to prompt failure. The presence of steel fibers will delay these wholeks. Thus, reducing theConcrete mixes reinforced with steel fibers showed significant improvement inat age180 days, thecontent in SCCreinforced with 0.75 and 1.5 steel fiber contents (% by Vol.) , were (60.46%, 45.71%,61.54%, 57.65% and 55.56%) and (117.91%, 95.86%, 119.23%, 122.35% and 130.56%)ive to corresponding plain SCC. This is mainly due to the increase in crackresistance of the composite and to the ability of fibers to resist forces after the concrete matrixhas failed. The SCC reinforced with 1.5 % steel fiber and contain 6% (by wt. of cement)content in concrete on flexural strength at (a) 7 days (b)Vf%=0Vf%=0.75Vf%=1.5Vf%=0Vf%=0.75Vf%=1.5
  10. 10. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March6.2.4 Modulus of ElasticityThe static modulus of elasticity for all mixes is experimentally determined at ages 28 and90 days, the results of this test are listed in Table (3).Fig.(8), show the optimum SO3presence of sulfates up to the optimum value of compressive strength means that moredensification of material occurs. Therefore, the modulus of elasticity of concrete also increases.Further increase in SO3 content above the optimum, resulted inspecimens due to the decrease in modulus of elasticity of the matrix caused by the degenerationof the interfacial bond strength between bulk cement paste and aggregate.percentages of change in elastic modulus for SCCs having 5 % 6 % ,7 and 8 % SOconcrete ,were (6.03%,-16.36%,-28.22% andreinforced with 0.75 (%by Vol.) the percentages of change were (13.14%,33.60%) and for SCC reinforced with 1.5 (% by Vol.) the percentages of change were (12.96%,5.69%, -19.96% and -32.30%) relative to their corresponding reference SCC reinforced with 0.75and 1.5 (%by Vol.) respectively. Steel fibers demonstrated similar impact oon compressive strength. However, the increments ,if any, due to incorporating steel fibers wereinsignificant. at age 90 days, the percentages of change in elastic modulus for SCCs having3.9%,5%,6%,7% and 8% SO3 content in SCC rein(% by Vol.) , were (-7.01%, -0.78%, 1.65%, 0.92% and 0.81%) and (2.39% and 1.51%) respectively relative to corresponding plain SCC.Fig.(8):Effect of increasing SO6.2.5 Length ChangeConcrete prisms (75×75×285) mm were tested to determine the length change(expansion) of concrete at ages of 3,7,14,28, 56, 90 and 180 days. From fig.(9) ,it is quitthat expansion increased with age and with increasing sulfates content in concrete for both plainand reinforced SCC, more ettringite formation can be anticipated since more sulfates will beavailable for the reaction forming ettringite. The expacrack enlargement. Ettringite deposited in rims surrounding aggregate grains, and ettringitedeposited in cracks considered as contributing to the overall expansion, through crackdevelopment and propagation by ettcompared to the energy needed for the formation of new cracks in concretetransformation of monosulfate to ettringite is well known to cause 2.3 times increase in volumeand thus represents another source for expansioncontent of 5% had little propensity to expand among the increased SOaaaa15171921232527293.5 4 4.5 5 5.5 6 6.5 7 7.Ec(GPa)Total SO3(% by wt. of cement)International Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM279lasticity for all mixes is experimentally determined at ages 28 and90 days, the results of this test are listed in Table (3). The results listed in Table (3) and plotted in3 content at which the modulus of elasticity is maxipresence of sulfates up to the optimum value of compressive strength means that moredensification of material occurs. Therefore, the modulus of elasticity of concrete also increases.Further increase in SO3 content above the optimum, resulted in decrease in elastic modulus ofspecimens due to the decrease in modulus of elasticity of the matrix caused by the degenerationof the interfacial bond strength between bulk cement paste and aggregate. at age of 90 days, themodulus for SCCs having 5 % 6 % ,7 and 8 % SO28.22% and -38.76%) relative to reference SCC. While, for SCCreinforced with 0.75 (%by Vol.) the percentages of change were (13.14%,-8.57%,-and for SCC reinforced with 1.5 (% by Vol.) the percentages of change were (12.96%,32.30%) relative to their corresponding reference SCC reinforced with 0.75respectively. Steel fibers demonstrated similar impact on elastic modulus ason compressive strength. However, the increments ,if any, due to incorporating steel fibers wereat age 90 days, the percentages of change in elastic modulus for SCCs havingcontent in SCC reinforced with 0.75 and 1.5 steel fiber contents0.78%, 1.65%, 0.92% and 0.81%) and (-8.18%, -2.17%, 3.54%,2.39% and 1.51%) respectively relative to corresponding plain SCC.Fig.(8):Effect of increasing SO3 content in concrete on modulus of elasticity at (a) 28days (b) 90 daysConcrete prisms (75×75×285) mm were tested to determine the length change(expansion) of concrete at ages of 3,7,14,28, 56, 90 and 180 days. From fig.(9) ,it is quitthat expansion increased with age and with increasing sulfates content in concrete for both plainand reinforced SCC, more ettringite formation can be anticipated since more sulfates will beavailable for the reaction forming ettringite. The expansion can be a direct consequence of thecrack enlargement. Ettringite deposited in rims surrounding aggregate grains, and ettringitedeposited in cracks considered as contributing to the overall expansion, through crackdevelopment and propagation by ettringite swelling or crystal growth, much less energy is neededcompared to the energy needed for the formation of new cracks in concrete [18]transformation of monosulfate to ettringite is well known to cause 2.3 times increase in volumethus represents another source for expansion [19]. It can be noticed that the mixtures of SOcontent of 5% had little propensity to expand among the increased SO3 contents of mixtures, thisbbbb18202224262830323.5 4 4.5 5 5.5 6 6.5 7 7.5 8Ec(GPa)Total SO3(% by wt. of cement).5 8(% by wt. of cement)Vf%=0Vf%=0.75Vf%=1.5International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMElasticity for all mixes is experimentally determined at ages 28 andThe results listed in Table (3) and plotted incontent at which the modulus of elasticity is maximum. Thepresence of sulfates up to the optimum value of compressive strength means that moredensification of material occurs. Therefore, the modulus of elasticity of concrete also increases.decrease in elastic modulus ofspecimens due to the decrease in modulus of elasticity of the matrix caused by the degenerationat age of 90 days, themodulus for SCCs having 5 % 6 % ,7 and 8 % SO3 content in38.76%) relative to reference SCC. While, for SCC-22.10% and -and for SCC reinforced with 1.5 (% by Vol.) the percentages of change were (12.96%,-32.30%) relative to their corresponding reference SCC reinforced with 0.75n elastic modulus ason compressive strength. However, the increments ,if any, due to incorporating steel fibers wereat age 90 days, the percentages of change in elastic modulus for SCCs havingforced with 0.75 and 1.5 steel fiber contents2.17%, 3.54%,oncrete on modulus of elasticity at (a) 28Concrete prisms (75×75×285) mm were tested to determine the length change(expansion) of concrete at ages of 3,7,14,28, 56, 90 and 180 days. From fig.(9) ,it is quite evidentthat expansion increased with age and with increasing sulfates content in concrete for both plainand reinforced SCC, more ettringite formation can be anticipated since more sulfates will bension can be a direct consequence of thecrack enlargement. Ettringite deposited in rims surrounding aggregate grains, and ettringitedeposited in cracks considered as contributing to the overall expansion, through crackringite swelling or crystal growth, much less energy is needed[18]. As well, thetransformation of monosulfate to ettringite is well known to cause 2.3 times increase in volume. It can be noticed that the mixtures of SO3contents of mixtures, thisVf%=0Vf%=0.75Vf%=1.5
  11. 11. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, Marchcontent was defined earlier as the optimum SOreally close to the expansion values of the reference mixes with SOcrucial role in this test by reducing expansion. Steel fibers provided internal restraint to concreteexpansion by bridging the micro-cracks and restraining further propagation of those cracks. As aresult, the expansion related stresses will be reduced and by this way, the steel fibers mitigate theeffect of sulfates on concrete.It was noticed at high expansion values there stistrength with progressing age. The last mix despite its high expansion at later ages showedrelatively some gain in strength. The occurrence of relatively slow expansion in concrete at laterages may not lead to concrete deteriorationFig.(9): Effect of steel fibers content on expansion for SOaaaacccc1001502002503003504000 50 100 150 200Expansion*10-6Age (Days)0501001502002500 50 100 150 200Expansion*10-6Age (Days)Expansion*10-6International Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM280content was defined earlier as the optimum SO3 content. In fact, the values of this content werereally close to the expansion values of the reference mixes with SO3 =3.9%. steel fiber played acrucial role in this test by reducing expansion. Steel fibers provided internal restraint to concretecracks and restraining further propagation of those cracks. As aresult, the expansion related stresses will be reduced and by this way, the steel fibers mitigate theIt was noticed at high expansion values there still a development instrength with progressing age. The last mix despite its high expansion at later ages showedrelatively some gain in strength. The occurrence of relatively slow expansion in concrete at laterages may not lead to concrete deterioration [20].Fig.(9): Effect of steel fibers content on expansion for SO3(a)3.9 (b)5 (c)6 (d)7 (e) 8 (% bywt. of cement))))bbbbddddeeee501001502002500 50 100 150 200Expansion*10-6Age (Days)200Vf%=0Vf%=0.75Vf%=1.51502002503003504004505000 50 100 150 200Expansion*10-6Age (Days)200Vf%=0Vf%=0.75Vf%=1.52503504505506507500 100 200Age (Days)Vf%=0Vf%=0.75Vf%=1.5International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMEthe values of this content weresteel fiber played acrucial role in this test by reducing expansion. Steel fibers provided internal restraint to concretecracks and restraining further propagation of those cracks. As aresult, the expansion related stresses will be reduced and by this way, the steel fibers mitigate thell a development instrength with progressing age. The last mix despite its high expansion at later ages showedrelatively some gain in strength. The occurrence of relatively slow expansion in concrete at later(a)3.9 (b)5 (c)6 (d)7 (e) 8 (% byVf%=0Vf%=0.75Vf%=1.5200Vf%=0Vf%=0.75Vf%=1.5
  12. 12. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March6.2.6 Ultrasonic pulse velocityUltrasonic pulse velocity UPV test was used to evaluate the effectsconcrete. The values of ultrasonic pulse velocity for the various types of concrete at (7, 28, 90and 180 days) are presented in Table (3).content at which the velocity is maximum, beyond tincrease in sulfates content as shown in Fig(10).change in pulse velocity for SCCs having 5 %, 6 %, 7% and 8 % SOwere (2.98%, -1.03%,-4.93% andreinforced with 0.75 (%by Vol.), the percentages of change were (2.35%,and -11.48%) and for SCC reinforced with 1.5 (% by Vol.), the percentages of change were(2.55%, -0.58%, -4.86% andreinforced with 0.75 and 1.5 (%by Vol.)disrupting effect of sulfates on the microstructure of concrete. Introducing steel fibersnegatively affected the ultrasonic pulse velocity. This might be attributed to the increase ofthe amount of entrapped air voids due to incorporation of fibers into the mixes. besides, thefibers inside cube were randomly oriented, when the wave pass through the fibers the wavemaybe deflected to other directions rather than pass straight forward to the end of the cube.Fig.(10):Effect of increasing SO28 days (c) 90 days (d) 180 daysaaaacccc3.63.844.24.44.63.5 4 4.5 5 5.5 6 6.5 7 7.5 8UPV(Km/sec)Total SO3 (% by wt. of cement)3.43.63.843.5 4 4.5 5 5.5 6 6.5 7 7.5 8UPV(Km/sec)Total SO3 (% by wt. of cement)International Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM281Ultrasonic pulse velocityUltrasonic pulse velocity UPV test was used to evaluate the effects of sulfates onconcrete. The values of ultrasonic pulse velocity for the various types of concrete at (7, 28, 90and 180 days) are presented in Table (3). The results indicated that there is an optimum SOcontent at which the velocity is maximum, beyond that value, the velocity decreased with theincrease in sulfates content as shown in Fig(10). at age of 180 days, the percentages ofchange in pulse velocity for SCCs having 5 %, 6 %, 7% and 8 % SO3 content in concrete,4.93% and -10.88%) relative to reference SCC. While, for SCCreinforced with 0.75 (%by Vol.), the percentages of change were (2.35%, -0.88%,%) and for SCC reinforced with 1.5 (% by Vol.), the percentages of change were4.86% and -9.72%) relative to their corresponding reference SCCreinforced with 0.75 and 1.5 (%by Vol.) respectively. The decrease in UPV is due to thedisrupting effect of sulfates on the microstructure of concrete. Introducing steel fibersltrasonic pulse velocity. This might be attributed to the increase ofthe amount of entrapped air voids due to incorporation of fibers into the mixes. besides, thefibers inside cube were randomly oriented, when the wave pass through the fibers the waveaybe deflected to other directions rather than pass straight forward to the end of the cube.Fig.(10):Effect of increasing SO3 content in concrete on pulse velocity at (a) 7 days (b)28 days (c) 90 days (d) 180 daysbbbbddddVf%=0Vf%=0.75Vf%=1.53.844.24.44.63.5 4 4.5 5 5.5 6 6.5 7 7.5 8UPV(Km/sec)Total SO3 (% by wt. of cement)3.43.63.844.24.43.5 4 4.5 5 5.5 6 6.5 7 7.5 8UPV(Km/sec)Total SO3 (% by wt. of cement)Vf%=0Vf%=0.75Vf%=1.5International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMEof sulfates onconcrete. The values of ultrasonic pulse velocity for the various types of concrete at (7, 28, 90The results indicated that there is an optimum SO3hat value, the velocity decreased with theat age of 180 days, the percentages ofcontent in concrete,relative to reference SCC. While, for SCC0.88%, -4.91%%) and for SCC reinforced with 1.5 (% by Vol.), the percentages of change wererelative to their corresponding reference SCCThe decrease in UPV is due to thedisrupting effect of sulfates on the microstructure of concrete. Introducing steel fibersltrasonic pulse velocity. This might be attributed to the increase ofthe amount of entrapped air voids due to incorporation of fibers into the mixes. besides, thefibers inside cube were randomly oriented, when the wave pass through the fibers the waveaybe deflected to other directions rather than pass straight forward to the end of the cube.content in concrete on pulse velocity at (a) 7 days (b)Vf%=0Vf%=0.75Vf%=1.5Vf%=0Vf%=0.75Vf%=1.5
  13. 13. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March6.2.7 Rebound NumberThe surface hardness of the 150 mm concrete cubes was assessed by the, "Schmidtrebound hammer test". The rebound number results of plain and the reinforced SCC withdifferent percentages of SO3 content in concrete at the ages ofare presented in Table (3).maximum, referring to densification effect due to ettringite formation at the plastic stage.Beyond the optimum value, the rebound number decreasshown in Fig (11). at age of 180 days, the percentages of change in rebound number for SCCshaving 5 %, 6 % ,7% and 8 % SO19.23%) relative to reference SCC. While,percentages of change were (1.07%,1.5 (% by Vol.), the percentages of change were (6.48%,their corresponding reference SCC reinforced with 0.75 and 1.5 (%by Vol.)decrease is ascribed to the detrimental action of sulfates which causes the weakness ofsurface. Incorporating steel fiber in SCC, decreased the rebound number for all specimensdue to the entrained air increase which gave rise to increasing in porosity of the surface.Fig.(11):Effect of increasing SO(a) 7 days (b) 28 days (c) 90 days (d) 180 daysaaaacccc212325272931333.5 4 4.5 5 5.5 6 6.5 7 7.5 8R.NTotal SO3(% by wt. of cement)222426283032343.5 4 4.5 5 5.5 6 6.5 7 7.5 8R.NTotal SO3(% by wt. of cement)International Journal of Civil Engineering and Technology (IJCIET), ISSN 09766316(Online) Volume 4, Issue 2, March - April (2013), © IAEM282The surface hardness of the 150 mm concrete cubes was assessed by the, "Schmidtrebound hammer test". The rebound number results of plain and the reinforced SCC withcontent in concrete at the ages of 7,28,90 and 180 daysThere is an optimum SO3 at which the rebound number ismaximum, referring to densification effect due to ettringite formation at the plastic stage.Beyond the optimum value, the rebound number decreased with increased SOat age of 180 days, the percentages of change in rebound number for SCCshaving 5 %, 6 % ,7% and 8 % SO3 content in concrete , were (1.44%, -9.86%,19.23%) relative to reference SCC. While, for SCC reinforced with 0.75 (%by Vol.) thecentages of change were (1.07%, -9.66%, -14.72%, -17.15%) and for SCC reinforced with1.5 (% by Vol.), the percentages of change were (6.48%,-5.93%, -9.17%,-11.77%) relative toCC reinforced with 0.75 and 1.5 (%by Vol.) respectively.decrease is ascribed to the detrimental action of sulfates which causes the weakness ofIncorporating steel fiber in SCC, decreased the rebound number for all specimensined air increase which gave rise to increasing in porosity of the surface.Fig.(11):Effect of increasing SO3 content in concrete on rebound number at7 days (b) 28 days (c) 90 days (d) 180 daysbbbbdddd222426283032343.5 4 4.5 5 5.5 6 6.5 7 7.5 8R.NTotal SO3(% by wt. of cement)8Vf%=0Vf%=0.75Vf%=1.52527293133353.5 4 4.5 5 5.5 6 6.5 7 7.5 8R.NTotal SO3(% by wt. of cement)8Vf%=0Vf%=0.75Vf%=1.5International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308April (2013), © IAEMEThe surface hardness of the 150 mm concrete cubes was assessed by the, "Schmidtrebound hammer test". The rebound number results of plain and the reinforced SCC with7,28,90 and 180 daysat which the rebound number ismaximum, referring to densification effect due to ettringite formation at the plastic stage.ed with increased SO3 content asat age of 180 days, the percentages of change in rebound number for SCCs9.86%,-15.62%,-for SCC reinforced with 0.75 (%by Vol.) the17.15%) and for SCC reinforced with11.77%) relative torespectively. Thisdecrease is ascribed to the detrimental action of sulfates which causes the weakness ofIncorporating steel fiber in SCC, decreased the rebound number for all specimensined air increase which gave rise to increasing in porosity of the surface.content in concrete on rebound number atVf%=0Vf%=0.75Vf%=1.5Vf%=0Vf%=0.75Vf%=1.5
  14. 14. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME283Table (3) Results of hardened concrete testsMixCompressive strength (MPa) Tensile strength test (MPa) Flexural strength test (MPa)7days28days90days180days7days28days90days180days7days28days90days180daysS1F1 34 43.25 49 50.5 3.385 3.95 4.35 4.65 4.5 5.1 5.4 5.64S1F2 34.91 44.4 48 49 4.65 5.015 6.44 6.55 7.2 8.25 9 9.05S1F3 33.1 42 46.57 47.2 5 5.54 7.19 7.25 11 11.7 12.15 12.29S2F1 35.4 46.65 51.75 52.7 3.55 4.1 4.6 4.88 4.8 5.6 6 6.52S2F2 33.5 45.11 50.9 51.5 5 5.54 6.72 6.75 7.46 8.7 9.3 9.5S2F3 34.16 43.6 48.19 49.4 5.21 5.9 7.7 7.9 11.3 11.96 12.45 12.77S3F1 29 37.1 42.5 45 2.45 3 3.87 4.05 3.9 4.48 4.9 5.2S3F2 30 38.5 42 46.1 3.4 3.77 5.78 5.895 6.2 7.3 8.22 8.4S3F3 31 41 44.7 45.6 3.76 4.1 6.83 7.09 9.6 10.37 11.3 11.4S4F1 23 29.84 34.5 37.54 2 2.39 3 3.4 3 3.55 4 4.25S4F2 25 31.7 34.67 37.72 2.85 3.124 4.1 4.5 5.09 5.59 6.4 6.7S4F3 25.5 32.22 35.05 38 3.29 3.69 4.94 5.53 8 8.9 9.1 9.45S5F1 20.3 24.5 29.74 32.25 1.75 1.96 2.85 3.1 2.7 2.95 3.4 3.6S5F2 21.33 25 30.12 32.64 2.54 2.9 3.99 4.16 4.2 4.6 5.3 5.6S5F3 22 26.1 31.65 33.39 3.06 3.232 4.7 4.94 6.9 7.2 8.17 8.3
  15. 15. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME284ContinuousMixModulus ofelasticity (GPa)U.P.V (Km/sec) Rebound number test28days90days7days28days90days180days7days28days90days180daysS1F1 28.2 30.37 3.88 4.23 4.35 4.365 30.6 31.6 32.5 33.28S1F2 27.2 28.24 3.84 4.21 4.33 4.338 29.78 30.84 31.2 31.66S1F3 27 27.89 3.82 4.2 4.31 4.32 28.33 29.13 29.3 29.58S2F1 29.6 32.2 3.92 4.33 4.47 4.495 31.7 32.5 33.2 33.76S2F2 29.38 31.95 3.87 4.29 4.44 4.44 30.7 31.45 31.6 32S2F3 29.25 31.5 3.835 4.26 4.4 4.43 29.47 30.8 31 31.5S3F1 24.2 25.4 3.77 4.15 4.28 4.32 26.9 27.9 28.73 30S3F2 24.44 25.82 3.74 4.115 4.23 4.3 26.1 27 28 28.6S3F3 25.72 26.3 3.72 4.095 4.22 4.295 25.25 26 26.77 27.83S4F1 20.25 21.8 3.64 3.99 4.108 4.15 24.57 25.7 26.54 28.08S4F2 20.64 22 3.6 3.97 4.094 4.125 23.61 25 25.6 27S4F3 21.2 22.32 3.6 3.94 4.075 4.11 23 24.5 25.9 26.87S5F1 17 18.6 3.5 3.63 3.77 3.89 23.75 24.25 25.3 26.88S5F2 17.55 18.75 3.49 3.615 3.74 3.84 22.88 23.6 24.8 26.23S5F3 18 18.88 3.5 3.6 3.75 3.9 22.45 23 24.5 26.1
  16. 16. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2857. CONCLUSIONS1. Overall, slump flow diameter (flowability) and L-Box blocking ratios (passing ability)decrease with the increase in sulfates content in concrete with respect to mixtureshaving the reference SO3, similarly, with the increase in steel fiber content of theconcrete mixtures with respect to plain mixtures. However, steel fibers affected theflow ability and passing ability more than the sulfates did.2. Slump flow time and V-funnel flow time increase with the increase in the sulfatescontent in concrete with respect to mixtures having the reference SO3 and also withincrease in steel fiber content of the concrete mixtures with respect to plain mixtures.3. The effect of sulfates and steel fibers together on the fresh properties of the mixtureswas greater than the effect of each one separately.4. The optimum SO3 content, at which a higher mechanical properties and little tendencyto the expanding were obtained, was at SO3 equal to 5 (% by weight of cement).Further increase in sulfates content in concrete after this optimum value showed aconsiderable reduction in mechanical properties; compressive strength, splittingtensile strength, flexural strength, static modulus of elasticity, U.P.V and reboundnumber, splitting tensile strength was more sensitive to sulfate attack than the othermechanical properties. Nonetheless, there was some recovering with advance in age atwhich the affected mixtures retrieve some of their lost strength.5. Steel fibers decreased compressive strength at low sulfates and increased it at highsulfates contents and in the same manner the modulus of elasticity was. Overall, steelfibers had a marginal increments on both compressive strength and modulus ofelasticity compared to the increments in the other mechanical properties.6. For different SO3 contents in concrete, all steel fiber mixes demonstrated a highersplitting tensile strength and flexural strength relative to plain mixes at all curing ages.The tensile strength increased as the fiber content increased, however, the incrementsin flexural strength were higher than splitting tensile strength with more than 100%increments having been recorded.7. Increased sulfates contents increased the expansion for all mixes with varied steelfiber contents. On the other hand, expansion of steel fiber mixes was less than plainmixes. The lowest expansion values were for the highest steel fiber content.8. For different SO3 contents, pulse velocity and rebound number decreased withincluding steel fiber.9. The highest steel fiber content 1.5 (% by Vol.) had, in general, best effect onhardened properties but the worst on fresh properties of SCC. As well, 0.75% steelfiber content was sufficient for achieving satisfying performance in fresh andhardened properties of SCC.10. SFSCCs showed similar to better resistance to sulfate attack than plain SCCs, theresistance to sulfates enhanced with increasing fiber content.11. Self compacting concrete containing SO3 of 6 (%by wt of cement) and reinforced with1.5 steel fiber (% by Vol.) suffered losses in strength within tolerable limits in thelater ages.
  17. 17. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME2868. REFERENCES1. Al-Rawi R.S., (1977),“Gypsum content of cements used in concrete cured byaccelerated methods”, Journal of Testing and Evaluation, Vol.5, No.3, pp. (231-237).2. Al-Rawi R.S., ( 1985), “Internal sulfate attack in concrete related to gypsumcontent of cement with pozzolan addition“, ACI-RILEM , Joint Symposium ,Monterey, Mexico, pp. 543 .3. Okamura H., and Ouchi M., (2003), “Self-Compacting Concrete”, Journal ofAdvanced Concrete Technology, Vol.1, No. 1, pp.(5-15).4. Iraqi Specification, No.45/1984, “Aggregates from natural sources for concrete andconstruction” Central Organization for Standardization &Quality Control COSQC,Baghdad, 2001.5. European Project Group, (2005), “The European Guidelines for Self-CompactingConcrete: Specification, Production and Use”, pp.63.6. Iraqi Specification, No.348/1992, “Determination of compressive strength ofconcrete cubes,” Central Organization for Standardization &Quality Control COSQC.7. Iraqi Specification, No.283/1995, “Splitting tensile strength of concrete” CentralOrganization for Standardization &Quality Control COSQC.8. Iraqi Specification, No.291/1991, “Modulus of rupture of concrete” CentralOrganization for Standardization &Quality Control COSQC.9. Iraqi Specification, No.370/1993, “Static modulus of elasticity of concrete” CentralOrganization for Standardization &Quality Control COSQC.10. Iraqi Specification, No.54/1989, “Testing concrete-determination of changes inlength on drying and wetting”, Central Organization for Standardization &QualityControl COSQC.11. Iraqi Specification, No.300/1993, “Pulse velocity through concrete” CentralOrganization for Standardization &Quality Control COSQC.12. Iraqi Specification, No.325/1993, “Determination of rebound number of concrete”Central Organization for Standardization &Quality Control COSQC.13. Mehta, P.K., and Monteiro P.J., (2006), “Concrete: microstructure, properties andmaterials”, Third Edition, McGraw-Hill, USA, pp.659.14. Al-Musawee H.A., ( 2011), “Effect of using fibers on some mechanical propertiesof self compacting concrete”, M.Sc. thesis ,college of Engineering, University ofBabylon.15. Miao B., Chern J.C., and Yang C.A., (2003), “Influence of fiber content onproperties of self compacting steel fiber reinforced concrete”, Journal of ChineseInstitute of Engineers, Vol. 26, No.4, pp.(523-530).16. Fu Y., and Beaudoin J.J., (1996), “Microcracking as a precursor to delayedettringite formation in cement systems”, Cement and Concrete Research, pp. (1493 –1498).17. McMullen T.M, (2004), “The St. Francis Dam Collapse and Its Impact on theConstruction Of the Hoover Dam”, M.Sc. thesis submitted to the Faculty of theGraduate School of the University of Maryland, College Park.18. Stark J., and Bollmann K., “Delayed ettringite formation in concrete”, Bauhaus-University Weimar., Germany.
  18. 18. International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME28719. Halawah M., (2006), “Effect of alkalis and sulfates on Portland cement systems”,Ph.D. thesis , College of Engineering ,University of South Florida.20. Al-Rawi R.S., Al-Salihi R.A., and Ali, N.H., (2002), “Effective sulfate content inconcrete ingredients”, In: Concrete for extreme conditions ,Dhir R.K, McCarthy M.J,Newlands M.D., eds, Thomas Telford publishing, London, Great Britain. pp.(499-506).21. Madan Mohan Reddy. K , Sivaramulu Naidu. D and Sanjeeva Rayudu. E, “Studies onRecycled Aggregate Concrete by Using Local Quarry Dust and Recycled Aggregates”,International Journal of Civil Engineering & Technology (IJCIET), Volume 3, Issue 2,2012, pp. 322 - 326, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.22. M. Venu and P. N. Rao, “Study of Rubber Aggregates in Concrete: An ExperimentalInvestigation”, International Journal of Civil Engineering & Technology (IJCIET),Volume 1, Issue 1, 2010, pp. 15 - 26, ISSN Print: 0976 – 6308, ISSN Online:0976 – 6316.23. Dr. Shanthappa B. C., Dr. Prahallada. M. C. and Dr. Prakash. K. B., “Effect of Additionof Combination of Admixtures on the Properties of Self Compacting Concrete Sub-Jected to Alternate Wetting and Drying”, International Journal of Civil Engineering &Technology (IJCIET), Volume 2, Issue 1, 2011, pp. 17 - 24, ISSN Print: 0976 – 6308,ISSN Online: 0976 – 6316.24. N. Krishna Murthy, A.V. Narasimha Rao, I .V. Ramana Reddy, M. Vijaya SekharReddy and P. Ramesh, “Properties of Materials used in Self Compacting Concrete(SCC)”, International Journal of Civil Engineering & Technology (IJCIET), Volume 3,Issue 2, 2012, pp. 353 - 368, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.25. Behrouz Mohebimoghaddam and S.Hossein Dianat, “Evaluation of the Corrosion andStrength of Concrete Exposed to Sulfate Solution”, International Journal of CivilEngineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 198 - 206,ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.26. Priti. A. Patel, Dr. Atul K. Desai and Dr. Jatin A. Desai, “Upgradation of Non-DuctileReinforced Concrete Beamcolumn Connections Using Fibre”, International Journal ofCivil Engineering & Technology (IJCIET), Volume 3, Issue 2, 2012, pp. 241 - 250,ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

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