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________________________________________ Author for correspondence E-mail: Ph: +914362264101-108 Fax: +914362 26420 Int. J. Chem. Sci.: 144 2016 2710-2722 ISSN 0972-768X PERFORMANCE OF SLURRY INFILTRATED FIBROUS CONCRETE SIFCON WITH SILICA FUME D. ELAVARASI and K. SARAVANA RAJA MOHAN Department of Civil Engineering Sastra University THANJAVUR – 613402 T.N. INDIA ABSTRACT SIFCON in our country in the construction of several structures that demand high standards of strength coupled with superior performance and durability. SIFCON possesses several desirable properties such as high strength and ductility. It also reveals a very high degree of ductility as a result of which it has superior stability under dynamic fatigue and repeated loading. The main objective of this study is to determine the effect of silica fume in slurry infiltrated fibrous concrete on compressive strength split tensile strength flexural strength and toughness. Experimental programme was carried out to study the performance of SIFCON containing 10 of fibre content with different percentage of silica fume 5 10 15 20 and 25 partially replaced by cement on compressive strength and split tensile strength. From the test results 15 of silica fume showed that optimum value in compression and tension. Compared to all other replacement level and FRC mix. Flexural test of reinforced SIFCON beam specimen of size 1.2 x 0.1 x 0.2 m containing optimum 15 of silica fume with various percentage of fibre content 6 8 and 10 were tested under flexure to enhance the performance of silica fume based slurry infiltrated fibrous concrete. The results showed that SIFCON beam contains 10 fibre content exhibits excellent energy absorption and ductility characteristics among all other SIFCON and FRC specimens. Key words: Silica fume SIFCON Toughness FRC Ductility factor. INTRODUCTION SIFCON is a high-strength high-performance fabric containing a especially excessive extent percent of metallic fibres in comparison to SFRC. It is also every now and then termed as ‘excessive-extent fibrous concrete’. The starting place of SIFCON dates to 1979 whilst Prof. Lankard carried out vast experiments in his laboratory in Columbus Ohio USA and proved that if the proportion of metal fibres in a cement matrix can be elevated notably then a cloth of very high strength could be received which he christened as SIFCON. The

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Int. J. Chem. Sci.: 144 2016 2711 matrix in SIFCON has no coarse aggregates however a high cementitious content material. However it may include quality or coarse sand and additives which include fly ash micro silica and latex emulsions. The matrix fineness must be designed so as to properly penetrate infiltrate the fibre network positioned in the moulds considering otherwise massive pores may additionally shape leading to a extensive reduction in properties. SIFCON was invented in USA in the year 1983 by Lankard 1 and investigated the primary properties of SIFCON along with load-deflection curve compressive and flexural strengths impact and abrasion resistance. Yazici et al. 215 studied the effect of incorporating excessive quantity of class C fly ash on mechanical properties of SIFCON and conclusions have been drawn that increases flexural strength and toughness of SIFCON due to higher percentage of fibre content. Katkhuda et al. 3 studied the isolated effect of silica fume on tensile compressive and flexure strengths on high strength lightweight concrete. The results showed that the tensile compressive strengths increased with incorporation of silica fume. Dagar 4 investigated the performance of SIFCON and indicated that the formation of cracks does not extended through the entire width of specimen in SIFCON compared to ferrocement composite and ultimate tensile strength depends upon the mix proportion and percentage of fibre content. Thomas and Mathews 5 indicated that 5 of fibre content yield higher compression tension and flexural strength Among three different percentage of steel and polypropylene fibres 4 5 and 6 yield higher in SIFCON containing 5 fibre volume. Tuyan and Yazaici 6 investigated the pullout behaviour of SIFCON matrix and concluded that pullout peak load was increased with increasing diameter of fibres and also pullout toughness was increased with increasing fibre length which is embedded in SIFCON. Parameswaran et al. 7 examined the behaviour of metal fibre mortar specimens having high quantity fraction of fibres within the range of 8 subjected to flexure and reported that they possess flexural strength more than 40 N/mm 2 . Sudarsana Rao et al. 814 tested SIFCON slabs under flexure and compared it with FRC and PCC slabs. It became reported that SIFCON slabs display tremendous toughness characteristics under flexural loading in comparison to PCC and FRC slabs and the spacing of cracks have been found to decrease with increased volume of fibre content. Rao et al. 9 tested SIFCON slabs under impact loading revealed that the SIFCON slabs with 12 fibre volume fraction ehibit excellent performance in strength and toughness characteristics. Farnam et al. 10 investigate the triaxial compressive behavior of high strength concrete high performance fibre reinforced concrete and SIFCON and found that increasing fibre volume increases the peak triaxial compressive strength. Ipeka et al. 11 through his experimentations on prisms pronounced that boom in pre- setting pressure suggests improvement in the flexural electricity and durability value. A most

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D. Elavarasi and K. S. R. Mohan: Performance of Slurry…. 2712 flexure strength of 67.5 MPa turned into accomplished when pre-putting stress given became 15 MPa. Kaikea et al. 12 tested development inside the mechanical properties of HPFRC with the alternate in mineral admixture and fibre concentration and mentioned that flexural durability of HPFRC is 33 times higher than plain concrete. Wang and Maji 13 examined the shear properties of SIFCON under pure torsion and obtained the shear resistance properties. From the above literatures it is able to be mentioned that studies on the flexural electricity characteristics of SIFCON beams were very rare. Flexural behaviour is a completely critical issue in case of beams as in realistic programs they should withstand numerous flexural loads. As a result there is a want to behavior experimentations on SIFCON beams under flexure. The aim of the research is to decide experimentally the flexural strength load- deflection response and strength absorption capability for SIFCON beams with 6 8 and 10 fibre quantity fraction. In this study cement has been replaced by partial replacement of fly ash so as to minimise the shrinkage as well as heat of hydration problems and henceforth reduce the negative effects of global warming. EXPERIMENTAL An experimental program was carried out to provide a excessive volume fibre reinforced concrete known as slurry infiltrated fibrous concrete consists of fibres and partial replacement of cement with silica fume slurry mix is infiltrated right into a bed of preplaced fibres inside the mould. To improve the workability of concrete composite with the aid of excessive range water reducing admixture during mixing of slurry. It accommodates of casting of cubes of size a 100 X 100 X 100 mm for compressive strength cylinders of 100 mm diameter and 200 mm top for split tensile strength and reinforced beam of length 1200 x 100 x 200 mm for flexural strength of SIFCON specimens. The reinforcement details of beam specimens are given below in Fig. 1. The substances used mix proportions and method of casting and trying out are defined below. Materials used Cement Ordinary Portland cement of 53 grade conforming to IS: 12269 were used. The specific gravity of cement was found to be 3.15. Silica fume Silica fume conforming to ASTM C 1240 and the specific gravity of silica fume was found to be 2.21.

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Int. J. Chem. Sci.: 144 2016 2713 Table 1: Chemical composition of cement and silica fume S. No. Chemical composition Cement Silica fume 1 Silica SiO 2 21.8 97 2 Alumina Al 2 O 3 6.6 0.2 3 Ferric oxide Fe 2 O 3 4.1 0.5 4 Calcium oxide CaO 60.1 0.2 5 Magnesium oxide MgO 2.1 0.5 6 Sodium oxide Na 2 O 0.4 0.2 7 Potassium oxide K 2 O 0.4 0.5 8 Sulphuric anhydride SO 3 2.2 0.15 9 Loss on Ignition LOI 2.4 - Fine aggregate Locally available river sand passing through 4.75 mm sieve was used. The fineness modulus of fine aggregate was found to be 2. 43 and specific gravity was found as 2.71. Fibre Hooked end steel fiber of diameter 1.00 mm and length of 30 mm giving aspect ratio of 30 was used. Fibers were oriented in the form in random manner. Reinforcement All the four beams were reinforced. 12 mm diameter Fe 415 grade steel rods for main reinforcement and 6 mm diameter bars for shear reinforcement with 6 mm diameter 2-legged stirrups spaced at 100 mm c/c. The beam reinforcement details were shown in Fig. 1 Water Fresh water available from local sources was used for mixing and curing of SIFCON. Super plasticizer To improve the workability of SIFCON CONPLAST- 430 a high-range water reducing agent has been used.

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D. Elavarasi and K. S. R. Mohan: Performance of Slurry…. 2714 Mix proportions SIFCON slurry consisted of cement and fine sand mixed in the proportion of 1:1 by weight and water cement ratio of 0.4. Hand compaction was done to ensure complete penetration of the slurry into the bed of pre-packed fibres. The cement was replaced by silica fume 5 10 15 20 and 25 slurry containing 10 of fibre content were used for optimization of silica fume in SIFCON mix. The reinforced SIFCON beams were also cast and tested under flexure. Cement was partially replaced by optimum percentage of silica fume for making slurry with different percentage of fibre content are illustrated in Table 2. High range water reducing admixture of 2 by weight of cement was added to improve the workability and flow ability of the slurry into the fibre bed. Table 2: Mix proportions of SIFCON specimens S. No. Nomenclature of mix Cement content Silica fume Fine Aggregate Fibre content W/C ratio Super plasticizer Mode of vibration 1 SF5SIF10 95 05 100 10 0.4 2 Hand tamping 2 SF10SIF10 90 10 100 10 0.4 2 Hand tamping 3 SF15SIF10 85 15 100 10 0.4 2 Hand tamping 4 SF20SIF10 80 20 100 10 0.4 2 Hand tamping 5 SF25SIF10 75 25 100 10 0.4 2 Hand tamping 6 SF15SIF6 85 15 100 6 0.4 2 Hand tamping 7 SF15SIF8 85 15 100 8 0.4 2 Hand tamping 8 SF15SIF10 85 15 100 10 0.4 2 Hand tamping Method of casting Initially the mould is placed on a smooth surface and the sides of mould are oiled so as to enable easy removal of specimen. Cement silica fume sand water and superplasticizer are weighed accurately and mixed for making slurry. Fibres are weighed according to the percentage by volume and SIFCON beams were made by using three layer technique. This technique follows the filling of fibres to one–third depth of mould and then slurry being poured to the pre-placed fibres upto this layer. Compaction was done to ensure complete infiltration of slurry into fibre pack. The process is repeated till the entire mould was filled and compacted. After 24 hrs of casting beams were demoulded and cured in water for

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Int. J. Chem. Sci.: 144 2016 2715 28 days. After curing days specimens were dried in air and painted in white so as to get clear visibility of cracks. Fig. 1: Beam reinforcement details Fig. 2: Casting of SIFCON beam Test program Compressive strength test The compressive strength of concrete is the most common performance measure in designing building and other structures. The compressive test on cubes were conducted on a computerised compressive testing machine of capacity 3000KN. Split tensile strength The split tensile strength on cylinders were conducted on a computerised compressive testing machine of capacity 3000KN the test specimens were placed horizontally between two platens. Load was gradually applied till failure of the specimen. Flexural strength Casting of three reinforced SIFCON beams of size 1.2 × 0.1 × 0.2 m with variation in fibre concentration as 6 8 and 10 by volume and FRC 1 specimens. The flexural test of beams were conducted on a computerized universal testing machine UTM of capacity 1000 kN. Loads were applied gradually in increasing rate till the failure of

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D. Elavarasi and K. S. R. Mohan: Performance of Slurry…. 2716 specimen and the maximum load applied to the specimen at failure and also yield and ultimate loads and their corresponding were recorded. RESULTS AND DISCUSSION Compressive strength The compressive strength results of slurry infiltrated fibrous concrete SIFCON with silica fume are shown in Fig. 3a. It can be seen from the table that the strength increased with the increase of silica fume replacement and at certain percentage of replacement the strength values get reduced. Furthermore at all percentage of replacement the strength value gets increased when compared to FRC specimen Control mix. Split tensile strength The test results shown in Fig. 3b that the split tensile strength gets gradually increased upto 15 of silica fume replacement after that the strength was decreased slightly. When compared to FRC specimen the strength of SIFCON specimens yield higher strength at all replacement level of silica fume in SIFCON when compared to FRC specimen. Fig. 3a: Type of mix vs Compressive strength  Fig. 3b: Type of mix vs Split tensile strength  Flexural strength The flexural strength of reinforced SIFCON beam containing 6 was higher value compared to SIFCON containing 8 and 10. The flexural strength gets affected because of slurry strength method compaction and orientation of fibres. The test result was shown in Fig. 4b.

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Int. J. Chem. Sci.: 144 2016 2717 Fig. 4a: Load vs Deflection  Fig. 4b: Type of mix vs Flexural strength Fig. 5a: Load vs Deflection  Fig. 5b: Load vs Deflection  Fig. 6a: Load vs Deflection Fig. 6b: Load vs Deflection

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D. Elavarasi and K. S. R. Mohan: Performance of Slurry…. 2718 Fig. 7a: Load vs Deflection Fig. 7b: Load vs Deflection Fig. 8a: Load vs Deflection Fig. 8b: Load vs Deflection Toughness The toughness was calculated from load deflection curve. The area under load deflection curve of different mixes were presented in Table 3. The energy absorption characteristics of SIFCON containing 10 of fibre content performed well among all other SIFCON specimens. When compared to FRC mix SIFCON specimens yields more energy because of incorporation of higher volume of fibre content enhances the properties SIFCON mix. Fig. 9a shows the types of mix vs toughness. Ductility factor Table 3 illustrated the ductility factor of various mixes. The increased percentage ductility factors were observed 22.74 70.04 and 96.03 in SIFCON containing 6 8 and

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Int. J. Chem. Sci.: 144 2016 2719 10 percentage of fibre content by volume fraction with respect to FRC specimen. It was observed that the ductility was increased due to increased percentage of fibre content. It was found that fibre plays a vital role to enhance the ductile properties of composites. Table 3: Behaviour of SIFCON with silica fume under flexure S. No. Nomenclature of mix Flexural strength N/mm 2 Ductility factor Increase w.r.t FRC Energy absorption Nm Increase w.r.t. FRC 1 SF15SIF6 41.19 3.40 22.74 751.180 7.45 2 SF15SIF8 34.18 4.71 70.04 1421.89 103.39 3 SF15SIF10 15.94 5.43 96.03 1515.84 116.83 4 FRC 1 16.62 2.77 - 699.10 - Fig. 9a: Type of mix vs Toughness Fig. 9b: Type of mix vs Ductility factor Load deflection response The load deflection curve is shown in Fig. 4a. From the results observed in SIFCON containing 6 of fibre content yields higher first crack and ultimate load when compared to all other specimens. It reveals that increased percentage of fibre content in silica fume based SIFCON decreases the load carrying capacity. Cracking and failure pattern It was noticed that the formation of cracks in SIFCON beams does not extend the full width of beam in all SIFCON beams. The cracks width was decreased with incorporation

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D. Elavarasi and K. S. R. Mohan: Performance of Slurry…. 2720 of higher percentage of fibre content 10 among all other SIFCON beams because of increase in percentage of fibre content will take place more crack-bridging. The propagation of cracks was observed to be slower in SIFCON beams when compared with FRC beam. The cracking and failure pattern was shown in Fig. 10. Table 4: Maximum deflection at first crack load and ultimate load S. No. Nomenclature of mix First crack load kN Deflection at first crack mm Ultimate load kN Deflection at ultimate load mm 1. SF15SIF6 48.75 2.5 155.45 8.0 2. SF15SIF8 45.05 3.5 129.2 16.5 3. SF15SIF10 29.65 7.0 58.05 38.0 4. FRC 1 10.35 1.8 66.45 5.0 Fig. 10: Crack pattern CONCLUSION Based on the test results obtained from the experimental programmes the following conclusions are drawn. i It is observed that the utilization of silica fume is well accepted for replacing cement with silica fume in the production of concrete composites because the incorporation of silica fume in SIFCON enhancing the mechanical properties. ii It improves the consistency and workability of fresh slurry because an extra capacity of fines is added to the mixture. Silica fume modify the microstructure of concrete and reduce its voids thereby increasing the load carrying capacity.

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Int. J. Chem. Sci.: 144 2016 2721 iii The effect of silica fume replacement in SIFCON increases the compressive and split tensile strength and the maximum strength attained at 15 replacement compared to all other replacement level of silica fume and FRC specimens. iv The test results shows that SIFCON beam containing 10 of fibre content yields higher energy absorption and ductility characteristics among all other SIFCON specimens and FRC specimen. v The increase in energy absorption capacity of SIFCON specimens is about 7.45 to 116.83 and ductility factor ranges from 22.74 to 96.03 when compared with FRC specimen vi It was concluded that toughness and ductility factor were increased and flexural strength was decreased with increased volume of fibre content in SIFCON when compared among all SIFCON specimens. REFERENCES 1. D. R. Lankard Properties of Slurry Infiltrated Fibrous Concrete SIFCON Int. J. Appl. Engg. Technol. 29 44-47 1984. 2. Halit Yazıcı Serdar Aydin Huseyin Yigiter Mert Y. Yardimci and Giray Alptuna Improvement on SIFCON Performance by Fiber Orientation and High Volume Mineral Admixtures J. Mater. Civil Engg. 49 1093-1101 2010. 3. H. Katkhuda B. Hanayneh and N. Shatarat Influence of Silica Fume on High Strength Lightweight Concrete World Academy Sci. Engg. Technol. 34 781-788 2009. 4. K. Dagar Slurry Infiltrated Fibrous Concrete Int. J. Appl. Engg. Technol. 2 99-100 2012. 5. A. A. Thomas and J. Mathews Strength and Behavior of SIFCON with Different Types of Fibers Int. J. Civil Engg. Technol. 5 25-30 2014. 6. Murat Tuyan and Halit Yazıcı Pull-Out Behavior of Single Steel Fiber from SIFCON Matrix Construction and Build. Mater. 35 571-577 2012. 7. V. S. Parasmeswaran T. S. Krishnamoorthy and K. Balasubramanian Behaviour of High Volume Fibre Cement Mortar in Flexure Cement and Concrete Composites 12 293-301 1990. 8. H. Sudarsana Rao N. V. Ramana and K. Gnaneswar Behaviour of Restrained SIFCON in Two Way Slabs Under Flexure Asian J. Civil Engg. 10 427-449 2009.

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D. Elavarasi and K. S. R. Mohan: Performance of Slurry…. 2722 9. H. Sudarsana Rao G. Vaishali Ghorpade Ramana and K. Gnaneswar Response of SIFCON Two Way Slabs Under Impact Loading Int. J. Impact Engg. 37 452-458 2010. 10. Y. Farnam M. Moosavi M. Shekarchi S. K. Babanajad and A. Bagherzadeh Behaviour of Slurry Infiltrated Fibre Concrete Under Triaxial Compression Cement and Concrete Research 40 1571-1581 2010. 11. Metin Ipeka Mecbure Aksu Kemalettin Yilmaz The Effect of Pre-Setting Pressure on the Flexural Strength and Fracture Toughness of SIFCON During the Setting Phase Construction and Building Materials 66 515-521 2014. 12. Adel Kaikea Djamel Achoura and François Duplan Effect of Mineral Admixtures and Steel Fiber Volume Contents on the Behavior of High Performance Fiber Reinforced Concrete Mater. Design 63 493-499 2014. 13. M. L. Wang and A. K. Maji Shear Properties of Slurry Infiltrated Fibrous Concrete Construction and Build. Mater. 8 161-168 1994. 14. H. Sudarsana Rao N. V. Ramana and K. Gnaneswarwar Behaviour of Simply Supported Steel Reinforced SIFCON Two Way Slabs in Punching Shear Indian J. Engg. Mater. Sci. 15 326-333 2008. 15. Halit Yazıcı Huseyin Yigiter Serdar Aydin and Bulent Baradan Autoclaved SIFCON with High Volume Class C Fly Ash Binder Phase Cement and Concrete Research 36 481-486 2006. Revised : 16.10.2016 Accepted : 18.10.2016