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Experimental Study On Flexural Strength Of Steel Fibre Concrete

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    International Research Journal of Engineering and Technology   (IRJET)   e-ISSN: 2395 -0056   Volume: 03 Issue: 06 | June-2016 p-ISSN: 2395-0072   © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 473 EXPERIMENTAL STUDY ON FLEXURAL STRENGTH OF STEEL FIBRE CONCRETE S.Vignesh 1 ,A.Mohamed Abubakar Sithik Ali 2 , D.Prasanya 3 ,R.Guru Lakshmi 4   1234  Assistant professor civil Engineering, sri vidya college of engineering & Technology, Tamilnadu, India ---------------------------------------------------------------------***---------------------------------------------------------------------  Abstract -   The main aim of the project is to determine the strength development of High Strength Concrete containing steel fibres. Compressive strength, Tensile strength and Flexural strength is to be determine to the study the effect of the steel Fibre on the properties of high strength concrete. Mix Design was prepared for the grade of M 50  . Two different trial mixers was prepared with the constant water ratio of 0.36 is added based on the required degree of workability compressive strength test conducted for a trial mixers as 14 & 28 days continuous curing . the test result to the trial mix is the effective combination. The result of steel  fibre concrete in increasing the strength and longevity of structures. Key Words :   steel fibre, flexural strength, compressive strength, split tensile strength  . 1.INTRODUCTION Concrete is considered a brittle material, primarily because of its low tensile capacity and poor fracture toughness. Concrete can be modified to perform in more ductile form by the addition of fibre in the concrete matrix. In Fibre Reinforced Concrete (FRC), fibre can be effective in arresting cracks at both macro and micro levels. For an optimal response, different type of fibre may be suitably combined to produce Steel Fibre Reinforced Concrete (SFRC).The use of optimized combinations of two or more types of fibre in the same concrete mixture can produce a composite with better engineering properties than that of individual fibre. This includes combining fibre with different shapes, dimension, t  ensile strength and young’s modulus to concrete matrices. If the fibre are sufficiently strong, sufficiently bonded to material and permit the FRC to carry significant stresses over a relatively large strain capacity in the post cracking stage. The real contribution of the fibre is to increase the toughness of the concrete under any type of loading. Recent investigations have shown that the steel fibre type provide a higher toughness. In a steel system micro fibre provide reinforcement mechanisms at small to medium crack opening while macro-fibre would carry stresses a cross cracks at medium to large crack openings. Reinforcement of concrete with randomly distributed micro -reinforcements may improve the toughness and ductility of cementitious matrices by preventing the initiation and propagation of cracks. It has been shown recently by various researchers that by using the concept of hybridization with two different fibre incorporated in a cement matrix, the steel composite can offer more attractive engineering properties than the composite with mono fibre system, because the presence of one fibre enables the more efficient utilization of the potential properties of other fibre. Also the addition of fibre can reduce the deflection and improve the post cracking behavior significantly. 1.1 Materials and methods 1 The most commonly available Portland pozzolana cement of 43 grade was selected for the investigation. The cement used was dry, powdery and free from lumps. All possible contact with moisture was avoided while storing cement. Ordinary crushed stone with size 20mm was used as coarse aggregate in concrete mixes. The generally passes all the essential passes all the essential qualities absorbtion value and least porosity. In general, water fit for drinking is suitable for mixing concrete. Impurities in the water may affect concrete setting time, strength, shrinkage or promote corrosion of reinforcement . Hence locally available purified drinking water was used for the work. The steel fibre was collected locally from a small cutting unit in the form of long size 10 mm steel fibre can be used.   1.2 Prepertation of test specimen 2 Various concrete specimens were prepared for m 50  grade concrete i.e. in the ratio of 1:0.98:1.96 and various percentages of steel fibres i.e. 0.5%,1%,1.5%,2%,2.5% were added and thoroghly mixed using drum mixer. Then water is added is added at water content ratio of 0.36 and mixed continously until uniform mix was obtained. Then the mixture is filled into the moulds which were properly oiled and compacted using table vibrator . cubes of size 150mm x 150mm x150mm were cast for compressive strength test and cylinder of size 150mm diameter and 300mm height were cast for split tensile strength test and beams of size 1000mm x 300mm x    International Research Journal of Engineering and Technology   (IRJET)   e-ISSN: 2395 -0056   Volume: 03 Issue: 06 | June-2016 p-ISSN: 2395-0072   © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 474 300mm were cast for flexural strength test.   2. CONCRETE 2 Concrete is the most widely used man-made construction material. It is obtained by mixing cement, water and aggregates in required proportions. The mixture when placed in forms and allowed to cure becomes hard like stone. The hardening is caused by chemical action between water and the cement and it continues for a long time, and consequently the concrete grows stronger with age.   Process of manufacture of concrete The various stages of manufacture of concrete are:   ã   batching ã   mixing ã   transporting ã   placing ã   compacting ã   curing ã   finishing Batching The measurement of materials for making concrete is known as batching. There are 2 methods of batching namely   ã   volume batching ã   weigh batching Volume batching It is not a good method for proportioning the material because of the difficulty it offers to measure granular material in terms of volume. Cement is always measured in weight; it is never measured in volume. Generally for each batch mix, one bag of cement is used. The volume of one bag of cement is 35 liters. Gauge boxes are used for measuring fine and coarse aggregate. Weigh batching Weigh batching is the correct method of measuring the materials. For important concrete, invariably, weigh batching system should be adopted. Use of weight system in batching facilitates accuracy, flexibility and simplicity. MEASUREMENT OF WATER When weigh batching is adopted, the measurement of water must be adopted accurately. It is usual to have the water measured in a horizontal tank or vertical tank fitted to the mixer. Mixing There are 2 methods of mixing   ã   Hand mixing ã   Machine mixing Hand mixing: Hand mixing is practiced for small scale unimportant concrete works. Machine mixing: Mixing of concrete is almost invariably carried out by machine, for reinforced concrete work. Machine mixing is not only efficient, but also economical, when the quantity of concrete to be produced is large. Many types of mixes are available they are batch mixers and continuous mixers. Concrete mixers are often used for mixing of concrete. Transporting concrete Concrete can be transported by a variety of methods and equipments. The methods adopted for transportation of concrete are: Mortar pan Wheel barrow Transit mixer Concrete pumps Concrete pumps Pumping of concrete is universally accepted as one of the main methods of concrete transportation and placing. The modern concrete pump is sophiscated, reliable and robust machine. in the past a simple two stroke mechanical pump consisted of a receiving hopper an inlet and outlet valve, a piston and a cylinder. The pump was powered by a diesel engine. The pumping action start with the suction stroke drawing concrete into the cylinder as the piston moves backward. .. Placing concrete It is not enough that a concrete mix correctly designed, batched, mixed and transported. It is of at most importance that the concrete must be placed in systematic manner to yield optimum result. Form work Form work can be designed and constructed so as to remain sufficiently rigid during placing and compaction of concrete. The joints are plugged to prevent the loss of slurry from concrete.    International Research Journal of Engineering and Technology   (IRJET)   e-ISSN: 2395 -0056   Volume: 03 Issue: 06 | June-2016 p-ISSN: 2395-0072   © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 475 Stripping time Formwork should not be removed until the concrete has developed a strength of at least the twice the stress to which concrete may be subjected at the time of removal of formwork. Compaction of concrete It is the process adopted for expelling the entrapped air from the concrete. In the process of mixing, transporting and placing of concrete. Air is likely to get entrapped in the concrete. The following methods are adopted for compacting the concrete. ã   Hand compaction ã   Rodding 2) Ramming 3) Tamping ã   Compaction by vibrations ã   internal vibrator ã   formwork vibrator ã   table vibrator ã   surface vibrator ã   Compaction by pressure and jolting Curing Curing methods may be divided broadly into 4 categories water curing membrane curing application of heat miscellaneous Water curing This is by far the best method of curing as it satisfies all the requirements of curing namely promotion of hydration, elimination of shrinkage and absorption of heat of hydration. Water curing can be done in following ways: 1. Immersion 2. Ponding 3. spraying 4. wet covering Finishing Finishing operation is the last operation in making concrete. Surface finishes may be grouped as: Formwork finishes Surface treatments Applied finishes Formwork finishes Concrete obeys the shape of formwork that is centering work. By judiciously assembling the formwork either in plane surface or in undulated fashion or having the joints in a particular V shaped manner to get regular fine , pleasing surface finish can be given to concrete. Surface treatment This is one of the widely used methods for surface finishing    Applied finish The term applied finish is used to denote the application of rendering to the external Concrete The Mix proportion is shows below For M 50  Grade concrete Cement Fine aggregate Coarse Aggregate W/c ratio 1 0.98 1.96 0.3 8. RESULTS AND DISCUSSION COMPRESSIVE STRENGTH Tests were conducted on compressive strength after 7,28 days of curing. The results of compressive strength for 0.5 to 2% volume of steel fiber are given in Table: Compressive Strength test SPLIT TENSILE STRENGTH Tests were conducted on Splitting Tensile Strength 7, 28days of curing. The results of Splitting Tensile Strength for 0.5 to 2% volume of steel fibers are given in   Fibre content (%) 7 days 28 days Load in KN Average Compressive strength N/mm 2  Load in KN Average Compressive strength N/mm 2  0 134.70 5.98 244 10.35 0.5% 140.50 6.24 297 13.20 1% 169.10 7.84 354 15.73 1.5% 176.43 7.84 436 19.37 2% 211.50 9.40 501 22.26    International Research Journal of Engineering and Technology   (IRJET)   e-ISSN: 2395 -0056   Volume: 03 Issue: 06 | June-2016 p-ISSN: 2395-0072   © 2016, IRJET | Impact Factor value: 4.45 | ISO 9001:2008 Certified Journal | Page 476 Table No.8.2 Splitting tensile strength test result (M50) Fibre content (%) 7 days 28 days Load in KN Average tensile strength N/mm2 Load in KN Average tensile strength N/mm2 0 38 0.53 48 0.67 0.5% 44.90 0.63 54 0.76 1% 61 0.86 77 1.08 1.5% 70.80 1.00 89.20 1.26 2% 85.8 1.20 111.5 1.57 FLEXURAL STRENGTH Tests were conducted on flexural strength after 7,28 days of curing. The results of Flexural Strength for 0.5 to 2% volume of steel fibers are given in   Flexural strength test result (M 50 ) 3. CONCLUSIONS An important focus of our vision should now be on increasing the strength and longevity of various structures. The life of all bridges, pavements and other concrete structures should double in the next century as our country's major financial resources are invested in the construction sector. Carefully selecting materials to optimize and control their properties and use of more performance based specifications will result in advances in the durability of concrete. REFERENCES [1]   Ganeshan N et al, (2007) „steel fibre reinforced high performance concrete for seismic resistant structure‟ Civil Engineering and construction Review, December 2007, pp 54-63 [2]   Balaguru P and Najm H (2004), “High -performance fibre reinforced concrete mixture proportion with high fibre volume fractions”, Material Journal, volume 101, issue 4, July 1, 2004 pp281-286 [3]   Tensing D,Jeminah and Jaygopal L S (2003) “ Permeability studies on steel fibre reinforced concrete and influence of fly ash” National seminar on advance in construction materials,14-15 feb 2003. [4]   Damgir R.M.and Ishaque M.I.M (2003) “Effect of silica fume and steel fibre composite on strength properties of high performance concrete”, proceedimg of the INCONTEST 2003, Coimbatore,10-12 sept 2003,pp281-286 [5]   S.K. Madan, g. Rajesh Kumar and S.P. Singh, “Steel fibers replacement of web reinforcement for RCC deep beam in shear”, Asian Journal of Civil Engineering (Building and Housing), Vol. 8, No. 56(2007), pp 479-489 [6]   Bayasi,Z and Zeng,J.(1993) “Properties of polypropylene fibre reinforced concrete””ACI Materials Journal, Novl -Dec 1993, vol. 90 No 6, pp 605-610 [7]   BIS 383:1970 Specification for coarse and fine aggregates from natural sources for concrete (second revision). [8]   K. Elissa, “Title of paper if known,” unpublished. BIOGRAPHIES S.vignesh BE civil Engineering ME Structural Engineering Working as a assistanr professor in sri vidya engineering college, tamilnadu, A.Mohamed Abubakar Sithik Ali BE civil Engineering   ME Environmental Engineering Working as a assistant professor in sri vidya Engineering college D.Prasanya BE civil Engineering   ME Structural Engineering Working as a assistant professor in sri vidya Engineering college R.Guru Lakshmi BE civil Engineering   ME Structural Engineering Working as a assistant professor in sri vidya Engineering college Fibre content (%) 7 days 28 days Load in KN Average Modulus of Rupture N/mm2 Load in KN Average Modulus of Rupture N/mm2 0 5.20 2.60 0 5.20 0.5% 6.60 3.30 0.5% 6.60 1% 8.80 4.40 1% 8.80 1.5% 11.70 5.85 1.5% 11.70 2% 14.90 7.45 2% 14.90
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