Research Article
a
April
2018
Special Issue: National Conference on Emerging Trends in Engineering 2018
Conference Held at Sri Venkatesa Perumal College of Engineering & Technology, Puttur, A.P., India
Computer Science and Software Engineering
ISSN: 2277-128X (Volume-8, Issue-4)
Study on High Strength Fiber Reinforced Concrete with Silica
Fume and Metakaolin as a Partial Replacement of Cement
M. Bhupal1 A.Roopa2 K. Naveen Kumar3
PG Scholar Associate Professor Assistant Professor
Department of CIVIL Department of CIVIL Department of CIVIL
SHREE Institute of Technical Education, Tirupati, A.P.-517501
SHREE Institute of Technical Education, Tirupati, A.P.-517501
SVPCET, Puttur, A.P.-517583
1
[email protected] 2 [email protected] [email protected]
Abstract: While plain concrete has poor tensile strength, low resistant to tensile cracking, low ductility, so its capacity to absorb energy is limited. Internal micro cracks are inherently present in concrete and its poor tensile strength is due to propagation of such micro cracks. Fiber when added certain percentage in the concrete improve the strain properties well as crack resistance, ductility, as flexure strength and toughness. Mainly the studies and research in fiber reinforced concrete has been devoted to steel fibers. In recent times, glass fiber have also become available, which are free from corrosion problem associated with steel fibers. in the present experimental investigation, high strength concrete of M60 is tried using Condensed silica fume (CSF) and Metakaolin (MK) as partial replacement by
weight of cement. Glass fibres having aspect ratio of 857 are also used at 2% as total volume of concrete and the properties of this FRC(fibre reinforced concrete) like compressive strength, flexure strength, split tensile strength and workability were studied.
Keywords: Silica fume, glass fiber, Metakaolin, Pozzolanic material, Ground granulated blast furnace slag (GGBS), Fly ash, Rice husk ash.
I. INTRODUCTION
Concrete is one of the most extensively used construction materials in the world, with two billion tons placed worldwide each year. In its production and use, no poisonous substances are emitted. The found in abundant all over the world. The only ecological disadvantage of concrete is the emission of carbon-di-oxide (Co2) gas during production of
cement clinker, have brought about pressure to reduce the cement consumption through the use of supplementary materials and storage devices that are connected to the mains at a single Point of Common Coupling (PCC). The EMS is maximizing the revenues according to DG bids and electricity market price. Once the power architecture and the predefined objectives are known, the EMS design can be undertaken by applying different methods. In this regard, there Pozzolans can be of natural or industrial origin. Natural pozzolans include volcanic ash and diatomaceous earth. Artificial pozzolans include Fly ash (FA), Silica fumes (SF), Metakaolin (MK), Ground granulated blast furnace slag (GGBS), Rice husk ash (RHA). Silica fume is harvested from the effluent gases produced in the manufacture of silicon metal and alloys. Metakaolin is thermally activated ordinary clay and Kaolinitic clay, which is water processed to remove the impurities to make 100% reactive pozzolan. The supplementary cementing pozzolanic materials such as Metakaolin, Silica fume Fly ash and Ground granulated blast furnace slag, etc. can generate additional quantities of Portland cement
Silica fume
Silica fume (SF) is a very efficient pozzolanic material, and it is also called by various names as Silica dust, Condensed Silica fume, Micro Silica and Fumed Silica. The use of SF in concrete should not be indiscriminate, but should be limited to specialized applications that can take full advantage of its unique properties. Silica fume was only a waste product a few years ago. Now the price of fume varies from half to twice the price of normal Portland cement. However in the production of high strength concrete one can take full advantage and can be effective replacement.
ISSN(E): 2277-128X, ISBN: 978-93-87396-07-4, pp. 360-366 Nomenclature of Silica fume
Electric arc furnaces used in the manufacture of Ferrosilicon or Silicon metal release Silica fume (SF) as a by-product. The fume which has a high content of very fine spherical particles of silicon-di-oxide (SiO2) is collected by filtering the gases escaping from the furnaces. Like Fly ash, development of SF as cementatious material was spurred by a devise to find a use for an industrial waste product.
Production of Silica fume
Silicon, Ferrosilicon and other silicon alloys are produced in electric furnaces of submerged-arc type, where quartz is reduced by carbon at very high temperature. Therefore the plans are generally located in the areas where inexpensive hydroelectric power is readily available. The chemical reactions occurring in the furnace are complex, but one of the reactions involve the formation of SiO2 vapour, which oxidize and condense in the form of very tiny spheres of non-crystalline silica.
Functions of Silica fume in Portland cement concrete
There are of two fold, both physical and chemical in nature. The three major physical attributes for Silica fume are:
Since the Silica fume (SF) particles are much, much smaller than cement particles with a surface area in the neighborhood of about, 20,000 m2/Kg, they can “pack” between the cement particles and provide a finer pore structure.
In the early stages of hydration, SF can help to accelerate the hydration process, because its tiny particles provide nucleation sites for hydration, much the same way micro fine dust particles, or cloud seeding, induce formation of rain droplets.
In the nucleation process, SF particles provides a site on which material in solution can “nucleate” or “centre” which helps the material precipitate sooner.
Methods of using Silica fume in concrete
Condensed Silica fume can be incorporated in to concrete in two different ways:
It can be blended or grinded with the Portland cement i.e., as a partial replacement for cement.
It can be used as a mineral admixture at the concrete batching plant.
Silica fume as a mineral admixture
Silica fume (SF) can be used as a mineral admixture in cement. The percentage may vary from 0%-30%. Though this does not change the weight of the cementatious materials, there is an increase in the water demand because of the extreme fineness of SF. In order to maintain the same water- (Cement + SF) ratios, super plasticizers are used to maintain the required slump. This approach also results in an increase in compressive strength at the age of 3 days and thereafter.
Metakaolin
Metakaolin is unique in that it is not the by-product of an industrial process nor it is entirely natural. it is derived from a naturally occurring mineral and is manufactured specifically for cementing applications. Unlike by products Pozzolanic, which can variable composition, MK is produced under carefully controlled conditions to refine its colour, remove its inert materials, and tailor particle size.
Metakaolin is obtained by calcinations of pure or refined kaolinitic clay at a temperature between 6500C and 8500C followed by grinding to achieve a fineness of 700 to 900m2/kg. The resulting material has high pozzolanic. Metakaolin is manufactured from pure raw material to strict quality standards
Properties of Metakaolin
Metakaolin grades of claimed clay are reactive aluminium silicate pozzolanic formed by claiming very pure hydrous china clay. Chemically Metakaolin combines with calcium silicate and calcium processed to remove uncreative impurities producing almost 100% reactive material. The particle size of Metakaolin is significantly smaller than cement particles. IS: 456-2000 recommends use of Metakaolin as mineral admixture.
Applications
The Metakaolin mixed concrete is finding place in the following applications from technical considerations.
ISSN(E): 2277-128X, ISBN: 978-93-87396-07-4, pp. 360-366
The low permeability and absorption of the Metakaolin mixed cement concrete as well as it enhanced resistance to deterioration in a variety of chemically aggressive environments, found a gainful use in shotcrete applications in chemical, mining, paper and pulp industries.
In the manufacture of concrete pipes, Metakaolin addition has shown to increase the external load bearing capacity of the pipes and increased resistance against chemical attack.
Glass fibers
The glass fibers used are Cem-FIL Anti-Crack HD with modulus of elasticity 72 GPA, Filament diameter 14 microns, and specific gravity 2.68, length 12 mm. (Properties obtained through the manufacturer)
Different forms of glass fibers are:
Mono filament form
Mesh form.
Bunchy form
Urdee form
Fiber reinforced concrete
Fiber reinforced concrete when compared with traditional reinforced concrete is rather a new engineering material. Natural fiber reinforced concrete has created deal of worldwide interest. The mass made fibers have gained greater ground on account of the experience gained with them and their proven long-term durability.“Fiber reinforced concrete is a concrete composed of normal setting hydraulic cement, fine aggregates, coarse aggregates and discontinuous discrete fibers with different lengths and different gauges as parameters.”
Chemical Admixture
Good concrete should be sufficiently workable in its fresh state and adequately strong in its hardened state. But workability and strength are usually not achieved simultaneously by more manipulation of water cement ratio. What an attractive proposition is concrete which can be placed easily and rapidly into awkwardly shaped from work containing a seemingly impregnable mass of reinforcement.
Category A: Sulphonated Melamine Formaldehyde condensates (SMF). Category B: Sulphonated Naphthalene Formaldehyde condensates (SNF). Category C: Modified Ligno Sulphonates (MLS).
Category D: Other super plasticizer such as sulphonic acids or carbohydrates esters. Mentioned super plasticizing admixtures is basically a marked dispersion
II. PROBLEM DEFINITION, OBJECTIVES AND METHODOLOGY Problem Context
ISSN(E): 2277-128X, ISBN: 978-93-87396-07-4, pp. 360-366
increased concerns regarding the depletion of raw materials, energy demands and the consequent environmental damage. When used as a partial cement replacement material, typically in the range of 20 to 40% by mass, the energy and cost savings are substantial. From an environmental point of view mineral admixtures are playing an undisputed role. They are responsible for substantial “environmental unloading” because their disposal can be hazardous to the environment and higher utilization of them can result in reduction of greenhouse gas emissions attributed to the cement industry.
Objectives
1. To study the slump property of concrete.
2. To study the strength properties such as compressive strength, split tensile strength and flexural strength of M60
grade of concrete while replacing Silica fume as a partial replacement at 5%, 10% and 15% by weight of cement. 3. To study the strength properties such as compressive strength, split tensile strength and flexural strength of M60
grade of concrete while replacing Silica fume as a partial replacement at 5%, 10% and 15% by weight of cement with addition of glass fibres at 2% by volume of concrete.
4. To study the strength properties such as compressive strength, split tensile strength and flexural strength of M60
grade of concrete while replacing Metakaolin as a partial replacement at 5%, 10% and 15% by weight of cement. 5. To study the strength properties such as compressive strength, split tensile strength and flexural strength of M60
grade of concrete while replacing Metakaolin as a partial replacement at 5%, 10% and 15% by weight of cement along with addition of glass fibres at 2% by volume of concrete.
III. METHODOLOGY
Recognizing in need for utilization of Silica fume and Metakaolin in concrete, the present investigation is taken up with an aim to establish or to understand the behaviour of Silica fume and Metakaolin cement concrete when it is reinforced by glass fibre. Thus the work study is laboratory oriented.
1. The materials have been collected from a specific location and properties have been studied. 2. Using these properties, mix design is carried out with suitable w/c ratio of M60 grade concrete.
3. Required slump is obtained experimentally by slump cone test.
4. Concrete cubes were casted to study the compressive strength of concrete. Then the cubes were tested in compression testing machine.
5. The compressive strength of the concrete will be determined by using 150 mm concrete cube specimens. The specimens will be tested at 3, 7, 14 and 28 days age, in 200 tons capacity hydraulic type compression-testing machine. The cube compressive strength will be obtained by considering the average of three specimens at each age. 6. Then the beams were tested in single point loading, and deflections under the load points will be recorded.
7. Using these test results suitable graphs are plotted. 8. Conclusions are drawn based on test results.
The following different combinations of cubes are casted for conduction of Compression test:
Twelve cubes of conventional concrete mix M60.
The next set of twelve cubes consists of M60 with 2% of Glass fibre concrete.
The next twelve cubes continue to be M60 with cement replaced by 5% of Silica fume.
The next twelve cubes continue to be M60 with cement replaced by 5% of Silica fume and 2% of Glass fibre.
The next twelve cubes continue to be M60 with cement replaced by 10% of Silica fume.
The next twelve cubes continue to be M60 with cement replaced by 10% of Silica fume and 2% of Glass fibre.
The next twelve cubes continue to be M60 with cement replaced by 15% of Silica fume.
The next twelve cubes continue to be M60 with cement replaced by 15% of Silica fume and 2% of Glass fibre.
The next twelve cubes continue to be M60 with cement replaced by 5% of Metakaolin.
The next twelve cubes continue to be M60 with cement replaced by 5% of Metakaolin and 2% of Glass fibre.
The following different combinations of cylinders are casted for conduction of Split Tensile test:
Six cylinders of conventional concrete mix M60.
The next set of six cylinders consists of M60 with 2% of Glass fibre. Concrete.
The next six cylinders continue to be M60 with cement replaced by 5% of Silica fume.
The next six cylinders continue to be M60 with cement replaced by 5% of Silica fume and 2% of Glass fibre.
The next six cylinders continue to be M60 with cement replaced by 10% of Silica fume.
The next six cylinders continue to be M60 with cement replaced by 10% of Silica fume and 2% of Glass fibre.
The next six cylinders continue to be M60 with cement replaced by 15% of Silica fume.
The next six cylinders continue to be M60 with cement replaced by 15% of Silica fume and 2% of Glass fibre.
The next six cylinders continue to be M60 with cement replaced by 5% of Metakaolin.
The next six cylinders continue to be M60 with cement replaced by 5% of Metakaolin and 2% of Glass fibre.
The next six cylinders continue to be M60 with cement replaced by 10% of Metakaolin.
The next six cylinders continue to be M60 with cement replaced by 10% of Metakaolin and 2% of Glass fibre.
ISSN(E): 2277-128X, ISBN: 978-93-87396-07-4, pp. 360-366
The following different combinations of beams are casted for conduction of Flexural test:
Three beams of conventional concrete mix M60.
The next set of three beams consists of M60 with 2% of Glass fibre. concrete.
The next three beams continue to be M60 with cement replaced by 5% of Silica fume.
The next three beams continue to be M60 with cement replaced by 5% of Silica fume and 2% of Glass fibre.
The next three beams continue to be M60 with cement replaced by 10% of Silica fume.
The next three beams continue to be M60 with cement replaced by 10% of Silica fume and 2% of Glass fibre..
The next three beams continue to be M60 with cement replaced by 15% of Silica fume.
The next three beams continue to be M60 with cement replaced by 15% of Silica fume and 2% of Glass fibre..
The next three beams continue to be M60 with cement replaced by 5% of Metakaolin.
The next three beams continue to be M60 with cement replaced by 5% of Metakaolin and 2% of Glass fibre.
The next three beams continue to be M60 with cement replaced by 10% of Metakaolin.
The next three beams continue to be M60 with cement replaced by 10% of Metakaolin and 2% of Glass fibre.
The next three beams continue to be M60 with cement replaced by 15% of Metakaolin.
IV. CHARACTERIZATION OF CONSTITUENT
The two major components of fibre-reinforced cement composites are the matrix and the fibre. The matrix generally consists of Portland cement, aggregates, water and admixtures.
1. Ordinary Portland Cement 2. Fine aggregate
3. Coarse aggregate 4. Water
5. Mineral admixture 6. Chemical admixture 7. Glass fibers
V. EXPERIMENTAL INVESTIGATIONS Workability Test
This test was carried out for determining the workability of concrete. The method of testing was done as per IS 1199-1959. The dimensions of the mould are as shown in Steel tamping rod of 16 mm in diameter, 0.6 m long and rounded at one end was taken.
Compression Test
The compressive strength of concrete i.e. ultimate strength or concrete is defined as the load which causes failure of the specimen divided by the area of the cross section in uni-axial compression, under a given rate of loading. To avoid large variation in the results of compression test, care should be taken during the casting of the test specimens and loading as well. It is however realized that in an actual structure, the concrete at any point is in a complex stress condition and not in uni-axial compression.
Split tensile Strength
The split tensile strength of the concrete is defined as the load which causes failure of the specimen divided by the area of the cross section in uni-axial compression, under a given rate of loading. To avoid large variation in the results of Split test, care should be taken during the casting of the test specimens and loading as well. The specimen is placed horizontally in the testing machine and the rate of loading is continuously adjusted through rate control valve by hand to 400 KN/minute. The load is increased until the specimen fails and record the maximum load carried by specimen during the test. The split tensile strength is calculated using the formula. The test results are given in results and discussions
Flexural Test
The standard sizes of the specimen are 15x15x70 cm. They are tested immediately on removal from the water whilst they are still in wet condition. The bearing surfaces of the supporting and loading rollers are wiped clean, and loose sand or other material removed from the surfaces of specimen where they are to make contact with
VI. MIX DESIGN OF M60 CONCRETE AND DESIGN OF REINFORCED CONCRETE BEAM
Mix Design of M60 Grade Concrete:
Step 1:- Design Stipulations for Proportioning
Grade designation:- M60
Characteristic Compressive strength at 28 days:- 60N/mm2
Type of cement used:- OPC 53 grade confirming to IS-12269
Maximum size of aggregates:- 20mm
Water/cement ratio:- 0.30
Workability:- 50 to 150mm slump
ISSN(E): 2277-128X, ISBN: 978-93-87396-07-4, pp. 360-366
Method of concrete placing:- Manual
Degree of supervision:- good
Type of aggregate:- Crushed angular aggregate
Chemical admixture:- Super plasticizer
VII. RESULTS AND DISCUSSIONS Observation and Discussion on Workability
Based on trial mixes, the tests showed decreased values of slump with the addition of CSF and MK. With water cement ratio of 0.30 and with an addition of maximum 2% superplasticizer the M60 concrete mixes with admixtures of condensed Silica fume and Metakaolin were found to have a slump value of 107 to 124. Hence in the fibre reinforced concrete mixes with steel fibres and somewhat high dosages of super plasticizers are necessary to maintain workability at medium level.
Observation and Discussion on Compressive strength
It has been observed that with the addition of Silica fume and Metakaolin, the compressive strength of concrete at the age of 28 days has increased with various proportions of the mix. The increase in strength is in the range of 2.57% - 7.78% for Silica fume concrete and 2.57% - 6.06% for Metakaolin concrete respectively. The same trend is observed with glass fibres in the M60 concrete mix with various combination of blended percentage of CSF and MK. It is clear from the above discussions that the additions of mineral admixtures, along with the fibres are giving higher compressive strength compared to the conventional concrete. However, silica fume concrete gives better result at all ages than metakaolin concrete.
Observation and Discussion on Split tensile strength
It has been observed that with the addition of Silica fume and Metakaolin, the split tensile strength of concrete at the age of 28 days has increased with various proportions of the mix. It is found that fibre based concrete gives the highest split tensile strength among all the fibrous mixes. The strength increased is 3.1% and 5.1% for Metakaolin and Silica fume concrete respectively along with theGlass fibres.
Observation and Discussion on Flexural strength
Flexural strengths are also higher for concretes with various combination, these values are further increased with addition of fibres and using nominal glass. It has been observed that with the addition of Silica fume and Metakaolin, the flexural strength of concrete at the age of 28 days has increased with various proportions of the mix. It is found that fibre based concrete gives the highest flexural strength among all the fibrous mixes. The strength increased is 5.1% and 6.08% for Metakaolin and Silica fume concrete with Glass fibres.
VIII. CONCLUSION
The purpose of introducing Silica fume and Metakaolin by partial replacing cement is to increase strength and performance of the concrete. And also strength and durability properties of concrete can be enhanced by introducing the glass fibres.
1. High strength fibre reinforced concrete mix has been produced with addition of condensed Silica fume and Metakaolin as mineral admixtures.
2. The workability of high strength high performed fibre reinforced concrete has been increased by adding Silica fume and Metakaolin with constant quantity of high range water reducing (HRWR) chemical agent.
3. The compressive strength of high performed concrete after 28days of curing with 5%, 10% and 15% of Silica fume and Metakaolin has been increased by 3.94%, 5.42% and 4.17% for Silica fume and 2.60%, 3.42% and 2.88% for Metakaolin.
4. It has been observed from the test results, the split tensile strength has been increased at 10% replacement of Silica fume and Metakaolin with 2% of glass fibres.
5. From the experimental results it has been observed that the appreciable improvement in compressive strength, split tensile strength and the flexural strength has been observed with 10% of silica fume and 2% of glass fibres. 6. By the addition of glass fibres in high strength concrete with different percentage of mineral admixtures, the
flexural strength has been improved in all the mix.
7. By analysing the experimental results of high strength fibre reinforced concrete, the addition of 10% of Silica fume and Metakaolin with 2% of glass fibres has achieved the maximum compressive strength, split tensile strength and flexural strength.
8. The high strength high performed fibre reinforced concrete is produced by introducing Silica fume and Metakaolin as partial replacement of cement from the experimental results it has been observed that these pozzolanic materials have been enhanced all the properties of the fresh and dry concrete in addition to this the split tensile strength and flexural strength have been improved by introducing the glass fibres.
REFERENCES
ISSN(E): 2277-128X, ISBN: 978-93-87396-07-4, pp. 360-366
[2] Vikas Srivastava, „„Effect of Silica fume and Metakaolin combination on concrete‟‟, International Journal of Civil and Structural Engineering, Vol. 2, No.3, 2012, pp 893-900.
[3] Michael Sydlowski “Concrete International” published in 1998.
[4] M.S. Shetty, “ Concrete Technology” S. Chand publication, 6th edition 2011.
[5] Vikas Srivastava, Rakesh Kumar, Agarwal V.C, Mehta P. K , “ Effect of Silica fume and Metakaolin combination on concrete”, International Journal of Civil and Structural Engineering, Vol 2, No.3, 2012, pp 891-889.
[6] Rafat Siddique “Fibre Reinforced Concrete”, Galgotia publications, 3rd edition.
[7] P. Muthupriya, K. Subramanian and B. G. Vishnuram, “Strength and Durability Characteristics of High Performance Concrete”, “International Journal of Earth Sciences And Engineering” ISSN 0974-5904, Vol. 03, No. 03, June 2010, pp. 416-433.
[8] Arfath Khan Md, Abdul Wahab, B. Dean Kumar “Fibrous Triple Blended Concrete Composites – Study of Strength Properties”, International Journal of Emerging Technology and Advanced Engineering , Vol. 3, Issue 5, May 2013, pp 541-546.
[9] M.J. Shannag “ High Strength Concrete Containing Natural Pozzolan and Silica fume”, Cement and Concrete Composites, Vol. 22, 2000, pp. 399-406.
[10] J.M. Khatib, E.M. Negim and E. Gjonbalaj “High Volume Metakaolin as Cement Replacement in Mortar”, World Journal of Chemistry, 7 (1), 2012 pp 7-10.
[11] Aquino, W., D.A. Lange and J. Olek, “Influence of Metakaolin and Silica fume on the Chemistry of ASR Product, Cement and Concrete Composites”, Vol. 23, No. 6,2001, pp. 485- 493.
