International Journal for Modern Trends in Science and Technology (ISSN: 2455-3778), Volume 4, Special Issue 4, July 2018 70
STRENGTH AND BEHAVIOUR OF SILICA FUME BASED STEEL FIBRE REINFORCED CONCRETE
K.NaveenBabuA [M-Tech,Stuc] G.GiriPrasadB[Ph.D]
A. M-Tech, structures, D.M.S.S.V.H College of engineering,machilipatnam e-mail:
knaveenbabu5@gmail.com
B. [Ph.D], D.M.S.S.V.H. college of engineering, machilipatnam, e-mail:girimtm@gmail.com
Abstract: The utilization of Ordinary Portland Cement (OPC) cause hazard due to emission of CO2.This will be reduced by replacing the cement with an admixture having similar properties. In the present experimental investigation is to study the effects of replacement of cement (by weight) with 5 percentages of silica fume and the effect of addition of steel fibres composite. A control mix of M30 was designed. Cement was replaced with five percentages (5, 10, 15, 20, 25) of silica fume. Four percentages of steel fibres (0.15, 0.30, 0.45, 0.60) having 35 mm length were used. This study reports on the feasibility of use of steel fibres on the structural properties of cube compressive strength, split tensile strength and flexural strength.
Key words: Silica fume, steel fibres, structural properties.
Introduction: plain cement concrete possesses a very low tensile strength, limited ductility and little resistance to cracking. Internal micro cracks are present in the concrete and its poor tensile strength is due to the propagation of such micro cracks. In the plain concrete, cracks will be develop even before loading, due to drying shrinkage or other causes of volume change .when loaded the micro cracks propagate and open up, changes to macro cracks. The development of such cracks is due to the main cause of inelastic deformation of concrete. Silica fume having pozzolanic properties as well as the cementatious properties. And it is very reactive, high strength and long lasting. It rects with the calcium hydroxide and forms the additional binder named as the calcium silicate hydrate. It helps in getting more strength and stiffness of concrete. When the fibres added to the silica fume concrete, both the compressive and tensile strengths are improved. Not only the strength charateristics, the permeability and durability also improved. That’s why the addition of steel fiber and silica fume in normal concrete improved the properties such as workability, brittleness, strength, corrosion resistance and ultimately increased life of the structure.
Materials used:
1. Cement: Ordinary Portland cement of 53 grade is used in present study.
Physical properties Test Results
Setting time
(a) Initial setting time (b) Final setting time
35 minutes 580 minutes
Normal consistency 30%
Fineness modulus 6%
Specific gravity 3.12
Specific surface area 3150 cm2/gm
International Journal for Modern Trends in Science and Technology (ISSN: 2455-3778), Volume 4, Special Issue 4, July 2018 71 Physical properties Test Result
Specific gravity 2.56
Fineness modulus 2.63
Water absorption 0.50%
Zone III
3. Coarse aggregate:
Physical properties Test Results
Specific gravity 2.82
Fineness modulus 6.63
Water absorption 0.44%
Maximum size 20 mm
4. Silica fume:
Very fine non crystalline silica produced in electric arc furnaces as a byproduct of the production of elemental silicon or alloys containing silica. Silica fume is usually categorized as a supplementary cementitious material and is known as admixture.
5. Steel fibres:
The small and discrete steelwires having the tensile strength of about 280 to 2800Mpa and the ultimate elongations of about 0.5 to 3.5% depending on the type of steel and type of production of fibre. These are mixed to the concrete at the time of mixing of concrete uniformly to inducing the tensile strength to the concrete. The steel fibres are prosuced in different ways with diffent shapes such as hooked end, plain…..etc.
6. Water: Clean, potable water is suitable for mixing and curing of concrete as per IS:456: 2000.
Mix design: As per IS: 10262: 2009, the M30 grade concrete mix is designed as 1:1.76: 2.96 with water/binder ratio of 0.45. Ordinary Portland cement of 390kg designed for 1 cubic metre of concrete.
Experimental investigation: The cubes (150mm), cylinders (150mm dia X 300mm length), prisms (100mm X 100mm X 500mm) are casted with various percentages of silica fume replaced with cement in the first phase of work. The specimens are cured by immersing in the water and tested at the age of 7,14 and 28 days.
The specimens of same dimensions are casted with various percentages of steel fibres along with the optimized silica fume content. They are tested at the age of 7, 14, and 28 days.
Test result and discussions:
Phase:1
% cement replaced with
silica fume
Compressive strength in Mpa
Split tensile strength in Mpa
Flexural strength in Mpa 3 days 7 days 14 days 28 days 7 days 28 days 7 days 28 day
0 16.60 29.00 35.30 40.00 2.13 2.54 2.60 3.80
5 17.00 30.20 36.00 42.00 2.50 2.92 2.90 4.10
10 18.50 34.00 40.00 46.00 2.67 3.11 4.20 4.90
15 18.10 32.50 38.50 45.30 2.56 2.95 3.20 4.20
20 17.50 31.00 36.50 43.00 2.50 2.92 3.20 4.10
25 15.98 30.60 36.00 42.20 2.20 2.56 2.80 3.90
International Journal for Modern Trends in Science and Technology (ISSN: 2455-3778), Volume 4, Special Issue 4, July 2018 72 0
5 10 15 20 25 30 35 40 45 50
0 5 10 15 20 25
strength in Mpa
percentage replacement of cement with silica fume compressive strength of concrete
3 days 7 days 14 days 28 days
0 0.5 1 1.5 2 2.5 3 3.5
0 5 10 15 20 25
strengh in Mpa
percentage replacement of cement with silica fume split tensile strength
7 days 28 days
0 1 2 3 4 5 6
0 5 10 15 20 25
strengh in Mpa
percentage replacement of cement with silica fume flexural strength
7 days 28 day
International Journal for Modern Trends in Science and Technology (ISSN: 2455-3778), Volume 4, Special Issue 4, July 2018 73
% steel fibre addition + 10%
silica fume
Compressive strength in Mpa
Split tensile strength in Mpa
Flexural strength in Mpa 3 days 7 days 14 days 28 days 7 days 28 days 7 days 28 day
0 18.50 34.00 40.00 46.00 2.67 3.11 4.20 4.90
0.15 24.00 34.60 41.00 46.60 2.92 3.27 4.34 5.36
0.30 25.00 35.00 42.86 47.30 3.12 3.63 4.72 5.53
0.45 24.60 34.50 40.76 46.50 3.00 3.52 4.70 5.40
0.60 23.50 33.40 40.26 46.30 2.89 3.30 4.46 5.36
0 5 10 15 20 25 30 35 40 45 50
0 0.15 0.3 0.45 0.6
strength in Mpa
% addition of fibres along with 10% silica fume
compressive strength
3 days 7 days 14 days 28 days
0 0.5 1 1.5 2 2.5 3 3.5 4
0 0.15 0.3 0.45 0.6
strength in Mpa
% addition of fibres along with 10% silica fume
split tensile strength
7 days 28 days
International Journal for Modern Trends in Science and Technology (ISSN: 2455-3778), Volume 4, Special Issue 4, July 2018 74 Conclusions:
Based on the experimental investigation on the mechanical properties of the silica fume based cement concrete reinforced with steel fibres such as compressive strength, split tensile strength and flexural strength, the following conclusions were made.
By adding silica fume to the concrete, strength parameters such as mainly compressive strength is increase due to close packing of particles.
By adding steel fibres to the concrete, strength parameters like tensile and flexural strengths are significantly improved.
The concrete having 10% cement replaced with silica fume and 0.30 % steel fibres showed increase in compressive, tensile and flexural strengths 18%, 26.15% and 26.31% as compare with normal concrete.
As well as the concrete having 10% cement replaced with silica fume and 0.30 % steel fibres showed increase in compressive, tensile and flexural strengths 3%, 16.14% and 14.28% as compare with silica fume concrete.
References:
1. Faseyemi Victor Ajileye “Investigations on Microsilica (Silica Fume) As Partial Cement Replacement in Concrete”, Global Journal of researches in engineering,Civil And Structural engineering Volume 12 Issue 1 Version 1.0 January 2012 Type: Double Blind Peer Reviewed International Research Journal Publisher: Global Journals Inc. (USA)
2. V. M. Malhotra and G. G. Carette “Silica Fume Concrete - Properties, Applications, and Limitations”
Concrete International Journal on MAY 1983.
3. AbhinavShyam, Abdullah Anwar, Syed Aqeel Ahmad, “A Literature Review on Study of Silica fume as Partial Replacement of Cement in Concrete “ International Journal of Advanced Engineering, Management and Science (IJAEMS) [Vol-3, Issue-3, Mar- 2017] ISSN: 2454-1311
4. R Rama Mounika, B.RaviKiran, A.Venkata Krishna, “A Study on Replacement of Cement with Fly Ash, Silica Fume and Addition of Steel Slag in Concrete” SSRG International Journal of Civil Engineering (SSRG-IJCE) – volume 4 Issue 5 – May 2017
5. Silica fume manual by Oriental TreximPvt. Ltd. (2003).
6. M.S. Shetty, Concrete Technology, S. Chand and Company Pvt Ltd. New Delhi, India, 1999.
0 1 2 3 4 5 6
0 0.15 0.3 0.45 0.6
strength in Mpa
% addition of fibres along with 10% silica fume
flexural strength
7 days 28 day
International Journal for Modern Trends in Science and Technology (ISSN: 2455-3778), Volume 4, Special Issue 4, July 2018 75 Parthiban.k associate dean and assistant professor.
8. ACI committee-544(1973), “State of airport on fibre reinforced concrete “, ACI journal, 70(11), pp 7- 16.
9. Swamy R.N (1974)”Fibre reinforced concrete mechanics, properties and applications”, Indian concrete journal,48(1), pp 7-16.
10. Sekar.T (2004), “Fibre reinforced concrete from industrial waste fibres- a feasible study” IEI journal-CE, pp 287-290.
Model calculations:
Compressive strength of concrete = load/area
=900000/(150 x 150) =40 N/mm2
Split tensile strength = 2P/Ld
= (2 x 180000)/ ( x 300 x 150) = 2.54 N/mm2.
Flexural strength = Pl/bd2
= (7600 x 500)/(100 x 1002) = 3.80 N/mm2.
