ppt on high performance concrete (steel fibre)
TRANSCRIPT
BY
Dharaneeswari.S.KPunithavalli.M
(3rd civil – PITS college Thanjavur)
INTRODUCTIONHIGH STRENGTH CONCRETE BY USING STEEL FIBERS.
CONCRETE
Concrete is characterized by brittle failure. It can be
overcome by the inclusion of a small amount of short
randomly distributed fibers (steel, glass, synthetic and
natural).
HIGH STRENGTH CONCRETE
High strength concrete the presence of more constituent ingredients than the
conventional concrete calls for an adequate proportioning of mixtures to satisfy
the specified performance characterstics . Addition of fibers, special admixtures,
composites and other new materials are available and being developed every day
to satisfy the required performance and functions of the challenging concrete to
give significant improvement in flexural strength, impact strength and fracture,
toughness of concrete with smaller improvements in compressive strength.
STEEL FIBER REINFORCED CONCRETE
Fiber reinforcement is mainly used in shocrete, but can also be used in normal
concrete. Fibre-reinforced normal concrete are mostly used for on-ground floors
and pavements, but can be considered for a wide range of construction parts
(beams, pillars, foundations etc) either alone or with hand-tied rebars.
SOME TYPES OF FIBER
METHODOLOGY
COLLECTIONs OF MATERIAL
1.Cement
2.Coarse aggregate
3.Fine aggregate
4.Steel fibre
1.Fineness (%) Not exceed 102.Specific Gravity 3.153.Finess modulus(%) 2.854.Initial setting time(min.) >305.Final setting time(min.) <600
Compressive Strength (N/mm2)
1. 3-days >272. 7-days >373. 28-days >53
Property of Cement
Property Coarse aggregate Fine
aggregate
1. Specific Gravity 2.775 2.67
2. Finess modulus 7.46 2.9
3. Water absorption 1.46 -
4. Moisture content nill nill
Steel fibres
The typical diameter lies in the range of 0.25-0.75 mm hook end steel fibres are being used in this project. Length of these fibres is 30 mm and the aspect ratio of 55. Density of steel fibre is 7900 kg/cum.
1. Cross Section : Straight , hook- end,
deformed
2. Diameter : 0.3-0.7mm ( max 1mm)
3. Length : 25 – 35mm
4. Density : 7900 kg/m3
5. Young‘s Modulus : 2.1 x 105 N/mm2
6. Resistance to Alkalis : Good
7. Resistance to Acids : Poor
8. Heat resistivity : Good
9. Tensile Strength : 500-2000 N/mm2
10. Specific Gravity : 7.90
11. Aspect Ratio : 45, 55, 65, 80
12. General Use : 10 kg/m3
13. Elongation : 5-35 %
GENERAL PROPERTY DESCRIPTION SFRC
PROPERTIES OF STEEL FIBRES USED
Fibre type : Hooked steel fibres
Fibre length : 50mm
Tensile strength : 1100 N/mm2
Young’s modulus : 2×105 MPa
Density : 7800 kg/m3
Aspect ratio : 67
Diameter : 0.75mm
CASTING OF THE CONCRETE
CURING OF THE CONCRETE
DISCUSSIONS OF TEST
The cube compressive strength obtained for steel fibre mixed in the proportion
of 2.5% and 5.0 % (by weight), was 64MPa. The percentage increase of
compressive strength is 1.57 and 1.79 for the specimens conventional, 2.5%
and 5% respectively.
Discussing about the column test results under axial load condition, the
column with proportion of steel fibres as 2.5 %, 5 %( 5%) has the highest load
carrying capacity of 78 KN. The percentage increase of ultimate load of the
column is 1.37, 5.04 and 7.17, for the specimens conventional, 2.5% and 5%
Initiation of the crack was arrested due to the addition of steel fibre.
COMPRESSION TEST OF THE CONCRETE CUBES
RESULTS AND DISCUSSION Compressive strength of cubes:
Compressive strength for 2.5% of steel fibre
Compressive strength for 5.0% of steel fiber
Ultimate Strength for 5.0% of steel fibre specimen
Comparison of Ultimate Strength of the Cubes
Flexural strength for conventional beam
Flexural strength for 5% steel fibre
TEST RESULTS
The results of this work, it can be concluded that the column containing the
mix proportion of steel fibre (5.0%) can greatly enhance the strength
compared with another proportion of steel fibre.
STRESS-STRAIN RELATION BETWEEN HPFRC & FRC
Flexural Strength: Flexural bending strength can be increased of up to 3
times more compared to conventional concrete.
Fatigue Resistance: Almost 1 1/2 times increase in fatigue strength.
Impact Resistance: Greater resistance to damage in
case of a heavy impact.
Permeability: The material is less porous.
Abrasion Resistance: More effective composition against abrasion and
spalling.
Shrinkage: Shrinkage cracks can be eliminated.
Corrosion: Corrosion may affect the material but it will be limited in certain
areas.
Properties of Concrete Improved by Steel Fibers
The mixing of the Hooked steel fibres in the cubes ands column of
two different percentage is improving the compressive strength of
the cubes. Steel fibre reinforced concrete column arrest the
initiation of the failure of the column and takes more load. The cube
and column containing proportion of steel fibre, 2.5% and 5.0%
carries more loads.
1) Increase in strength of mixed steel fibre reinforced concrete of
proportion 5 % of 50 mm sizes were,
2) 13.55 percent in cube compressive strength
3 )14.03 percent in ultimate load carrying capacity of column
CONCLUSION OF THE TEST
Advantages of SFRC:
Fast and perfect mixable fibers and High performance
and crack resistance
Optimize costs with lower fiber dosages
Steel fibres reinforced concrete against impact forces,
thereby improving the toughness characteristics of
hardened concrete.
Usage of SFRC in Indian Projects:
• KRCL-MSRDC Tunnels.• NafthaJakarihydro electric project.• KOLhydro electric project.• Bagliharhydro electric project.• Chamerahydro electric project.• Uri dam.• Sirsisilam project.• Tehri dam project.• Salalhydro electric project.• Ranganadihydro electric project.
Major SFRC structures all over the world
REFERENCES
1. Ezeldin A.S and Balaguru P.N,” Normal and High Strength
Fibre Reinforced Concrete under Compression”, Journal of
materials in Civil Engineering, Nov 1992, Vol.4, No 4, pp 415-
429.
2. Ganesan, N. and Murthy, J.V., “Strength and Behavior of
Confined Steel Fibre Reinforced Concrete Columns”, ACI
materials journal, 1990, vol.87, no.3, pp.221-227.
3. Hsu, L.S. and Hsu, C.T., “Stress-Strain Behaviour of Steel
Fibre High Strength Concrete under Compression”, ACI
Structurel Journal, 1994, Vol.91, No.4, pp.448-457
THANK YOU . . .
ANY QUESTIONS…