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Self Compacting
Concrete (SCC)
PRESENTED BY
KISHAN KANHAIYA
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Contents
Introduction
Problems with conventional concrete
Benefits of SCC
REQUIREMENT OF SCC
Constituent materials
Properties of fresh SCC
Properties of hardened scc
Tests
Application
Conclusions
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Introduction
Self-compacting concrete is a concrete which has little resi
flow so that it can be placed and compacted under its ownwithout any external vibration .
Developed initially in japan in 1988 by professor okamura the growing shortage of skilled labour.
It does not require vibration to achieve full compaction.
It can be considered as major evaluation in construction indu
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Problems with Conventional Concrete :-
Requirement of skilled worker for compaction inconventional concrete.
Conventional concrete has low workability and flo
ability .
Difficult to use mechanical compaction for
Underwater concreting
Cast in-situ pile foundation
Columns with congested reinforcement
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Benefits of SCC
Faster construction Reduction in site manpower
Safer working environment
Improved aesthetics
Easier placing Improved durability
Reduced noise level
Better surface finish
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Types of self-compacting concrete:
Powder type :- In powder type scc is made by increthe powder content.
Viscosity modifying agent type :-In VMA type scc ismade by using viscosity modifying admixture .
Combination type :-In combined type it is made by
increasing powder content and using viscosity modadmixtures .
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Requirements for Self-compacting
concrete
A concrete mix can only be classified as self-compactin
has the following characteristics .
Filling ability
Passing ability
Segregation resistance
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Characteristics of scc :-
SCC should haveLow coarse aggregate content
Increased paste content
Low water powder ratio
Increased super plasticizer dosage
Viscosity modifying agents
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Materials required for scc :-
Cement Aggregate
Water
Admixture
1. Chemical admixture
2. Mineral admixture
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Aggregate:
Aggregate should be of uniform quality with respect to shape agrading .
Well graded cubical or rounded aggregate are desirable
The maximum size of aggregate is depend on type of construct
is generally limited to 20 mm. Aggregate of size 10 to 12 mm i
desirable for structure having congested reinforcement .Wherevpossible size of aggregate higher than 20 mm could also be use
Aggregate should be free from any impurities like silt,clay,dirt
In order to obtain a good quality concrete it should be hard and
strong and chemically stable .
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Chemical Admixtures
Different types of chemical admixtures :-
1. Super plasticizers
2. Viscosity modifying agent
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SUPER PLASTICIZERS :
Super plasticizers are low molecular water soluble
polymer.
It is designed to achieve high amount of water reduction
These materials are used to prevent segregation, bleeding
and increase flow ability . It is used in scc to achieve full compaction .
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ROLE OF SUPER PLASTICIZERS
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Mineral Admixture Fly ash:It is residues obtained from the combustion of
pulverized coal collected by mechanical separators, from the
fuel gas of thermal plants . It reduces free drying shrinkageand restrains the shrinkage cracking width.
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Properties of fresh SCC :
Workability : super plasticizers is used to improvworkability
Segregation resistance : Due to high fluidity of s
risk of segregation and blocking is very high. Th
tendency to segregation can be reduced by using
modifying admixtures .
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Properties of hardened scc :
Compressive strength :-Scc compressive strength are comparable to those ofconventional concrete made with similar mix proportions and water/cement ratio
.
Contd
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Contd.
Bond strength :- The strength of the bond betweenconcrete and reinforcement was assessed by pullout tests
using deformed reinforcing steel of two different
diameters . Bond strength of scc related to the standard
compressive strength was higher then those of
conventional concrete .
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Test methods for scc :
Slump flow test
J-Ring test
V-Funnel test
L-Box test
U Box test
Fill box test
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Slump flow test :
It determines the passing ability of SCC.
Slump cone of 300 mm height ,100 mm upper dia and 20
mm bottom dia is taken on a horizontal plate .
Scc is filled in the cone without any compaction .
Then cone is lifted and allowed to spread.
Measure the final diameter of the concrete in two
perpendicular directions and calculate the average of the
two diameters. This is the slump flow in mm.
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J-Ring test
It determines the passing ability of scc
J ring consist of a ring of reinforcement bars that waround the slump cone .
Place the j ring centrally on the base plate and the s
cone centrally inside the j-ring .
Fill the slump cone with the scoop .
Slump cone is filled with concrete and lifted up as
slump cone test
Final spread is measured
Difference between above and normal slump is me
and it should not be more than 50 mm.
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J-ring Test Apparatus
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L-box test
It measure passing ability
L ring test apparatus has a vertical channel and horizontal
channel separated by trap door.
Vertical part is filled with scc.
Door is opened and concrete is allowed to pass throughblocking bars
Height of concrete left in vertical section and end of
horizontal section is measured
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L-BOX TEST APPARATUS
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Application of scc
Two anchorages of Akashi-Kaikyo (Straits) Bridge
The volume of the cast concrete in the two anchoraamounted to 290,000 m3.
The highest use of SCC in India was done at Delhiproject. About 10000 m3 of SCC has been Used.
At Kaiga nuclear power plant, SCC of Characterist
strength 30 MPa was used. The trial use of SCC has been successively done in
TARAPUR ATOMIC POWER Plant, KAIGA NUCPOWER PLANT and BANDRA WORLI SEA LIN
Contd
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Contd.
The Burj Khalifa is the tallest building in the worwas used throughout the building and was pumpe
stories above the ground. The Trump Tower in Chicago, Illinois was a majo
SCC. It is a 92-story reinforced concrete project trequired 3500 m3of SCC to be cast-in-place contifor 22 hours to construct the mat foundation that the finished structure. The mix had a 7-day compstrength of 68 MPa and a 28-day strength of 82 Msingle pour is the largest ever recorded to date in America using SCC
Conclusion
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Conclusion
In conclusion, self-consolidating concrete is an ex
technology that has found many successful applic
In recent developments it has been observed that pfor future applications of SCC for new structural d
and construction systems is vast.
Further research are required to interpret influence
hardened properties of SCC more precisely.
SCC can be effectively placed in most congested a
also where normal methods of vibration are not po
We can reduce the in-place cost and maker a safer
environment for the workers.
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