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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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