selfcompactingconcrete

1. Self compacting concrete (scc)

2. CONTENTS
Introduction
Development
Materials required
Properties of scc
Mix design
Tests
Uses
Advantages & disadvantages
Conclusion

3. INTRODUCTION
oSelf compacting concrete is an innovative
concrete that does not require vibration for
placing and compaction.
oSelf compacting concrete is a concrete that
can be compacted into every corner of a
formwork purely by means of it’s own weight ,
with out using any external vibrators.
oIt is a highly engineered concrete with much
higher fluidity.

4. DEVELOPMENT OF SCC
• In 1983,there occurred a great problem while
studying the durability of concrete structures in
japan.
• The problem is that to made a durable concrete an
adequate compaction is necessary by skilled
labour.
• So as a solution for the above problem “scc” was
created by okamura in 1986.
• Hence okamura is known as the father of “scc”
technology.

5. • At first scc is only used in pre-fabricated
products and ready mixed concrete in japan.
• Self compacting concrete has been described as
“the most revolutionary development in concrete
construction foe several decades”.

6. MATERIALS REQUIRED
oCement
oFine aggregates
oCoarse aggregates
oWater
oChemical admixtures such as super plasticizers ,
Viscosity modifying agents(VMA),Air entraining
agents(AEA)
oMineral admixtures such as fly ash , GGBFS ,
silica fume.

7. Cement : Ordinary portland cement of 43
or 53 grade can be used.
Aggregates : well graded cubical or
rounded aggregates are desirable.
Water quality : maintained same as
reinforced concrete.
Chemical Admixtures : Super plasticizers
particularly poly-carboxylated ethers are
used in scc. VMA and AEA are also used.
Mineral Admixtures :
• Fly ash : it improves the quality and durability of
concrete.
• GGBFS : It improves rheological properties( semi-solid
& liquid state)
• Silica Fume : it improves mechanical properties.
Stone powder : finely crushed
limestone,dolomite,granite may be added to
increase powder content.

8. COMPARISION OF MATERIALS USED IN
NORMAL CONCRETE AND SCC
NORMAL CONCRETE
SCC

9. PROPERTIES OF SCC
In fresh state , scc have the following
properties
oFilling ability : flows easily at certain
speed into formwork
oPassing ability : Passes through reinforcement
without blocking
oSeggregation resistance : the distribution of
aggregate particles remains homogeneous in
both vertical and horizontal direction

10. Requirement of SCC
1.Flowability: SCC must exhibit high flowability, allowing it to spread and
fill formwork smoothly and uniformly without segregation or blocking.
Flowability is essential for achieving proper compaction and ensuring
complete filling of complex shapes, congested reinforcement, and tight
formwork corners.
2.Passing Ability: SCC should have excellent passing ability, enabling it to
flow through narrow gaps, tight spaces, and around obstructions without
clogging or bridging. This property ensures that the concrete can reach all
areas within the formwork, including hard-to-access regions.
3.Segregation Resistance: SCC must resist segregation, which occurs
when heavier aggregates settle and separate from the mortar matrix
during transportation or placement. Segregation resistance ensures
uniform distribution of aggregates, cement paste, and admixtures
throughout the concrete mixture, maintaining consistency and
homogeneity.
4.Cohesion: SCC should exhibit sufficient cohesion to prevent segregation
and maintain homogeneity during handling, transportation, and
placement. Cohesiveness is crucial for maintaining the integrity of the
concrete mass and preventing separation of its components, especially
under the influence of gravity and flow.

11. 5.Stability: SCC should demonstrate stability under its self-
weight and external forces, maintaining its shape and form without
excessive spreading or deformation. Stability ensures that the
concrete maintains its desired position and consistency during
placement, minimizing the risk of slump loss or flow-induced
defects.
6.Viscosity: SCC should have appropriate viscosity to control its
flow and prevent excessive spreading or bleeding. Viscosity
influences the resistance of SCC to segregation, flow-induced
segregation, and excessive deformations, balancing flowability
with stability and cohesiveness.
7.Ease of Placement: SCC should be easy to handle, transport,
and place, requiring minimal manual effort or mechanical
assistance. Ease of placement facilitates efficient construction
operations and reduces labor requirements, contributing to overall
project productivity and cost-effectiveness.
8.Consistency: SCC should maintain consistent workability
properties over time and across batches, ensuring reliable
performance and uniformity in construction. Consistency allows
contractors to predict and control the behavior of SCC during
placement, minimizing the risk of unexpected complications or
quality issues.

12. PRODUCTION AND PLACING
Proportions of materials are taken based on
volume rather than by mass
Aggregates : should come from same source
Mixing : it should be done for longer time
when compared to conventional concrete
Placing : some rules need to be followed while
placing the concrete:
Limit of vertical fall distance to 5 meters
Each layer should be at a height of 500 mm
Horizontal flow should not exceed 10 meters
Curing : early curing is necessary for scc

13. MIX DESIGN principles
• The flow ability and viscosity of paste can be
controlled by proper proportioning of
water/power ratio and then adding super-
plasticizers and VMA.
• The paste is the vehicle for the transport of
the aggregate, therefore the volume of the
paste must be greater than the void volume in
the aggregate.
• In order to control the temperature rise and
thermal shrinkage cracking as well as
strength, the fine powder should be added to
keep the cement content at an acceptable level
.e.g.., fly ash, mineral filler, silica fume,
GGBFS (Ground-granulated blast-furnace slag)

14. MIX DESIGN
The following sequence is followed:
• Determine the desired air content
• Determine the coarse aggregate volume
• Determine the sand content
• Design the paste composition
• Determine the optimum volumetric water/powder
ratio and super-plasticizer dosage in mortar
Scc should have:
• Air content is taken as 2%
• Low coarse aggregate content
• Increased paste content
• Low water powder ratio
• Increased super plasticizer dosage

15. EXAMPLES OF SCC MIXES
• POWDER TYPE : powder type scc is made by
increasing the powder content.
• VMA TYPE : In this type viscosity modifying
agent is added for seggregation resistance.
• COMBINED TYPE : Both powder and viscosity
modifying agent is added

16. MECHANISM FOR ACHIEVING SELF
COMPACTION

17. TESTS CONDUCTED ON SCC
The tests are not standardized till now.
Slump flow test
T50 slump flow test
V-funnel test and v-funnel test at T5 MIN
L-Box test
U-Box test
Fill box test
GTM screen stability test
Orimet test

18. SLUMP FLOW TEST
• This test is done to know the horizontal flow of
concrete in the absence of obstructions.
• It gives good assessment of filling ability.
• This test can be done in the field itself
PROCEDURE:
*A normal slump cone and a flat square plate is
taken . Some concentric circles are drawn on square
plate . A firm circle of 500 mm dia is drawn.
*The slump cone is filled with about 6litre of concrete
and is raised vertically and allow the concrete to
flow free in horizontal direction.
*Measure the final dia of concrete in 2 perpendicular
directions and note the average of two diameters.
ACCEPTABILITY:
The higher the flow rate , the grater is the ability
to fill form work
A value of at least 650 mm is required for scc.

19. T50 SLUMP FLOW TEST
The procedure for this test is as same as for
slump flow test.
When the slump cone is lifted , start the stop
watch and find the time taken for concrete to
reach 500 mm mark.
This time is called as T50 time.
A lower time indicates greater flowability.
It is suggested that T50 time may be 2 to 5
seconds.

20. J-RING TEST
• It denotes the passing ability of concrete.
• The equipment consists of a rectangular section and
and a ring of reinforced bars with holes.
PROCEDURE :
*A slump cone is taken and is filled with 6 litres of
concrete.
*Raise the cone vertically and allow the concrete to flow
through the j-ring.
*Measure the final diameter in 2 perpendicular directions
and take the average value.
*Also measure the difference in height between the concrete
just inside J-ring bars and just outside J-ring bars.
*Calculate the averge of difference in height at 4 loacations.
ACCEPTABILITY:
*The acceptable difference in height between inside and out
side should be 0 to 10 mm.

21. V-FUNNEL TEST & V-FUNNEL AT T5 MIN
*V-funnel test is used to find filling ability of aggregates of
maximum
size of 20 mm and v-funnel at T5 min is used to find
seggregation resistance
*The equipment consists of a v-shaped funnel
PROCEDURE FOR V-FUNNEL TEST :
*The door present below the v-funnel is closed and
about 12 litre of concrete is poured inside.
*open the door within 10 seconds and record the time
taken for concrete to flow down.
*The whole test is to performed within 5 minutes.
PROCEDURE FOR V-FUNNEL AT T5 MIN :
*Do not clean or moisten the inside surface of funnel.
*Close the trap door and refill the v-funnel.
*Now open the trap door after 5 min and allow the
concrete to flow down.
*Calculate the time taken for complete fall of concrete.
It is called the flow time at T5 min.
ACCETABILITY:
*For v-funnel test the flow time should be b/w 8to12min
*for v-funnel at T5 min,+3 sec is allowed i.e.,11 to 15 min

22. L-BOX TEST
*This test is used to know the passing ability
of concrete.
PROCEDURE:
*About 14 litres of concrete is taken and fill
the
vertical section of L-BOX.
*Lift the gate and allow the concrete to flow
out into the horizontal section.
*Start the stop watch and note down the time
taken to reach 200 and 400mm marks.
*When the concrete stop flowing the heights
H1 and H2 are measured.
*Calculate blocking ratio H2/H1.
*The test is to be performed within 5 min.
ACCEPTABILITY:
*If the concrete flows like water then H2/H1=1
*The minimum acceptable value is 0.8.

23. U-BOX TEST
*This test is done to measure the passing ability of
concrete.
PROCEDURE:
*About 20 litre of concrete taken and is poured on
one
of the side of u-box.
*Leave it stand for 1 min . Lift the sliding gate
and allow
the concrete to flow to other side.
*Once the concrete has come to rest measure the
height of
concrete at both sides.
*H1 is the height of concrete in 1st compartment
*H2 is the height of concrete in 2nd compartment
*Calculate the filling height H1-H2.The whole test
is to
be completed in 5 min.
ACCEPTABILITY :
*If the concrete flows like water , then H1-H2=0.It
represents the better flow and passing ability of
scc.

24. Fill Box Test
 The apparatus consists of a clear plastic box with
35 plastic 20 mm diameter bars, as shown in Figure.
 Concrete is poured at a constant rate into the
funnel and allowed to flow into the box until the
height of the concrete reaches the height of the
top row of bars. After the concrete comes to rest,
the height of the concrete at the two ends of the
box is measured.

25.  These measurements of the height of the concrete
at the side nearest the funnel, h1, and
the height at the opposite end, h2, are used to
calculate the average filling percentage:
 Filling percentage =( h1+h2/2h1)*100
 The closer the filling percentage is to 100%,
the greater the filling ability of the
concrete.

26. GTM SCREEN STABILITY TEST
• Equipment
10 Litre Bucket with lid
5 mm sieve 350 mm diameter
Sieve pan
Balance, 20 g minimum capacity 20 kg
Stopwatch

27.  To perform the test, a 10 liter sample of concrete is
placed inside a bucket and allowed to sit for 15
minutes to allow any internal segregation to occur.
The container is sealed to prevent evaporation. After
sitting for 15 minutes, the top approximately 2
liters of the concrete is poured from the bucket into
a smaller pouring container. This 2 liter sample of
concrete is then poured from a height of 500 mm onto
a 5 mm sieve. Mortar from the sample is allowed to
flow through the sieve into a lower sieve pan for a
period of 2 minutes. The mass of the concrete poured
onto the sieve, Ma, and the mass of mortar in the
sieve pan, Mb, are measured and used to calculate the
segregation ratio:
Mb/Ma * 100%
 The segregation ratio should be between 5-15% for
acceptable segregation resistance. Concretes with a
segregation ratio above 15% will exhibit too much
segregation. Severe segregation is suspected if the
segregation ratio is above 30%. If the segregation

28. HOW ECONOMICAL IS SCC?
• The cost of scc is lower than normal concrete of
high strength.
• The cost of construction of scc material is
about 10-15% higher than normal concrete.
• But the cost of compaction , finishing etc will
be low for scc and it leads to labour savings.

29. ADVANTAGES OF SCC
 Reduction in site manpower
 Problems caused by vibrators are reduced
 Easy to place
 Faster construction
 Better surface finish
 Improves durability due to better compaction and
homogeneity of concrete

30. DISADVANTAGES OF SCC
 Higher paste volume results in greater
shrinkage and creep.
 The mix design and procedure adopted is too
complicated for practical implementation
 It requires more trial batches
 Costlier than conventional concrete based on
materials(except placement costs)

31. CONCLUSION
Self compacting concrete can save time , cost
, enhance durability.
Scc can be effectively transferred in
congested reinforced areas such as columns ,
drilled shafts.