Self-compacting concrete (SCC) is considered as a concrete which can be placed and compacted under its own weight with no vibration. It is not affected by the skills of workers, the shape and amount of reinforcing bars or the arrangement of a structure. Due to its high-fluidity and resistance to segregation, it can be pumped longer distances. It consists of the same components as conventionally vibrated concrete, which is cement, aggregates, and water, with the addition of chemical and mineral admixtures in different proportions. Usually, the chemical admixtures used are superplasticizers and viscosity-modifying agents. SCC is especially useful in confined zones where vibrating compaction is difficult.

1. SELF COMPACTING
CONCRETE
Presented by,
Ahsan Rabbani
Civil Engineering Department

2.  Self-compacting concrete (SCC) is considered as a concrete which
can be placed and compacted under its own-weight with no vibration .
It is not affected by the skills of workers, the shape and amount of
reinforcing bars or the arrangement of a structure.
Due to its high-fluidity and resistance to segregation it can be pumped
longer distances .
It consists of the same components as conventionally vibrated
concrete, which are cement, aggregates, and water, with the addition of
chemical and mineral admixtures in different proportions .
Usually, the chemical admixtures used are super plasticizers and
viscosity-modifying agents.
SCC is especially useful in confined zones where vibrating compaction
is difficult

3. Development of SCCDevelopment of SCC
 In 1986, concrete capable of compaction by its own weight withIn 1986, concrete capable of compaction by its own weight with
no need of vibration was proposed (Concept given by Professorno need of vibration was proposed (Concept given by Professor
Hajime Okamura).Hajime Okamura).
 In 1988, first successful prototype of self compacting concreteIn 1988, first successful prototype of self compacting concrete
was developed in the University of Tokyo by Prof. K. Ozawa.was developed in the University of Tokyo by Prof. K. Ozawa.
 SCC, that can be compacted in every corner of form work by itsSCC, that can be compacted in every corner of form work by its
own weight, gained market thereafterown weight, gained market thereafter
*Three essential features envisaged*Three essential features envisaged
during designduring design

4. Achieving self
compactability
 Increased w/c ratio increases
deformability but increases
segregation too
 Reducing coarse aggregate
reduces friction and collision,
supplying intense energy for
flow
 Increase in deformability with
constant viscosity became
possible by superplasticizer

5. Key Characteristics of SCC
 Filling ability:-Ability of scc to flow into
all spaces within the formwork under its
own weight.
 Passing ability:-Ability of scc to flow
through tight openings under its own
weight.
 Resistance to segregation:- Maintaining
homogeneity throughout mixing &
during transportation & casting.

6. EXPERIMENTAL PROGRAM
Materials:-Locally available materials were used for preparing the concrete mixes.
(a) Cement: OPC 43 grade having
soundness “0.6 mm”, initial setting
time “52 mins” & final setting time
“430 mins”.
(b) Fine aggregate :Natural
river sand having
sp.gr.“2.64”,fineness modulus
“2.7” & water absorption”1%”
(c) Coarse aggregate : Maximum size
of aggregate is limited to 20mm. 10-
12mm is desirable for structures
having congested reinforcement.
(f) Water: Potable tap water
having pH of “7.3”
(e)Fly Ash: Some quantity may be
added to improve the quality and
durability of SCC.
(d) GGBS: Some quantity
may be added to improve
rheological properties.
(g) Chemical admixture: Super plasticizer &
Viscosity Modifying Agents are used.
An experimental program was developed to study the effect of size of
aggregates on the strength of self compacting concrete made with two filler
materials viz. Fly-ash and GGBS.

7.  Generally air content may be assumed to be 2%.
 Coarse aggregate content in concrete is fixed at 50% of the solid
volume.
 Fine aggregate is fixed at 40% of the mortar volume
 W-p ratio by volume is assumed between 0.9 to 1
 Superplasticizer dosage and the final water-powder ratio are
determined so as to ensure self compactability
Procedure:-The following sequence is followed
•Determine the desired air content.
•Determine the coarse aggregate volume.
•Determine the fine aggregate content.
•Finally the concrete properties are assessed by
standard test.

8. The most basic test for self-compact ability is U-flow test
Height, H> 300 mm
LaboriousLaborious
Figures: U-test apparatus
(Source: H. Okamura & M. Ouchy/ J.
Adv. Conc. Tech. 1(1), 5-15, 2003)
Slump flow ,V-Slump flow ,V-
Funnel ,L-B0x ,Funnel ,L-B0x ,
J-Ring test etc.J-Ring test etc.
OtherTest

9. This test gives good assessment of filling ability of concrete.
The higher the flow value, the greater
its ability to fill formwork under its
own weight.
Fill the cone with the scoop. Raise the cone vertically and allow
the concrete to flow out freely .
Time taken for the concrete to reach the 500mm circle was
recorded (This is the T50 time).
Measure the final diameter of the
concrete in two perpendicular
directions. Calculate the average of the
two measured diameters. (This is the
slump flow in mm).
6
ltrs

10. This test gives filling ability of the concrete.
The apparatus consists of a V-shaped box is made with a narrow
opening at the bottom (a gate is fixed ) & a bucket of 12 liters capacity.
The total time taken by the SCC discharge was in
the range of 6- 12 sec in the experiment
About 12 liters’ of concrete was filled into V-funnel without any compaction
and concrete was leveled with a trowel
After 5 second trap door was opened and concrete was allowed to flow under
gravity.
The time taken was recorded for the complete
discharge using a stop watch..
12
ltrs

11. This test is a measure of the passing ability as well as filling ability of concrete.
The apparatus consists of a rectangular section
box in the shape of 'L' with a vertical and
horizontal section separated by a movable gate.
The computed ratio of h2/hl for the SCC mix was between 0.8-0.9.
The computed ratio of H2/H1 for the SCC
mix was between 0.8-0.9.
Figure:-L-Box Test
14 liters
of
concrete
needed
When the concrete stops flowing , height H1
and H2 are measured.
The time taken by the concrete to reach these
points were recorded .
The horizontal section was marked with 200
mm and 400mm markings from gate.

12. METHOD
(TEST)
UNIT TYPICAL RANGE OF VALUES
MINIMUM MAXIMUM
Slump Flow (T50 cm) Seconds 2 5
Slump Flow by Slump Cone mm 650 800
V- Funnel at t = 5 seconds 6 12
L – Box H2
/H1
0.8 0.9
U - Box ( H1
-H2
) mm 0 30

13.  SCC is considered as the “most revolutionarySCC is considered as the “most revolutionary
development in concrete construction fordevelopment in concrete construction for
several decades”(Source: EFNARC guidelines)several decades”(Source: EFNARC guidelines)

14. Uses of SCC
Akashi-Kaikyo bridge: longest suspensionAkashi-Kaikyo bridge: longest suspension
bridge in the world (1991 m long suspension)bridge in the world (1991 m long suspension)
SCC
SCC
*SCC has been successfully utilized in almost all sectors that utilized
conventional concrete: like dam, bridge, tunnel, culverts, walls,
ordinary and high rise buildings
*Proved highly beneficial for precast concrete industry
*As of 2006, SCC makes up about 5% of the Japanese concrete
market and around 15% of the Danish and Swedish markets.
Osaka Gas Terminal:Osaka Gas Terminal:
the World’s Largest PC LNGthe World’s Largest PC LNG
Storage TanksStorage Tanks
Remains the largest
single application of
SCC (500 000 m3)
Opened in April 1998.