Self-Compacting Concrete or Self Consolidating Concrete (SCC) is a highly flowable, stable concrete which flows readily into place, filling formwork without any consolidation and without undergoing any significant segregation. The use of SCC eliminates the need for compaction therefore saving time, reducing labor costs and conserving energy.Fresh SCC must possess the key properties including filling ability, passing ability and resistance to segregation at required levels. The filling ability is the ability of the SCC to flow into all spaces within the formwork under its own weight. Without vibrating the concrete, SCC has to fill any space within the formwork and it has to flow in horizontal and vertical directions without keeping air entrapped inside the concrete or at the surface. Passing ability is the ability of the SCC to flow through tight openings such as spaces between steel reinforcing bars, under its own weight. Passing ability is required to guarantee a homogenous distribution of the components of SCC in the vicinity of obstacles. The resistance to segregation is the resistance of the components of SCC to migration or separation and remains uniform throughout the process of transport and placing.

1. SELF-COMPACTING CONCRETE
Dr. M.L.V.PRASAD
Department of Civil Engineering
NIT Silchar

2. SELF-COMPACTING
CONCRETE

3. SELF-COMPACTING
CONCRETE

4. SELF-COMPACTING
CONCRETE

5. Threats to future of Concrete
•Shortage & availability of natural Aggregate
•Increasing quantity of steel (Cost & Possibility of
corrosion)
•Perceived lack of concrete durability
•Increased Labour Cost
•Availability of Skilled Labour
•Reluctance to change methods and practices
•Reluctant to specify and use new materials and new
methods
•Gross delays in revision of Indian standards to match the
global research and development

6. Defined as a concrete, which can be placed and
compacted in to every corner of form work, purely by
means of its self-weight without any compacting effort.
Also referred as Self Consolidating Concrete, Super
workable concrete, Non-Vibrating concrete.
SCC is highly flowable, non segregating concrete
that can spread into place, fill the frame work and
encapsulate the reinforcement without any
mechanical consolidation-ACI 237
Self Compacting Concrete

7. Historical Development
 Intention behind developing this was the concerns
regarding the homogeneity and compaction of cast-in-
place concrete within congested reinforcement
sections.
And also improvement of over all durability due to
lack of skilled labor.
Originated from research into in-situ concrete piling,
filling of inaccessible areas and under water concrete
technology.

8. CASTING PROBLEMS WITH CONVENTIONAL
DRILL-SHAFT CONCRETE

9. CASTING PROBLEMS WITH CONVENTIONAL
DRILL-SHAFT CONCRETE

10. The Important Properties
 Self-compactability
 Avoidance of bleeding and segregation
 Low shrinkage
 Low permeability
 Strength as needed

11. The Benefits
 Faster Construction
 Reduction in site manpower
 Better appearance
 Easier Placing
 Improved durability
 Thinner concrete sections
 Reduced noise levels, absence of vibration
 Safer working environment

12. What’s Different?
 Segregation resistance from mortar
viscosity, not aggregate grading
 Workability through admixtures, not
water content

13. What’s The Snag?
 Higher cost – especially if high strength
not needed
 Plant control has to be better

14. What is the secret?
Paste Viscosity! Attained by one of three
means:
 High cement content
 High content of Fly Ash, Silica Fume etc
 Use of Viscosity Modifying Admixture
Plus low water content using HRWR

15. Constituent Materials of SCC
Cement +Additions +Aggregate +Admixture +Fibers +Water
Self compacted concrete
•Additions : Stone Powder,Mineral Filler, Fly ash, Silica
Fume, Ground Blast furnace Slag (GGBS), Other
additions (i.e Metakaolin,natural pozzolana, ground glass
etc.,)
•Aggregate : Coarse & Fine Aggregate
•Admixture : Super plasticiser/ High range water reducing
admixtures (HRWR), Viscosity modifying admixtures
(VMA), Air entaining admixtures
•Fibres : Metallic and polymer fibres

16. How to Check Suitability?
 There are some important tests: V-
funnel, L-box, U-box, Slump Flow and J-
ring
 While several of these may be used in
mix development, mainly the slump test
will find site use

17. WORKABILITY TESTS ON
VIBRATED CONCRETE

18. Tests on SCC
H-FLOW TEST
J-RING TEST

19. Tests on SCC
L-BOX TEST
V-FLOW TEST

20. Tests on SCC
U-BOX TEST
SCC WORK IN PROGRESS

21. Traditional Concrete
•Vibration required
•Skill dependent
•Labour intensive
•Quality varies
Self Compacted Concrete
•No Vibration needed
• Faster Construction
• Less Noise
• Improved quality and
durability

22. Why Does It Look Better?
 Perfect compaction
 No bleeding

23. S.No Method Unit Typical range of values
Minimum Maximum
1 Slump flow by Abrams cone mm 650 800
2 T50cm
Slump flow sec 2 5
3 J-ring mm 0 10
4 V-funnel sec 6 12
5 Time increase, V-funnel at T-5 min
sec 0 +3
6 U-box (h2
-h1
)mm 0 30
EFNARC SPECIFICATIONS

24. For SCC, the powder content is in
between 160 and 240 litres/m3.
Flyash is to
be added in addition with the cement
content obtained.
Extra volume of fly ash added is
replaced to coarse aggregate.
Some quantity of cement is also
replaced by fly ash. The fly ash
replacement is varying from 5 to 20 %.
MIX DESIGN

25. After obtaining the quantity of cement and fly
ash for different grades, the optimum dosage of
super plasticizer for each grade has been arrived
by conducting basic tests on SCC.
The total aggregate content obtained is
distributed to the ratio of 50: 50 for sand and
coarse aggregate.
The water content obtained is taken as it is and
the check is to be made that the maximum water
should not exceed 210 litres/m3
.
MIX DESIGN

26. Grade Normal Concrete
by ACI
SCC
by ACI
Normal Concrete
by IS
SCC
by IS
M20 1:2.38:2.65:0.51 1:2.65:2.20:0.53 1:1.48:3.36:0.49 1:2.67:2.19:0.54
M25 1:2.26:2.55:0.49 1:2.49::2.18:0.52 1:1.30:2.96:0.44 1:2.51:2.15:0.51
M30 1:2.02:2.39:0.45 1:2.36:2.14:0.49 1:1.17:2.65:0.42 1:2.35:2.07:0.49
M35 1:1.74:2.12:0.4 1:2.15:1.97:0.46 1:1.09:2.48:0.40 1:2.21:2.03:0.47
M40 1:1.46:1.89:0.36 1:1.97:1.82:0.43 1:1.03:2.32:0.36 1:1.97:1.85:0.44
MIXES DEVELOPED

27. S.No Method Unit
With out
Fiber
With
PPF
With
GF
EFNARC
Specifications
1.
Slump flow by Abrams
cone
mm 725 723 720 650-800
2.
T50cmslump
flow
sec 4.00 4.10 4.15 2-5
3. V-funnel sec 4.11 4.13 4.17 Upto 12
4.
Time increase,
V-funnel at T5minutes
sec 1.00 1.24 1.30 0-3
5. J-ring mm 8.0 8.9 8.6 0-10
6. U-box mm 23 34 28 0-30
SCC Properties

28. Applications of SCC
AKASHI KAIKYO BRIDGE KAIGA PROJECT

29. Will it happen?
 My guess is that 50% of concrete will be
self-compacting within 10 years
 In USA and Japan and many European
Countries a very large proportion of precast
concrete is already SCC

30. CONCLUSION
 We are going to expect concrete that is a little
more expensive per cubic metre to buy
BUT
 It will require less skill and effort to place
 It will look better with no appearance defects
 It will be more durable
 It will require a little more skill at the batching
plant

31. THANK YOU