Application of Self Compacted Concrete in Precast

Industry :

Sustainability Technology with Green Concrete

by :

Gambiro Soeprapto

(PT Wijaya Karya Beton)

Self-compacting concrete (SCC) is an innovation of concrete which not

require for placing and compacting.

Concrete is able to flow :

• Gravity or self weight

• Fill the mould with full compactness

• Pass through the closed reinforcement.

Concrete has density, homogenous, engineering properties and durability

as well as with concrete which is compacted in conventional method.

SELF COMPACTED CONCRETE

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CRITERIA :

• Self Compaction : the level of fluidity of proportion is

able to compact concrete itself without external energy.

• Deformability : concrete mixing is homogen in

formwork during and after placing.

• Flow Ability :Easy to flow and breakthrough the closed

reinforcement.

• High Resistance to Segregation : coarse aggregate

can be float in mortar without segregation

[stablilizer/viscosity-modifying agents, fines material

(< 150 m)]

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MATERIAL COMPOSITION OF SCC

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SCC Type based on mortar composition

1. Powder Type

• Reduction of water/powder ratio (material < 0.1 mm)

• Sufficient in resistance to segregation.

• Super plasticizer dan air entraining admixture as requirement of

deformability.

2. Viscosity-modifying agent (stabilizer) type

• To use viscosity modifying admixture to obtain resistance of

segregation.

• Super plasticizer dan air entraining admixture as requirement of

deformability.

3. Combination Type

• Reduction of water/powder ratio, viscosity modifying admixture to

reduce fluctuation the quality of fresh concrete due to the variation of

surface moisture content and gradation of aggregate during

production.

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1. Improve Concrete Quality:

• Concrete easy pass in tight reinforcement, difficult access etc..

(passing ability)

• Concrete able to fill the gap around the reinforcement and space

between the reinforcement and formwork (good filling ability)

2. Protection to Environment and Human Health :

• SCC can reduce the noise around factory, site and surroundings.

• SCC reduce vibration effect of compaction tool for the health of worker.

• SCC shortens construction or production time with acceleration

process, especially for precast industry.

ADVANTAGES of SCC

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3. Economical and time savings :

• Easy concrete placing will reduce the worker and tool, so it improve

productivity and save the cost..

• SCC reduce usage time and mold defect, so it extend durability of

mold.

• SCC can reduce the number of worker. Normally it is needed 1.5

manhours, whereas SCC can minimize it to be 0.35 manhours

• SCC reduce cost and energy consumption, because it has high

fluidity and concrete can be placed without vibration.

• SCC can reduce cost and worker for finishing to precast component.

• SCC can increase capability of concrete supplier to give better

consistency during delivery.

(…… continued) 6

3. Economical and time savings : (continue ….. )

• Worker capability in steel reinforcement assembly does not affect

construction with SCC.

• Reducing of toll can prevent work accident.

• SCC can be made as production mass.

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The reducing of cement will contribute positive effect to

environment such as :

• Energy for cement production can be saved.

• Heat of cement hydration can be reduced.. Excessive heat of

cement hydration will increase temperature around it.

EFFECT TO ENVIRONMENT

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Flowability and resistance to segregation of SCC are obtained by :

1. More fine particles are subtitute coarse aggregate partially. The coarse

aggregate content is limited to prevent seggregation (lubricate coarse

aggregate).

2. The low water/powder ratio [powder = cement + filler (fly ash, silica fume

etc..)] can prevent seggregation.

3. Superplasticizer can be increase flow ability (reduction liquid limit and

improve workability) (Okamura dan Ouchi, 2003 dan Audenaert et al., 2002)

4. Viscosity modifiers admixture can prevent seggregation (increase viscosity.

Flowability and resistance to segregation of SCC

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Admixture Type Functtion

1 High Performance

Superplasticizer (HRWR)

Improve the cement dispersion

(workability and flow ability)

2 Viscocity Modifying Admixture Segregation Resistance

THE ROLE OF ADMIXTURE

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Typical Dosage

(ratio to cement

weight)

Water reduction

Modified ligninsulphonates

(MLS)0.2 – 0.8 % until 10 %

Melamine sulphonates (SMF) 1.0 – 3.0 % until 25 %

Napthalene sulphonates (SNF) 0.8 – 2.0 % until 25%

Polycarboxylic ethers (CE) 0.5 – 1.5 % Until 40 %

Performance of water reducing admixtures

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Wika Beton applies SCC for non-centrifugal member such as I girder, box

girder, sheet pile, square pile etc.

SCC gives saving such as :

1. Reduce 10 – 30 % for consumption of cement.

Cement saving can be get with 2 methods :

• Usage of superplasticizer will reduce water consumption. With constant

w/c ratio and water reduction, it also will reduce the cement.

• Usage of silica fume as cementitious material can reduce the cement.

2. Saving until 3 % for energy consumption.

3. The number of concreting worker can be reduced until 50 %.

4. Concrete placing time can be saved 25 – 40 %

Wika Beton Experience

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1. The knowledge about SCC is not still limited. Sometimes SCC

just mean only flow concrete.

2. Indonesia does not have code about SCC. Slump control with

spread measurement is still assumed as uncommon method.

3. Quality of natural materials have not been ensure continuously.

4. Additive material as substitution of cement has not been

assume as needs, even so the usage of additional materials as

cement replacement is not essential, even sometimes is not

permitted.

Constraints in application of SCC

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THANK YOU