Concrete Technology Project: Self Compacting Concrete
Introduction:
In the current era of
construction industry attractive designs are the frontier leading part of the
any building. New attractive as well as unique building designs impose
challenges in the design field of the construction. Design of elements will be
as complicated as the design of building. These challenges of design require an
elegant solution in the materials as well. We need to identify new unique and
special materials as well as its methods of application to face the design
challenges and fulfill the criteria of stability and safety along with beauty
of the structure. Use of special concrete is one of the alternate options to
fulfill the said criteria. For the current article we are going to discuss the
self compacting concrete. This special type of concrete has made its unique
place in the industry due to its properties and ease of use.
Basics of Self Compacting Concrete:
The self compacting
concrete covers each and every void and corners between dense reinforcement
with help of its own weight without application of compaction. It is a special
type of high performance concrete having higher fluidity with resistance
against segregation[1][3][4][5]. After the primary identification of
performance of this concrete in 1988 it was named as high performance concrete
which was later on changed to self compacting high performance concrete. The
property analysis and the important identification about the self compacting
concrete were completed by Ozawa K. et al. (1990) [1][5] under the framed
advisory group in the University of Tokyo. The advancement in the self
compacting concrete was compiled and through the work of H. Okamura (1997) [1][3].
There are other names for this concrete like self consolidating concrete, self
leveling concrete, super workable concrete etc.[1] The specification guidelines
about the SCC, its material, its application and other several topics are
covered in the standard code named EFNARC.
It is a special type of concrete that can cover every spot of corners and tiny gaps between dense reinforcements without any type of provision of compaction just with the help of its own weight. It is also known as a special kind of High Performance Concrete (HPC) with greater fluidity and excellent resistant towards segregation [1][3][4][5].
Advantages: [1] [2]
- Higher fluidity
- Improves rate of concrete placing
- Zero compaction requirement
- Cost effective option
- Smooth surface, reduces surface works
- High workability provides filling up gaps between dense reinforcement
- Due to high fluidity, can be placed and form any shape helps to achieve aesthetic architectures
- Possess good bonding with reinforcement
- Fine dust can also be incorporate with SCC mix, helps to avoid higher disposal cost of processing of fine dust
- Thin sections can be cast due to high filling ability, provides practical approach towards economic sections
- Providing higher resistance against segregation
- Eliminates air bubbles from the concrete mix
Materials:
The
SCC is produced by the mixing of special admixtures in the conventional
concrete ingredients. That concludes that common concrete ingredients as per
the standards should be selected. Rather than common ingredients SCC comprises
superplasticizers which are of two different types. One is high range of water
reducer (HRWR) and other one is viscosity modifying agent (VMA). Where HRWR
used in large amount in contrast VMA is used in very small portions[2].
Considering the proportion of admixture is a very essential topic for the mix
design calculations as error in admixture calculation leads to the damage of
concrete. In addition, not only admixtures but conventional ingredients are
also need to be selected for the suitability. In the mix of SCC maximum 20 mm
size of aggregates are to be utilized. The complete proportion guidelines and
specifications for the powder content, paste, water, water / powder ratio,
coarse and fine aggregates are provided in the EFNARC guidelines. It is
advisable to work along with Indian standards and European standards as well in
case of SCC for the better performance.
Method:
For
the application of SCC there are two common methods in the industry. The first
method is known as powder method in which superplasticizers are mixed with the cementitious
materials to form a paste. The paste imparts the high workability and keeps the
constituents together. The second method is known as admixture method in which superplasticizers
are mixed in the concrete mix as an admixture. The admixtures are introduced in
the mix by the medium of water with precise proportion.
Methodology:
- Identifying the area to be explored for the SCC
- Selection & purchase of appropriate admixtures
- Mix design calculations as per Indian standard code along with EFNARC guidelines
- Production of SCC as per the calculated materials from the mix design
- Discussion of result and analysis
- Conclusion
Project Scope:
There
are numbers of scope for the academic research project related to concrete technology
specifically for the property analysis in terms of effects of other materials.
Working on SCC is the same as working with conventional concrete and modifying
it with several agents to check their effects. Some of the possible area or
basic topics are listed below for the SCC. The presented list topics are just
not the limitation. You can explore the SCC by your own views and innovative
ideas. The list only comprises the basic ideas that can be explored at the
under graduate or post graduate level.
- In depth Review on Self Compacting Concrete
- Comparison of conventional concrete and SCC in terms of strength characteristics
- Comparison of conventional concrete and SCC in terms of general properties and behavior
- Analysis of SCC properties by applying other admixtures in solid/chemical form
- Partial or complete replacement of fine aggregate in SCC & identifying its behavior
- Partial or complete replacement of cementitious materials in SCC & identifying its behavior
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