This document provides an overview of self-consolidating concrete (SCC), including:
- What SCC is and its history beginning in 1986 in Japan.
- The key benefits of SCC are reduced labor, faster construction, and improved quality due to its ability to flow and fill formwork without mechanical consolidation.
- Case studies demonstrate significant schedule and cost savings achieved with SCC on large, complex projects.
- SCC has similar hardened properties to traditional concrete if designed properly, though special attention must be paid to shrinkage and temperature control with large pours.
- Proper mix design, focusing on paste content and viscosity-modifying admixtures, is required to develop the
2. TABLE OF CONTENTS
INTRODUCTION........................................................................................................................................ 1
WHAT IS SELF-CONSOLIDATING CONCRETE?............................................................................... 1
HISTORY...................................................................................................................................................... 1
BENEFITS .................................................................................................................................................... 1
CASE STUDIES ........................................................................................................................................... 2
ENGINEERED/HARDENED PROPERTIES........................................................................................... 3
MIX DESIGN ............................................................................................................................................... 5
BEST PRACTICES...................................................................................................................................... 8
TESTING METHODS................................................................................................................................. 9
LIMITATIONS OF SCC............................................................................................................................10
SCC AND FORMWORK ...........................................................................................................................11
TRAINING...................................................................................................................................................12
SCC APPLICATIONS................................................................................................................................12
SUMMARY..................................................................................................................................................14
APPENDICES
APPENDIX A – SELF-CONSOLIDATING CONCRETE MIX DESIGNS
APPENDIX B – PLACEMENT TIME AND LABOR
APPENDIX C – FORMWORK PRESSURES OF SELF-CONSOLIDATING CONCRETE
APPENDIX D – SELF-CONSOLIDATING CONCRETE AND MASS MAT APPLICATION
APPENDIX E – COST ANALYSIS
APPENDIX F – PRE-POUR CHECKLIST EXAMPLE
REFERENCES
3. 1
Introduction
Self-consolidating concrete (SCC) is a
high-performance concrete that has been a
growing commodity among the construction
industry acting as an alternative to conventional
concrete. While SCC was first introduced as a
solution for durability, engineers and contractors
have seen the added benefits, which have
propelled its popularity. It should be noted that
self-consolidating concrete is in no way intended
to be utilized for all concrete structures. The
production team must consider the benefits and
weigh the organizational and project constraints
to determine if self-consolidating concrete is the
correct alternative for their project. This
document will act as a general overview,
shedding light on the benefits, limitations, and
examples of SCC to answer questions and
dismiss any misconceptions. Thus, it is
encouraged for those who choose to utilize self-
consolidating concrete to further educate
themselves and their team on all of self-
consolidating concrete’s characteristics.
What is Self-Consolidating Concrete?
Self-consolidating concrete (SCC) is
highly flowable, non-segregating concrete that
can spread into place, fill the formwork, and
encapsulate the reinforcement without any
mechanical consolidation. In general, SCC is
concrete made with conventional concrete
materials and, in some cases, with a viscosity-
modifying admixture (VMA). SCC has also
been described as self-compacting concrete,
self-placing concrete, and self-leveling concrete,
which are all subsets of SCC.1
SCC is composed of similar materials as
traditional mixes; Portland cement, fine
aggregate, coarse aggregate, water, chemical
admixtures, and typically supplementary
cementitious materials such as fly ash, slag,
silica fume, and metakaolin. In some cases,
limestone powder or very fine sands are used to
increase the mixture’s powder or fine material
content. Because common materials are used,
evaluating the performance of SCC relative to
conventional concrete either in a laboratory
setting or in full-scale production can be a fairly
simple process.2
History
SCC was conceived by Professor
Hajime Okamura of Japan in 1986 to address the
growing durability concerns from the Japanese
government, stemming from inadequate
consolidation of concrete. Because of its
success, by 1988, the concept of SCC was
developed and ready for full-scale testing.
Since its development, SCC has been a
growing commodity among the construction and
engineering community, acting as a critical
component to some of the most revered projects
of the modern era; such projects include The
Freedom Towers, Trump Tower, and the Burj
Khalifa.
What once was a thought conceived by
Professor Okamura has now grown into a
formidable technology that provides an
economical and high-performance alternative to
some of our industries most complex problems.
Benefits
The use of SCC on a project can result
in cost and performance benefits when properly
proportioned and placed. The following is a list
of recorded benefits taken from the American
Concrete Institute (ACI 237) 2
:
• Reduced Labor and equipment:
o Since SCC’s main characteristic
is self-consolidation, there is no
need for vibration during
placement operations, which
results in a reduction of labor
man-hours and eliminates the
need for mechanical vibration
equipment.
o Due to SCC’s ability to self-
level, there is a reduced need to
screed after placement to ensure
flat surfaces.
• Accelerated construction because of the
ability to place or cast structures at a
higher rate.
• Expedite the filling of highly reinforced
sections and complex formwork while
ensuring good construction quality. This
can ensure better productivity, reduce
the labor requirement and cost, or both.
4. 2
• Enable more flexibility in spreading
placing points during casting. This can
reduce the need for frequent movement
of transit trucks and the need to move
the pump lines to place concrete. A
greater flexibility in scheduling
construction activities and procuring the
required resources results in both time
and resource savings.
• Reduction in noise pollution, which can
be critical in urban areas and for
sections requiring heavy mechanical
vibration:
o Reduce the need of vibration for
construction typically requiring
the use of heavy consolidation
(such as fiber-reinforced
concrete and precast
operations). In some cases, the
use of noise-free or silent
concrete can potentially extend
construction hours in urban
areas, enabling the scheduling
of some construction activities
during otherwise curfew periods
to alleviate difficulties related to
traffic conditions in urban areas;
and
o Diminish insurance premiums.
Precasting facilities generating
considerable noise pollution are
sometimes required to pay
premiums to national insurance
agencies responsible for
eventual treatment of hearing-
impaired workers. Insurance
premium reductions can
partially offset the additional
material cost of SCC, making it
attractive for precast operations.
• Decrease employee injuries by
facilitating a safer working environment
where strenuous and labor-intensive
operations can reduce safety hazards.
• Permit more flexibility for detailing
reinforcing bars. Avoid the need to
bundle reinforcement to facilitate
placement and consolidation, and in
some cases, enable the use of small and
closely spaced reinforcing steel to
control cracking.
• Create smooth surfaces free of
honeycombing and signs of bleeding
and discoloration, obtained when using
a well-proportioned SCC mixture, high-
quality formwork with an adequate
release agent, and sound placement
practices.
• Eliminate the need for materials, such as
underlayments that are used to level and
prepare substrates for final flooring
materials, such as carpeting and tile,
whenever allowed by building
regulations.
Case Studies
The following case studies saw direct
benefits through the use of SCC via performance
and/or value engineering.
The Freedom Tower (Tower 1) at the
World Trade Center site is 1,776 feet tall. The
shear walls were 16,149 psi @ 56 days (modulus
of elasticity of 7,700,000 psi) from the
foundation to 70 feet above street level. 12,000
psi concrete was used for the remainder of the
tower. (Modulus of elasticity is a key
requirement for high-strength concrete used for
construction of tall buildings).3
SCC was chosen
for this monumental project because of its high
compressive strength, modulus of elasticity, and
its ability to be pumped vertical distances with
ease.
The Trump Tower in Chicago, Illinois
was a major user of SCC. It is a 92-story
reinforced concrete project that required 4,600
cubic yards of SCC to be cast-in-place
continuously for 22 hours to construct the mat
foundation that supports the finished structure.
The mix had a 7-day compressive strength of
9,950 psi and a 28-day strength of 12,000 psi.
This single pour is the largest ever recorded to
date in North America using SCC and is
nicknamed “The Big Pour.”3
Because the mat foundation was
approximately ten feet thick and required 4,600
cubic yards, it had to be treated as mass
concrete. The project team had to work closely
with the local batch plant to limit the
5. 3
temperature differential between the core of the
mat and the ambient temperature.
Although the exact mix design isn’t
known, materials such as, grade 120 slag cement
and Class C-fly ash were used to mitigate the
heat of hydration.
The Burj Khalifa is the tallest building
in the world and located in Dubai, United Arab
Emirates. SCC was utilized in both the cast-in-
place piles and the 3.7 meter thick mass mat
foundation. Specifically, SCC was pumped over
600 meters vertically using two of the world’s
largest pumps to cast the tower’s core and in
order to mitigate the risk of thermal cracking,
due to heat of hydration, concrete pours were
performed during the night.
The Pearson International Airport is one
of the largest projects to utilize SCC technology
in Canada. There was 2,745 cubic yards of
Ready-Mix SCC successfully placed in 180
columns, 101 feet tall by 28 inches in diameter.
Since there was insufficient overhead clearance
to allow placement of concrete using
conventional methods, the concrete had to be
pumped from the bottom of the columns and this
could only be achieved by using SCC.
The traditional method would have been
to fill the column through portholes at different
levels, with no assurance of the overall quality
(consolidation, segregation, etc…) of the
concrete inside the column. This method would
have incurred additional cost and a longer
placement window.8
SCC was able to meet all challenges of
the project while retaining quality assurance and
providing a cost effective solution.
An LNG Storage Tank in Tokyo, Japan
at the Hitachi terminal is the largest above
ground cast-in-place tank in the world. The
approximate height and inner diameter of the
structure is 194 ft. by 282 ft.
The case study indicates that due to the
utilization of SCC to cast the walls, the
contractor was able to reduce the labor force
from 150 to 50 laborers, and the duration of
construction reduced from 22 months to 18
months.
Kaikyo Bridge, also known as the Pearl
Bridge crosses the busy Akashi Straight in
Japan. The contractor performed months of
upfront testing and trial batches in order to
produce an SCC mix that could be pumped from
the shore to the bridge’s foundations. By using
this innovative method, the contractor was able
to eliminate the need for concrete trucks and
reduced the project schedule from 2.5 to 2 years.
From the highlighted case studies, one
can concur that there is great opportunity by
using SCC on a project. The high performance
characteristics of SCC result in more durable,
longer lasting structures. Most case studies
highlighted saw a significant percentage of labor
reduced on the affected operations. This
reduction in labor force is a direct safety benefit
for that operation using SCC and the labor
reduced can then be used on other operations to
accelerate the projects schedule.
Being able to estimate and quantify the
benefits of SCC is the true challenge. Site
specifics will yield varying results from project
to project and some items may not be as easily
captured from the estimate, such as, project
schedule, safety, and patching labor.
Engineered/Hardened Properties
When SCC was first introduced to North
America questions were raised in regards to the
engineered properties based on two common
areas:
1) A frequent misconception that a higher
slump and a more fluid mixture
adversely affects the quality compared
to traditional mixes.
2) In its infancy, SCC called for a higher
paste and sand content which raised
concern with shrinkage and creep.
Do the engineered properties of an SCC
mixture really vary all that greatly when
compared to traditional mixes? In this section,
the engineered properties will be further
explained and hopefully provide the reader with
a general overview and more familiarity with the
various properties. This section is in no way
intended to provide the reader with equations,
engineering conclusions, or testing data that
would bypass the need to perform the proper
testing to develop an SCC mix design.
6. 4
Compressive Strength
Like traditional mixes, the compressive
strength will vary depending on the admixtures,
aggregate, and w/c ratio used in the mix design.
In general the compressive strengths of SCC are
higher than traditional mixes with similar w/c
ratios due to the improved interface between the
aggregate and hardened paste.9
Tensile Strength
Compared to traditional mixes with
similar compressive strengths and maturity, SCC
has approximately the same tensile strength. In
large part, this is due to the paste volume not
having a significant effect on the tensile strength
of concrete mixes.
Modulus of Elasticity
The modulus of elasticity is often an
important parameter in slab, pre-stressed, post-
tensioned, and precast applications and is
directly dependent on past content, compressive
strength, and aggregate content. Because of this,
the ACI committee 237 recommends that for
applications where the modulus of elasticity is
critical, it should be determined from trial
mixtures.10
Creep
For traditional and SCC mixes alike,
creep is dependent on the mixture proportions
used. ACI 237R.07 says that for mixtures using
the same proportions and materials for both
conventional and SCC mixes, the creep of the
SCC mixture will be similar to that of the
conventional slump concrete. For example, if the
w/c ratio and paste content increase in either a
traditional or SCC mixtures, then there will be
an increase in creep for both mix designs.
Shrinkage
The shrinkage of concrete is typically
categorized as plastic, drying, and autogenous
shrinkage.
Plastic shrinkage occurs from the
evaporation of bleed water surpassing the rate
for the bleed water to rise to the surface before
hardening and developing sufficient strength. It
should be noted that SCC mixtures that have low
water/powder ratios, high powder contents, and
high doses of viscosity modifying admixtures
(VMAs) will be more susceptible to plastic
shrinkage cracking.
In addition, drying shrinkage is affected
by the type of materials and proportions used in
the mix design. As water content increases and
the amount of coarse aggregate decreases, the
amount of shrinkage will increase similarly for
both traditional and SCC mixes.
Coefficient of Thermal Expansion
Coefficient of thermal expansion of
concrete varies with its composition, age and
moisture content. SCC typically exhibits similar
properties to conventional concrete.9
Bond to Reinforcement
With conventional concrete mixes, the
bond between the concrete and the
reinforcement all has to do with the consistency
of vibration during the placement process. The
bond to steel of conventional concrete can be
impaired if the mixtures are over-vibrated. If a
suitably fluid and stable SCC mixture is used
instead, this variable in construction can be
removed.11
Due to the fluidity of SCC, testing has
proved that SCC does create a better bond with
reinforcement. This all is dependent on the
consistency of the mix, of course. If the SCC
mixture is unstable, the bond will be
compromised.
Durability
As was discussed previously in the
history of SCC, this unique mix design was
created to combat durability concerns from
improper consolidation with traditional mixes.
Durability of concrete is directly
proportional to the amount of permeability in its
surface layer. The less permeable the surface
layer is to chlorides, sulphates, water, oxygen,
etc. the more durable the concrete. Since SCC
mitigates improper consolidation, and in turn the
amount of bug-holes and honeycombing that can
occur at the surface of concrete, SCC is expected
to be equal to or more durable than traditional
mixes.
7. 5
Mix Design
The mix design of any concrete mix is
tailored for specific structure types in order to
develop a certain performance criteria and
service life. Like traditional concrete mix
designs, SCC can be affected by anything
ranging from material characteristics from
different regions, to the admixtures that help
develop desired functionalities.
This section is intended to give a general
overview of the materials that create an SCC
mixture and is in no way intended to take place
of site specific mix designs. If the development
of an SCC mix is desired, one should
communicate closely with local batch plants and
quality teams to ensure a quality and consistent
SCC mix design.
Aggregates
Aggregates comprise between 60% and
80% of the total volume of a concrete mixture.12
For SCC mixtures the fluidity of the mix comes
from the paste content rather than the gradation
of the aggregates. Because the aggregate
particles experience friction they actually
consume the flow energy and restrain the
fluidity of the mixture. Therefore, typical SCC
mix designs call for a reduced amount of
aggregate, which greatly benefits production
teams, giving them the ability to place densely
reinforced structures. It is imperative to note that
keeping a good balance between SCC’s fresh
and hardened properties is crucial. Too little of
aggregate content, the more susceptible the mix
is to shrinkage and cracking. While too high of
aggregate content will reduce the self-
consolidating characteristics of the mix and
inhibit its ability to flow.
The separation of aggregates during
flow through restricted sections (passing ability)
or by settlement is one of the primary stability
concerns during the development of SCC
mixtures.13
Communication between the
engineer of record, supplier, and quality
personnel is essential because these separation
issues can be solved with proper material
selection and mixture proportioning.
Coarse Aggregates
SCC mixtures have been produced with
maximum size of coarse aggregates ranging
from 10 to 40 mm.14
Because of SCC’s flowable
and self-consolidating characteristics, care
should be taken when choosing the coarse
aggregate size of the mix. Larger particles will
have a tendency to settle during placement and
the added particle size will reduce the mix’s
fluidity.
The aggregate shape of concrete is
categorized by angular or rounded particles.
Rounded particle shapes lower the viscosity of
SCC mixes, allowing the particles to roll and
tumble as the mix is placed. Test results have
shown that, at identical volumes, rounded
aggregates will produce a lower-viscosity
mixture than angular particles in the same mix
design. Not only does particle shape affect the
viscosity of SCC, but it will affect its passing
ability, especially through restricted sections.
The potential for segregation during
placement is affected by aggregate selection as
well. Larger particles in lightweight aggregates
have a lower density and have the potential to
float to the surface in unstable SCC mixes.
Fine Aggregates
When selecting aggregates for SCC mix
designs, the geographical locations from which
these aggregates come from is essential to
developing quality SCC. In specific locations
there can exist a considerable amount of clays
that can be present within fines that can cause an
increase in water demand and/or high range
water reducer (HRWR).
The shape and gradation of fine
aggregates also has an effect on the final quality
of SCC. Like coarse aggregates, having fines
with rounded shapes tend to give SCC the ability
to flow more easily. The gradation of fine
aggregates in SCC is directly related to the
amount of bleeding that can occur. Studies have
shown that the more fine material passing the
300 sieve in an SCC mix will result in more
bleeding. Thus, it compromises the durability of
the mixture.
8. 6
Cements
As well as aggregates, the properties of
the cement used in SCC can also affect the
overall product.
Portland cement’s particle shape is
angular. If another type of powder was chosen
with an alternate particle shape, this could
directly affect the fresh properties of the SCC.
Like fine aggregates, as discussed
previously, the finer the powder the higher the
HRWR or water demand in order to reach a
desired slump flow. Increasing the amount of
fines also increases the viscosity of the cement
paste while increasing the rate of cement
hydration, thereby shortening the setting time
and increasing the rate of strength
development.15
Furthermore, the increase in rate
of hydration has the potential to shorten the
workability retention time of an SCC mixture.
Water demand differs depending on the
source and can have an impact on the admixture
dosage required to achieve an SCC mixture.16
ASTM C 187, Normal Consistency, can be used
to determine the amount of water demand for
various cements.
Pozzolans such as fly ash, silica fume,
and slag cement are used extensively in
traditional concrete mixtures to lower the heat of
hydration for mass concrete, reduce chloride
permeability, inhibit alkali-silica reactivity,
etc… In recent years, pozzolans have been used
to reduce the amount of Portland cement in
order to lower the carbon footprint of mixes.
One of the most common topics of discussion is
whether or not these pozzolans can be used in
SCC mixtures. In fact, pozzolans have been, and
are currently being used in SCC mixtures for the
same reasons as conventional concrete.
According to ACI 318, for durability
reasons, fly ash is limited to 25% replacement
by weight of cement for the most severe class.17
Since the specific gravity of fly ash ranges from
1.9 to 2.8,18
this can increase the paste volume
and enhance the fresh properties of the mixture.
The particle size of fly ash compared to other
cements is very similar, but the shape of fly ash
is round where other alternative cements are
more angular. This round shape of fly ash gives
SCC mixtures enhanced flowability and can
even permit a reduction in water content, or
HRWR dosage. The amount of carbon in fly ash
needs to be considered when adding this
pozzolan to an SCC mix. Mortar studies have
shown that the loss on ignition (LOI), which is
an indicator of the amount of carbon in fly ash,
influences SCC’s flowability. In other words,
the higher the trace of carbon in fly ash may
affect the initial flowability of SCC and could
result in a higher water demand and/or higher
HRWR requirement to achieve a target slump.19
Like fly ash, ACI 318 limits slag to 50%
replacement of Portland cement for the most
severe exposure class. The difference is that slag
has a similar particle shape, therefore allowing
one to replace Portland cement with slag without
any significant impact due to particle shape. It
should be noted that if a production team were to
consider using slag as a substitute for Portland
cement, that team would need to check the
owner’s project specifications to see if slag is an
allowable pozzolan additive.
Water/Cement Ratio
The water/cement ratio (w/c) of SCC
like traditional mixtures ranges depending on the
desired performance need for specific structures
or projects. Generally, SCC has a lower w/c
ratio than traditional mixtures, resulting in
higher compressive strengths at similar testing
intervals. According to data shown in Table 4.3
of ACI 237R, the water cement ratio can range
from .37 to .40 depending on the desired
performance. Additional examples can be seen
in Appendix A of this document illustrating a
handful of case studies from around the world.
As you will see from the provided case studies,
the w/c ratios range from .27 to .34 and with the
decrease in w/c ratio, there is a notable increase
in compressive strength.
Chemical Admixtures
An admixture is a material other than
cement, aggregate, and water that are added to
concrete either before or during its mixing to
alter its properties and ensure quality, such as
workability, curing, temperature, or set time.
Within the concrete industry there exists a whole
list of chemical admixtures, most of which can
be used in SCC mixtures. Several of these
admixtures, such as HRWRs and VMAs, are
used more often than others in SCC mixtures.
The following table highlights the most readily
9. 7
used admixtures in SCC and briefly describes
why each is utilized.
Chemical Admixtures Typically Used in SCC20
Admixture Type Reason for Use
High-range water
reducer(HRWR)
Minimize water content to
ensure adequate viscosity.
Adjust dosage to increase or
decrease slump.
Viscosity-modifying
admixture (VMA)
Enhance viscosity to
promote greater mixture
stability and reduce
bleeding.
Workability-retaining
admixture
Provide controlled
workability/slump flow
retention without
retardation.
Accelerating admixture Increase early age
compressive strength
development. Facilitate
normal setting in cold
temperatures.
Retarding and hydration
control admixtures
Slow the rate of cement
hydration to delay setting in
hot temperatures and extend
workability time.
Air-entraining admixture
(AEA)
Enhance freeze/thaw
durability, and increase
paste content to promote
flow and stability.
As depicted in the previous table, each
chemical admixture gives SCC unique
characteristics. For example, using a high-range
water reducer (HRWR) and a viscosity-
modifying admixture (VMA) increases slump
flow and at the same time increases the mixtures
stability. Since SCC was introduced in North
America and even today, there is a
misconception that SCC is purely a chemical
mix and even hesitation when discussing a
mixture with these types of admixtures. But,
from the descriptions, these chemical admixtures
shouldn’t cause hesitation. They simply give
SCC advantageous characteristics based on
certain project specific criteria. Traditionally,
one would increase the w/c ratio to create a more
flowable concrete mixture. With SCC, a HRWR
can be added to obtain a more flowable mix
without making any additional adjustments to
the w/c ratio.
Not all of these admixtures have to be
used in order to produce SCC. However, the use
of a HRWR is required to give SCC its
flowability and a quality SCC mix cannot be
produced without this admixture. The other
admixtures listed are generally used based upon
site and structural specific criteria.
High-Range Water Reducer (HRWR)
As previously mentioned, HRWR
admixtures are the most important ingredient in
an SCC mixture because they induce flowability
without the use of water and in turn mitigate the
potential for bleeding and segregation.
Chemically, a HRWR is able to achieve this
characteristic by dispersing the cement particles
in a mixture. PCEs, or Polycarboxylate Ether,
are comb polymers that are characterized as
having a backbone with pendant side chains
similar to the teeth of a comb. Along this
backbone are negatively charged binding sites.
The structure of these molecules can be altered
in such a way to provide certain performance
characteristics to the mixture. Depending on
these desired characteristics, the backbone and
side chains can be altered to be larger or smaller
giving the molecules a more or less attractive
force over the cement particles. In other words,
the PCEs in an HRWR can be modified to
control the flowability of SCC.
Viscosity-Modifying Admixtures
Viscosity-modifying admixtures
(VMAs) were developed from water placement
technologies. To have concrete placed
underwater, the mixture needs to be highly
workable and greatly mitigate the tendency to
segregate. Therefore anti-washout admixtures
were developed to alter the mixtures viscosity to
resist segregation while remaining workable.
These admixtures later evolved into what is
known now as viscosity-modifying admixtures
(VMAs).
For SCC applications, the VMA helps
retain a level of stability and robustness while
the addition of an HRWR increases the
workability. When added to a concrete mixture,
a VMA can either increase the viscosity of the
paste content, or the water. There is a wide
variety of VMAs that can be chosen to tailor an
SCC mixture to specific design criteria. Some
VMAs can be used to specifically control
bleeding, or others can be chosen to effectively
reduce coarse aggregate separation.
10. 8
In conclusion, it is imperative that
effective communication between the engineer
of record, quality team, and batch plant
technicians be established as early as possible to
ensure the correct admixtures are selected and
proportioned properly. As briefly discussed,
certain chemical admixtures will alter the
characteristics of SCC in different ways and this
early communication will allow productions
teams to plan accordingly.
Best Practices
There are many advantages when using
an SCC mixture on a project that will be directly
beneficial to the contractor. Decrease in labor
force and rapid discharge rates are a few
examples of previously discussed advantages.
But, before a contractor can benefit from the
characteristics of SCC, there are several key
items that need to be addressed before placement
can occur.
Preparation
The following are fundamental action
items that should be resolved during the early
stages of planning. These items include, but are
not limited to:
• Confirming that the proposed SCC mix
design is appropriate for the project site
conditions prior to the ordering of SCC.
• Selecting an appropriate delivery rate
and time with a competent concrete
producer.
• Clearly documenting the jobsite
acceptance test methods and ensuring
that the owner, concrete producer,
contractor, testing company, and
engineer of record are all aware of the
acceptance procedures (slump flow
testing, etc.).
• Ensuring that the concrete placement
crew is aware of the significant
differences between SCC and
conventional concrete prior to
placement.
• Ensuring the formwork is properly
designed and constructed to both
support the pressure exerted by the
concrete and produce the necessary
surface finish.
Placing and Finishing
As previously discussed, admixtures are
specifically used in order to mitigate separation
during placement and give SCC its unique
flowable characteristics. This is why SCC
typically is not mechanically vibrated during
placement. If vibration or rodding occurs, there
is a significant chance that the aggregates and
particles will severely segregate. For example,
when placing conventional concrete placement
crews may be directed to vibrate the concrete in
order to consolidate the mix and allow it to flow
through densely reinforced sections. Thus, the
placement crew should be aware of the
characteristics of SCC and be educated as to
why vibration induces segregation. The rule of
thumb with SCC mixes is to simply step back
and let the mixture do the work for you.
Once SCC is placed, there is generally
no need to finish the mix. There should be
someone assigned to look at the final placement
to check for discoloration in the surface, which
can be a sign of trapped air bubbles that could
lead to unwanted defects.
If a consistent, high quality SCC mix
has been produced and placed properly, the
benefits will be immediately evident to the
contractor. This can only be achieved if
everyone involved in the placement operation
understands the characteristics of SCC and
follows proper placement and finishing
procedures.
Curing
For most cases, the bleeding
characteristics are lower compared to
conventional concrete mixtures. Moreover, the
bleeding characteristics are directly related to
the mix proportions and materials used,
therefore wide ranges of bleeding levels are
possible. During mixture proportioning and
testing, the risk of surface crusting and plastic
shrinkage can be greatly alleviated. In regards to
curing practices, SCC can actually be treated
similarly to conventional concrete. ACI 237
recommends that the established guidelines for
curing conventional concrete, such as found in
ACI 308R, should be followed with SCC.21
11. 9
Testing Methods
The following characteristics should be
evaluated prior to placement:
• Ability to fill a mold or form under its
own weight;
• Resistance to segregation (stability);
• Ability to flow through reinforcing bars
or other obstacles without segregation
and without mechanical vibration; and
• Surface quality and finishability.
According to ACI 237R, ASTM
committee C09.47 is responsible for the
development of standard test methods and
developing a specification for SCC. The
following are the various testing methods for
SCC, as described by ACI 237R.
Slump Flow
The slump test is a common procedure
used to determine the horizontal free-flow
characteristics of SCC in the absence of
obstructions. This procedure is based on ASTM
C 143/C 143M, with a modification for
determining the slump of conventional concrete.
The concrete is placed in one lift and not
consolidated by any means of mechanical or
manual agitation. The mold is raised, and the
concrete is allowed to subside. The average of
the two diameters measured perpendicular to
each other of the resulting spread is reported as
the slump flow of the concrete.
A common range of slump flow for SCC
is 18 to 30in. The higher the slump flow, the
farther the SCC can travel under its own self-
weight from a designated discharge point. This
slump flow value can also be used to determine
the consistency of SCC, and shouldn’t differ by
more than 2in. from truck to truck.
Visual Stability Index (VSI)
The Visual Stability Index (VSI) testing
procedure is exactly what its name suggests. A
visual examination of the slump flow spread
resulting from performing the slump flow test.
This test is primarily used to determine the
stability of batches of the same or similar SCC
mixtures.
This test is performed in the same
sequence as the Slump Flow test with the
addition of a visual observation after the
diameters of the two slump flows have been
recorded. When performing the visual
observation, the technician will record a VSI
number of 0, 1, 2, or 3 in order to characterize
the stability of the mixture in Table 8.2 of
Appendix B.
A VSI designation of 0 or 1 indicates
the SCC mixture is stable and suitable for
placement. Furthermore, a VSI rating of 2 or 3
indicates possible segregation potential and the
concrete producer should take action and modify
the mixture to achieve the desired stability.
Because this testing method is visual and can be
subjective, this makes this a perfect quality-
control tool for placing SCC. However, the VSI
test method should not be used for SCC
acceptance or rejection prior to placement.
T-50
This testing method allows the user to
measure the viscosity of the SCC mixture by
recording the amount of time for the slump flow
to reach a certain point designated on a rigid
surface.
The SCC mixture is placed in a slump
cone similar to the slump flow test previously
described. After the cone is lifted the user
measures the amount of time it takes for the
SCC slump flow to reach a diameter of 20 in.
A longer time indicates a mixture
with a higher viscosity; the opposite is true for a
shorter time. As a rule of thumb, a time
of 2 seconds or less is typically considered a low
viscosity, where a time greater than 5
seconds characterizes the SCC mixture as a high
viscosity mixture.
J-Ring
When SCC is being utilized in structures
with highly congested reinforcement, it is crucial
that the mixture remains cohesive and the
aggregate doesn’t separate from the paste
fraction of the mixture when it flows between
these congested areas. In instances such as this,
the J-ring test can help characterize the ability of
an SCC mixture to flow through reinforcing
steel.
12. 10
In order to conduct the test the user
places an SCC mixture into a slump cone as they
would a slump flow test, with the exception that
the slump cone is surrounded by a J-ring. The J-
ring consists of steel bars spaced evenly around
a ring in order to simulate the reinforcement
within the formwork. Once the slump cone is
lifted and the mixture is allowed to flow through
the J-ring, the user then measures the average of
the two diameters perpendicular to each other.
The resulting slump flow is a direct
indication of how the SCC will pass through the
reinforcement during placement. Therefore, the
higher the J-ring slump flow, the faster the SCC
will fill a steel reinforced form or mold, and the
further it will travel through the reinforcement
under its own mass. This test method can also be
used to determine the potential for blocking of
an SCC mixture during placement. If aggregate
becomes lodged during the testing procedure,
then this is a good indication that this will likely
occur during the actual placement of the SCC.
L-Box
The L-box was developed in order to
evaluate the placement of SCC underwater. The
test can determine the confined flow of SCC and
the extent to which it is subject to blocking by
reinforcement. Unlike the previously mentioned
testing methods, the L-box is typically
performed in a laboratory setting.
The test consists of a mold in the shape
of an L, with vertical and horizontal sections
separated by a moveable gate in which vertical
bars are fitted. The vertical section is filled in
one lift of SCC and the gate is lifted. The SCC
mixture is then allowed to flow through the
vertical bars, into the horizontal section. When
the flow has subsided, the height of the SCC at
the end of the horizontal section is expressed as
a proportion of that remaining in the vertical
section.
The minimum ratio of SCC for the L-
box is 0.8, compared to water which results in a
ratio of 1.0. Therefore, the closer the ratio is to
1.0, the more flowable the SCC mixture.
Limitations of SCC
As identified previously, there are many
benefits when utilizing SCC for the engineer,
contractor, and owner. But, like all technologies,
there are certain restraints that can limit where
and when SCC can be used. Project and
organizational constraints are two areas in which
limitations could exist that can hinder SCC’s
utilization.
Project constraints are scenarios where
the SCC would be required to perform in a
particular way to meet project specifications. For
example, when placing a floor slab that is
required to slope the concrete must be able to
support itself under its own self-weight. Since
SCC is specifically produced to consolidate
under its own self-weight, it is impossible for
SCC to be sloped during or after the placement.
This kind of scenario is common within the
construction industry, ranging from industrial
warehouses, maintenance buildings, concrete
roadways, slabs cast on a sloping grade, etc…
Additionally, because of SCC’s ability to flow
through confined spaces, placing SCC on
elevated floors/decks becomes a potential
project constraint. There is considerable risk
associated with this operation in that if there is a
considerable gap in the stay form or shoring, the
SCC will begin to spill through.
Organizational constraints include, but
are not limited to, the ability of the concrete
producer, contractor, and/or the specifier. Some
concrete producers are limited in their ability to
produce consistent, quality SCC. This typically
isn’t due to a lack of knowledge or will. It
mostly comes from a lack of resources and
equipment needed to produce a high-
performance concrete technology. Even if the
concrete producer was willing to invest in the
necessary updates, it is good practice to check
the concrete producers resume for extensive
experience in producing consistent and quality
SCC. In addition, the delivery logistics of SCC
requires special attention. As depicted in the
tables in Appendix B, the placement rate is
significantly reduced (30%-70%) when using
SCC as compared to conventional concrete. This
increase in placement rate and reduction in cycle
time can result in a considerable burden on the
13. 11
concrete supplier when staging trucks, especially
at the beginning of the placement.
When considering concrete suppliers,
one must take into account the terrain in which
the placement will be located. In mountainous
regions, SCC has the capability to spill out the
back of the concrete trucks if filled to their full
capacity. Most concrete mixers do not have lids
to mitigate this issue; therefore the concrete
supplier will need to batch the trucks at a lower
capacity, which will affect the time and
utilization of the trucks. According to ACI 237R
section 6.2, the volume of SCC placed into a
truck should not exceed 80% of the capacity of
the drum. If competent personnel are available
on site, a way to solve this issue is to batch the
SCC mixture at a lower consistency and add the
remaining HRWR on site, bringing the SCC to
the appropriate consistency.
Organizational limitations may also
apply to contractors as well. SCC should be
viewed as a new technology or tool, and should
be treated with the appropriate respect. As with
any other concrete placement on a project site,
production teams should properly plan ahead to
get their teams familiar with the differing
characteristics of SCC. This way, the technical
and economic benefits of SCC can be realized.
On the other hand, if the proper planning isn’t
exercised, then the benefits of SCC will be
significantly limited, making a lack in
preparation a limiting factor when using this
mixture.
SCC and Formwork
Over the years, since SCC was first
developed, there has been extensive research
conducted on the interaction between SCC and
its formwork. According to the most recent code
(ACI 347R) contractors and engineers are
prompt to design the formwork to resist full
hydrostatic pressures. Most researchers believe
that the lateral pressures that are exerted by SCC
are actually less than full hydrostatic pressures,
but current research has yet to come up with
formulas that can accurately predict SCC’s
induced pressures. This design constraint has
slowed the production of SCC in cast-in-place
applications, but the lack of knowledge of lateral
pressures exerted by SCC is more to blame.
When placing conventional concrete,
one calculates the rate of placement to match the
set time for each lift so that the calculated lateral
pressures for each lift do not exceed that of the
designed formwork. This set time of the
concrete during placement is a common
characteristic with conventional concrete that
allows the engineer to design efficient
formwork, and directly benefits the contractor
by purchasing an economical formwork system.
Unlike conventional concrete, SCC has
unique characteristics that don’t allow it to set
during placement. This is primarily due to SCC
having thixotropic characteristics – that is, under
static conditions SCC acts as a viscous fluid, but
under stress from being agitated, vibrated or
poured, SCC will become more fluid. For
example, when SCC is being placed by chute or
by pump hose, the vibrations that are induced
throughout the duration of the placement will
agitate the SCC, keeping it in a fluid-like state
for the duration of the placement. For vertical
placements, this means as the SCC is placed in
consecutive lifts; the entire vertical length
remains fluid, which increases the hydrostatic
pressure.
The full hydrostatic pressure of SCC can
exceed the calculated pressures used for the
design of the formwork, which could result in
formwork failure. It is possible to place SCC
from the base of formwork systems with the
assistance of a specialty pipe fitting at the base
of the formwork. Due to the pressures needed to
force the SCC vertically to fill the formwork, the
pressures induced by the pump at the base can
exceed the basic calculations used to determine
the full hydrostatic pressures. Placing SCC from
the base of formwork can be advantageous to
production teams if the project constraints allow
for this type of alternative placement. If so,
production teams should work closely with
formwork suppliers and ensure that they have
developed these types of formwork systems in
order to mitigate the risks associated with this
placement technique. Another instance where
the in-situ hydrostatic pressures can exceed the
calculated pressures is when unnecessary
external vibration of SCC occurs during
placement. External vibrations can range from
repeated contact with the outside face of the
formwork to the use of mechanical vibratory
14. 12
equipment. For example, if a crew member were
directed to tighten the through-ties while
placement is ongoing, the vibrations that could
be induced during this adjustment can activate
the SCC’s thixotropic characteristics.
Conversely, the vibrations from the mechanical
vibratory equipment can reactivate the SCC at
the base and result in an increase in pressure.
This is why training and communication to all
levels of craft is crucial to successful SCC
placement.
As previously discussed, research and
testing has shown that the pressures at the base
of the formwork are approximately 80% of the
calculated hydrostatic pressure. This in turn,
results in over designed and potentially
uneconomical formwork systems. Engineers
have been conducting research and tests for
years to develop equations that can be published
in the ACI 347R code that would allow
formwork designers and contractors to more
accurately predict the in-situ hydrostatic
pressures. Unfortunately, until these equations
can be developed and approved by the ACI
committee, the industry is forced to design all
formwork for SCC use to full hydrostatic
pressure. This is primarily the reason why
SCC’s growth within the cast-in-place industry
has been so slow, but many predict that when
equations are passed that accurately predict the
pressures of SCC, this high-performance
concrete will be the way of the future.
To further understand the formwork
pressures associated with SCC, refer to the
testing reports produced by N.J. Gardner and the
CTL Group found in Appendix C.
Training
Since SCC is a high-performance
concrete and considered a new technology, all
employees should be trained and qualified
appropriately. This ensures that all personnel
associated with SCC placement operations are
familiar with the unique characteristics and fully
understand the implications if quality assurance
and quality control procedures are not followed.
Quality personnel directly associated
with SCC operations need to be familiar with
inspection requirements and testing procedures.
According to ACI 237R section 5.5.1, at a
minimum the quality personnel need to be
certified as an ACI Field Technician and
Concrete Special Inspector. Every quality-
control inspector needs to be trained on the
various testing methods of SCC and more
importantly, be able to understand and evaluate
the results of those tests. If the desired quality of
SCC is to be realized, then the quality personnel
should understand the engineering properties,
placement techniques, element characteristics,
and raw materials used in the mix design.
Additionally, the quality personnel should be
involved in all levels of planning when using
SCC and should have an open line of
communication to the designated SCC producer.
The field personnel, ranging from the
craft and field engineers to the superintendents
in charge of the operation, need to receive
training on the effects that production methods
have on the properties of SCC. Field personnel
should understand that each SCC mixture has
been carefully designed to take into account all
aspects of material selection, form condition,
placement methods, and engineering
properties.22
Having well trained field personnel
can provide essential input when developing
effective corrective actions that may need to be
put into practice if quality and/or performance
isn’t being achieved. In order to give the field
personnel a level of comfort with SCC, it is
advantageous to perform on-site mockups to
reach a site specific mix design and train
personnel on the characteristics of SCC. It is one
thing to train field personnel by discussing the
characteristics and how SCC will perform in the
field, but it is another thing entirely to give them
hands on training prior to placement. This mock-
up will also allow quality and field personnel to
more accurately predict the form pressures that
will be experience during placement and the
consistency of the mix design produced by the
concrete supplier; among other aspects of the
placement procedure.
SCC Applications
The following structures mentioned
within this section have been discussed between
engineers and construction personnel internally
within the Kiewit organization as the most
15. 13
beneficial areas to utilize SCC. These structure
types are as follows, but not limited to:
• Slab on Grade (SOG)
• Mass Mat
• Piers/Columns
• Walls
• Traveling Tower Crane Foundations
• Grade Beams
Slab on grade (SOG) and mass mat
foundations make for an ideal SCC placement as
long as the finished top-of-concrete elevation
does not call for a sloping finish. As mentioned
previously, the self-consolidating characteristics
of SCC make it impossible to form slopes in
slabs. Due to the congested nature of most
Kiewit project sites, placing a mass mat or slab
on grade using few points of access to the
foundation because a major benefit of using
SCC because of its ability to freely flow and fill
the form work. Care should be taken though
when planning such a placement operation,
because the limiting spread distance with SCC is
typically 30 feet. But, even having just a few
points of access could allow the SCC to
completely fill the formed foundation without
the worry of redirecting trucks to multiple
placement points along the formwork. Most
mass mats placed on Kiewit projects have
considerable amount of reinforcement and a
large labor force to oversee the placement. With
SCC, the need for laborers to vibrate the mixture
is completely eliminated and the labor force can
be significantly reduced. Although, with most
mass mat placements, production teams will
need to consider the effects of mass concrete and
would need to consult outside engineering
services such as, CTL Group, in which Kiewit
has benefited from their services on several
projects. Using SCC in mass mat applications is
possible, but production teams need to use care
when accepting mix designs from concrete
suppliers and have the proper thermal mitigation
plan in place for mass mat applications. An
example of SCC being utilized for mass mat
placement can be seen in Appendix D.
Piers/columns and walls are structures
that are densely reinforced and are constantly
riddled with the risk of inadequate consolidation
resulting in honeycombing, bug holes, and
durability concerns when not properly placed.
With SCC’s self-consolidating characteristics,
there is no need for vibratory action to take place
during placement, ensuring the final quality of
the structure. In addition, these structure types
typically require a craft employee to climb into
the formwork and consolidate the concrete as it
is being placed. This has been the result of
numerous incident alerts and even recordables
on Kiewit projects. One incident in 2009 on the
Bascule Bridge project resulted in a craft
employee trying to dislodge the vibrator from
the reinforcement. Because the employee had to
submerge his arm in the concrete, this resulted in
concrete burns on his arms. In 2011, on the
Mayo Hydroelectric Project, a craft employee
was inside a congested wall form when concrete
splashed into his eye while he was vibrating the
concrete during placement. All employees on
Kiewit projects are the most valued asset to the
organization and their welfare is paramount.
With SCC utilization in column/pier and wall
structures, there is an added design for safety
eliminating the need for personnel to crawl into
the formwork during placement, and
significantly decreasing the risk of personnel
injury.
Traveling tower cranes are widely used
on all types of Kiewit projects due to their
ability to access and assist such a wide area. The
rail system that is required for this type of crane
has tight elevation tolerances and therefore, the
concrete cannot have any significant defects. In
addition to the tolerances, the foundations are
significantly reinforced, making it difficult to
mechanically consolidate the concrete. Utilizing
SCC for this type of foundation, results in a top-
of-concrete surface that will exceed the rail
tolerances due to the mixtures self-leveling
attributes. In addition, the significant decrease in
labor force for this foundation type can result in
cost savings if proper planning is established.
Grade beam systems are a common
foundation type utilized throughout Kiewit.
Often, these grade beams are placed in unison
with spread footer pedestals and require access
from several points along the grade beam for
adequate placement. The reinforcement
congestion isn’t necessarily a concern with this
foundation type, but the ability to utilize SCC
16. 14
and cast the grade beam from limited points of
access with truck chutes can result in schedule
and economic benefits. Casting a grade beam
with a concrete technology that can freely flow
to fill the entire length of the grade beam can
increase the speed of the placement. In addition,
eliminating the need for a pump truck has direct
savings to the project and the reduction of labor
force required for the placement will result in
increased safety and economic benefits.
The cost of SCC will vary from project
to project depending on the concrete supplier
and region. Typically the cost of SCC ranges
from $15 to $25 more than conventional
concrete per cubic yard. As a result, the upfront
cost would seem to weigh in favor of traditional
mixtures, but when the estimated labor and
equipment savings is factored into the
assessment, SCC becomes the more economical
option. Internal cost analyses were performed on
several structures to understand the magnitude
of savings that could be seen from the use of
SCC. These cost comparisons are located in
Appendix E. The estimated cost comparisons are
only intended to give an illustration of potential
SCC savings. The costs presented in Appendix E
will vary from project to project.
These are examples of only a few
structure types that can have advantageous
results when utilizing SCC. Other structure types
can be cast using SCC, but production teams
should weigh the organizational and project
constraints against the projected benefits
associated with SCC’s use.
Summary
Self-consolidating concrete has been,
and continues to be successfully placed every
day. Millions of cubic yards have been placed
since its development in Japan, and there isn’t
any indication that the growth of SCC will stall.
Over the past 20 years, extensive research has
been conducted producing specific testing
methods, mixture proportioning techniques, and
chemical admixtures. SCC has rejuvenated the
industries attention on aggregate characteristics,
placement techniques, and formwork pressure
calculations. In short, SCC has brought forth
new advancements within construction, and
overall, propelled the industry into the future of
concrete construction.
Conversely, SCC is a high-performance
concrete that is still considered a new
technology that can result in many benefits if the
correct planning and training procedures are
conducted. Because of its limitations, SCC may
not be utilized on every structure, or project, but
when the conditions are right this high-
performance concrete can prove to be very
rewarding. The lack of awareness that most
engineers and contractors have with SCC, is the
primary reason why its use is constrained.
Historically, new technologies are met with
resistance because they are new and unfamiliar.
This shouldn’t be the reason to discount SCC
from projects. In a 2011 survey given to the
American Society of Concrete Contractors
(ASCC), when asked the question, “Which one
statement best describes your awareness of
SCC?”, 40% of respondents said they had used it
successfully and planned to use it again, less
than 5% said they had used it and would not use
it again, and 50% said they had heard of it, could
see it potential value, but had never tried it.
Thus, is a clear indication that the biggest
limitation of SCC’s use is the industries
understanding of it.
Every new tool or technology will have
learning adjustments. When driving a nail for
the first time, the nail may be bent from an
imperfect strike or the hammer might miss the
nail completely. This doesn’t mean that
hammering a nail should be reconsidered. In the
beginning, there are trial swings, and then the
process gets refined until it becomes second
nature. Similarly with SCC, mock-ups should be
conducted on projects to get the concrete
supplier and the contractor on the same page.
Only with this trial batch, will the process be
refined and improved until this placement
method becomes more familiar.
To conclude, SCC should not be
discounted because it is relatively new, but
should be seen as an innovation and an
opportunity to excel. Through innovation our
industry is allowed to grow, adapt, and become a
better adaptation of itself.
20. Savings in Placement Time and Labor with the Use of SCC for Three Projects6
Project Placement
Technique
Volume
( )
Percent Reduction
Placement
Time (hours)
Placement
Labor (people)
Placement
Man-Hours
Retaining
Wall
Pump 35 36 50 68
Footing Pump 92 50 60 80
Drilled Pier Chute 7 66 50 83
Savings in Placement Time and Labor with the Use of SCC for Two Projects and Two Pours for Each Project6
Project Volume
( )
Percent Reduction
Placement Time
(hours)
Placement Labor
(people)
Placement Man-
Hours
Bridge 1 Superstructure 47 0 75 75
Bridge 1 Superstructure 90 33 75 83
Bridge 2 Superstructure 207 30 0 30
Bridge 2 Superstructure 207 37 0 37
62. TVA Paradise SCC Item Analysis-Clearwell FDN.xlsITEM ANALYSIS
Project TVA Paradise Location Paradise, KY Item #
Description Clearwell Sump Cost Analysis Engineer Max Pafunda Sheet #
Bid Quantity Checked By Date 4/23/15
U.P. Total U.P. Total U.P. Total U.P. Total U.P. Total U.P. Total U.P. Total
MHF Units
Other
Sub Contracts
Labor Expense
Units
Wages
Subtotal
Description Quantity
Equipment Rental
Man-hours
Permanent Materials Total Direct Cost
Services Tools and
Supplies
Rebar and Embed quantities along with mud mat CY are excluded from this analysis - Identical for both scenerios
Comments ST&S prices are based upon TVA Paradise Awarded Quotes
Crew composite is based on TVA Paradise estimate
Unit rates for the placement of concrete were adjusted to reflect crew sizes and labor reductions for both Traditional and SCC
Cost Item Analysis does not include schedule, rework, or safety impact analysis
All Permanent Materials and Equipment Rental costs came directly from the TVA Paradise Control Budget
Cost of concrete came directly from supplier (IMI) (Traditional = $99/CY, SCC = $119/CY)
CT-Demin Tank Analysis 2 OF 2 4/23/2015, 7:43 PM
64. AREA: POUR DATE:
Project: Job #
Location:
Drawing & Rev:
Type Concrete: 4500 psi Mix Design# QTY:
*Timely sign-off of completed work and hold points by designated personnel are a condition of employment.
SUPT ENG FMAN
QC HOLD
POINT
Proper Access Ramps
Chamfer Edges Sealed to Prevent Leakage
Formwork Flush with Mudmat
Tie Holes Sealed
Ready to Place Concrete
SELF-CONSOLIDATING CONCRETE PLACEMENT RELEASE - POUR CARD
Invert elevations per plan/secure from floating for entire placement. Not
Design Spread:
CHECKED BYCOMMENTS
Corners Tight & Sealded
Scaffolding and tie-off meet Company Standard
MECHANICAL
Pipe Risers Plumb and Secure to withstand concrete flow
Subgrade Elevation (Mudmat or Soil)
STRUCTURES
PIPING
Sufficient Pour Access
Ready to Place Concrete
ELECTRICAL
Grounding Tails Installed
Form Joints Spliced Properly/Inside and Outside corners secure
Ties Secure and Correct Size
Forms have been oiled.
Conduit Caps Installed to Prevent Concrete Inside Conduit/joints
inspected to prevent leakage into conduits.
Holes in forms Sealed
Tie system installed and designed for full liquid head
Ready to Place Concrete
Chamfer Installed - top/corners/BO's
Bracing per Work Plan
TOC Elevations Correct & designed to be level (No Sloping)
Waterstop Installed Properly & Secured for concrete flow
Blockouts Secure (Bolted) to prevent uplift, Proper Location
Construction Joints per Drawings
Placement tell tales in place for adjustments during placement
WORK ITEM
CIVIL
Ready to Place Concrete
Ready to Set Forms/Rebar
Expansion material around pipe penetrations secured
Poly Pipe needs to be braced to withstand bending during placement
Pipe sleeves secured as to not pull away from formwork
Prepared to Bush concrete after placment if necessary
Conduit installed to resist uplift from placement
Anchor Bolt size, embedment, & projection checked
Conduit installed per drawing
Joints are watertight
Plugs for holes are metal NOT plastic
Bulkheads need to be installed to resist full liquid head
Bulkheads are sealed to prevent leakage
Plan to install relief joints day after forms are stripped
Foam Blockouts secured to mudmat or rebar
Yokes or Dry Ties installed at top of formwork for wall placement
65. SUPT ENG FMAN
QC HOLD
POINT
Concrete Structures Superintendent KPC Quality Manager
Mechanical Equipment Representative (if applicable)
Comments:
Mockup has been completed
Pour rates have been established
Mix Design Checked?
Forms are Completely Sealed
Crew Has Been Briefed on Proper Placement Practices of SCC
Ready to Place Concrete
Mechanical Couplers are per the Mfr. recommendation.
Splice lengths and locations
Top of Plate Elevations Correct
Anchor Bolts Plumb and Secure
Dowels in Correct Location
Do we need to blast for later pour
Curing compound available / type of cure to use
Does craft know what finish requirements (trowel / broom)
POUR
Enough access for trucks and pumps
Anchor Bolt Sleeves Installed
ANCHOR BOLTS / EMBEDS
WORK ITEM ACTION TAKEN (see
comments)
Size and location of embeds checked
Bar Sizes per Drawings
Sole Plates Level and Secure
Dowels at Correct Projection
Bar Spacing Correct
Structure Location Per Drawing
REBAR
Reinforcing size and material is per contract drawing (ASTM A615 Gr 60)
SURVEY
CHECKED BY
Anchor Bolt Locations Correct
Anchor Bolt Projections Correct
Ready To Place Concrete
T.O.C Elevations set within tolerance 1/8" for trowel 1/4" for float
Electrical Conduit / riser Locations
Ready to Place Concrete
Secure Standees to prevent racking during placement
Rebar tied to account for uplift during pour
T.O. Embed Plate Elevations
Embed plates flush with formwork & bolted
Anchor Bolt projections set
Embed Plates Level and Secure
66. References
1) Self-Consolidating Concrete. Farmington Hills, Mich.: American Concrete Institute, 2007. pp. 2.
2) Daczko, Joseph A. Self-consolidating Concrete Applying What We Know. London: Spon, 2012.
pp. 2-3.
3) Phelan, W., “Self-Consolidating Concrete (SCC): Today and Tomorrow,” September 2011. pp.
34
4) Self-Consolidating Concrete. Farmington Hills, Mich.: American Concrete Institute, 2007. pp. 3.
5) Frank, D., “Acceptance of SCC – Precast Concrete Industry Perspective,” Presented at the Fall
2008 ACI Convention, St. Louis, November 4, 2008.
6) Daczko, J., “North American Acceptance of Self-Consolidating: A Diffusion of Innovations
Perspective,” Concrete Plant International, April 2009, pp.18-22
7) BASF, “Concreting Technology for Contractors Survey,” March 2011.
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