Elkem Microsilica®
CONCRETE
Burj Khalifa – shaping the future
With the tower's opening, Dubai has given the UAE and the
world a new landmark
United Arab Emirates - Dubai now has the
world's tallest reinforced concrete
skyscraper at 828 metres.
The developer of the tower said it cost
about US$1.5 billion to build the tapering
spire billed as a "vertical city" of luxury
apartments and offices. It boasts four
swimming pools, a private library and a
hotel designed by Giorgio Armani.
Elkem provided the microsilica addition
that helped the contractor to pump the
high performance high strength concrete
to a record height of 601 metres
The Burj Khalifa is the
worlds tallest Building. It
will hold that title for some
time at a height of 828m.
Using many innovative
design features, to allow
for wind stresses, deadweight and loading, and the
environmental affects.
This tower is now aiming
for the sky using high
performance concrete to
achieve the performance
characteristics necessary
for such innovative design.
The construction the tower
owes much to state of the
art concrete mix design as
to its architectural
elegance. Self compacting
concretes (SCC) with high
strengths, have been used
for the piling foundations
and the huge raft on
which the structure
stands. High strength, high
workability and extremely
durable concrete was used
to create the sweeping
superstructure and take
the building to the
dizzying heights it has
reached. This tower has
now completed its long
stretch up into the sky
over Dubai.
Aiming for the sky
High strength, high workability concrete is
used to create the sweeping superstructure. Special design
features - such as the levels and step-backs - will mean that even
in high winds, the people at the top of the tower will feel
minimal movement. The concrete volumes are as stunning as the
building itself:
Piling: 70,000m3 SCC
Raft: 16,000m3 SCC
Tower: 260,000m3
The state of the art mix design specifies a triple blend of
Portland Cement (low C3 A - MSRPC – Medium Sulfate Resistance
Portland Cement) , Fly Ash (FA) and Elkem Microsilica (MS). The
durability requirements are as tough as the tower is tall:
Maximum water penetration is 10mm (BSEN 12390-8)
Maximum water permeability 5mm (Din 1048)
Maximum water absorption 1.5% (BS1881: Part122)
Rapid Chloride Permeability result of less than 1200
coulombs (ASTM C-1202)at 28 days
Piling concrete mix contained
a total binder content of
450kg/m3 of which 37% is fly
ash and 7% silica fume with a
maximum aggregate size of
10mm The mix was also selfcompacting.
Pumping
In November, 2007, the
highest reinforced concrete
core walls were made using
concrete pumped from ground
level to a vertical height of
601 metres. This broke the
previous pumping record for a
building of 470m on the
Taipei 101 in Taiwan and the
previous overall world record
for vertical pumping of 532
metres for an extension to the
Riva del Garda Hydroelectric
Power Plant in 1994.
The superstructure
concrete mix contains 13%
fly ash and 10% silica fume
with a maximum
aggregate size of 20mm
The mix is virtually self
consolidating with an
average slump flow of
approximately 600mm and
was used until the
pumping pressure
exceeded approximately
200 bar.
Elkem Silicon Materials with its local personnel
and technical back up supplied the material that
contributed to pumping concrete 601m vertically
- and also achieved the durability and strength
requirements for such a construction, including
zero water permeability and chloride resistance
that was twice as good as the specified level.
Burj Khalifa is the world's tallest
building (828 metres), features the
highest observation deck and was
renamed after Sheik Khalifa bin
Zayed Al Nahyan, the ruler of
neighbouring Abu Dhabi and the
President of UAE
Special design features - such as the
levels and step-backs - will mean
that even in high winds, the people
at the top of the tower will feel
minimal movement.
‘its reinforced concrete structure makes it
stronger than steel-frame skyscrapers’
Confidence in safety
Work on the Burj began in 2004
and moved ahead rapidly. At
times, new floors were being
added almost every three days,
reflecting Dubai's raging push
to reshape itself into a
cosmopolitan urban giant
packed with skyscrapers.
The Burj's developers say they
are confident in the safety of
the tower, which is more than
twice the height of New York's
Empire State Building's roof.
Greg Sang, Emaar's director of
projects, said the Burj has
"refuge floors" at 25 to 30 story
intervals that are more fire
resistant and have separate air
supplies in case of emergency.
And its reinforced concrete
structure, he said, makes it
stronger than steel-frame
skyscrapers.
"It's a lot more robust," he said.
"A plane won't be able to slice
through the Burj like it did
through the steel columns of
the World Trade Centre."
During the peak construction
periods, some 12,000 people
worked at the tower each day,
according to Emaar.
The tower is more than 50
stories higher than Chicago's
Willis Tower, the tallest
building in the U.S. formerly
known as the Sears Tower.
The Burj is the centrepiece of a
500-acre development that
officials hope will become a new
central residential and
commercial district in this
sprawling and often
disconnected city. It is flanked
by dozens of smaller but brandnew skyscrapers and the Middle
East's largest shopping mall.
That layout — as the core of a
lower-rise skyline — lets the Burj
stand out prominently against
the horizon. It is visible across
dozens of miles of rolling sand
dunes outside Dubai. From the
air, the spire appears as an
almost solitary, slender needle
reaching high into the sky.
Organisations & Specifications
Construction Data Project data:
Type of building: Hotel, residence, office tower
Location: Dubai / UAE
Total construction time: ~ 40 months
Construction time cores: ~ 30 months
Building data:
Height: ~ 828 m
Method: Cores ahead
Step height: 3,20 m / 3,50 m / 3,70 m / 4,00 m
Floors: 162
Contractor:
Joint Venture: Samsung, Besix, Arabtec
Kontakt: Kim, Ivan Bruyninckx, (Robin), Kang
Consultant:
Hyder Consultants
Designer:
SOM
Concrete Supplier:
Universal Concrete Product LLC
Specifications for concrete.
Compressive Strengths:
Minimum Cement:
W/C ratio:
Flow (at site):
45 to 80MPa
252+168+30 Kg/m3
(MSRPC+PFA+SF)
0.34
> 600mm
Water Penetration
Water Absorption
RCPT
Water Permeability
<10mm (BS EN 12390 - 8)
<1.5% (BS 1881:122)
<1200 (AASHTO T-277)
<5mm (Din 1048)
Elkem Silicon Materials
PO Box 8126 Vaagsbygd
NO-4675 Kristiansand, Norway Tel:+47 38017500 Fax:+47 38014970