Elkem Microsilica®CONCRETE

Burj Khalifa – shaping the future

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, dead-

weight 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

With the tower's opening, Dubai has given the UAE and the world a new landmark

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.

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 SCCRaft: 16,000m3 SCCTower: 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

Aiming for the sky

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 UAESpecial 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.

PumpingIn 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 superstructureconcrete 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.

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 self-

compacting.

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.

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 brand-

new 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.

Confidence in safetyWork 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.

‘its reinforced concrete structure makes it stronger than steel-frame skyscrapers’

Organisations & Specifications

Elkem Silicon Materials

PO Box 8126 Vaagsbygd

NO-4675 Kristiansand, Norway Tel:+47 38017500 Fax:+47 38014970

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, ArabtecKontakt: Kim, Ivan Bruyninckx, (Robin), Kang

Consultant: Hyder Consultants

Designer: SOM

Concrete Supplier: Universal Concrete Product LLC

Specifications for concrete.

Compressive Strengths: 45 to 80MPa

Minimum Cement: 252+168+30 Kg/m3

(MSRPC+PFA+SF)

W/C ratio: 0.34

Flow (at site): > 600mm

Water Penetration <10mm (BS EN 12390 - 8)

Water Absorption <1.5% (BS 1881:122)

RCPT <1200 (AASHTO T-277)

Water Permeability <5mm (Din 1048)