Budowa budynku Burj w Dubaju –

omówienie urządzeń do pompowania betonu

ConstruCtion works at the Burj DuBai tower ConstruCtion

site - maChinery anD ConCrete pumping operation

Streszczenie

Referat omówi sprzęt zastosowany do pompowania betonu na placu budowy najwyż-
szego na świecie budynku w Burj Dubai, jego usytuowanie oraz rozwiązania techniczne
umożliwiające pompowanie betonu na wysokość ponad 600 m.

Abstract

The paper presents the industrial machine for pumping concrete at the construction site of
the highest building in the world - the Burj Dubai Tower in the United Arab Emirates. It
was discussed the set-up of the machine and the over 600 m high-rise concrete pumping
technology.

Steffen Kimmerle

Steffen Kimmerle – Putzmeister Concrete Pumps GmbH

2

Steffen Kimmerle

DNI BETONU 2008

After repeated extension of the use of the last remaining Putzmeister Super High

Pressure trailer concrete pump 14000 SHP D over the past months at Burj Dubai, on 9
April 2008 the concrete delivery was completed reaching a new world record height of
606 m. The pump height is calculated from the length of the riser secured in the structure
and the vertical delivery line including the tubular column and stationary boom.

As a result of the predominantly steel construction of the last tower levels and the low

concrete quantities used above 586m, the concrete pump was barely working to capacity
for more than a few hours per week. Due to the disassembly started in the meantime, the
building’s guided delivery line is no longer interfering Burj Dubai’s interior fittings.

During the last pump operations, a concrete pressure of 200 bar was measured on

the Putzmeister trailer concrete pump with S transfer tube 14000 SHP D with an output
of 28 m

3

/h. Overall, the three Putzmeister high-performance pumps have, during their

32 months of operation, pumped approximately 165,000 m

3

of high-strength concrete.

This exclusively involves concretes of the property classes C50 for the floors as well as
C60 and C80 for the walls of the central core. With a 606 m height difference, the concrete
required approximately 40 minutes from the filling into the hopper to its discharge from
the delivery line. The concrete volume in the line (nominal diameter 150mm up to 550 m
height, after this ND 125) amounted to approximately 11 m

3

with this installation height.

This equates to a weight of over 26 tonnes on the Putzmeister concrete pump after every
piston stroke when the S transfer tube is switched.

Not only the pump operator Unimix, but also Putzmeister Concrete Pumps GmbH as

the manufacturer of the high performance concrete pumps, have seen confirmation of the
results gathered during the extensive trials before starting the extreme high-rise pumping.
Through intensive support of the machines and logging of extensive data and system infor-
mation during the concrete placement, PM engineers gained extensive experience for future
high-rise projects. Incidentally, the consortium’s briefly discussed suggestion of installing a
relay pump at a height of around 400 m “by way of precaution” to support high-rise concrete
pumping if necessary, was not implemented. Instead, all those involved assumed that the
final pumping height would easily be reached with this BSA 14000 SHP D.

This extreme pump height was possible due to the trusting cooperation between the

Samsung-led team, the machine operator Unimix, the local Putzmeister agent German
Gulf Enterprises, as well as the Putzmeister parent company in Germany.

The Putzmeister high-performance pump on the ground
also provides for a consistent concrete stream at a
height of over 600m.

Construction works at the burj dubai tower construction site ...

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DNI BETONU 2008

The Burj Dubai in April 2008 –
the 159th structural level already
concreted in the meantime.

The client, Emaar Properties (UAE), has commissioned a consortium managed by

Samsung (Korea) together with BeSix (Belgium) and Arabtec (UAE) with carrying out
the construction works on what will be the highest building in the world, at over 800 m.
Turner Construction (USA) is responsible for the project management.

With three Putzmeister high performance concrete pumps, a sophisticated delivery

line system, four stationary booms and challenging concrete mixtures, the carcass of the
Burj Dubai has been under construction since the start of 2005. Due to the rapid progress
in construction and the narrowing building structure as it rises upwards, three of the
stationary booms have in the meantime been dismantled and one of the stationary pumps
removed.

A proper amount of trust in the know-how and reliability of the partner was requ-

ired when Unimix - responsible for concrete production and delivery at the Burj Dubai
- decided to commission Putzmeister AG with the supply and installation of the pumps
and boom systems. Through earlier pump tests, Putzmeister had already determined
that the concrete pumps and pipelines for delivery heights of up to 600 m were suitable
at an output of around 30 m

3

/h. It was also known that the tip of the Burj Dubai would

be erected in a lighter steel construction from level 156, for static reasons, and that only
the decks would be concreted up to level 160 (611 m height).

High-rise pumping simulated in extensive preliminary tests

PM’s preparations at the start of 2005 were correspondingly thorough as well as extreme-
ly time-consuming and human-resource intensive, both at the Aichtal Works and at the
construction site in Dubai. On site, extensive tests were carried out with horizontally laid
pipelines in a large series of tests and with the support of the local PM agent German Gulf
Enterprises (GGE – see info box on page 11). The reason was to simulate the pressure be-
haviour and the expected friction of the concrete in the pipeline based on the later mixture
breakdown and to convert it to the high-rise pumping. The tests were carried out using a
series produced BSA 14000 HP-D high-rise pump and ZX delivery line (DN 125).

4

Steffen Kimmerle

DNI BETONU 2008

To simulate high-rise concrete
delivery under extreme condi-
tions, hundreds of metres of
delivery line were laid horizontally
in a test phase, measurement va-
lues and factors such as friction
coefficients were determined and
converted to high-rise pumping.

Super high pressure pumps adapted to the extreme conditions

In the Putzmeister Aichtal Works, the details of the new super high pressure pump to
be developed were already fixed at this time. It had to be constructed and delivered by
summer 2005 for the imminent high-rise pumping. With the BSA 14000 SHP-D – the cor-
rect name for extreme pumps – components including the frame and hopper have been
reinforced to be able to withstand the enormous forces. Putzmeister had also adjusted
the S transfer tube and S transfer tube bearings in respect of the expected pressures. To
avoid contamination of the hydraulic fluid with water or dirt particles from the outset,
the BSA 14000 SHP-D also has a particularly effective filter system. Above all, however,
Putzmeister engineers have modified the drive hydraulics so that the translation ratio

One of the BSA super high-pressure pumps during
night-time use

Construction works at the burj dubai tower construction site ...

5

DNI BETONU 2008

between the hydraulic and the concrete pressure is less than i=1 with piston side ope-
ration. Due to this hydraulic ratio, concrete pressures of over 400 bar (max./theor.) are
possible with the high-performance pumps. As the Putzmeister engineers were expecting
significantly lower pressures during the later job, however, the pressure of the concrete
pumps was limited and delivery lines were installed with “just” a maximum of 250 bar
operating pressure.

Unimix has combined two of these BSA 14000 SHP-D super high pressure pumps and

the “normal” BSA 14000 HP-D high pressure concrete pump from the test phase to form one
pump station. The machines are around 70 m from the centre of the building tower. The super
high pressure pumps are driven by series produced 470 kW Caterpillar diesel engines.

Different concrete mixture breakdowns

To keep the measurements of the decks and bearing walls as low as possible, and to be
able to carry the increasing loads as height increases, only concretes with high compressive
strength are being used on Dubai’s most spectacular high-rise construction site. According
to the original plans, the distribution of the individual concrete mixture breakdowns was
as follows:
– base plate:

C80A (maximum particle size 20 mm)

– Up to level 26 (height 95 m) for the walls:

C80A (maximum particle size 20 mm)

– Up to level 126 (height 452 m) for the walls: C80 (maximum particle size 14 mm)
– Up to level 154 (height 570 m) for the walls: C60
– Concrete with compressive strength C50 is required for creating the decks of all sto-

reys.

Although concrete class C80A with 20 mm maximum particle size was originally only

intended for installation up to 95 m height (level 26), this concrete was pumped with a 50
cm spread and a w/c value of 0.3 to a height of 352 m (level 100) with a slightly modified
mixture breakdown. For this height and this material, the concrete pressure during rod
side operation was just 150 bar at 30 m

3

/h.

Costs saved with maximum particle size

There were two main reasons for keeping the mixture breakdown. On the one hand,
all those responsible were pleasantly surprised by how easily the concrete pumps were
able to pump this material even beyond the 300 m mark. On the other hand, there were
clear cost advantages. This is because significantly less cement and fines are required
for concrete with a maximum particle size of 20 mm than for a concrete mixture with a
maximum aggregate particle size of 14 mm.

Although a compressive strength of “just” 80 N/mm

2

was prescribed for this concrete,

later measurements often indicated a strength of over 100 N/mm

2

. This high-strength

concrete contains around 20 different additives, which influence, amongst other things,
the flowability and the setting behaviour.

6

Steffen Kimmerle

DNI BETONU 2008

Testing the concrete strength on a test cube

Concrete with ice

Due to the high external temperatures, concrete is generally placed in the evening and
night-time hours. Often, the thermometer still shows a temperature of around 40

o

C. As

the concrete may only be placed when its temperature is at most 35

o

C, the aggregates are

chilled in the concrete plant before preparation and part of the water is replaced with ice
(shards of ice). This means the concrete manufacturer Unimix is able to transfer concrete
with a temperature of around 27-28

o

C to the concrete pumps at the Burj Dubai construction

site, even in the summer months.

For concrete production water is
partly replaced by ice.

Numerous checks guarantee concrete quality

The production of each batch is monitored and logged in the concrete mixing plant. Before
transferring the concrete to the pumps, the temperature and flowability are checked re-
gularly and sample cubes are poured to check pressure. In addition, the site management
determines the setting and shrinking measurement and extracts cores from placed concrete.

Construction works at the burj dubai tower construction site ...

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DNI BETONU 2008

Each line is pumped with two m

3

pumping aids, which are collected in a container up in

the building and which are then dumped to the ground team by a crane.

The concrete temperature ...

... and slump are measured regularly.

Rigid and, at the same time, elastic tower construction

As no active shock absorption is planned for the Burj Dubai, great value was placed on
optimised aerodynamics during the design of the architecture of the three-winged tower.

The Burj Dubai tower at a construction height
of about 600 m

8

Steffen Kimmerle

DNI BETONU 2008

The floor plan is set further back as the building gets higher, but in principle, it remains
the same. This means the high-rise construction is extremely rigid and yet still elastic. This
construction method is extremely suitable above all in respect of the wind direction in the
mornings and evenings, which rotates around 180

o

, and the sometimes strong Schamal

wind with speeds of over 100 km/h. For even stronger storms (“50 year wind event”),
tower oscillations of around 40 to 50 cm have been calculated at a height of 605 m. The
data is based on extensive modelling tests in a wind tunnel.

Complex system of pump lines

Developing efficient concrete pumping for the spectacular delivery height at the Burj
Dubai was just one of the many tasks for Putzmeister engineers. A particular challenge
was the delivery line system, its wear behaviour and its compressive strength as well
as the line routing and attachment in the structure. Putzmeister Concrete Pumps GmbH
applied for several patents in connection with this.

For concrete placement in the decks, Unimix used its stationary Putzmeister standard

concrete pump with standard ZX delivery line (DN 125) from the outset. The machine
pumped mostly concrete with a strength of C50 up to a height of 452 m. This was the same
BSA 14000 HP D which had already been used for pumping in the test series.

At the request of the site management, pump lines with 150 mm (6”) internal diameter,

which are fitted over nearly the entire delivery height, were selected for pumping the
particularly high-strength concretes. Only in the uppermost 10 storeys were the normal
Putzmeister ZX delivery lines (DN 125) installed due to their easier handling. In this ar-
rangement, they can be operated with pressures of up to 130 bar.

In the central core of the Burj Dubai, the two
main lines can be converted to four risers in
just a few movements. The lines lead to the
stationary Putzmeister booms on the three decks
and to a boom that is secured in the wall
formwork in the building core. In the meantime,
part of the lines and all booms have already
been dismantled.

Construction works at the burj dubai tower construction site ...

9

DNI BETONU 2008

“Thick” line has advantages and disadvantages

Increasing the cross section of the line has a direct influence on the flow rate, the wear
behaviour, the pressure requirement and the period for which the concrete remains in
the pipeline – given the same output per hour. In comparison with the 125 mm delivery
line, the cross section for the 150 mm diameter increases by around 44%. This results in a
pressure reduction of around 25%, and the wear also reduces accordingly.

However, as the flow rate drops, the period for which the concrete remains in the line

increases. This longer flow time must be taken into account when developing the concret-
ing concept. With a pump height of 606 m, the period for which the concrete remains in
the 150 mm delivery line is around 40 minutes.

In addition to the 45,000 m

3

concrete for drilled pilings and the base plate, a concrete

requirement of around 260,000 m

3

is calculated for construction of the platform, the three

wings and the tower. Given this huge volume of concrete and in order minimise the
necessary changes of delivery pipes, which wear through natural friction, Putzmeister
supplied particularly long-life pump lines with a wall thickness of 11 mm. The abrasion
of the pipes is monitored regularly through ultrasound measurements.

From the central pumping station at the Burj Dubai, two of these massive delivery

lines will initially be routed to wing “A”. Provided the decks in the wings have been
concreted, the two main lines are split into four sections which had each been connected
to a stationary Putzmeister boom. A further, fifth pipeline was provided for stand-by
operation. Some of these pump lines and all the booms have now been dismantled.

Massive wall bearings hold the 55 ton concrete line

To support the weight of the risers (they are still full during the concreting works!), every
delivery line is propped by a massive support after the transition to the vertical. These
U-shaped mounts are welded with heavy steel plates which have been concreted into
the walls and bear the weight of the respective riser. With a desired pumping height of
611 m, the weights involved are immense. The combined weights of the main line and
the weight of the concrete comes to more than 55 tons!

The individual 3 metre pipes of the pump lines are fixed by deck holders between

two storeys, so that they are freely mobile in the vertical, but cannot break out or bend
horizontally – despite the weight.

Stationary boom without counter ballast

The concrete delivery lines were initially connected to a total of four stationary Putzme-
ister booms. Three of the lines were connected to MX 28-4 T type booms, which carry out
concrete placement in the wings. The MX 28-4 T booms were secured on the platforms
of the auto-climbing wall formwork (Doka) and stood on 16 m high tubular columns.
These three booms were dismantled one after the other after completion of the walls in
the individual wings and dumped at level 0 by crane in three parts (arm package, boom
stand with separated “A” arm and tubular column).

Concrete placement in the central building core up to a height of 585 m (level 155) was

undertaken by a fourth, even bigger MX stationary boom with a reach of 32 m. This MX
32-4 T was set up on a 20 m high tubular column and installed on a Doka wall formwork
in the shaft. The climbing processes were carried out hydraulically in several steps per
storey. All four MX booms were supplied by Putzmeister without ballast, at the request

10

Steffen Kimmerle

DNI BETONU 2008

of the customer. The consortium had requested this to prevent any obstacle to the cranes
and formwork through the ballast holders of the stationary booms. As the peak of the
building core on the Burj Dubai is a steel construction from level 156, both the climbing
formwork and the last stationary boom have now been dismantled. The concreting of the
remaining decks will now be carried out with horizontally laid pipelines and hoses.

Simple but thorough cleaning

Around 100 cubic metres of concrete were placed in the walls of the central core for each
section (there are three sections per storey). The concrete requirement for the decks varied
in the wings from 150 m

3

in the lower levels to 50 m

3

for the upper storeys.

With a gentle hand and sensitive radio remote
control, the Indian machine operator Harbans
Singh controls the Putzmeister boom at a height
of 600 m.

At the end of the individual concrete works, the pipelines and concrete pump are

thoroughly cleaned. To do this, Unimix, on the recommendation of the PM engineers,
has installed so-called cleaning gallows next to each BSA. These consist of a short hori-
zontal delivery line and a riser of about 4 m in length, which is bent twice by 90

o

at the

open end. Immediately before cleaning, the concrete line directly behind the BSA pump
is interrupted by a hydraulic shut-off valve and the connection to the cleaning gallows
is produced by slewing a 90

o

angle. Beneath the gallows, an empty truck-mounted mixer

waits for the shut-off valve to be opened and for the concrete to flow from the line into
the truck-mounted mixer drum by means of gravity. The machine operator can already
begin cleaning his BSA 14000. A trough under the hopper collects the concrete residue.

As the pump line is not yet completely empty – there is still residue in the 70 m long

horizontal line - the last of the concrete residue is pushed out of the delivery line from
the top end of the delivery line using a sponge ball and compressed air. To do this, two
people from the concreting team remove the end hose from the top of the stationary boom,
place a wet sponge ball in the line, connect a wash-out adaptor and apply compressed
air. With this method, the damp sponge ball is pushed down through the riser and any

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11

DNI BETONU 2008

concrete residue is removed. Thorough final cleaning is then carried out in a similar way,
except this time a plug created from a sponge ball, water and a second sponge ball is
forced through the concrete line. The whole process does not take more than around 20
minutes. At the end of the high-rise concrete pumping, the pipeline contains a volume
of around 15 m

3

concrete.

To improve concrete placement in the tigh-
tly packed reinforcement, a flexible plastic
nozzle is fitted on the end hose