High-rise pumping at the Burj Dubai at over 400 bar ... - Putzmeister

Site reportHigh-rise pumping at the Burj Dubaiat over 400 bar delivery pressureMXR 32-4 T3 x MXR 28-4 T1With several Putzmeister high performanceconcrete pumps, a sophisticateddelivery line system, nonballastedstationary booms and demandingconcrete mixtures, thecarcass of the Burj Dubai is currentlyunder construction. The constructor, Emaar Properties (UAE), hascommissioned a consortium managedby Samsung (Korea) togetherwith BeSix (Belgium) and Arabtec(UAE) with carrying out the constructionworks on the prestigioushigh-rise project.Turner Construction (USA) is responsiblefor the project management.The building with a finalhight of approx. 800 m, will be thehighest building in the world. It hasnot only fascinated internationalexperts since the start of construction(excavation in August 2004), butalso a wide public.3 x BSA 14000A proper amount of trust in the knowhowand reliability of the partner wasrequired when Unimix – responsible forconcrete production and delivery at theBurj Dubai – decided to commissionPutzmeister AG with the supply andinstallation of the pumps and boomsystems. Putzmeister had already ascertainedby pumping tests, that the concretepumps and pipelines were suitable fordelivery heights up to 570 m with apump output of around 30 m 3 /h. For staticreasons, the building section toweringabove this should consist of a steel construction.The Burj Dubai at a construction height of around 400 mBP 3893 GB

High-rise pumping simulated inextensive preliminary testsPM's preparations at the start of 2005were correspondingly thorough as wellas extremely time-consuming andhuman-resource intensive, both at theAichtal Works and at the constructionsite in Dubai. On site, extensive testswere carried out in a large test series withhorizontally placed pipelines in order tosimulate the pressure behaviour andexpected friction of the concrete basedon the later mixture in the line and toconvert it to high-rise pumping. Thetests were carried out using a series producedBSA 14000 HP D high-rise pumpand ZX delivery line (DN 125).In the meantime, the base plate for thetower and the three tower wings was producedby truck-mounted concrete pumpswith different boom reaches. The 7,000 m 2foundation is supported on 200 concretepiles (diameter 1.5 m) running 50 m deepfor the actual tower, and on around 650platform piles (diameter 0.9 m) running36 m deep for the wings. In total, 45,000m 3 of concrete was laid at the Burj Dubaifor the foundation, including base plate.Super high pressure pumps adaptedto the extreme conditionsIn the Putzmeister Aichtal Works, thedetails of the new super high pressurepump to be developed were already fixedat this time. It had to be constructed anddelivered by summer 2005 for the imminenthigh-rise pumping. With the BSA14000 SHP D – the correct name forextreme pumps – the frame and hopperhave been reinforced to be able to withstandthe enormous forces. The S transfertube and S transfer tube bearingshave also been adjusted in respect of theexpected pressures. To minimize contaminationof the hydraulic fluid withwater or dirt particles from the outset, theBSA 14000 SHP D also has a particularlyeffective filter system. Above all, however,Putzmeister engineers have modifiedthe drive hydraulics so that the translationratio between the hydraulic and theconcrete pressure is less than i = 1 withpiston side operation. Due to thishydraulic ratio concrete pressures ofover 400 bar (max./theor.) are possiblewith the high performance pumps. Becauseof the expected demands for theBurj Dubai project the conveying pressureof the pump system was limited. Thesuper high pressure pumps are driven bya standard, 470 kW Caterpillar dieselengine, which is also integrated in otherBSA concrete pumps.Checking the slump during the trials3 4Overview of the layout of the delivery lines at the pump station – the two super high pressureBSA 14000 SHP D pumps are shown on the left and rightTo simulate high-rise concrete delivery under extreme conditions, hundreds of metres of delivery line were first laid horizontally, measurement values andfactors such as friction coefficients were determined and converted to high-rise pumping.2Unimix has combined two of these superhigh pressure BSA 14000 SHP D pumpsand the "normal" BSA 14000 HP D highpressure concrete pump from the testphase to form one pump station. Themachines are around 70 m from the centreof the building tower.High-strength concretes requirepressure reservesTo keep the measurements of the ceilingsand supporting walls as low as possible,and to be able to carry the increasingloads as height rises, only concretes withhigh compressive strength are beingused on Dubai's most spectacular highriseconstruction site. According to theoriginal plans, the distribution of theindividual concrete mixture breakdownslooked as follows:■ Base plate: C80A (maximum particlesize 20 mm)■ Up to level 26 (height 95 m) for thewalls: C80A (maximum particle size20 mm)■ Up to level 126 (height 452 m) for thewalls: C80 (maximum particle size14 mm)■ Up to level 154 (height 570 m) for thewalls: C60■ Concrete with compressive strengthC50 is compulsory for creating theceilings of all storeys.Although concrete class C80A with 20mm maximum particle size was originallyonly intended for installation up to 95m height (level 26), this concrete waspumped with 50 cm spread and a w/cvalue of 0.3 to a height of 352 m (level100) with a slightly modified mixturebreakdown. For this height and with thismaterial, the delivery pressure for rod sideoperation was just approx. 150 bar at30 m 3 /h. There were two crucial reasonsfor keeping the mixture: On the one hand,all those responsible were pleasantlysurprised at how easily this materialcould be pumped even beyond the 300 mmark. On the other hand, there were clearcost advantages. This is because significantlyless cement and fines are requiredfor concrete with a maximum particlesize of 20 mm than for a concrete mixturewith a maximum aggregate particle sizeof 14 mm. Each line is also pumped with2 m 3 grout, which is received at the top ofthe building in a container and can bedumped to the floor team with a crane.Time-consuming mountingof the pump linesDeveloping efficient concrete pumpingfor the spectacular delivery height at theBurj Dubai was just one of the manytasks for Putzmeister engineers. A particularchallenge was the delivery linesystem, its wear behaviour and its compressivestrength as well as the line routingand mounting in the structure.Putzmeister applied for several patents inconnection with this.For gradual concrete placement in theceilings, Unimix used its stationaryPutzmeister standard concrete pump, aBSA 14000 HP D, with standard ZXdelivery line (DN 125) from the outset.This machine predominantly pumpsconcrete with a strength of C50 and hasin the meantime (as at March 2007)reached a delivery height of over 400 m.This is the same BSA that was alreadyused for pumping the test series.2BP 3893 GBBP 3893 GB 3

At the request of the site management,pump lines with 150 mm (6") internaldiameter, which are fitted over nearly theentire delivery height, were selected forpumping the particularly high strengthconcretes. These lines are designed for amaximum concrete pressure of 250 bar.Only in the uppermost 10 storeys werethe normal Putzmeister ZX delivery lines(DN 125) installed due to easier handling.In this arrangement, they can beoperated with pressures up to 130 bar.As the flow rate drops, the residence timeof the concrete in the line increases. Thislonger flow time should be taken intoaccount when the concreting concept isdeveloped. With an assumed structureheight of 570 m, the residence time of theconcrete in the 150 mm delivery line isaround 35 minutes. Add to that the significantlyhigher load on the shut-off valvedue to the much heavier concretecolumns in the line.In addition to the 45,000 m 3 of concretefor drilled piles and base plate, a furtherconcrete requirement of around 180,000m 3 is estimated for the high-rise pumpingfor the tower and the three wings.Due to these immense concrete quantities,the delivery pipes are of course subjetto friction wear. To ensure that they donot have to be changed, Putzmeistersupplied especially long-life pump lineswith an 11 mm wall thickness.From the central pumping station at theBurj Dubai, two of these massive deliverylines will initially lead to wing "A". In thebuilding, the two main lines divide intofour legs, each of which runs to aPutzmeister stationary concrete placingboom. A further, fifth line is provided forstand-by operation.In the central core of the Burj Dubai, the two mainlines can be folded down onto four risers in just afew movements. The risers lead to the stationaryPutzmeister booms on the decks and up in thetower."Thick" line has advantages anddisadvantagesIncreasing the cross section of theline has a direct influence on the flowrate, the wear behaviour, the pressurerequirement and the period for whichthe concrete remains in the pipeline –given the same output per hour. Incomparison with the 125 mm deliveryline, the cross section for the 150 mmdiameter increases by around 44 %.This results in a pressure reduction ofaround 25 %, and the wear also reducesaccordingly.65Massive wall brackets hold theconcrete lines which weigh over50 tonsTo support the weight of the risers (theyare still full during the concretingworks!), every delivery line is supportedby a massive mount after transition to thevertical. These U-shaped mounts have7If individual pipes have to be replaced, the entireriser can be lifted by hydraulic cylindersbeen welded with heavy steel plateswhich have been concreted into the wallsand bear the weight of the respectiveriser. With an assumed pumping heightof approx. 570 m, the weights involvedare immense. The combined weights ofthe pipes and couplings and the weightof the concrete comes to more than 50tons!The individual 3 metre pipes of the pumplines are fixed by floor fixing plates betweentwo storeys, so that they are freelymobile in the vertical, but cannot breakout or bend horizontally – despite theweight. This expensive routing andmounting of the pump lines was requiredas, according to Putzmeister's calculations,the stress on the pipes due to thebuilding settlement, axial tension andtemperature expansion would otherwisehave been too great.8 9The pump lines are routed along the sidesbetween the ceilings so that they cannot bendhorizontally, although they are freely mobileverticallypossible at all times. To this end,Putzmeister engineers developed the socallediron sword, which works like ahydraulic shut-off valve and is optimallyadapted to the space conditions thanksto its low construction width. So, if theconcrete batches are not placed within90 minutes, emergency emptying wouldbe triggered, i.e. the riser would be isolatedwith the iron sword, the deliveryline bend beneath it would be opened,the sword would move back and the concretecould flow freely from the line.10"Iron sword" for emergenciesDue to the high temperatures, concreting work is carried out predominantly at night timeComponents of thedelivery line conceptHigh-rise concrete begins to set afteronly two hours. In order not to lose theentire line section due to setting concrete– e.g. due to problems in the mixer, failureof a pump, blockages in the 70 mlong horizontal line, delays in concretedelivery or concrete placement – fastemptying of the delivery line must beFor emergencies: with the "iron sword" fastemptying of the riser is possible at all times4BP 3893 GBBP 3893 GB 5

Hydraulic lifting device makesit easier to replace pipesSpecial lifting devices were developedby Putzmeister to replace individualdelivery pipes. They consist of asleeve that is connected to the couplingof the pipe section above. Twoanchor rods are then routed throughthe deck above and supported by it.The complete line section is lifted byhydraulic drive cylinders, that areactuated via the hand pump.12 13As the pump line is not yet completelyempty – there is still residue in the 70 mlong horizontal line – the last of the concreteresidue is pushed out of the deliveryline from the top end of the pumpline using a sponge ball and compressedair. To do this, two people from the concretingteam remove the end hose fromthe top of the stationary boom, place awet sponge ball in the line, connect awash-out adaptor and apply compressedair. With this method, the damp spongeball is pushed down through the riserand any concrete residue is removed.Thorough final cleaning is then carriedout in a similar way, except this time aplug created from a sponge ball, waterand another sponge ball is forcedthrough the concrete line. The wholeprocess does not take more than around20 minutes.11The non-ballasted Putzmeister MX booms do not pose an obstacle to backward walls nor other craneson the formworkStructure of the cleaning station: on the right, one of the Putzmeister super high pressure concretepumps, in the centre a shut-off valve with 90° pipe bend, which is either connected to the dischargeconnection of the concrete pumps for pumping operations, or to the connection for the cleaning towerChanging the pipeline using the hydrauliclifting mechanismStationary boom without ballastThe delivery lines are connected to a totalof four stationary Putzmeister booms.Three of the lines are connected to MXR28-4 T type booms, which carry out concreteplacement in the wings. The MXR28-4 T booms are secured on the platformsof the self-climbing wall formworks(Doka) and stand on 16 m hightubular columns. The concreting work inthe central heart of the building is continuedby a fourth, even larger, MXstationary boom with a 32 m reach. ThisMXR 32-4 T is set up on a 20 m hightubular column and installed on a Dokawall formwork in the shaft. The climbingprocesses are carried out hydraulically inseveral steps per storey. Three days areneeded on average to complete one storeyin the central tower building. Incidentally,Putzmeister supplied all four MXbooms without ballast. The consortiumwanted to ensure that the ballast beamsof the stationary boom would not pose anobstacle to cranes and formworks.Simple but thorough cleaningAround 100 m 3 of concrete are placed inthe walls of the central core for each section(there are three sections per storey).The concrete requirement for the ceilingsvaries in the wings from 150 m 3 in thelower levels to 50 m 3 for the upper storeys.At the end of the individual concreteworks, the pipelines and concrete pumpare thoroughly cleaned. To do this,Unimix, on the recommendation of thePM engineers, has installed so-calledcleaning towers next to each BSA. Theseconsist of a short horizontal delivery lineand a riser of about 4 m length, which isbent twice by 90° at the open end.Immediately before cleaning, the concreteline directly behind the BSA pump isinterrupted by a hydraulic shut-off valveand the connection to the cleaningtowers is produced by slewing a 90°angle. The machine operator can alreadybegin cleaning his BSA 14000. Beneaththe towers, an empty truck-mixer waitsfor the shut-off valve to be opened andfor the concrete to flow from the line intothe truck-mixer drum by means of gravity.A trough under the hopper collectsthe concrete residue.6BP 3893 GBBP 3893 GB 7

14Teleservice informs centralPutzmeister After Sales department– own personnel are on siteWork at the Burj Dubai is carried out inthree shifts. Due to the high day timetemperatures – up to 50 °C – the concreteworks are usually carried out during theslightly cooler night time hours. In orderto always remain informed of the conditionof the super high pressure pumps,the two BSA 14000 SHP D pumps aremonitored by Teleservice by the centralPutzmeister After Sales department inAichtal, Germany. Important parameters,such as hydraulic pressure, control signals,oil temperature, etc. are transmitted.In addition, experienced Putzmeisterservice engineers attend to concrete deliveryon site. These engineers were alsoinvolved in the specification of the superhigh pressure pumps and when workingout the concreting concept. Also, duringthe subsequent installation of the pipelinesand booms, the PM specialistswere at the side of the customer Unimixand the site management to advise.Putzmeister Products and ServicesConcrete Pumps · Industrial Technology PIT ·Telebelt · Mörtelmaschinen GmbH · DynajetHigh Pressure Cleaners · Services · ConcreteProject Division CPD · Consulting and DataTechnology · AcademyPutzmeister AGMax-Eyth-Str. 10 · D-72631 AichtalP.O.Box 2152 · D-72629 AichtalTel. +49 (7127) 599-0Fax +49 (7127) 599-520www.putzmeister.comE-mail: pmw@pmw.deBP 3893 GBRight to make technical amendments reserved · © by Putzmeister AG 2007 · All rights reserved · Printed in Germany (20704RR)