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Since June 2018, Uni­beton Ready Mix has de­liv­ered and pumped 26,000m3 of con­crete to con­struct 520 piles at the Medium Pyra­mid ho­tel apart­ment con­struc­tion site in Fal­concity of Won­ders Dubai. PMV Mid­dle East ex­plores the lo­gis­tics and equip­ment be­hind the con­crete pump­ing op­er­a­tion.

Since June 2018, Uni­beton Ready Mix has de­liv­ered and pumped 26,000m3 of con­crete to con­struct 520 piles at the Medium Pyra­mid ho­tel apart­ment con­struc­tion site in Fal­concity of Won­ders Dubai. PMV Mid­dle East ex­plores the lo­gis­tics and equip­ment be­hind the con­crete pump­ing op­er­a­tion.

Con­crete pump­ing is the fi­nal, crit­i­cal link in the jour­ney of ready-mix con­crete from a batch­ing plant to var­i­ous heights and depths on a con­struc­tion site. Con­crete pump­ing op­er­a­tions re­quire ex­per­tise in se­lec­tion of the ap­pro­pri­ate sta­tion­ary or mo­bile pumps, in­stal­la­tion and test­ing of the pumps, and sched­ul­ing con­crete batch­ing and de­liv­ery ac­cord­ing to real-time con­struc­tion ac­tiv­ity. The to­tal amount of con­crete re­quired for a con­struc­tion site is usu­ally spec­i­fied for the en­tire year, and monthly de­liv­ery sched­ules are fi­nalised in ad­vance. In prac­tice, con­crete de­liv­ery and pump­ing sched­ules for con­struc­tion ac­tiv­i­ties such as pil­ing are con­firmed a day in ad­vance by the en­abling works con­trac­tor ac­cord­ing to the quan­tity of con­crete re­quired for the day and the progress of drilling and in­stal­la­tion of re­in­forc­ing steel cages.

To find out more about the con­crete pump­ing process and its lo­gis­tics, PMV Mid­dle East re­cently ac­com­pa­nied Uni­beton Ready Mix on one of its ready-mix con­crete de­liv­ery and pump­ing op­er­a­tions in Dubai. The con­struc­tion site was the Medium Pyra­mid ho­tel apart­ment build­ing at the Fal­concity of Won­ders real es­tate project in Dubai, where Mid­dle East Foun­da­tions Group, the en­abling works con­trac­tor, was com­plet­ing the pil­ing work.

The Medium Pyra­mid (B+G+19 floors + health club build­ing) is one of three pyra­mids – Small, Medium and Large – to be built at the Pyra­mid’s Park in Fal­concity of Won­ders, em­u­lat­ing the Egyp­tian ar­chi­tec­tural won­der in a modern day con­text. Ac­cord­ing to the de­vel­oper, the Large Pyra­mid will be the largest pyra­mid ever built and will be a mixed use com­plex hous­ing res­i­dences, of­fices and other recre­ational av­enues.

Since June 2018, Uni­beton has de­liv­ered 26,000m3 of con­crete to the Medium Pyra­mid site for con­struc­tion of 520 piles. Each pile re­quired 50m3 of con­crete trans­ported in five mixer trucks and poured through a truck­mounted con­crete pump. Drilling at the Medium Pyra­mid site was done dur­ing nights and re­in­forc­ing steel cages in­stalled early in the morn­ings. As a re­sult, the con­crete pil­ing was done dur­ing day­time.

Talaat Mouin Ab­dul Karim, se­nior gen­eral man­ager, Uni­beton, ex­plains the or­der­ing and de­liv­ery process: “We pro­duce con­crete batches for pil­ing ac­cord­ing to the mix de­sign spec­i­fied by the en­abling works con­trac­tor. The con­crete strength spec­i­fied for this project is 60N/mm2. The en­abling works con­trac­tor also con­firms the ready-mix con­crete quan­tity re­quired for a day and the time of pump­ing. Once we re­ceive the book­ing, we as­sign truck-mounted pumps to the site,” says Karim.

The or­der is re­con­firmed on the day of the pump­ing and Uni­beton starts con­crete batch­ing only af­ter the suc­cess­ful in­stal­la­tion and test­ing of the con­crete pump by the com­pany’s staff. This en­ables the com­pany to dis­patch its mixer trucks so that they ar­rive on the site just in time for slump test­ing and con­crete pump­ing.

When a truck-mounted pump reaches a site, Uni­beton’s staff in­spects the en­trance and ac­cess points for in­stal­la­tion of the pump and en­sures that the land is well com­pacted for sta­bil­ity of the pump.

“Se­lect­ing the right lo­ca­tion for in­stal­la­tion of the con­crete pump is a cru­cial part of the process. If the land is un­even or un­sta­ble, we alert the en­abling works con­trac­tor to com­pact the land. Only then can we in­stall and test the pump,” says Karim.

Uni­beton as­signs 3–4 staff on site for qual­ity con­trol, su­per­vi­sion and as­sis­tance. They

in­clude a supervisor, tech­ni­cian for slump tests, con­crete pump op­er­a­tor and helper.

“The qual­ity con­trol process starts with the batch­ing of the con­crete, fol­lowed by slump tests at the batch­ing plant as well as on the site in or­der to en­sure the con­sis­tency of the con­crete in ac­cor­dance with the mix de­sign. Sub­se­quently, the con­crete is ap­proved for pump­ing. If the slump value is low, the pump will not be able to func­tion and the batch is re­jected from the site,” says Karim.

Uni­beton main­tains a fleet of 253 mixer trucks and 61 truck-mounted, mo­bile con­crete pumps in the UAE to trans­port and pour ready-mix con­crete. The com­pany’s mixer trucks have 9m3 and 12m3 ca­pac­i­ties, and the av­er­age out­put ca­pac­i­ties of its con­crete pumps is 70-80m3/h.

Ac­cord­ing to Karim, a de­liv­ery of 50m3 of con­crete would re­quire five 12m3 mixer trucks. Be­cause high-slump con­crete is used for pil­ing, the trucks are not loaded to full ca­pac­ity in or­der to main­tain the con­sis­tency of the con­crete and avoid spillage on the road.

“We are able to batch and de­liver readymix con­crete within an hour af­ter re­ceiv­ing con­fir­ma­tion from the site. The con­crete batch­ing re­quires about 5-7 min­utes, and then it is de­liv­ered to the site in 50-60 min­utes,” says Karim.

The time re­quired for con­crete pump­ing is al­most the same as that re­quired for batch­ing. Each mixer truck takes 7–8 min­utes to trans­fer all its con­crete to the pump. If the time re­quired for the trucks to en­ter and leave the site and con­nect with the truck-mounted pump is con­sid­ered, it takes about an hour to pump 50m3 of con­crete for a pile.

“The amount of con­crete to be pumped for pil­ing de­pends on the di­men­sions of a pile and its load bear­ing re­quire­ments. It’s com­mon for con­struc­tion sites in the UAE to have 100m3 of con­crete per pile. Re­cently, we pumped 250m3 of con­crete to con­struct a sin­gle pile at the Shindagha bridge con­struc­tion project in Dubai,” says Karim.

Uni­beton is not a stranger to push­ing the bound­aries of con­crete pour­ing. In 2016, the com­pany set the Guin­ness World Record for pour­ing over 19,793m3 of con­crete con­tin­u­ously for a pe­riod of 42 hours at the Geepas tower project in Al Bar­sha, Dubai. The con­crete was de­liv­ered us­ing more than 300 mixer trucks that made over 2500 trips from three plants, and the con­crete pour­ing was car­ried out with 14 con­crete pumps on site with an ad­di­tional 5 pumps on standby. Over 600 work­ers were em­ployed in mul­ti­ple shifts round-the-clock to com­plete the job.

One of the pop­u­lar truck-mounted con­crete pump mod­els used by Uni­beton reg­u­larly is the Sch­wing Stet­ter S42SX, which has a max­i­mum ver­ti­cal reach of 42.1m and hor­i­zon­tal reach of 38.1m. The max­i­mum con­crete out­put is 162m3/h at a max­i­mum pres­sure of 85 bar on the con­crete. The tur­ret

can be ro­tated 370° in ei­ther di­rec­tion and the tip sec­tion can ro­tate 240°.

“The length of the boom de­ter­mines the reach of the pump in a pil­ing area. The longer the boom, the more the con­crete piles that can be cov­ered by a truck-mounted pump from a fixed po­si­tion of the truck. This saves a lot of time and avoids the need to cre­ate ac­cess points on large sites, par­tic­u­larly sites with low qual­ity soil,” says Karim.

“Con­crete pumps such as the Sch­wing Stet­ter S42SX are work­horses de­signed to op­er­ate 24 hours. We’ve used Sch­wing Stet­ter pumps to de­liver 800m3 of con­crete in 24 hours at an av­er­age rate of 40m3 per hour for a foun­da­tion work project in the UAE. Such pump­ing ca­pac­i­ties have been tried and tested and can be guar­an­teed for any project,” he adds.

Karim elab­o­rates on the com­pany’s main­te­nance process for con­crete pumps. “Truck-mounted con­crete pumps move from one site to an­other, and we of­ten as­sign a pump on 2–3 sites a day. Gen­er­ally, we as­sign a sin­gle truck-mounted pump to a site, un­less it’s a large project that can­not af­ford down­time and re­quires standby pumps. The com­mon is­sue fac­ing mixer trucks and pumps is break­down and their down­time costs. We have im­ple­mented sched­uled in­spec­tion and main­te­nance pro­cesses to avoid such is­sues. It’s rel­a­tively easy to fix a truck. How­ever, a con­crete pump break­down could cause sig­nif­i­cant de­lays. There­fore, we do not com­pro­mise on the qual­ity or main­te­nance of our con­crete pumps,” says Karim.

En­abling works at the Medium Pyra­mid, Fal­concity of Won­ders, Dubai.

Work­ers set­ting up the out­rig­ger sys­tems (above) while a re­in­forc­ing steel cage is in­stalled (be­low).

The raised boom of the Sch­wing S42SX con­crete pump mounted on the truck.

Uni­beton's mixer truck de­liv­er­ing con­crete to Sch­wing Stet­ter's truck-mounted con­crete pump.

Uni­beton set the Guin­ness World Record in 2016 for pour­ing 19,793m3 of con­crete at the Geepas tower in Dubai.

Con­crete pour­ing via the S42SX pump.

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