HAVING been awarded the construction contract for the landmark HQ project on Al Raha Beach, the joint venture construction team of Aldar-Laing O’Rourke (ALOR) proceeded to seek the most efficient and effective method of construction for the two central core walls, which would form the concrete backbone, of this composite steel structure.

After selective initial discussions, ALOR made the decision to retain the services of Dubai-based BRM Construction as its specialist slipform provider to enable it to complete the project to the standard required within the necessary timeframe.
Upon award of the contract for the slipform works to BRM, the teams began working closely together to ensure that the slipforms provided would offer the best opportunity to fulfill the requirements of, not only the vertical insitu concrete casting but also, the aerial activities initially required by the steel contractor retained for the project.
Following the award of the slipform contract in June 2007, BRM undertook to preassemble the two slipforms required for the project in its Dubai-based works facility. “We designed the slipform system and preassembled it off site,” says Nihad Al Hashemi, business development director of BRM Construction.
The system was delivered to the site in large-format sections to enable an accelerated installation under the supervision of BRM personnel in August 2007.
BRM recommended that the discontinuous slipform method be adopted for HQ as this, in general, is the preferred method of slipforming building cores in the UAE.
“The discontinuous slipform approach allows the slipforms to stop at each of the floor levels,” Al Hashemi explains. “This principle enables the installation of the cast in steel embed plate and vertical reinforcement to be undertaken when the slipform is not moving, thus ensuring correct location and level for these critical items.”
“Each of the cores was cast using a four-decked slipform system, with each system lifted by 115 synchronised hydraulic jacks,” says Al Hashemi. “With BRM operating the physical slide of the system during the concrete pours, the ALOR team was typically achieving three to five-day floor cycles which were timed to meet the core requirements of the steel contractor,” he says.
The system was provided with a standard-format upper deck, working deck and trailing deck. However, an additional external trailing deck was fitted to facilitate the welding and NDT (non-destructive testing) work required for the steel embed plates for the steel superstructure. This approach enabled all elevated steelwork operations prior to the installation of the floor beams to be undertaken from the slipform itself without the requirement of additional access works.
By the end of the project, the slipforms had successfully slipped more than 114 m of vertical concrete, casting a surface area of approximately 36,100 sq m on each core within a vertical tolerance of +/-15 mm.
Upon completion of the corewall works, the slipforms were stripped and dismantled under BRM’s supervision prior to their return to Dubai.
BRM is the largest local supplier of slipform equipment and services in the GCC. Some of the other projects the company is involved with include the Barwa Financial District in Doha, Infinity Tower and Novotel Hotel in Dubai, and Cleveland Clinic and the Abu Dhabi Investment Council (ADIC), both in Abu Dhabi.