Construction World April 2019

PROJECT PROFILE

The company needed to schedule its trucks and truck-drivers for a night shift, while ensuring that enough trucks and drivers were available during the day to supply other projects. “A special feature of the building is the ‘key-wall’ columns, where each of these columns had to be cast in one single pour of 55 m 3 of concrete, with 19 tons of steel reinforcing placed inside these 11 metre- high walls,” Pienaar explains. Hi-tech sonic vibrators were successfully used in the columns for optimal compaction; congestion of the rebar did not present any particular challenge. “For the construction of the main lift core of the building, hydraulic climbing formwork from PERI was used,” he continues. “This was only the second time that this specialised formwork has been used in South Africa, and the experience gained at such heights enabled the development of a new skill set for future projects.” Vertical alignment The vertical alignment of any tall building is always critical. So, to control the plumb of the Leonardo, state-of-the-art GPS technology was used – similar to that used on the 828-metre Burj Khalifa in Dubai. Traditionally, laser beams have been used in tall buildings, but there was a concern that in a building as tall as the Leonardo, inaccuracies could occur due to wind loads, crane loads, construction sequence or other factors. The specialised GPS technology is based on a series of automated sensors employed to deliver precise and reliable coordinates on demand, not influenced by building movements. These coordinates are used to control the position of the hydraulic climbing and slab edge prior to each concrete pour. The technology had not been used on building projects in South Africa before. Keim, a specialist German-manufactured concrete waterproofing and protective coating, was applied to off-shutter concrete elements. Initially sold as a phased development, the 43 floor Phase 2 of the development was boosted to 55 floors when the owners decided to increase the building height for a future five/six star luxury hotel. It will offer luxury residential units in the form of apartments and penthouse suites, as well as over 7 500 m 2 of premium office space. The ‘crown’ of the building is The Leonardo Suite, a 3 200 m 2 apartment with 360° views of the surrounding city. The development will also house a business and conference centre and other amenities like a gym, spa, restaurants and recreation zone. It will be the most technologically advanced, environmentally-friendly building on the continent. 

State-of-the-art GPS technology was used to control the plumb.

28

CONSTRUCTION WORLD APRIL 2019