The use of mechanisation, precast construction and BIM are helping Gammon Construction’s innovation drive in Asia.
The Cathay Pacific Cargo Terminal has been a showcase for the offsite pre-construction and mechanised construction methods of Hong Kong-based contractor Gammon Construction.
The recently completed HK$5.9 billion project involved construction of a seven- storey warehouse with access ramps and an office, covering some 240,000 square metres, at Hong Kong International Airport.
“At tender stage, the client said they would consider alternative designs, so we went for a predominantly precast solution,” explains Ted Lawton, Gammon’s Senior Engineering Development Manager.
Gammon’s design for the 48-metre-high terminal’s structure – which saw precast units barged in from the Chinese mainland 100 kilometres away – provided benefits in terms of quality, speed, cost-effectiveness, carbon reduction and safety.
The primary floor slab beams, which have 20-metre spans and weigh 240 tonnes each, were cast in situ using an innovative mechanised steel shuttering system, instead of traditional formwork.
“The mechanised beam shutter gave us a precision finish to match precast beams, and made construction eight times quicker compared with formwork,” explains Lawton. “There are also environmental benefits – we estimate it saved 3,500 tonnes of timber.”
For the precast secondary beams, Gammon’s alternative design replaced the T-beams of the original design with pre-stressed I-beams, which supported precast semi-slabs and a lattice girder. This cut the slab thickness from 245 mm to 175 mm, reducing concrete requirements by 12,000 cubic metres and rebar by 5,000 tonnes.
“Our approach reduced the man-hours required by 50 per cent – which made the site safer and less congested – and delivered the floor slabs in a quarter of the time,” says Lawton.
Another bonus was early handover of sections of the terminal for Siemens to install the cargo handling equipment. BIM was used to avoid clashes with other work packages during the installation.
“The project’s success was helped by the client being receptive to our alternative design, and the three-month lead-in to plan the precast design and shuttering system,” says Lawton. “On future projects, we see the growing use of BIM helping our mechanised approach, as it brings the design and engineering disciplines together, making it easier to co-ordinate all the different packages on site.”
For further information please contact Kieran Curtis, Divisional Director, JLT Asia on +852 2864 5320