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Composites specialists Aerontec (Cape Town, South Africa) reports that it recently completed a project to install 300 tons structural composite decking on a quay of the Cape Town container terminal to increase the height of a section of the concrete deck by 190 mm/7.5 inches.
The problem addressed by the decking was a cable tray, 1,200m/3,937 ft long and 3m/9.8 ft wide, that houses the electricity cables for the gantry cranes along the edge of the quay. The cables were considered a trip hazard, thus a solution was needed to make the work surface safer.
The goal was to build an elevated surface under which cables could pass, thus providing a flat unencumbered surface on which workers could walk.
“A first proposal was to cast a second concrete layer 190 mm thick to be level with the crane rail," says Graham Byth, Aerontec's owner. "However, this presented too many disadvantages. Weighing in at about 1,000 tons of concrete and rebar it was too heavy, too costly, too long to construct and too long to wait the prescribed 28 days for the concrete to cure — not ideal for a working quay with ships berthing all the time."
Aerontec was approached for a composite solution. The entire project had to be completed in 12 months and the solution had to be light weight, cost effective, easy to install, able to allow waves to wash over the panels and allow water to drain away quickly underneath the panels, strong enough to endure loads of up to 40 tons, weather resistant, safe and have a slip-proof coating and fastened onto the existing deck surface without damaging the surface or the rebar lattice such that damaged panels can be replaced and to allow access to existing manholes and fire-hydrant access points
Aerontec settled on a panel design that uses woven glass fiber-reinforced polyester resin vacuum infused and coated with a UV-stabilized non-slip finish. Aerontec partnered with MMS Technology, specialists in the infusion of large solid composite panels, to manufacture the composite panels.
A gap was left between the panels adjacent to the rail and the panels at the water’s edge where a Panzer belt had to be installed to cover the electric crane cables. The Panzer belt is lifted by a special belt lifter attached to each crane to withdraw the cable, and to nest the cables back into the hidden cable cavity as the crane passes down the rail system. Blyth explains that the top panel is 32 mm solid glass fiber composite. This is then raised to the specified height using stepped solid feet, bonded and cored with a pultruded rod.
“There is an undulated variance of about 80 mm over the existing concrete quay. We needed to be virtually level with the crane rail to eliminate any trip hazard, so countless GFRP shims had to be made and bonded in place to keep the GFRP panels level,” he adds.
Panels had to be manufactured to account for several variables, including transport, stacking, fitting of panels around bollards, accomodation for manhole lids and fire hydrant access points. The total weight of all panels was 250 tons, within the weight constraint set for the new quay. The entire project was completed within the 12 months and within the allocated budget.