A memorial for the 267 residents of New York’s Staten Island who died in the September 11, 2001 attack on the World Trade Center (WTC) was produced with Hydrex 100-HF vinyl ester resin from Reichhold, Inc.
Designed by architect Masayuki Sono, the monument was produced using the vacuum infusion process by New England Boatworks (NEB) of Rhode Island in the US.
The 37-foot tall (11.2 m) monument, entitled “”Postcards,”” includes two, 12-foot (3.65 m) cantilevered, composite wings which rise in honour of the 9/11 victims from Staten Island. The 40-foot (12.2 m) long rectangular main box-beams, consisting of 40 mm girders, were contoured to follow the shape of the sculpture’s “”wings.””
Sono’s twin “”postcards”” makes a metaphoric reference to the site of the twin towers, and features touchable “”commemorative stamps”” that bear the name and profile of each victim. The wings frame a view of lower Manhattan featuring the former site of the WTC.
The challenge New England Boatworks faced with the memorial’s softly curving design was how to build it. NEB personnel knew that post-reinforced concrete would be unable to withstand the loads that high winds would impose on the design’s cantilevered wings.
After conducting a structural analysis, NEB’s engineers specified a composite laminate of E-glass, foam core, and vinyl ester resin. Once testing was conducted, Reichhold’s Hydrex 100-HF, low-styrene, 100% vinyl ester resin was selected, and NEB began building the structure using a vacuum infusion technique with Hydrex 100-HF resin specifically designed for the vacuum infusion process.
The vacuum infusion process uses vacuum pressure to drive resin into a laminate. Materials are laid dry into the mould and the vacuum is applied before resin is introduced.
Once a complete vacuum is achieved, resin is “”pulled”” into the laminate via carefully placed tubing.
“”Composite construction can withstand high loads and repeated flex without cracking,”” noted David MacBain, a partner at NEB. “”By applying composite technology to buildings and sculptures, we are able to find elegant solutions to structural problems.””
By choosing composites instead of concrete, the weight was reduced by around 90 percent with a round 30 percent costs savings.
Building the Staten Island 9/11 Memorial gave New England Boatworks’ Composites Team an opportunity to perfect the vacuum infusion process. To obtain the strength that the structure will need to withstand repeated flexing in high winds meant pulling resin through as many as 38 layers of heavy fibreglass. Small channels scored into the foam core allowed the Hydrex 100-HF resin to migrate.
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