It is hardly surprising there were problems getting the Alexandria Library roof cladding through Egypt's customs. Even the most experienced official would be unsure of how to classify the exotic honeycombed material - especially if he knows it is more commonly used on jet fighters.
The 160m diameter sloping library roof is divided into rectangular bays by long span concrete beams. Each bay is filled with aluminium and steel panelling with a glass step running diagonally across it. The building is orientated so the step follows the line of the sun, to minimise the amount of sunlight shining directly into the library. This complex shape requires accurate workmanship and rigid materials.
To achieve the required levels of accuracy and rigidity in the roof panels, Egyptian contractor Amreya and its Austrian joint venture partner GIG used Hexcell, an extremely strong, honeycomb material used in construction of jet fighter planes, sandwiched between two aluminium sheets.
The material was fabricated by GIG in Austria before being shipped to Egypt where Amreya put the sandwich together in a factory and installed the panels on site.
Sheets of a special glue called Redux bonded the layers together.
The glue sheets were placed between the layers and compressed using 3.5t/m2 of pressure. Special heating plates melted the glue to form the bond.
More complex curved panels were glued together by GIG in Austria.
'The problem was finding glue that could stand the 80¦ to 90¦C heat, ' says Amreya managing director Ahmed Sid Ahmed. 'The solution was found with the Redux sheet glue but this had to be melted on at 200¦. We had to do this slowly over five hours so that the anodised panels were not damaged.'
Sid Ahmed became managing director of Amreya in 1989 10 years after his father set up the company. Amreya's £10.75M Alexandria Library package also includes the glass curtain walling.