The EXPO Pavilion on the boulevard in Hoek van Holland was realized in 1994 by the Municipality of Rotterdam as a temporary exhibition building. The original intention was to dismantle the pavilion after five years, once it had fulfilled its function as an information center on the handling of shipping on the Nieuwe Waterweg.
It didn’t get that far, however. Today, the spaces are used as a restaurant and bar, a place where day-trippers like to stay. Early in the day they unfold their chairs to watch the impressive ocean liners pass by from the promenade
Because the building was originally intended for a period of only five years, building physics measures were kept to a minimum. For example, hardly any cold bridges were taken into account during construction, and the facade glass was glued directly to the steel structure. Double glazing was used only in the vision strip to prevent condensation there.
Across the New Waterway is the vast Europoort industrial area, which includes ore transshipment, fuel refining and a power plant.
The building is beautifully constructed of hot-dip galvanized steel. More than 28 years after its installation, CEPEZED’s design is still in good condition; corrosion is nowhere visible. However, a gray-black discoloration of the zinc layer is visible on columns that are fully exposed to the wind and on the parts where stainless steel nets have been applied. According to the owner of the pavilion, who bought the building from the Municipality of Rotterdam years ago, these nets were intended to reduce noise. In fact, the lattice elements used in the facade had a tendency to whistle in the wind.
Due to galvanic corrosion, caused by the direct contact between stainless steel and zinc in a humid climate with a high concentration of (sea) salts, the zinc layer is locally discolored from brown to anthracite gray and sometimes even black.
In 2010, the average zinc coating thicknesses were 191, 225 and 289 microns, respectively, with a lowest measured value of 161 microns. Measurements were taken again in 2022; an average coating thickness of approximately 185 microns was measured on the hot-rolled beams, with a highest value of 214 microns and a lowest value of 146 microns. Unfortunately, these results cannot be properly compared because the exact measurement locations from 2010 are not known.
On balance, it can be concluded that there is a very normal decrease in zinc coating thickness, consistent with the zinc corrosion that can be expected in a C3 environment, namely about 1 to 1.5 microns per year. It should be noted that this is one of the most heavily stressed locations in the Netherlands: right by the sea, fully exposed to the wind and, in addition, in the vicinity of chemical industry, which, depending on the wind direction, can certainly affect life expectancy.
It can be expected that the main structure of this beautiful pavilion will withstand a second term of 28 years without any problems. The question remains whether the structure will be dismantled in the future in order to be relocated. In that case, the galvanized steel can easily be treated again, after which it will once again be a striking and durable presence for decades.
In short: might this galvanized structure also be a pioneer of the circular economy? We are following it with interest.
