XX. századi műemlékek és védelmük (A 26. Egri Nyári Egyetem előadásai 1996 Eger, 1996)

Előadások: - Maija Kairamo: The rebuilding of the Olympic Satadium of Helsinki 1991-94

Yrjö Lindegren, who was a talanted and skillfull architect, had been the architect responsible for the Stadium from the beginning up until this Olympic period. However he died in the autumn 1952 and so the later works were planned by his partner Toivo Jäntti. After the Olympic Games the wooden enlargement was taken down and the vast spaces under the seating stage were rebuilt as offices and a youth hostel. The original functional beauty has, perhaps, dimmed in recent times but, however, the Olympic Stadium is considered to be a national monument, which schould be preserved both for its historical and architectural value. When it was decided that the European Championships in Athletics was to take place in Helsinki, a detailed technical survey of the Stadium was started. It was found that the reinforced concrete constructions of the seating stage were in a critical state. The northern curve of the seating stage was immediately closed because it was near to collapse. The high tower and the painted surfaces had at some time been repainted with synthetic paints and the surfaces were now flaking. Part of the interior spaces were dilapidated. On the basis of the technical survey it was recommended that: — all supporting constructions be repaired — the seating stage construction be repaired and covered by waterproof surface — the benches with their iron supports be renewed — a new rain water channels to be built on the sports field and the drainage renewed — new protective surface coating on all concrete roofs to prevent carbonization — damp-proof insulation of all open concrete planes — all moving joints to be repaired — replastering and painting of the tower — repair of all the iron fences and rails. In the 1930s concrete was new and it was considered to be an eternal material. Now we know that this is not true. The concrete deteriorates through the actions of rain and frost. The most problematic phenomena of the concrete is the carbonization. When the reinforced concrete is cast, a protective layer on the irons is formed. The fresh concrete is alkaline and this protects the reinforcement irons against rusting. In time the cement in concrete carbonizes during a chemical process where the carbondioxide of the air joins with the calcium of cement. This process continues at a rate of about 1 to 2 mm per year and when it reaches the reinforcement irons, these begin to rust. The volume of the rusting iron grows and eventually blows the concrete surface away. Water can now enter the inner parts of the construction and the deterioration process will accelerate. This process had violated the Stadium which — as you remember — was completely cast in concrete. The damage to the constructions led to a very substantial rebuilding. The Stadium is owned by a foundation in which the State and the City of Helsinki have the major responsibility. The budget for the refurbishment was calculated as 170 million Fmk (c. 35 million dollars). The State and the City of Helsinki decided to divide the costs 50% to 50%. The planning of the refurbishment started and the execution was divided into several phases. Although the Stadium is generally considered to be a national monument, it is not protected by any legal measures. First in the spring 1991, when the works started, it was realized that the execution of the refurbishment meant that large parts of the original construction would be demolished. In practise the preservation of the architectural values of the stadium were threatened. Thus the National Board of Antiquities (NAB) was contacted. The Ministry of Culture gave a small sum of money for a historical inventory and documentation of the Stadium.