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Baking walls requires oil


The central library construction site will remain busy throughout the summer as the construction of new walls, pillars and other concrete structures continues. So far, approximately one third of the concrete work on the basement has been completed, and the upright pillars at the north end will soon be ready to hold up the basement ceiling, which will also form the ground floor of the library.

But how is casting concrete walls similar to baking? The large wall moulds are oiled to prevent the wet concrete from sticking to the moulds when poured, just as you should grease a baking tin to prevent the dough from sticking to it. An oiled mould is also easier to dismantle once the wall has dried enough to support itself. The photograph above shows carpenter Juha-Matti Komu (on the left) and supervisor Jarmo Ahokas from E.M. Pekkinen Oy fixing an oil tank pressure hose just before Midsummer. Such repairs are crucial, as this isn’t the kind of oil that you can just pick up at your local corner shop.

By Midsummer, 12 of the basement walls had been cast, with a further 10 elements left to go. The large moulds can be used to cast individual concrete elements measuring 11 metres long and 6 metres high. The wall at the northern end of the construction site is already looking complete, but in the south section parts of the bedrock are still visible. The construction of the basement ceiling, or vaulting, is set to begin in the north end at the turn of June and July. As the construction progresses, the vault will obscure the view into the currently visible basement.

For the purpose of service traffic access, the design of the library includes a ramp leading down to an inner loading area located in the basement. The loading area can be seen in the middle of the photograph above. The square room on the left of the loading area is a pumping station, which will be used to manage rain and waste water as well as waste from the library restaurant’s grease filters, for example. The ramp will be constructed on the right edge between the straight concrete wall and the curved wall currently under construction. The curved wall cannot be cast with a mould, requiring some old-fashioned handwork instead, as well as plenty of plank boards and plywood.

The curved wall, which is marked in purple above, will lead vehicles down to the loading area along a 60-metre-long, concrete floor ramp. The ramp begins at ground level and descends approximately six metres. The basement loading area will be used for unloading library book deliveries and restaurant and café goods as well as loading bin lorries.

Next to the loading area there is also a large concentration of toilets in the basement. Since the library is a public space located in a busy area, the building will naturally include a large number of toilet facilities. People are expected to spend a lot of time in the library, as the building will also include workspaces, a cinema and a restaurant. The picture above shows the foyer of the toilet area; the stall doors will be placed on the right. The area will be accessible by both stairs and lifts. The building will house a total of six lifts, but only four of them can be used to access the basement.

Foundations of the steel arch completed

The foundations of the massive steel arch that will support the building have been completed at both the north and sound ends, and the installation of the arch’s housing structures is to be carried out in July.

The north foundation of the arch is shaped like a plus sign. The housing structure of the arch will be installed on top of the footing, after which the parts will be welded together. The steel bridge that will be drawn between the northern and southern footings will have a span of 105 metres, and the arch will include a spring structure set in the basement ceiling.

The south foundation of the steel arch is located next to Sanomatalo near a stairwell, which was constructed in anticipation of the planned city centre tunnel. Jarmo Ahokas and Site Manager Kyösti Kontio say that the footings are in good shape: they have been drawn and fastened to the bedrock with jag bolts. The force needed to achieve this is generated using hydraulics.

Viewed from the northern end, the construction site can hardly be called a pit anymore, as it has been filled with a number of pillars and will continue to fill up with separating walls and ceiling tiles. One of the building’s stairwells has also been completed at the north end, visible in the right corner of the above photograph.

Even though the summer holiday season has just begun, the clock is still ticking, almost audibly, on E.M. Pekkinen’s construction contract. The schedule is tight, so the workers’ holidays have to be staggered to keep the construction work going regardless.

The beaver mascot has already been immortalised on a clock face and on the backs of Pekkinen’s worker’s hoodies. Demand for the signature of the artist behind the mascot, Salla Savolainen, has also proved high among the workers!

On the other side of the construction site fence, people are enjoying the summer sun and having picnics. In fact, that is exactly what Lucy Abrams (on the left) and Kaisa Johansson were doing just before Midsummer. Lucy, who is from Chicago, has been living in Finland for three years and studies clarinet at the Sibelius Academy, which is housed in Musiikkitalo across the road from the construction site. Kaisa Johansson also works in the same building. Lucy says that the practice rooms on the upper floor offer a good view of the construction site, but luckily her studies have not been hindered by the sounds resulting from the construction work.

The two women welcome the new library, saying that the location near other cultural buildings is ideal for it. They continue by saying that they’ve been impressed by the illustrations of the central library, and are sure to visit the library once it is completed.

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