Don your hard hat, safety shoes and high-visibility vest, climb the stairs and enter our future art museum.
It is cramped, dark, dirty, cold – and very exciting.
Into the old silo pipes, back out again, between concrete beams, under makeshift lifts, up 15 steep ladders; and suddenly, we see the light. We have a view of the sea, the city and the Cultural Centre.
We are on the roof of the silo, 38.6 metres (127 feet) above ground.
Site manager Simon Hartveit is our guide. Just now he is standing next to one of the hatches where they used to pour in the grain. He tells us about the workers who according to plan will be lowered down between the silo pipes to reinforce the structure.
“We will be cutting the pipes at a height of 20 metres (66 feet), and so we must first create a beam structure between the cylinders. That is quite a complex process. We need to get in between all the pipes, make holes and then pour concrete for reinforced concrete beams. After that we can start demolishing inside the silo,” says Kruse Smith’s site manager.
There is history in the silo walls; it is concreted into place. Before long, however, this building will begin an entirely new chapter – containing art, culture, debates and discussions. We hope the silo will soon be teeming with people.
For the moment it is a typical building site with around 60 workers. When they begin demolishing the silo cells in the autumn, nearly three times as many workers will be busy here.
The staircase tower and harbour warehouse have already been demolished, and the building has been given a new foundation. Once the silo has been properly reinforced, concreting will begin between the pipes.
“It is a cool job,” says Hartveit. “I build things all the time, but I think this is really cool”.
And a little out of the ordinary, of course.
“We can’t claim to have rehabilitated a lot of silos before, so this is not a routine job. But that doesn’t mean it is a problem. We have plenty of experience with many of the processes, but we have never done a whole job like this one before. What really sets it apart from most other projects is the changes we need to make in the supporting structures of the existing silo. There is a lot to do before we can start pulling anything down,” he explains.
The silo construction was built to stand as 30 separate silo pipes, but that will now be changed quite radically.
“We will move the entire supporting structure onto new foundations and new concrete, and that is a challenging part of the project. A lot of engineering work, mathematics and detailed design had to be done first. You can’t just start demolishing in a corner,” says Hartveit, who is in charge of health, safety and the environment as well as logistics at the building site.
The grain silo was built in two stages. Half the cells were built on rock in 1935, while the other half was erected on a landfill in 1939. One half of Kunstsilo will therefore be built on piles reaching 16 metres (52 feet) below ground.
The original concrete from the 1930s has been repaired by Kruse Smith. It was in better condition than expected.
“In general, concrete is greatly affected by chlorides from the sea and carbon dioxide from the air. Concrete is alkaline, and the alkaline in the concrete protects the iron from corrosion. But when concrete absorbs chlorides and carbon dioxide, its alkaline structure changes, and the iron might start to corrode. The iron will then expand and burst the concrete. The quality here is surprisingly good, however, with little impact from the elements,” Hartveit explains.
The concrete structure is now being reinforced with a further 20 cm (8”) of concrete on the outside of the silo pipes. This is done using the slip form technique, just like in 1935. At that time it was an entirely new method, whereas now it is routine. It is still a demanding task, however. It is intense work where the concrete is formed in layers, while the casing is regularly lifted further up the construction by means of jacks or special devices.
This process takes place over three weeks in May and June, with the work continuing 24 hours a day. The rehabilitation will require a total of around 13 000 tons of concrete and nearly 900 tons of steel.
Our guided tour is coming to an end. We are down at ground level again, and hard hats and safety shoes have come off. We are back in the office, and the site manager can devote himself to more important duties.
Hartveit is pleased with the progress made, and is looking forward to the day when one can enter the cathedral-like building and enjoy top-notch exhibitions. As an art devotee he will also be visiting Kunstsilo as a guest.
“That’s why it is so exciting to be part of this project. From a construction point of view I would have thought so anyway – this is a really fantastic project! It is an interesting building which has won a prestigious architectural award and it is very typical of the functionalist period. Aesthetically it is spectacular, and I think it’s really cool that they erected this kind of industrial buildings at the time. This building shouts functionalism all the way to the moon, and it seems absolutely right that it should now become an art museum.”