Dec 23, 2015

Concrete steps, part 2

So the mold was ready and it was time to mix the mud. Pekka borrowed a concrete mixer from his friend Stenkka, whose tools and knowledge have been invaluable during these 3.5 years of renovation. Once again, thank you!

Concrete mixer

Mixing and pouring concrete to the mold is an iterative process. You start from the bottom of the stairs and work your way up. Every now and then you need to get a rid of bubbles inside the mix. In case of a small mold like this one, this was simply done by hammering the mold from various directions.

One down, seven to go

We knew it would be a bit of a gamble with the weather. Thus, Pekka worked the entire day to get the job done at once before the temperature would drop. Luckily, the weather stayed warm enough through the process.

Concrete man

These were quite intense moments. Step by step Pekka worked his way up the mold, but even if he had 3D-modelled the structure in order to estimate the amount of concrete needed, he wasn't quite sure how close he was, would there be enough concrete.

Fresh-out-of-oven concrete stairs

Finally, just before the darkness fell the all the steps were ready. It also seemed the mold was holding well and out of the 37 sacks of concrete, he had used 34. Perfect!

Daughter & Father team

Sofi of course helped. For a three year old, what could be more exiting that making mud and playing with it with her father. She is such a great apprentice, and truly interested in everything renovation related. One of her most frequently asked questions at the moment is: "How has this been made?"

Wrapped in a zillion layers

Apparently it requires approximately 400 C / hours for concrete to harden. At the moment the temperature in Southern Finland varies between 0 - 10C, Pekka wanted to minimise the risks. Therefore, he first wrapped his precious mold with a felt, then covered it with a tarpaulin to prevent contact with water. He also set a 110W light bulb to create heat underneath the cover and monitored the temperature carefully by adding a thermometer. Nearly as in a scientific experiment, the end result was stable 8C.

Sound a bit extensive? Yes, we would need to agree.

And what is revealed underneath?

One week is a long time when all you can do is wait. Would it settle? Would the rhythm of the stairs be convenient to walk?

Brand new stairs

In the end, everything went as planned. Yes, the concrete has some visible bubbles, but is not a problem. Next spring Pekka will cover the steps with the same slates we used downstairs and at the terrace. So exciting! It will be the first summer with a yard, instead of a muddy mess!

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