City of Corten

One of the materials I always admired for its inherent rough beauty is weathering steel. Also known by its trademarked name ‘Corten’. It is a steel alloy which forms a stable rust surface if exposed to the weather. This eliminates the need for protecting it by painting. Its popularity in Denmark might be caused by a fact that it would be quite expensive to paint steel, because of the high labour cost. This lead to the spread of the use of Corten. However, its place of origin is the USA. In 1933 Corten was patented by U.S. Steel. Today, weathering steel is also known by the brand name Patinax and others and is produced worldwide.

As a material, corten radiates both strength, as is common for metals, and the beauty of passage of time. The oxide layer on its surface, commonly known as rust, gives the building appearance of a titan, standing in its place for centuries. Earthy brown reddish tones, which may differ, depending on the local climate, anchors the building to its place. It can be used for many purposes such as a structural steel or cladding. Another important use is also for many outdoor sculptures.

And during a few days in my current hometown, I captured many examples how Corten can be used. And I was not even looking for it. I was just casually cycling to the work or Danish courses and all these examples were just popping at me at every corner. I felt like Alice in Wonderland, so many great examples, eye-candies and textures.

There is a cinema clad in corten panels with cut sign with the names of famous cities connected with movie industry.


Corten can be used as landscaping tool. In a park near Vejle Municipality, Corten plates hold the ground, where the path cuts through the moulds of grass.

Corten can be cut to produce different patterns, as seen at this fence, dividing the street and back of the parking area with dumpsters.


Another park in Vejle incorporates Corten oculus.


And patterns cut into corten.


There is also a shopping mall ‘Bryggen’. Whole clad in Corten plates.


Detail of Vejle’s coat of arms carved to a bridge over Grejs river in the city center.


Sculpture in one of the side alleys running parallel to the main shopping street.


And the cover of drainage channels.


And those are examples just from Vejle. Small, town in Jutland. And even here, we can spot many great architectural pieces. It is not big and pompous architecture, however, it is an example of clever use of materials and principles in local context. The city combines old with new and is not afraid of changes. This attitude allows the city to grow and adapt to the future instead of dwelling in the past. And the Corten might be seen as a symbol of it.




EPS is dead long live to GraphiteEPS

This might be one of the more technical posts. Since this blog is still in its cradle, constantly evolving, you might find  funny, thoughtful or technical posts here. However, I will try to keep all information as much accessible for anybody interested. If you have your opinion how should I steer my blog you are welcome to leave a comment or write me a mail.

On a building site at Tusinfryd, I stumbled upon a sample of graphite extruded polystyrene glittering in the morning sun. Distinguished by its grey colour. However otherwise seemed like the normal polystyrene. I must admit I have never seen this kind of polystyrene before, and therefore I checked it up and actually write a part of our building site report about it.


Normal polystyrene has been used for insulation for a long time. In Denmark mostly for insulating under the floor slab, in many countries, it is used on walls from outside as well. Standard polystyrene insulates quite well and it lasts very long time, probably longer than nature would like, but in construction, its longevity is a plus.

In recent years, new technique during a manufacture of polystyrene has been invented. Each foam bubble is coated in graphite power. Graphite further increases the insulation properties of the polystyrene, because it reflects the heat back.

This made me very interested, so as a part of research and because I had to write building site report I delved deeper into this process.

I found a company which makes both standard and graphite polystyrene and made a comparison based on premise that I want to achieve certain U-Value (that is a fancy technical word which describes how well certain materials insulate).

Below you can see that I wanted to achieve U-value of 0,15. And from my calculation, we can see that the graphite polystyrene is about 3% more expensive per same insulation properties. But that’s not the whole conclusion. Aaaaand since I spend quite a lot of time with that I will do one amazing thing. I will quote myself (evil laugh). Isn’t that amazing thing you can do?


From my calculation, we can see that both kinds give us nearly the same U-value to price ratio. Expanded polystyrene has the ratio slightly better. However, we can assume, that by using graphite expanded polystyrene we are cutting down the transportation cost since we have to transport around 20% less volume. Also, there might be a small difference in labour cost, since we have to move less volume of insulating material around the building site. Same is true for the excavation process since we do not have to dig that deep, which is another slight advantage which cuts down overall construction price by a small percentage. The last thing might also be the construction thickness. When we do not have the luxury of simply digging deeper, we might use graphite polystyrene when we need thinner construction, e.g. insulating of the floor above non-heated basement. All those advantages give an edge to the use of graphite expanded polystyrene. And since the company building the house we are observing builds hundreds of similar houses, they probably calculated these advantages as well and in order to cut down the construction cost and maximise their profit, they decided to use graphite expanded polystyrene. The difference might not be much, but details make the difference when they are put together. As a conclusion, we might see, that the advantages of graphite polystyrene are subtle. However, even small advantage makes difference, especially in larger quantities and therefore I would recommend using graphite expanded polystyrene instead of normal expanded polystyrene. (Slunecko, 2017)

However don’t take that too seriously. But seriously, graphite expanded polystyrene is amazing and I believe it should be used basically everywhere normal polystyrene can be used.

Like below, graphite polystyrene used in a foundation block. Bang boom win win. Superinsulation!IMG_0383

And as with standard polystyrene, easy manipulation, cut with a hot wire cutter. Very useful and universal insulation material. I strongly encourage its use. Its super cool to use the best you can get. Once you go grey you never go back.


Happy insulating



Concrete for dummies

And tonight´s star is ………(ba-dum -tssss). Concrete. We have been waiting for his visit a long time and finally he found some time in its busy schedule to tell us some interesting facts about itself.

As we all know, concrete is a mixture of three basic components; aggregate, cement and water. The aggregate is of two types; fine(sand) and coarse(different sizes of gravel and stones).

The basic process of making concrete involves mixing all the components together in a specific ratio, which influences properties of finished concrete. Once you mix components together, you have to be quick, because concrete slowly hardens. Because of the liquid nature of fresh concrete, you can essentially sculpt anything you can imagine if you have the right formwork.


The concert hall of Santa Cruz de Tenerife. Designed by the architect Santiago Calatrava

And now beware my reader, because now I will get all educational so leave immediately if you are bored because it will get worse, I will describe in detail all the components and its types, so it will get very nasty soon. I warned you.



Cement is a general name for a material that binds other materials together, so yes, it is kind of another name for glue. In construction industry we commonly speak about Portland cement, which is the most usual type. When water is added to the cement, it sets off chemical reactions and the cement starts to harden. Portland cement is a basic component in concrete, mortar and stucco.

Most of the production of Portland cement in Denmark is carried out in Aalborg. We can choose from standard general purpose cement which is suitable for walls/columns/beams and foundations. Another type is rapid cement, which is more resistant to cracking and is used mostly for floors. Then we have special mortar cement and white cement, which is more expensive and therefore used only for decorative purposes.



We can normally use standard drinking water for most uses and we can also use sea water. If sea water is used, the concrete develops white powdery surface, but unfortunately also quickens the corrosion of used steel, so it is generally not suitable for most uses.

Fine aggregate.


In Denmark, particles smaller than 4mm are classed as fine aggregate. Choosing the right sand is essential. The usual demands are uniformity of shape, round or cubical, and also  appropriate strenght. Best sand also has a wide range of sizes (from tiniest through medium sized to “biggest” 4mm). Because of these demands, sand used is either specifically crushed stones in a factory environment or river sand. Other types (desert, beach or pit sand) are for one or another reason unsuitable.

Coarse aggregate.


Stones have smaller impact on the quality of concrete than sand, nevertheless, they should be hard, clean and durable. Sizes of these should not exceed one-fifth of the thickness of the wall we are pouring. Usual sizes are 19 to 25 mm.

Once you mix these, you can see our star driving around in its limo. (I would kill to be able to drive this baddass piece of machinery)Kenworth_W900S_concrete_truck

And once it arrives on a construction site. It is poured into the formwork.


Fun fact nr. 18. Since concrete quickly hardens, pouring the concrete must be exceptionally well organized, when pouring concrete on bigger projects, there are dozens of baddass vehicles arriving and leaving the construction site in cca. 15-30 minutes intervals. On exceptionally big projects, the concrete on one side might be already hardened and on the other side, a fresh batch is being poured. Also on huge projects, the concrete is actually being pumped around. See the picture below.


Well, I guess those of you who made it this far are already showing symptoms of brain-dripping-out-of-the-ear syndrome, so I am going to stop myself, since you are educated enough for today. Hope you at least found something useful.