The tree grille is made from cast iron with a thickness of 50/44 cm.
The sub-frame is made from hot-dip galvanized steel with U-beam USP80.
The root control barrier is made from reinforced concrete with a thickness of 10 cm (there are openings in the bottom to enable roots to grow deeper).
Nola uses high-quality steel of good strength in our products. Steel rusts if left untreated and must therefore be surface treated. For this we use two main methods for surface treatment of steel parts; electrogalvanizing and powder coating as well as hot-dip galvanizing.
Cast iron is iron with a carbon content between approximately 2 and 4 percent with a large proportion of recycled material. Compared to steel, it has a lower melting point and is therefore easier to melt and requires less energy. Thanks to the high carbon content, so-called graphite is formed. This is the main reason why cast iron, unlike steel, does not rust as quickly and thus has a very long life cycle. Still, the cast iron should be painted and maintenance painted at regular intervals.
Hot-dip galvanizing provides very strong protection against corrosion. The steel is dipped into a bath of hot liquid zinc. The zinc attaches and creates a surface coating on the steel part, which is then taken out of the bath and drained of excess zinc.
Concrete is cement mixed with crushed stone or aggregate. The material is very strong in compression but fragile in tension. To compensate for this concrete can be reinforced, often with steel.