Berlin Town Hall Square – Kara Kül Basalt

In the renovation of a town-hall square in western Berlin, 9,400 m² of Kara Kül basalt was used. Resistance to winter frost and de-icing salts was the reason for choosing basalt.

Project summary

• Two sizes, 10x20x8 cm and 40x40x5 cm, in flamed-and-brushed finish
• Freeze-thaw test (EN 12371): 56 cycles, mass loss < 0.3%
• Resistance to salt and slipping: PTV 70+
• Bevelled edge slabs for accessibility ramps
• Petrova laboratory reports and EN 1341 declaration of conformity

The stones were delivered to Hamburg port in 22 containers across 18 packages. The city administration reported no ice or slipping complaints in the first winter after the square opened.

Result

After the opening the square hosted 40 events a year. De-icing salts used in winter maintenance caused no damage to the basalt surface; the municipality chose the same stone for two surrounding streets.