241 – Double spiral

241 – Double spiral

A staircase that is two-directional to create an organised order of flow is designed to be prefabricated through modular concrete steps. A double spiral means that less floor area is used for a two-directional staircase.
The steps have a 160mm riser and 280mm tread, and are 1.5m wide to allow sufficient amount of space for users to pass alongside each other rather than in a single file.
The steps are designed as UHPFRC which has increased strength and durability. A superplasticizer which reduces the water content in the concrete mix gives a W/C ratio of <0.25. Very fine quartz sand in the mixture instead of ordinary coarse aggregate helps gain a better microstructure and performance.