Formwork is used to have a clean edge and support the concrete when pouring the slab. The material used for the formwork is timber, and it is supported by strut-like members that are pegged to the ground. In this case we have an infill slab, where the slab is poured when all the structure is up. This slab isn't supporting any of the structural members. The infill slab is composed of fabric mesh, coarse aggregate and damp proof membrane. Due to the large open space, the slab isn't poured in one go, it may take several pours to complete the job.