Concrete shaft for building site installation has upper ring resting on plastic strips over a lower ring

摘要

A concrete shaft (3) on a building site has first (2) and second (4) rings. The lower face of the upper ring has a series of embedded equidistant load-bearing plastic strips (1). The upper ring lower edge has one or more cross-pieces that maintain a gap (D3) between the two rings (2, 4) following assembly. The plastic strips are presented at an angle inclined to the geometrical normal.