Cavity, 2-part cavity-form for realising openings in poured surfaces

摘要

The former consists of two identical parts of approx. semicircular shape. One end has a straight length bent inwards towards the centre of the circle. The two halves fit with their straight legs bolted together within one another to form a circular cross-section. The free ends of the straight lengths each bend inwards to maintain a small clearance between them. The end of the semicircular leg is straightened slightly outwards. The two parts come into close contact to seal the void during casting. After hardening and unbolting they are separated by driving a wedge between the straight legs or hammer blows at the corners (a,b), then removed to leave the void.