Stacked entry shaft for sewage system - has sections of asbestos cement with annular space filled with concrete

摘要

The entry shaft for a sewage system is made from stacked hollow sections. The shaft is built up of circular or box shaped prefabricated sections. Each hollow section of the stacked assembly has internal fibre containing cement lining which determines the inner bore size. It has also an outside fibre containing cement cover. Both these concentric components of a section are held apart by radial spacers. The space between the components is filled with conventional concrete. The external and internal components can be cylindrical and vertical or they may form a truncated double wall shell.