The catenary arch vaulted roofs span 8.0m using 80mm thick earth bricks – equivalent to twice the thickness of an eggshell. The vaults work in pure compression only.
We wrote our own design tool using Python script to analyse the arches, using the elastic-centre method, to cross check our finite element analysis models. Finite element analysis does not always accurately model compression-only structures, to give us confidence in the design.
The cement stabilised earth-bricks ‘CSEB’ were manufactured on site using a ‘Hydraform’ machine, and used to create the vaulted roofs and supporting walls of a new hospital in Sachibondu, Zambia.
The ‘hydraform’ was available in the village, and it makes consistent bricks with interlocking features to allow mortarless construction. A small amount of cement is mixed with earth from the ground (and local sand if clay content in the soil is too high).
This hospital was completed in September 2017 by a dedicated team of local people, local skilled workers, and volunteers from the UK, all organised monitored and coordinated by Orkidstudio.