Reversed arc catenaries? Sheet metal offers a "bottom line" or bottom curve tension surface to complement ferrocement above it-- Tensioned curve reinforcement is connected in every direction. Would this not effect a truss like reinforcement in every direction?  (This page is under construction).

A ferrocement reinforcement concept which uses sheet material on the bottom surface. An instant ceiling can be created with a range of qualities. Choices range from metal sheets , (painted or textured before installation) to fabrics with both structural and aesthetic qualities. A prototype metal ceiling is pictured below. (Wood joists are shown, but not to particularly be recommended). Used in this instance for expediency, not ideals.

Schematic detail below shows sheet metal in speckle blue-purple color. Reinforcing rods of joist-truss are red. Dark rings are ferro mesh in flat coils, (thickness not rendered to scale).  Two coils wrap around two rods on bottom and two more at top, (not drawn). The green flat coil ties the bottom of joist together. The cement is not shown in picture.  The sheet metal is shredded along ends and tool bent for hooking around rods.

Note: These pages are placed in the public domain and are furnished "as is". The author assumes no responsibility for the use or misuse of the concepts in this series. All pertaining laws of life should be satisfied, in building or testing my concepts or descriptions, as are posted on my linked pages.