Calculation a concrete rings

Calculation a di volume a materials fi di manufacture a concrete rings

Please indicate dimensions inna millimeters

D - Concrete ring diameter
A - Wall thickness
H - Height

Di program is design fi calculate di materials an volume a concrete rings.
Di volume a concrete, di internal volume an diameter a di ring, di dimensions an area a di reinforcing mesh dem calculate.
Concrete rings dem use fi di construction a wells an septic tanks.