If you have round columns, then in order to calculate how much concrete you need on the foundation, you will need to know their radius. For example, the radius of the column is 0.125 m. We build this number in a square, multiply by 3.14 (that is, the number of «pi») and we get approximately 0.05. We change the result with a pillar height of 1.2 m and get 0.06 m3 of concrete per column. Therefore, for 20 supports will need 12 m3 of the solution.
