This process is intended for small non-structural repair or replacement of equipment with commercial projects where the building owner can obtain a permit to repair or replace the same or existing features of a building without architectural plans.
1 Mark the area that will need concrete and divide it into smaller areas. 2  Calculate its volume of the area after determining the shape of the area (see chart below) by multiplying in the height.  Convert the volume from feet to cubic yards to get the number of cubic yards of concrete youâll need.
Water/cement ratio. As engineers will tell you, the water/cement ratio is the weight of the water per yard in the mix divided by the weight of cement per yard. Concrete's water/cement ratio is usually somewhere between .4 and .6. As an example, let's take an average yard of concrete, a typical five-bag residential mix.