Once the soil has been compacted and the tests have been done, we cover the bare soil with a thin layer of concrete to stop it getting wet and soggy as this would weaken the soils ability to take the pressure of the building.
The foundation is made up of around 1440 tons of steel reinforcing bar (Rebar) which is twisted and shaped into boxes. (using our earlier elephant analogy that 288 big ones..)
The rebar has different names depending on its diameter. For this foundation we use 7 types of rebar
R6 - 6mm round Bar - mild Steel
T10, 13, 16, 20, 25, 32 - which is t for torsional and the diameter of the bar in MM.
You can see the steel rebar being laid out to form a grid, and if you look closely you can see were we put more rebar at the column positions, to prevent the columns "punching" through the foundation (the punching shear). The punching shear of these these columns positions is around 600 tons of pressure...most of our columns will be around 1m x 1m in diameter.
Laying the first layer of rebar, its a very unpleasant job under the sun all day!
The final project - A complete mesh (not mess) of steel, like a box, ready to have concrete poured into it...