Concrete

The wall of Paddington Police Station in Edgware Road has a row of repeated human figures which recall Michael Angelo's statues of slaves struggling to free themseIves from the stone. Each figure is identical. They are examples of concrete casting. Concrete shapes can be repeated time after time by pouring suitable concrete mixtures into moulds. This is the use of solid concrete slabs.

Ferro-concrete

Ferro-concrete is a very different material. Concrete is strong in compression (it can stand great weights being placed on it) but is weak in tension (it can be pulled apart quite easily at the slightest crack). Thin steel bars are strong in tension, but collapse under compression. Ferro-concrete combines both advantages, as it is strong in both compression and tension.

A traditional building is a box with holes in it for the doors and windows. Ferroconcrete buildings can be thought of as a series of openings with lines drawn round them. The process of constructing the beams and posts which form the ferro-concrete network is shown below.


Paddington Road Police Station

Showing the repeated panels of cast concrete and the ferro-concrete building behind.

 

The process of casting ferro-concrete


The wooden shuttering with the mild steel reinforcement bars wired together and the wooden shuttering in place.

The first concrete pillar poured
and the shuttering removed.

Horizontal and vertical mild steel
bars wired in place

The joint poured and all shuttering removed

These steps are repeated time and time again to form gigantic frameworks which can be filled in a hundred different ways.

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