CONCRETE STORY 2 (31 march 2004)
In my last weblog you could read a (somewhat technical) story about concrete. One of the things mentioned was that concrete can withstand great pressure.
But we saw that concrete cannot withstand great pulling forces. But we can reinforce it with steel (blue in the diagram below). This reinforcement will give it tensile strength. In the same diagram, the mass of concrete above the reinforcement is compressed. This concrete gives it compressive strength.
Certain constructional elements are not easy to make with bricks. Take for instance a door opening. The diagram below shows a construction that may look alright at first sight. But it is clear that the bricks at the top of the opening will collapse easily. They're only held together by little more than the cement - which acts as 'glue'.
Openings in brick walls are usually constructed in the form of arches . A well-known arch is this one:
If pressure is exerted on this arch, the bricks will be pressed together. They will hold each other in place.
But not all shapes can be made with bricks. Architects can make a lot more with concrete than with brick. Making buildings like the three shown below here would have been quite a problem using bricks:
I have heard concrete described as an archtitect's dream. And indeed, the use of reinforced concrete has brought about a revolution in architecture.
But concrete does not only have positive aspects. In my next weblog I'll try to go deeper into some of its negative aspects.
