Concrete
From the Simple English Wikipedia, the free encyclopedia that anyone can change
Concrete is a very useful material for making all sorts of buildings and structures.
Its biggest advantage is that it bonds together bricks and stones and post more tightly than any other method known to mankind.
Concrete is as old as 5600 BC, and it was not invented by Romans as it is told.
Some kinds of concrete are waterproof, and some kinds even set underwater.
The ingredients of concrete include the cement, sand, gravel and water in varying proportions depending on the task.
The ingrediants are mixed together into a "paste", a bit like making "dough" for bread.
The concrete is then poured into place into formwork, and after a few hours it sets hard.
Since the semi-liquid concrete fills all spaces, a post set into concrete will not wobble.
Concrete is strong in compression but weak in tension, and for some purposes it needs to be reinforced with say steel rods. These rods are best galvanised to prevent rusting and corrosion.
Reinforced concrete buildings can be made to link all the parts together, the foundations, walls, floors and roofs, but concrete construction does not make building earthquake-proof.
