Concrete Facts

Some interesting facts about concrete.

Concrete usually hardens to walk on in around 24 to 48 hours. 
Drive on with a car or machinery i would leave for around 28 days to be 100% sure as the mix should be at least 70% dry by then.
But actually it never stops curing as it's constantly reacting to moisture and air. This is why some of the old 60-70s buildings are harder to drill as they have cured a lot longer.

Cement and concrete are not the same product as concrete is 60 to 66% aggregates like gravel, crushed stone, and sand, mixed with 20% water and incorporating 10-15% cement. So when someone says they have just had a cement driveway or patio laid, they really mean concrete. 

Concrete is a material used for all sorts of engineering and building projects, domestic and commercial.

It has similarities to organic rock with a combination of particles closely bonded together,

Concrete is like an artificial rock, very strong and great at resisting compression.

When tensile stress will be present, the concrete structures will be reinforced with steel.

Concrete is so versatile and can be moulded or poured, which has created some of the worlds most impressive structures.

Reinforced concrete buildings are some of the safest in the world as they are very resistant to fire and water.

Concrete used for building roads is highly durable, asphalt is initially cheaper but concrete once laid will out last asphalt and work out cheaper in the long run.

Ancient Roman builders mixed lime, water, and volcanic ash to form what they called "pozzolana". Some of their structures still stand and hold up today.

Concrete will actually set and harden under water.

The largest concrete unreinforced dome structure in Rome (Pantheon)
which is around 2,000 years old.

Worlds largest modern day concrete structure is located in China. 
The three gorges dam on the Yangtze river. It stands 185 metres high and 2,309 metres long. Constructed between 1994 - 2006. 
16 million cubic metres of concrete had to be mixed and poured to create this dam.