What is Concrete?
It's components:
Concrete is made up of the three basic components:
water, aggregate (sand, stone) and cement.
Cement powder is the binding agent for the water and aggregate mixture, that hardens into concrete.
Other components can be added to concrete:
Color for appearance.
Accelerators to reduce curing time. (This allows for pouring in cold weather, or early removal of forms.)
Retarders to slow the set time. (This allows concrete to set properly in hot weather, or a delay for a special finish.)
Air Entrainment to help prevent concrete from cracking in harsh conditions. (Small air pockets to capture water, and allow it to expand when it freezes, without cracking concrete.)
Fiber for reinforcement. (This will increase the concretes structural integrity.)
Concrete is measured by its compressive strength, the Mpa (megapascals),
the higher the Mpa the stronger the concrete.
The strength is achieved by the components mixed ratio. Commercial and residential buildings will use a strength from 17 to 34 Mpa depending on the specifications of the building.
A LITTLE CONCRETE HISTORY
Concrete dates back as far as the Egyptians and the Romans; using a mixture of limestone and clay mortar mixed with aggregates to create concrete.
Many advances in concrete were made by the Romans, the most significant was the discovery of volcanic ash (pozzolona, so named for the town at the base of Mount Vesuvius) was added to the mixture to create a stronger binding agent.
Portland cement, now widely used today, was developed in the early 19th century by Joseph Aspdin.
Portland Cement was named for the Portland stone quarried on the Isle of Portland, England, and patented in 1824.