1. Concrete
By Mr. Brower

2. Uses of Concrete
Roads, bricks, canals, dams, caskets, tunnels, bank vaults, headstones, water tanks, steps, buildings, missile silos, walls, floors, sculptures, mantels, picnic tables
List goes on and on ...

3. Is it cement or concrete?
Cement is an ingredient in concrete
Cement makes up about 25% of concrete

4. Purpose of Cement Cement is added to water to make a “cement paste”
Adding water to cement starts a chemical reaction (hydration)that forms hard crystals called “hydrates.”
Demo CuSo4.5h20

5. Hydration

6. Hydration

7. Purpose of Cement The cement paste is called a “binder”
To make cement cheap to buy a “filler” is added to the cement paste
“Aggregates” (sand and gravel) are used as filler. They make up 70% of concrete.

8. How is Cement Made? Limestone, clay and sand are dug out of the Earth
Heated to 2732 degrees
Other materials such as gypsum are then added
End product is ground to fine grey powder called Portland cement.

9. “Admixtures”
Admixtures that speed up the rate of hydration are called “accelerators.” Example: Sugar
Admixtures that slow down hydration are called “retardants”
Example: Calcium Carbonate

10. Concrete
After a mixture of cement, sand, gravel and water undergoes hydration, concrete forms
Before complete hydration, the concrete is held in place by “forms”

11. Concrete
After the concrete hardens, the forms are removed

12.
Portland Cement Video Review