Cement

Q: What is portland cement?

A: Portland cement is the most common cement used in concrete. The patent dates back to 1824 in England and is so named because the color of the cement resembled a stone found on the Isle of Portland. Portland cement is made by combining a mixture of ingredients, usually limestone, clay and shale, at very high temperatures. When mixed with water, portland cement forms a paste, which cures into a hardened mass. This chemical reaction is known as hydration.

Portland cement is a hydraulic cement. Any cement, which sets and hardens when mixed with water and is capable of doing so under water, is hydraulic cement.

Portland cement is usually gray in color but can be made in white or buff by adjusting the basic ingredients.

The two most commonly used types of portland cement are:

Type I - For general concrete work.
Type II - For moderate sulfate resistance.
The most commonly used form of Portland cement is designated Type I/II because it meets the requirements of both I and II.

Q: Does “cement” and “concrete” mean the same thing?

A: No.  Although often used interchangeably, cement is one of three basic ingredients in concrete.  The other two are sand and stone.