The terms cement, concrete, and mortar can be confusing to beginning builders because they are often used interchangeably, which is inaccurate. Cement, concrete, and mortar are three different materials. The basic difference is that cement is a fine binding powder (which is never used alone), mortar is composed of cement and sand, and concrete is composed of cement, sand, and gravel.
Cement is the binding element in both concrete and mortar. It is made most commonly of limestone, clay, shells, and silica sand. These materials are crushed and then combined with other ingredients (including iron ore), and then heated to about 2,700 F. This material, called Clinker, is ground into a fine powder.
You might see cement referred to as Portland cement. This is because it was first made in the 1800s in England by a mason, Joseph Aspdin of Leeds, who likened the color to the stone from the quarries on the island of Portland, off the coast of England.
Today, Portland cement remains the most common type of cement used in building materials. It is a type of "hydraulic" cement, which simply means that it will set and harden when combined with water.
Concrete is a complete building material used for foundation walls, concrete slabs, patios, and many other masonry structures. It is uniquely versatile because it starts out as a simple, dry mixture, then becomes a liquid, flexible material capable of forming into any mold or shape, and ends up as the hard-as-rock material we know as concrete. In many concrete structures, metal reinforcement, such as wire mesh or rebar, is added for strength and to resist the effects of cracking in the concrete.
Concrete is composed of cement, sand, and gravel or other fine and coarse aggregate. The addition of water activates the cement, which is the element responsible for binding the mix together to form one solid object.
You can purchase ready-made concrete mixes in bags that combine cement, sand, and gravel so that all you need to do is add water. These are useful for small projects, such as anchoring fence posts or building small pads. For large projects, you can either buy bags of cement and mix them with sand and gravel yourself, using a wheelbarrow or other large container, or order premixed concrete delivered by a truck (commonly called "ready-mix" concrete).
Mortar is composed of cement and sand. Adding water to this mix activates the cement so that it hardens, or cures, just as with concrete. Mortar is not as strong as concrete and typically is not used as a sole building material. Rather, is it the "glue" that holds together bricks, concrete block, stone, and other masonry materials. A special type of mortar, called thinset, is used as an adhesive to install ceramic and stone tile.
Mortar is commonly sold in bags, in a dry pre-mixed form that you combine with water. It can also be mixed on-site, using a cement mixer or simply mixing with a shovel or hoe in a wheelbarrow or mixing tub. There are many different types of mortar designed for different applications. When working with brick and other masonry units, it is important to use the right type of mortar for the masonry, as some mortars are too hard for some types of masonry and can lead to cracks.