Concrete is a building material composed of coarse and fine aggregates (gravel and sand) bonded together with a fluid paste (portland cement and water) that hardens over time. Lime-based concrete such as Portland cement concrete is one of the most common concretes. Actually, asphalt concrete is also a type of concrete, which is usually used to pave road surfaces.
Through mixing, aggregates, dry Portland cement and water can form a fluid slurry that is easy to be poured and molded. Adding water and other ingredients can improve the physical properties of cement, which is contributed to binding the materials together into a durable stone-like material. Additionally, concrete can also be poured with reinforcing materials (such as rebar) embedded to provide tensile strength, producing reinforced concrete.
Cement is a kind of binder, a substance commonly used with other raw materials such as sand and gravel (aggregates), can set, harden and adhere to other materials, binding them together and giving concrete its strength. It has a lot of applications in construction industry. For example, you can use it with fine aggregates to produce mortar for masonry, or with sand and gravel aggregates to produce concrete that has many uses. Cement is a key ingredient comprising from 10% to 15% of the concrete mixture, by volume.
As two important kinds of materials, concrete and cement are often used interchangeably, so concrete mixer is also mistakenly called cement mixer by many people.