Concrete is formulated by mixing four basic ingredients: Portland cement, small aggregates such as sand, large aggregates like gravel or crushed stone, and water. Cement is manufactured in five different grades, based on their setting and curing time. These options allow you to choose different levels of durability and blend.
The perfect mix of concrete for any working condition can be met simply by altering the ratios of one or more of the ingredients (and the occasional help of certain additives). The concrete can also be reinforced with steel or wire mesh to add to its strength.