Working with concrete is something most of us will experience at one time or another when we work on our homes. It may be something as simple as a sidewalk or as complicated as footings for a foundation wall. But what exactly is "concrete"? Key Concrete Ingredients Concrete contains three basic ingredients: cement, aggregate, and water. Cement, or Portland cement, is the glue that holds everything together; a fine, dry powder that solidifies and becomes quite strong when mixed with water. The majority of concrete is the aggregate. Aggregate is...