The Real Deal on Building Dirt is sometimes compacted and utilized as a structural foundation. At times, the dirt is heaped up to form a hill or other elevated place. Fill dirt is used by a building firm in the same way that clay is used by an artist; we can mold and use it to create a beautiful completed product. The difference is that clay can be reworked while concrete cannot. Concrete has many uses beyond buildings, such as bridges, sidewalks, and swimming pools. Concrete is a mixture of sand, gravel, cement, and water. Cement contains calcium oxide (CaO) which when mixed with water forms a solid called calcium hydroxide Ca(OH)2. The hydroxide reacts with additional calcium oxide to release heat, which causes the remaining water to evaporate or be driven off. This process leaves a hard material that can be used in place of stone, brick, or wood for building structures such as roads, bridges, or foundations. When constructing a new home, builder's typically use a grade beam to establish a flat floor surface upon which to build. The grade beam is usually made of wood and is placed so its bottom edge is just below the highest expected water level during flooding or heavy rain. Soil should not be allowed to accumulate above the top of the grade beam because this creates a risk of house damage or collapse if there are any changes in elevation near the home.