A cubic yard of normal concrete weighs approximately 4,000 pounds, according to Cemex. This may vary based on the mix design, the amount of hydration and environmental conditions.
Concrete contains cement, sand and gravel, and water is used to hydrate these materials and initiate the chemical reaction that causes the materials to form crystals and compounds while gaining strength. As the material dries over time, the weight of the finished concrete decreases. The majority of this process occurs in the first month after concrete is poured. Commercial products include both lightweight and heavyweight concrete, grouts, architectural concrete, pavement concrete and other high-performance materials.