Concrete, which contains Portland cement or a combination of cement types, is one of the most common building materials. Concrete is used frequently in residential building projects but also plays a key role in the construction of commercial and industrial structures. One of the most common uses for cement and concrete in terms of industrial development is with infrastructure. Our roads, highways, and bridges are most often made, at least in part, of concrete. Concrete is also a popular building material for tornado shelters and safe rooms. Large structures, such as gravity dams, arch dams, and breakwaters are other examples of the industrial application of concrete and cement, as are the foundations and components of many of large factories and warehouses that help drive our economy.