Concrete is a composite construction material composed of cement and water, which hardens after a period of time. Cement is composed of water-absorting calcium-silicate and calcium-aluminate compunds. This substance is obtained by firing a mixture of limestone and clay. Portland cement, first made in 1824 and patented as reinforced concrete by the French Joseph Monier in 1867, slow-sets due to a complex chemical reaction in which the cement paste fills the void around coarse and fine particulates and any reinforcements.
The quality of the numerous roads constructed in the United States in the 1950s largely depended on the quality of concrete used at the constructions. Durability and strength depend on the careful control of the cement manufacturing process ; and adding different chemicals to the initial concrete mixture reduces shrinkage and improves corrosion resistance.