Joseph Aspdin of Leeds is credited with the invention of Portland cement, one of the key ingredients in concrete. Aspdin discovered how to burn impure limestone and transform it into hydraulic cement, taking out a patent on the process in 1824. Today cement is an indispensable ingredient in modern construction.

Cement is manufactured by combining a homogenous blend of carefully proportioned raw materials (chalk and clay/shale) at a very high temperature (1400 ºC) in a rotary kiln. The raw materials fuse together to form ?clinker?, a hard granular material. Clinker is ground to a powder along with gypsum to make cement.

By altering the chemistry of the raw material and selecting specific materials for grinding alongside the clinker and gypsum, different types of cement can be made with properties suited to their intended use. Portland cement is the most widely-used type of cement.