Blue Circle Industries was a British public company manufacturing cement. It was founded in 1900 as the Associated Portland Cement Manufacturers Ltd through the fusion of 24 cement works, mostly around on the Thames and Medway estuaries, together having around a 70% market share of the British cement market. In 1911, the British Portland Cement Manufacturers Ltd was formed by the addition of a further 35 companies, creating a company with an initial 80% of the British cement market.

Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the early 19th century by Joseph Aspdin, and is usually made from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of portland cement are available. The most common, called ordinary portland cement (OPC), is grey, but white portland cement is also available. Its name is derived from its resemblance to Portland stone which is quarried on the Isle of Portland in Dorset, England. It was named by Joseph Aspdin who obtained a patent for it in 1824. His son William Aspdin is regarded as the inventor of "modern" portland cement due to his developments in the 1840s.