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. In 2001 the company was bought by Lafarge.