Cement History of cement | Britannica
Clays, shales, slates, and estuarine muds are the common argillaceous raw materials. Marl, a compact calcareous clay, and cement rock contain both the calcareous and argillaceous components in proportions that sometimes approximate cement compositions. Another raw material is blastfurnace slag, which consists mainly of lime, silica, and alumina and is mixed with a calcareous material of