Materials used to produce portland cement

Q. What are the raw materials used in the manufacture of portland cement?

A. The two principal materials from which portland cement is made are a material of high lime content, such as limestone, chalk, shells, or marl, and a material of high silica and alumina content such as clay, shale, or blast-furnace slag. A small amount of iron is also needed. Sometimes the principal materials are combined in naturally occurring deposits. The proportions of the raw materials need to be controlled to ensure a uniform product.

References:  SP-1(02); ACI 225R-19; E3-13

Topics in Concrete: Cementitious Material; Concrete Fundamentals