Raw Material Substitutes

Cement manufacturing is an exacting science that involves heating raw materials, such as, limestone, clay, shale, sand, and other materials that have been ground up to a fine powder. These materials are needed due to their chemical make-up. Limestone is typically used because it provides calcium carbonate (CaCO3) and makes up the vast majority of the raw materials needed to produce clinker. Clay and shale are used primarily to provide alumina (Al2O3) and iron oxide (Fe2O3), with sand typically adding silica (SiO2). Once clinker is produced, it is ground to a fine powder and mixed with gypsum to make cement. Certain waste materials coming from multiple industries possess some of these chemical characteristics and have potential for raw material substitutions in cement manufacturing.

Some examples of raw material substitutions include:

• Fly ash
• Bottom ash
• Catalyst
• Foundry sand 
• Iron dust
• Slag