What aggregates does ABC use to produce cement?

• A. Limestone and clay
• B. Sand and gravel
• C. Granite and basalt
• D. Chalk and gypsum

Answer: (A)

The key idea is understanding what goes into making cement itself. Cement is produced from raw materials that supply the main chemical components: calcium oxide from limestone and silica/alumina from clay. These two materials are blended, heated in a kiln to form clinker, and then ground into cement. Gypsum is added during grinding to control how quickly the cement sets.

The other materials listed aren’t used as the primary inputs for making cement. Sand and gravel are aggregates used when cement is mixed with them to create concrete, not to make cement itself. Granite and basalt are rocks not typically used as the main cement feedstock. Chalk and gypsum aren’t the standard combination for producing cement either; gypsum is used later as a setting regulator, while chalk can be a calcium carbonate source but is not the typical pair with clay used in cement production.