Rationale

Limestone is a common constituent in portland and blended cements. However, there is no definition in Terminology C219 for limestone. It is currently defined in Specification C595/C595M in its Terminology section, and in Specification C150 in the Ingredients section. Both of these existing definition reference Terminology C51, the terminology standard for  Committee C07 on Lime and Limestone. The Terminology C51 definition does not address the forms of limestone used in hydraulic cements. Additionally, for a term that is important to Committee C01, such as limestone, maintaining that term in in the Committee C01 terminology standard is preferred.