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Portland cement is defined as a hydraulic cement produced by pulverizing clinker, consisting essentially of crystalline hydraulic calcium silicates, and usually containing one or more of the following: water, calcium sulfate, up to 5% limestone, and processing additions (NSF PCR 2020, ASTM C150, ASTM C219). Portland Cement Type I—For use when the special properties specified for any other type are not required. Portland Cement Type II—For general use, more especially when moderate sulfate resistance is desired. Some cements are designated with a combined type classification, such as Type I/II, indicating that the cement meets the requirements of the indicated types and is being offered as suitable for use when either type is desired.