7.2 Blended Cements

Blended hydraulic cements are produced by intimately and uniformly blending hydraulic cement with other types of fine materials at the cement plant during the clinker grinding process. The primary blending materials are fly ash, slag cement, and limestone. Other pozzolans, such as silica fume, can also be used in blended cements. In Item 421, four types of blended cements are allowed:
  • Type IP consists essentially of an intimate and uniform blend of Portland cement and a pozzolan. DMS-4600 requires Type IP cements used for TxDOT projects to contain 20% to 40% of a Class F fly ash.
  • Type IS consists essentially of an intimate and uniform blend of Portland cement and slag cement. DMS-4600 requires Type IS cements used for TxDOT projects to contain greater than 35% of slag cement.
  • Type IT consists of an intimate and uniform blend of Portland cement and a combination of two other materials such as fly ash and silica fume, or fly ash and limestone.
  • Type IL consists essentially of an intimate and uniform blend of Portland cement and a maximum of 15% limestone.