In 1981 the Canadian Standards Association (CSA) Committee A5 on Hydraulic Cements approved carbonate addition to normal portland cement Type 10 to a maximum of 5%. The decision was based on a considerable amount of data indicating no adverse effects on the properties of concrete and even improvements at optimum level of carbonate addition. The CSA Committee is now considering a proposal for extending carbonate addition to high-early strength portland cement Type 30 that has essentially the same chemical composition as Type 10 cement. Since Type 30 cement is used primarily in precast and prestressed concrete operations, a project has been initiated at the Research and Technical Center of Lafarge Canada Inc. to study the effect of steam curing conditions on the properties of concrete made with Type 30 cement containing carbonate addition. The main parameters will be the tricalcium aluminate (C3A) content of the cement, the presence of carbonate addition, and the curing temperature. The properties investigated will be compressive strength, freezing and thawing resistance ASTM Test for Resistance of Concrete to Rapid Freezing and Thawing (C 666, Procedure A), and volume change ASTM Test for Length Change of Hardened Hydraulic Cement Mortar and Concrete (C 157).
The available test results show that carbonate addition contributed to the development of compressive strength of heat-cured concrete made with the cements investigated. It was not detrimental either to length change or to the resistance to freezing and thawing.