Work Item
ASTM WK91913
Revision of C595/C595M-24 Standard Specification for Blended Hydraulic Cements
Rationale
Currently, Type IT ternary blended cement containing limestone is permitted to contain only one pozzolan or one slag. Blending multiple pozzolans is well established in concrete, such as use of slag and pozzolan in combination with a portland or portland-limestone cement. Therefore, this ballot item permits Type IT cement to include one or two pozzolans or slag in addition to limestone and portland cement. No change is made to the total amounts of limestone, pozzolan and slag permitted or to any other performance requirements. The manufacturer is still required to report the target amount of each limestone (in excess of 5%), pozzolan, and slag.
The term “binary blended cement”, which refers to Type IP and IS, is removed to simply refer to Type IP and IS directly.
Currently, there is confusion over whether Type IP and IS are permitted to contain limestone. Specifically, Type IP and IS are defined as a blend of portland cement with pozzolan and slag, respectively. Per 6.1.1, portland cement meeting ASTM C150/C150M, which allows up to 5% limestone, is suitable but not required. Likewise, the following definition of portland cement in ASTM C219 includes up to 5% limestone.
portland cement, n—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.
Therefore, the maximum amount of limestone is set at 5% for Type IP and IS.
For greater clarity, the composition limits are stated in a new Table 2 (subsequent tables to be renumbered by the editor) rather than in the text.
Work Item Status
Date Initiated: 08-07-2024
Technical Contact: Eric Koehler
Item: 000
Ballot:
Status: