A Higher Degree of Assurance
The American Society for Testing and Materials International (ASTM) recently approved revisions to C936 Standard Specification for Solid Concrete Interlocking Paving Units that include an optional lower temperature for laboratory freeze-thaw durability testing while paver units are immersed in a 3% saline solution. For freeze-thaw durability testing, C936 references C1645 Standard Test Method for Freeze-thaw and De-icing Salt Durability of Solid Concrete Interlocking Paving Units. This test method includes a minimal freezing temperature of -5° C (23° F) though 49 freeze-thaw cycles. Mass lost is measured from the tested paver units and that loss is divided by the total surface area expressed in square meters to determine if the pavers meet the requirements in ASTM C936.
This standard now includes the optional use of -15° C (5° F) as the lowest temperature in C1645. Deciding to use the -15 ° C option is supported by a map identifying geographic cold climate zones for project locations where the specifier might want to use this colder temperature in freeze-thaw durability testing per C1645. The reason for introducing this option is that some areas of the U.S. see colder temperatures than -5° C and use deicing materials. The colder temperature option of -15° C can help provide a higher degree of assurance for winter paver durability to manufacturers and specifiers.