ASTM C309: Modern Conversations on an Established Standard

ASTM C309 has long been the standard by which membrane-forming concrete curing compounds are judged.
While applicable for its time and still a valid indicator when dealing with rougher finished concrete, the preparation method prescribed by ASTM C156 and then tested by ASTM C309 does not take into account current finishing techniques involved with today’s steel troweled floor slabs. To understand why this is relevant, the preparation procedures for the test itself need to be understood to make a comparison to the specific type of finish being discussed here.

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