Rationale

Add reporting requirements for curing that are consistent with other standards under C09.61. ASTM C31/C31M requires documentation of curing method at the time of specimen fabrication and initial curing. However, ASTM C39/C39M does not require this information to be included with compressive strength test reports. As specimens move from the field to the laboratory and through testing, curing condition information may be separated from the associated strength results. Because curing history significantly affects measured compressive strength, the absence of this information can lead to misinterpretation of results, improper acceptance or rejection decisions, and disputes among laboratories, contractors, and owners. Standard-cured specimens are typically used for specification acceptance and quality control, while field-cured specimens are used to evaluate in-place strength and construction operations. Reporting the curing method and temperatures provides necessary context for proper interpretation of the data and improves traceability. This revision does not introduce any new testing or documentation requirements and simply ensures that information already required by ASTM C31/C31M is preserved and reported with the compressive strength results.