Which ASTM standard governs the procedures for making and curing concrete test specimens in the field?

• A. ASTM C39.
• B. ASTM C143.
• C. ASTM C31.
• D. ASTM C231.

Answer: (C)

Field-casting and curing concrete test specimens on the job site follow a standardized process to ensure the specimens represent the in-place material. This standard lays out how to prepare molds, select specimen sizes, mix and fill, consolidate to remove air pockets, finish surfaces, and strip the specimens from their molds. It also specifies curing requirements—how long to keep the specimens moist or submerged, the temperature limits, and how to maintain those conditions until testing. The aim is to produce specimens whose properties reflect the concrete as placed, so strength and other tests yield meaningful, comparable results for quality control and project performance.

Among the options, the standard that specifically covers these field procedures is the one that addresses making and curing concrete test specimens in the field. The other standards are focused on different tests: one covers compressive strength testing of lab-cast cylinders, another covers the slump of fresh concrete, and a third covers the air content of fresh concrete.