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What procedure should be followed for standard curing of specimens for strength tests?

Q. What procedure should be followed for standard curing of specimens for strength tests?

 

A. ASTM provides separate standard practices for making and curing concrete specimens in the field (ASTM C31) and in the laboratory (ASTM C192). In the field, the specimens are to be kept in the molds at a temperature of 16 to 27°C (80°F) for a period of up to 48 h, then removed from the molds and stored in a moist condition at 23 + 2°C (73 + 4°F) until tested. For laboratory cast specimens, the curing is at 23 + 2°C (73 + 4°F) from the time of molding until testing. ASTM C31 also prescribes a field curing procedure intended for use when the strength of the concrete in the structure is to be estimated. In this case, the specimens are stored in or on the structure and exposed to the same environment as the structure. The acceptable strength levels for properly field-cured concrete are given in ACI 318.

 

References: SP-1(02); ACI 318-19; ASTM C31; ASTM C192

Topics in Concrete: Curing; Testing of Concrete