domingo, 12 de junho de 2011

MANAGING CONCRETE TEST DATA



With this highly effective curing box used by the Washington DOT, the cooler is partially filled with water to increase thermal mass and slow temperature changes.
Credit: Kenneth C. Hover

But even when the cylinders are gently moved to a safer place, ASTM C31-09, “Standard Test Method for Making and Curing Concrete Test Specimens in the Field,” requires “Immediately after molding and finishing, the specimens shall be stored for a period up to 48 hours in a temperature range from 60° F and 80° F [16° C and 27° C] and in an environment preventing moisture loss from the specimens. For concrete mixes with a specified strength of 6000 psi [40 MPa] or greater, the initial curing temperature shall be between 68° F and 78° F [20° C and 26° C].” Although there are a few jobsites in which the air temperature will not dip below 60° F nor rise above 80° F for a couple of days after casting (Waikiki in January comes to mind, but a field trip is required for verification), such limited temperature swings cannot generally be relied upon. Curing boxes therefore are required most of the time, winter and summer.

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