EARLY STIFFENING
ASTM C451 Standard Test Method for Early Stiffening of Hydraulic-Cement (Paste Method) is used to determine the degree to which a cement paste develops early stiffening or to establish whether or not a cement complies with a specification limit on early stiffening. This is done by comparing the behavior of the initial test and in the remix procedure to differentiate a relatively less serious and less persistent tendency to early stiffening (false set) from one that is more persistent and, consequently, more serious (flash set).
Early stiffening resulting from false set is not likely to cause a cement to fail the applicable time of setting requirement, while that resulting from flash set (depending on severity) can cause a cement to fail.
