The purpose of this standard is to establish a test method to determine, in the aggregates used for the manufacture of concrete, the load that produces, as a result of confined compression, 10% of fines, understood as fines those particles released from the " standard fraction" (10/14) that pass through the 2.5 UNE 7-050 sieve. The load value obtained is a reflection of its compressive strength. As in the UNE 83-112 standard on the determination of the crushability index, to determine the loading value corresponding to 10% of fines, other fractions other than 10/14 can be used, but their results must be used with caution. caution as they differ from those obtained with the "Standard Fraction" (see table 1). This method is directly related to the determination of the crushability index (see UNE 83-112 standard), and is applicable to aggregates of any hardness.