The piston was gradually lowered and
readings of the force exerted at a compression speed of
10 mm/min were made by the data collection system of the
machine. The compressive strength was determined by
crushing the pellet in the same direction as the compaction,
i.e., parallel to the cylindrical axis (Fig. 1a). The peak force
obtained from the data collection was used to calculate the
compressive strength (r) according to the following
equatio