Comparison of the values shown in Table 3.6 indicates that the modified Bogue gives much higher C3S content and a lower C2S content than the standard Bogue, and that these values are in better agreement with the SEM/X-ray analysis. For the C3A and C4AF phases the agreement is not as good. It is difficult to draw any conclusions on this, because it is difficult to distinguish the C3A and C4AF experimentally. In any case, the C3S content of the cement is the most important aspect of the mineral composition, and this is certainly more accurate with the modified Bogue.