When your sample contains material larger than 3 inches the program's classification system recalculates the Smaller than #4 and Smaller than #200 values to remove the influence of the plus 3 inch material (i.e., the #4 and #200 values are calculated based on a sample that has no material larger than 3 inches). This is done because the ASTM D2487 classification is based exclusively on material smaller than 3 inches.
- The calculation is:
biased #4 material = actual #4 material / (100 - plus 3 inch).
While the program can remove the influence of the plus 3 inch material from the #4 and #200 sieve percentages, it cannot do the same for the Diameters at X percent values, so the D60, D30 and D10 values will continue to reflect the numbers calculated for the whole sample (including plus 3 inch material); the #4 and #200 values will reflect a sample without any material larger than 3 inches. This may or may not cause the program's classification to be invalid (the Dx values are only used to distinguish between GW and GP and between SW and SP).