The Fineness Modulus (FM) of fine aggregate (sand) is calculated as:
Choose the correct answer
Percentage retained on 4.75 mm sieve / 100
(Sum of cumulative percentages retained on standard sieves 150 micron to 80 mm) / 100
D50 of the aggregate
Ratio of coarse to fine particles
Correct Answer
B. (Sum of cumulative percentages retained on standard sieves 150 micron to 80 mm) / 100
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FM = (sum of cumulative % retained on IS sieves: 80, 40, 20, 10, 4.75, 2.36, 1.18 mm, 600, 300, 150 micron) / 100. For fine aggregate (sand): FM = 2.0-3.5 (FM 2.6-2.9 is ideal for concrete). Higher FM = coarser sand. FM of CA alone is used in mix design (IS 10262).
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