Fineness of fine aggregate is related to term fineness modulus; most commonly sand. Fineness modulus is a measure to define fineness of aggregate precisely it defines coarseness or fineness of aggregate to be used in concrete.
This can be defined as value that is derived by following expression:
F.M = (cumulative percentage retaining of aggregate)/100
The retaining means retaining on standard sieves.
Here we will discuss about ranges of fineness modulus of sand according to different standard.
IS 383:
Unfortunately this Indian Standard did not provide any specific limit of fineness modulus. Rather they divided sand in four zones:
a. Zone I
b. Zone II
c. Zone III
d. Zone IV
Where Zone I indicates a very coarse sand and Zone IV defines a sand very fine size. The intermediate zones are fall between them. They provided that, for mix proportioning for a structural concrete zone IV should be ignored and zone III are recommended.
USBR:
USBR provided specific limits for fineness of sand these are:
F.M ≥2.5
F.M≤ 3.0
ASTM:
This standard provided that FM should be
F.M ≥2.3
F.M≤ 3.1
AASHTO:
They also provided same limit of FM as that of ASTM that is
F.M ≥2.3
F.M≤ 3.1
Dear reader we have just discussed about limits from fine aggregates in terms of fineness modulus, but there have some additional requirements about fine aggregates which we like to include in our next post according to AASTHO and ASTM.
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