In india -Delhi
the sand available is Fine Jamuna. In the Sand mica particles are
found
Pl. tell,what will be the affect of mica particles on the
strength
especially for plaster work. Can we measure the quanity of the mica
particles?
(Question
asked by Mr
Sanjay Kumar Deedwania)
Mica
being flaky & laminated affects strength & durability of mortar
/concrete in the same way as other such particles do. The effect
on workability
& strength is more for leaner mixes.
In
Indian river
sands, mica content could be as
high as 12%. The problem is further aggravated if the sand is of
finer
variety (Ganges sand could have
fineness
modulus as low as 0.6) .
Muscovite
variety of mica is more harmful than the mica biotite variety. Jamuna
sand is
mainly biotite with small percentage of muscovite particles; whereas Ganga sand is mainly muscovite with small
percentage of
biotite particles;
Indian Standards do not prescribe any test
for measuring the quantity of
mica. You can, however, measure the mica content by Floatation/Density
separation method or the Wind
blowing method; former being more accurate."
