Civil Engineering - Concrete Technology - Discussion

GRADING LIMITS FOR FINE AGGREGATES.

Sieve Size Percentage of Passing For,
Grading
Zone-I

Grading
Zone-II

Grading
Zone-III

Grading
Zone-IV

10 mm 100 100 100 100
4.75 mm 90 " 100 90 " 100 90 " 100 95 " 100
2.36 mm 60 " 95 75 " 100 85 " 100 95 " 100
1.18 mm 30 " 70 55 " 90 75 " 100 90 " 1000
600 micron 15 " 34 35 " 59 60 " 79 80 " 100
300 micron 5 " 20 8 " 30 12 " 40 15 " 50
150 micron 0 " 10 0 " 10 0 " 10 0 " 15

Zone-I represents the coarse sand and zone-IV represents the finer sand in all the four zones. Hence correct answer should be D.

The correct answer is Zone IV.

As per the Indian Standard (IS) 383, the zones for sand are classified based on the fineness modulus, which is a measure of the sand's gradation.

Zone IV corresponds to very coarse sand, which typically requires a higher water-cement ratio.

From zone-I to zone-IV, fineness is increasing. So specific surface area (SSA) increases. As SSA increases it requires more water for surface coating.
So, w/c ratio increases from zone I to IV.

Hence, the correct option is (D).

Zone 1.

It is asked about w/c ratio, not about only water. Zone 1 sands are coarser so they have the comparatively lesser surface area, so they require a lesser amount of cement hence higher w/c ratio.

@All,

Here, the question is not talking about water it's is taking about ratio if water is increased cement will also increase in zone 4 so it's experimental that zone 1 requires less w/c ratio.

How to categorize the sand that whether it is from zone-1 or from an other zone, just by seeing it physically, without conducting any test or analysis? Any one can explain?

Since finer sand has the more specific surface area, and hence it will require more water to lubricate it.

Zone 4 correspond to fine aggregates, D is the correct answer.

Aswer should be zone 4. Zoning start from coarser to finer. So, zone 4 is the finer one. For finer sand surface area is more so more high water cement ratio.

Zone 1 is coarser and zone 4 is finer sand. It can be analysed by the sizes of the particle. Since the surface area is large in zone1, it requires more w/c.

The answer must be (d) because zone 4 contains fine sand grading and therefore it has a large surface area and required more paste to fill up these voids.