I want to know about which sieves are important while Grading of 10,20,sand, wmm, gsb, gsbc and other asphalt material? Do we fail the material if one sieve limit is not within the limit.
Question about Grading
- Thread starter Vbseries007
- Start date
Dnyan Deshmukh
Staff member
You need to refer IS codes for particular type of material and their gradation details along with their limits.
Example : for sand sieves required
4.75mm, 2.36mm, 1.18 mm, 600 micron, 300 micron, 150 micron.
There are 4 zones of sand from coarse to fine and each zone specify lower and upper acceptable limit on each size of sieve according to cumulative percentage passing.
Apart from this there is one more additional +/- 5% limit is given for single sieve size.
Say 4.75mm Passing in Zone 1 sand is 90 to 100 and if in sieving you get result 87% passes through 4.75mm sieve, in that case too, material is acceptable.
For sand Zone is decided as per the % passing on 600 micron sieve, according to it we need to refer acceptable limits for that sand.
If we want Zone 1 sand and as per sieve analysis if 600 micron passing shows its Zone 2 sand - You can reject it.
For 150 micron sieve, we should never use additional tolerance of +5%.
Same way details about all material and their acceptable gradation limit is given in IS codes, we should follow that.
For WMM, GSB and asphalt etc. we need to do designing of it first to get the desired parameter, once design is finalized, production is done as per that and we can verify it according to final mix which we provided to party.
Example : for sand sieves required
4.75mm, 2.36mm, 1.18 mm, 600 micron, 300 micron, 150 micron.
There are 4 zones of sand from coarse to fine and each zone specify lower and upper acceptable limit on each size of sieve according to cumulative percentage passing.
Apart from this there is one more additional +/- 5% limit is given for single sieve size.
Say 4.75mm Passing in Zone 1 sand is 90 to 100 and if in sieving you get result 87% passes through 4.75mm sieve, in that case too, material is acceptable.
For sand Zone is decided as per the % passing on 600 micron sieve, according to it we need to refer acceptable limits for that sand.
If we want Zone 1 sand and as per sieve analysis if 600 micron passing shows its Zone 2 sand - You can reject it.
For 150 micron sieve, we should never use additional tolerance of +5%.
Same way details about all material and their acceptable gradation limit is given in IS codes, we should follow that.
For WMM, GSB and asphalt etc. we need to do designing of it first to get the desired parameter, once design is finalized, production is done as per that and we can verify it according to final mix which we provided to party.
Thanks for reply.. could you give is code regarding these as well as wmm, gsb, gsbc asphalt design code ?
Thanks
Dnyan Deshmukh
Staff member
Do refer IRC and MORTH Specifications - Search on internet, You will find all for free.
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