How to identify the Grade of GSB

Dnyan Deshmukh

Staff member
If you refer a Morth Specifications, you will find the data required for assessment of grade of GSB.
GSB Grading.jpg

Above table shows the requirement of % cumulative passing through each sieve, upon doing sieve analysis and calculating the cumulative % passing.
You can look at the table to determine its grade.

Once the grade either specified or designed to achieve max density (MDD), it is important to verify, received GSB is as per it.

Before starting work, following need to be done
Getting the report from third party laboratory for its MDD and OMC.
Doing CBR value test on GSB for source approval - required for designing of section and thickness of layer.
Verifying other parameters like Abrasion resistance, 10 % fine value etc.

For aggregates having more than 2% water absorption, wet aggregate impact value should be calculated.