Angularity number is used to give an indication of shape of aggregate. The concept of angularity number was suggested by Shergold. It gives a qualitative representation of shape of aggregate.
Angularity Number Test
Angularity number test gives an idea of how angular the aggregate is. This is based on the percentage of voids in the aggregate after compaction in a specified manner.
In angularity number test, a quantity of single sized aggregate is filled into metal cylinder of 3 liter capacity. Then the aggregate is compacted in a standard manner and the percentage of void found out. To know the detail procedure click here.
If the void content of the aggregate is 33% the angularity of such aggregate is considered 0. If the void is 44%, the angularity number of such aggregate is considered 11.
Importance of Angularity Number
The normal aggregate which are suitable for making concrete may have angularity number anything from 0 to 11.
Angularity number 0 represents the most practicable rounded aggregate
Angularity number 11 indicates the most angular aggregate that could be used for making concrete.