The layer between Bituminous Course and Crushed Aggregate Base Course (WBM & WMM) is called Prime Coat. Its purpose is to bind the loose aggregates of (WBM & WMM) so that it can be prepared for subsequent construction activity of laying bituminous layer.
The thin layer between two bituminous course is called Tack Coat. The purpose of Tack Coat is to form a bond between two bituminous layer. There is certain specification mentioned in any project for rate of application of Prime coat & Tack coat.
For measuring that application rate of Tack Coat & Prime Coat , we shall have a Aluminium or any other suitable light tray with dimension 200 mm(L) x 200 mm(B) x 20 mm(H) . A set of three plates are essential for this test.
1. Weigh all the three trays & numbered them.
2. Place these trays along the road in path at 10 metre interval between wheels of distributor.
3. Now pass the distributor .
4. After distributor crosses a length of 50 metre , remove the tray.
5. Immediately without losing time , weigh them to the first place of decimal.
6. Fill all readings into the format.
Take the average of them & compare with the specification. If more are less result is obtaining , adjust the speed of distributor .
Reference : IRC 2008