Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

Annex-III & IV
DETERMINATION OF IN-SITU DENSITY OF BITUMINOUS COURSE
114
ANNEX- III
The metallic tray of the field density is kept on a level spot of the bituminous surface and a hole, 100 mm
in diameter, is cut up to the full thickness of the layer. All bituminous materials removed from the hole
are carefully collected and weighted. The thickness of the layer is also recorded.
A known weight of dry standard sand passing 600 micron sieve and retained on 300 micron sieve, is
taken in the sand-pouring cylinder. The cylinder is kept directly over the hole, and the shutter of the
cylinder is released without any jerk and closed when the hole is filled with the sand. The quantity of
the residual sand in the cylinder as well as the quantity filling the cone of the cylinder are separately
weighed.
Where,
The In-situ density of the layer is calculated as follows:
In-situ density = (A*D)/(W-(W 1 + W 2 ))g/cc
A = Weight of bituminous materials removed from the hole cut in the layer, g
W = Initial weight of sand taken in the cylinder, g
W 1 = weight of sand filling the cone of the cylinder, g
W 2 = weight of sand remaining in the cylinder, g
D = bulk density of sand, g/cc
Prior calibration for depth of hole, in necessary.
D. RATE OF SPREAD OF AGGREGATE IN SURFACE DRESSING
ANNEX- IV
The rate of spread of aggregate by the aggregate spreader or any other suitable means can be checked
by measuring the area covered by each lorry/truck/any other device of known capacity. This can also
be checked by removing the spread aggregate from small areas of the road surface and weighing them.
A 200 mm square metal frame is laid on the new surface dressing, and all the aggregate within the
enclosed area are collected, washed in solvent to remove bitumen and then weighed, and the rate of
spread of aggregate is calculated. It is measured along the road at intervals of between 4 m to 8 m. The
variation in the rate of spread of aggregate should be within + 20 per cent of the mean.