Quality Assurance Handbook for Rural Roads Volume-I - pmgsy

3. Section-500
3. The primer should be sprayed uniformly over the dry surface of absorbent granular base, using
suitable bitumen pressure distributor or sprayer capable of spraying primer at specified rates and
temperature so as to provide a uniformly unbroken spread of primer. Normal temperature range
of spraying emulsion should be 20°C to 60°C. The rate of application depends upon the porosity
characteristics of the surface to be primed and is given in Table 502.1
TABLE 502.1: RATE OF APPLICATION OF BITUMINOUS EMULSION FOR PRIME COAT
Porosity Type of surface Viscosity at 60°C Rate of
Kinematic Saybolt Furol application per
Viscosity
(Centistokes)
(seconds) 10 sq m(kg)
Low WMM/ WBM 30 – 60 14 –28 6 – 9
Medium Cement stabilized 70 – 140 33 – 66 9–12
soil base
High Gravel base 250 – 500 117 - 234 12- 15
4. A very thin layer of coarse sand may be applied to the surface of the primer to prevent it from
getting picked up under the wheels of vehicles delivering materials for construction of bituminous
layer
5. The surface should be allowed to cure preferably for 24 hours. Unabsorbed primer should be
blotted with sand using the minimum quantity possible.
B. Quality Control Requirements
1. The viscosity requirements for bitumen emulsion will depend upon the type of surface as already
given in Table 502.1.
2. A priming grade bitumen emulsion (slow setting ) conforming to IS:8887 should be used.
3. Quality Control Tests:
3.1 Tests Prior to Construction
The quality control tests to be carried out prior to construction are indicated in Table 502.2. These
tests shall be carried out on the bitumen binders (Emulsion/Cutback) brought on the site by the
Contractor for use in the work.
TABLE 502.2: QUALITY CONTROL TESTS PRIOR TO CONSTRUCTION
Type of Test Frequency
1. Viscosity (using Saybolt Furol Viscometer) (IS:8887) One test for each lot
2. Residue on 600 micron sieve (IS:8887) -do-
3. Storage Stability Test (IS:8887) -do-
4. Flash Point Test, where bituminous cutback is to be used (IS:217) -do-
5. Viscosity Test (IS:217), where bituminous cutback is to be used -do-
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