Specification Part 3 - Road & Bridge Works - Urban Administration ...

6. Emergency Response
6.1. The Contractor shall plan and provide for remedial measures to be implemented in the
event of occurrence of emergencies such as spillages of oil or bitumen or chemicals.
7. Measurement
7.1. No separate measurement shall be made in respect of compliance by the Contractor with
the provisions of this Section of the Specification. The Contractor shall be deemed to have made
allowance for such compliance with these provisions in the preparation of his prices for items of
work included in the Bills of Quantities and full compensation for such complianc e will be deemed
to be covered by them.
502. PRIME COAT OVER GRANULAR BASE
502.1. General
This work shall consist of the application of a single coat of low viscosity liquid bituminous
material to a porous granular surface preparatory to the superimposition of bituminous treatment
or mix.
Prime coat is an initial application of a binder to an absorbent road surface.
A coat of low viscosity binder is applied as a primer over an existing road surface (generally a
water bound macadam) if it is dust, porous and absorptive, to develop a bond between the
existing road and the surface. Road built with laterite, kankar, brick metal, moorum, etc., (water
bound macadam) are absorptive. The function of the primer is to penetrate the existing surface,
fill the pores, bond together any loose material, and in general, produce a firm impervious layer to
serve as a foundation for the material to be superimposed.
Priming coast are not given on cement concrete or dense bituminous surface, but a track
cost is applied instead, a coat of primer is not usually required where surfacing is to be done with
bar.
502.2. Materials
502.2.1. Primer: The choice of a bituminous primer shall depend upon the porosity
characteristics of the surface to be primed as classified in IRC: 16. These are:
(i) Surfaces of low porosity; such as wet mix macadam and water bound macadam,
(ii) Surfaces of medium porosity; such as cement stabilized soil base,
(iii) Surfaces of high porosity; such as a gravel base.
502.2.2. Primer viscosity: The type and viscosity of the primer shall comply with the
requirements of IS 8887, as sampled and tested for bituminous primer in accordance with these
standards. Guidance on viscosity and rate of spray is given in Table 500-1.
TABLE 500-1.
VISCOSITY REQUIREMENT AND QUANTITY OF LIQUID BITUMINOUS PRIMER
Type of surface
Kinematics
Viscosity of Primer at 60°C
(Centistokes) (kg)
Low porosity 30 – 60 6 to 9
Medium porosity 70 -140 9 to 12
High porosity 250-500 12 to 15
Quantity Of Liquid
Bituminous Material
Per 10 Sq. m.
502.2.3. Choice of primer: The primer shall be bitumen emulsion, complying with IS 8887 of a
type and grade as specified in the Contract or as directed by the Engineer in charge.
The choice of a bituminous prime, as to its viscosity and quantity, depend upon the
porosity characteristics of the surface to be primed. The more porous the surface and cooler the
weather, the lower should be the viscosity. Conversely if too much material is being absorbed, a
more viscous grade should be used. A more viscous primer should be used on open textured
roads and a thin primer on close textured roads. The amount applied should ordinarily be
absorbed in 24 hour. The primer should be applied uniformly by means of a sprayer.
502.3. Weather and Seasonal Limitations