What is tack coat?
A tack coat is a thin layer of bituminous binder applied on existing asphalt or concrete surface before a new layer is added. It helps in creating a bond between the old and new layers, enhancing the overall stability and durability of the road or pavement.
METHODOLOGY FOR application of TACK COAT:
(Acceptance Criteria: Ref. Section 503 of MORT&H)
General
This work is consisting of application of a Single Coat Cationic emulsion of rapid setting type confirming to IS 8887.
Machinery
For this tack coat distributor of capacity ‘4 MT’ shall be used. This distributing unit, so called as tack coat tanker is facilitating self-propelled pressure distributor for spraying the material uniformly at the rate of 2.0 to 3.0 Kg/10 Sq .m under normal temperature and pressures. Sometimes few small patches near junctions, or narrow space where the primer tanker is not reachable then for those areas spraying of primer shall be done manually, after approval from the engineer.
Preparation of Road Surface
The surface on which the tack coat is to be applied will be cleaned, of dust and extraneous material before the application of the binder.
Application of Tack Coat
The tack coat “bituminous emulsion” will be heated to the temperature 20°C – 70°C. This tack coat will be applied uniformly at the rate of 0.25 to 0.30 Kg/Sq.m for granular surface and 0.20 to 0.30 kg/Sq.m for normal bituminous surfaces with the help of self-propelled emulsion pressure Sprayer with self-heating arrangement and spraying bar with nozzles having consistent volume or pressure system, capable of spraying emulsion at specified rates and at 20 °C -70°C to provide unbroken spread of emulsion.