A prime is always recommended over granular pavements that are to be surfaced with a sprayed seal, or to be surfaced with asphalt where the depth of surfacing is less than 100 mm. A prime is also recommended for bonding of sprayed seals or asphalt to timber or concrete surfaces.
A prime is used to:
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penetrate the surface of an unbound granular layer filling all surface pores
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provide a bond onto which a subsequent bituminous surfacing can adhere
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provide a surface which retards the absorption of the bitumen, from a subsequent bituminous surfacing, into the pavement
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assist in waterproofing and protecting the pavement
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assist with the curing of stabilised pavements
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provide a temporary surface for traffic (though it should be noted that the life of the primed surface exposed to traffic is brief).
