Paveking uses fog spray as a light application of diluted bitumen emulsion to a bituminous surfacing as a part of the construction of such a surfacing or as a maintenance measure.
The net bitumen content of the fog spray is part of the overall design binder content required for the entire chip seal. This situation is also applicable to a re-seal operation where a fog spray is required.
Paveking also fog sprays as a maintenance procedure on an existing bituminous surfacing to assist in retaining the aggregates in place, sealing the layer against water ingress or to “rejuvenate” the surfacing when it is showing signs of “dryness” resulting from ageing/hardening of the bitumen. A process we refer to as a surface enrichment.
In our experience, a fog spray is most effective when the layer still has sufficient skid resistance and the surface texture such that the fog spray can penetrate into the layer and not lie on the surface of the aggregates which may result in tyre pick-up of the binder residue and/or poor skid resistance. Binders used for fog spray are generally either cationic or anionic emulsions. Cationic emulsions are more suited to dilution on site whereas anionic emulsions should be delivered already diluted for use from the manufacturer. Client application rate for a fog spray will be specified by the client or his agent, but will generally be 0.8 – 1.0 L/sqm of 50/50 emulsion/water blend, with the net quantity of bitumen normally not less than 0.25 L/sqm.
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