1. What are Prime Coats?
Many pavements particularly lower traffic pavements are constructed with gravel or granular material. Often roads have been constructed as gravel roads and an upgrade is required. If Emulsions are applied directly to granular pavements, especially high binder content chip seal emulsions or very quick set slurry emulsions they can fail to wet the surface of the pavement creating poor adhesion. A prime coat can over come this.
In the past prime coats have been based on cutbacks but VSS Emultech Emulprime 1000T™ is based on a special emulsion.
2. What is it used for?
The function of a prime coat is:
- Coat and bond any loose material
- Harden or toughen the surface
- Waterproof the base during construction
- Plug capillary voids
- Provide adhesion between the base and the next course
To be able to do this it must penetrate the surface.
A penetration of 1-2cm is usually satisfactory
Emulsions are discrete particles dispersed in water with an emulsifier. This emulsifier will often increase surface tension and prevent penetration into capillary void, dilution can help but the particle size of the asphalt particles and the emulsifier holds the key.
Emulprime 100™ perform both functions it creates very small particles that are able to penetrate capillary voids due to the low surface tension.
Emulprime1000™ penetrates surface, standard emulsions often do not
3. Are There Different Types?
™ is emulsion based. Other types of prime can be MC or SC cutbacks or invert emulsions. All have very high levels of solvents and high VOC potential. So
Emulprime is the most environmentally sound
4. How Is Prime Coating Done?
Priming is a multistage process. First the pavement must be swept and any soft spots repaired. The pavement may be dampened with water to optimize emulsion penetration. DO NOT OVER WET.
The prime is sprayed at about 1.4-2.0lt/m2. Do a test area to check he level of penetration first. Adjust spray temperature if necessary, for VERY tight pavements dilution with water is possible, do not add more than 30% water and always add water to emulsion not emulsion to water. Spray using a standard emulsion sprayer that is properly calibrated.
|Spraying Prime at 60C on a cold morning|
Allow penetrating and drying. Usually traffic should not be allowed on to this construction for 24 hours but if traffic must use the road a thin layer of sand can be spread. Final surfacing may be done next day.
The road is usually opened to traffic after sweeping or may be opened to slow moving traffic almost immediately.
5. What does it do?
Prime Coats seal and bond surfaces and make a good base for the next layer of surface course.
6. What Does It Cost?
Priming is very is economic ensure premium surface seal performance. A VSS estimator will be pleased to measure your job and give you an exact price.
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