COLOURED DISPERSIONS

These dispersions are highly concentrated and can be added to the mixer box to produce coloured Asphalt or Macadam.

The basic dispersions at 1% in clear binder with 6mm graded aggregate.

ADVANTAGES OF DISPERSIONS

1) Cleaner to use than dry pigment.

2) Gives stronger results than with dry pigment in many cases giving economic advantages.

3) Cuts mixing cycle times.

4) Improves handling of finished product for hand laying.

5) Gives better colour control from batch to batch.

6) Does not effect the hardness of the binder.

7) Can be pumped allowing it to be automated and controlled from the consul.

8) Low level of volatile matter.

9) Suitable for sand carpet.

10) The dispersions have long shelf life.

11) All pigments used are fully lightfast.

12) The level of binder does not have to be increased when adding dispersion from the normal levels for either the asphalt or macadam.

RED DISPERSION

The following sample block shows the effect of adding increasing levels of dispersion to 200 pen macadam. The top left is with no dispersion and the level increases by 0.5% to 3.5% in the bottom left sample.

While the major colour used for surface coating is red the following shows the effect of Green, Blue, White, Yellow and Red at a level of 3% in 200 pen bitumen.

Colour when laid ..................... Colour after 2 months.

The blackness of the bitumen tends to fade after a period of exposure to sun. The time depends on the situation and the source of the bitumen.

For more information on the effects of light on coloured bitumen based coatings contact David J Higham.

There is also a similar range of dispersions for water based coatings see AQUEOUS DISPERSIONS

Copyright © 1996 David J Higham