MANUAL 4 - Construction Industry Development Board

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MANUAL 4 – BITUMINOUS PAVEMENT SEALS
4. Construction
4.1 Preparation of the base
Preparation of the unstabilised base
All loose dust or debris must be broomed off the surface and inspected for false layers which
must also be removed for rectification after priming.
• Establish the centre line of pavement and mark out the edges of the surface to be
primed with sisal twine, 200 mm wider than width of final surfacing.
• Place 2 3 210 litre drums of water and 2 3 210 litre drums of inverted emulsion prime
at suitable distances along the road.
• Using the motorised hand sprayer, spray a 210 litre drum of water uniformly over
the surface of the base at approximately 0,5 litres/m 2 . (The 210 litre drum will cover
± 400 m 2 or ± 100 m of 3,5 m wide road). .
• Allow the water to soak in and when the surface is damp, apply the prime (inverted
emulsion prime). (See note)
• If the ambient temperature is > 20°C, it is not necessary to heat the prime.
• Apply the prime at approximately 0,7 litres/m². If over applied, the prime will run. It is
difficult to over apply as 0,7 litre/m² is the approximate top limit. If the gradients are
steep, the prime may run at 0,5 to 0,6 litres/m².
• Ensure that the spray screens are methodically used to prevent over spraying of the
shoulders and ensure neat edge lines are achieved.
Note
Do not wet the surface using more than a drum of water at a time. This can be alternated
with a drum of prime. The amount of prime sprayed/day will depend on the square
metres of base completed per day.
4.1.2 Preparation of stabilised bases
• Emulsion-treated bases (ETB) can be opened to light traffic (< 500 vpd) for extended
periods (one to two months), without special treatment. However, before surfacing,
the road must be swept clean and apply diluted emulsion (60% stable grade Anionic),
i.e. one part emulsion: 6 parts water, at a rate of 0,6 litres/m².
• Lime stabilised bases must be allowed to dry out and then treated and primed as for
unstabilised base.
4.2 Spraying of binder
Controls prior to spraying
• Set out centre line and edge lines of the road with 3 mm sisal twine.
• Place reinforced paper at start and end of spray joints.
• Ensure that the supplier of binder has fixed fish plates at ends of spray bar fitted to the
tanker.
• Ensure that end-nozzles are fitted to spray bar.
IMPLEMENTING EMPLOYMENT INTENSIVE ROAD WORKS 76