MANUAL 4 - Construction Industry Development Board

MANUAL 4 – BITUMINOUS PAVEMENT SEALS
• While the tanker is parked on a level surface, check dipstick reading and record
quantity of binder in the tank.
• Ensure the distributor has a valid up-to-date spray certificate. If not, let the laboratory
carry out the distribution test on spray bar.
• Check width of spray for spray bar and correct setting of spray guide to ensure spray
falls on correct surface of road.
• Before spraying, check spray for blocked nozzles and setting of nozzles.
• Check the temperature of the binder and ensure the same temperature is used for
each spray – this will ensure more accurate spray applications.
• Record weather conditions and temperature of road surface.
• Check tachometer for condition setting and recording.
• Spray a test section to check if tanker is spraying at the correct rate, as determined
by the engineer and if the spray is even. Repeat until the process is functioning
satisfactorily (the material used in this process should be to the suppliers’ account).
Note dipstick reading, prior to spraying of actual road.
• Ensure there is sufficient labour to cover the binder with aggregate, e.g. if a medium
grading is specified and 10 000 litres have been sprayed, 5 882 m² must be covered
with aggregate:
= 5 882 m² 3 ,016 m 3 /m²
= 94 m3 (2 – 3 m 3 /labour unit)
= 31 – 47 labour units required for 8 hours.
• After spraying the section, again take dipstick reading (if entire load not sprayed).
4.3 Spreading of aggregate
Two methods of applying the aggregate are described:
• Spotting of aggregate and spreading by hand.
• Application of aggregate by manual chip spreader.
Note
• Where the aggregate consists of screened material it shall be screened in accordance
with the engineer’s specification.
• Where crushed stone from a commercial source is used in the construction of the seal
the quality and grading of the stone must be controlled at the crusher, prior to
delivery, to eliminate disagreements arising when the material is delivered to site.
4.3.1 Application by spotting of aggregate and spreading by hand
• Spot the heaps of aggregate accurately along the length of the road, at the spacing
determined by the engineer, based on the determined application rate in m3 /m2 of the aggregate. This will assist in obtaining a uniform rate of application of the
aggregate (Photos 4.46 and 4.47). The aggregate should be placed on plastic sheets of
1,5 m 31,5 m to reduce wastage.
IMPLEMENTING EMPLOYMENT INTENSIVE ROAD WORKS 77
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