MANUAL 4 - Construction Industry Development Board

MANUAL 4 – BITUMINOUS PAVEMENT SEALS
4.2 Construction of the slurry seal
4.2.1 General operation
The preparation and construction of the slurry will need the careful
operation and co-ordination of the labour force.
Concrete mixer operator responsibilities:
• Checking the mixer before any work starts. The mixer must
be checked for oil and fuel.
• After work is completed for the day, the concrete mixer
operator must make sure that the mixer is cleaned. The
operators must have a 25 litre drum or ½ x 200 litre drum of water and a large piece
of mutton cloth available, as freshly splashed slurry or emulsion can easily be washed
off tools and mixer if dealt with immediately. It is better than using diesel or power
paraffin.
• It is not necessary to wash out the mixer after every mix, on condition the work is being
done on a continuous basis. For long stoppages, e.g. lunch break or major problem,
then it is advisable to wash out the mixer.
• Caking of the mix will occur at the mouth of the drum during the process of discharging
the mix into the barrows. These cakes tend to break off and contaminate the slurry
mix, causing problems during the screeding of the laying process. Use the watersoaked
mutton cloth to wash the mouth of the drum. Some of the excess water will fall
into the drum, but is of a very limited quantity. This washing process should be done
after each barrow load. If done on a continuous basis, the drum would be kept clean.
• The concrete mixer operator and an assistant are responsible for measuring out the
correct amount of cement and emulsion to be used, and he/she must also check the
consistency of the mix. If too dry, the slurry already discharged must be returned to
the mixer for further addition of water and mixing.
Wheelbarrow operator’s duties:
• They are required to fill the 25 litre cans or wheelbarrows with aggregate and deliver
them to the mixer platform or hopper, ready for use.
• They must place the barrows correctly at the discharge point below the drum of the
mixer.
• They must avoid any mud being carried onto the new work.
Slurry seal workforce
• They must place the slurry with shovels just ahead of the spreader box (or screed),
in sufficient quantities for the squeegee operators to spread the material sufficiently
thick for the spreader box (screed) to level the surface quickly and efficiently. The
slurry must be placed in approximately straight lines across the width being treated,
for relatively easy spreading by the rubber squeegees.
• During the process of shovelling the slurry from the barrow to the road, the shovels
must be dipped into the drum of water and wiped with the wet mutton cloth.
• Immediately when the barrow is empty, it must be wiped with a wet cloth to remove
any slurry sticking to the barrow as these eventually break loose and contaminate the
slurry.
IMPLEMENTING EMPLOYMENT INTENSIVE ROAD WORKS 41
• Batching and concrete mixer operators.
• Wheelbarrow operators.
• Spreader/laying operators.
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