MANUAL 4 - Construction Industry Development Board

MANUAL 4 – BITUMINOUS PAVEMENT SEALS
• 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.
• They must place the slurry with shovels just ahead of the squeegee operators in
sufficient quantities for the squeegee operators to spread the material quickly and
efficiently to a sufficient thickness. The slurry must be placed in approximately
straight lines across the width of the area being treated, for relatively easy distribution
by 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, the barrow must be wiped with a wet cloth
to remove any slurry sticking to the barrow as these eventually break loose and
contaminate the slurry.
• The barrow operators are responsible for site hygiene at the mixing site and road
works site. Any spillage of slurry, emulsion or mud must be cleared, either by picking
up the material and burying it or covering it up with gravel.
• At the end of the shift, the operators must clean their equipment and help clean the
mixer, as well as park the mixer in a safe place.
– Two operators using the squeegees.
– One operator cleaning any untoward spillage of slurry behind the screed and using
the water hose.
– Two operators laying the rails.
– One operator on the mixer.
– One operator measuring out cement, emulsion, water and diluting emulsion as
required.
5.2 Batching and mixing of slurry in concrete mixers
• The area on which the concrete mixer and emulsion drum stand is situated must be
clean, well drained and have a sound surface to avoid dirt and mud being carried onto
the base by the wheelbarrows. It must also be kept clean during operations to avoid
bitumen being carried on to the new work by the wheelbarrows.
• The aggregate to be used in the slurry must be dumped as close to the working site as
possible, preferably at the midpoint of the length of road that one load of aggregate
will cover.
• Using the measuring cans (Photo 4.37) add the correct amount of aggregate to the
mixer drum, as determined by the engineer while the drum is turning. (Photo 4.38)
IMPLEMENTING EMPLOYMENT INTENSIVE ROAD WORKS 61
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