PRODUCT FOCUS
COMPACTORS
IN ACTION
A case study by Anro Impact Compaction
Fraser Alexander recently purchased two five-sided impact compactors from Anro Impact Compaction
for use on their Elikhulu site where they are constructing a large tailings storage facility.
T
he project involves constructing a
tailings dam with large earth-filled
walls, two smaller HDPE-lined water
dams, as well as various other civil works.
The impact compactors are being used
to compact the imported fill material on
the dam walls. The use of the impact
compactors was necessary because the
project is being constructed over a very
short period and has strict milestone dates
that have to be achieved. In order to do
so, Fraser Alexander need to compact
in excess of 18 000 cubic metres of
compacted fill every day. The material for
the dam walls comes from borrow inside
the dam.
Contracts manager Johannes Vorster
says: “The impact compactors work great
where you have thick layers of even up to
a metre to compact. We are actually filling
34
in 300mm layers due to the very stringent
compaction specification required by the
design engineer. Our reason for using Anro
impact compactors on this site is that we
can compact twice the amount of earth
per day than we could using normal 10-ton
rollers.”
Roger Stromsoe, from Anro Impact
Compaction, says that they manufacture
two types of impact compactors: a five-
sided and a three-sided compactor. They
are rated according to their energy output;
the five-sided being a 15kJ compactor
and the three-sided a 30kJ compactor.
The five-sided impact compactor is a more
general-purpose compactor, mainly used
on earthworks where use of this impact
compactor makes it possible to place
material in thick layers. Depending on the
material type, fill can be placed in layers
of 500mm to 700mm thick and more.
This gives the compactor an output of
about 2 000m 3 per hour compared to the
output of a vibro roller of about 300m 3 per
hour on the same material. The five-sided
compactor is also used on in situ material
on sites where only moderately deep
compaction is required.
The 30kJ, three-sided impact compactor
is generally used for the compaction
of in situ material on sites where deep
compaction is required. Because the
depth of influence of an impact compactor
is significantly greater than that of
conventional equipment, use of the three-
sided compactor usually makes it possible
to satisfactorily compact soil from the
surface, instead of having to remove the
soil and replace it in layers, as would be the
case with vibro rollers.
Depending on the material type, in situ
material can be improved to depths of up
to three metres. On many construction
sites, the impact compactor has been the
only compactor that could achieve the
required densities by compacting the site
surface without having to remove and
replace the material in layers, resulting in
significant cost saving. The three-sided
compactor is also used on fill where
there is an advantage in placing very thick
layers. ■
A three-sided Anro impact compactor towed
by a Bell 2806 hauler.
JUNE 2018