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d
&
ri
JULY-AUGUST 2013
Swedish contractor Demcon is using a diamond cutting wheel to demolish a quay
at the Port of Gothenburg.
D&Ri
reports on this unusual demolition method
Full circle
demolition
wide spacing. The bottom 100 mm (4 inch)
layer contains a very closely meshed matting
of rebar. By cutting down to the top of this
matting, Demcon uses the matting to support
the weight of the 35 tonne slab while lifting
chains are connected. The chains then support
the weight of the slab while the fourth side is
cut. Cutting through the rebar matting using
torches or breakers fitted with extra-long
chisels is the final operation before the slabs
are lifted using a 110 tonne mobile crane. They
are loaded onto flat-bed trailers and towed to
an offsite recycling facility. After separating
the rebar, the crushed material is used for road
embankments on roads under construction
nearby.
It is vital that the demolition process does
not slow construction of the new quay so every
effort has been made to make each operation as
efficient and fast as possible. Using an OilQuick
automatic coupler to connect attachments to
a Cat 336D excavator has reduced attachment
changing times down to 15 seconds. The
presence of rebar in the concrete has had a
major influence on pick consumption, which
was averaging around four picks per cut meter.
Fitted with Erkat QuickSnap retainers, picks
could be changed in seconds. To keep pick
consumption to a minimum, Erkat designed a
The Erkat cutting wheel
is teamed to a Cat 336D
excavator by an OilQuick
coupler to allow rapid
attachment changes
L
ocated on Sweden’s west coast, the Port
of Gothenburg has the capacity to take
the world’s largest ocean-going container
vessels. In 2011, traffic passing through the
port included 42 million tonnes of freight,
900,000 containers, 534,000 ro/ro units,
163,000 new cars and 1.67 million passengers.
To maintain its position as the largest port
in Scandinavia, Gothenburg Harbour Ltd
commissioned Skanska to carry out a €1.5
billion (US$1.9 billion) renovation project at
Skania Harbour. In addition to building a new,
stronger quay to deal with expected future
container traffic, the project also included
the construction of a dedicated transport link
to a Volvo factory 2 km (1.3 miles) from the
harbour.
Renovation of the southern quay requires
the removal of a 900 m (2,953 ft) long section
leaving only the piling. The 50 year old quay
consists of a slab of reinforced concrete 15
m (49.2 ft) wide and 700 mm (28 inch) thick
weighing 40,000 tonnes. The contract for its
removal, including foundation work, was
valued at €44 million (US$56.6 million). As it is
removed, a new quay is constructed in its place
made up of 300-400 mm (12-16 inch) slabs
of concrete with reinforced sections capable
of supporting new and existing Super Post
The unit at work on the concrete
quay of the Port of Gothenburg
SITE REPORTS
Panamax cranes for the larger container ships
planned for the future. The new quay will also
offer ships at berth an electrical connection
to shore, eliminating the need to keep engines
running to maintain systems.
SLAB REMOVAL
Skanska Sweden started the project to
demolish and reconstruct the Southern quay at
Scandia Harbour in May 2012 and the work is
expected to be completed in autumn 2015. The
demolition work was contracted to Demcon,
who tried out traditional methods to cut the
concrete into slabs to be transported off site for
recycling. Using diamond wire and diamond
cutting wheels, the average production rate
was 2.5 m/hr (8.2 ft/hr). However, by using an
ERW 600 cutter wheel from Erkat, Demcon
were able to increase the cutting speed to 6-10
m/hr (20-33 ft/hr), an increase of up to 400%.
Demolition has to be carried out with
minimal disruption to the normal operations
of the container port. Demcon concluded that
the most efficient removal method is to cut
a 130 mm (5.2 inch) wide slot on three sides
of a 4 x 4 m (13.2 x 13.2 ft) slab to a depth of
600 mm (24 inches). The 18 mm (0.8 inch)
diameter rebar running through the upper
600 mm section of the quay has relatively
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