The column shoes do not require any temporary
bracing during the erection stage. Typically, four
column shoes are enough to create a moment
resisting connection (see figure 3).
CHASING THE CIRCULARITY of construction
products and buildings is Peikko’s passion and
ambition.
While concrete is the most widely used
construction material, it is also one of the
biggest consumers of raw materials on our
planet: over 10 billion tons of sand and natural
rocks, as well as 1 billion tons of water are used
annually for concrete production around the
world 1. Additionally, the concrete industry has
a significant influence on CO2 emissions, and
it consumes a great deal of energy every year.
Producing one cubic meter of concrete using
Portland cement and clinker results in emitting
approximately 0.2 t of CO2. About one ton of CO2
is generated for each ton of clinker 2.
In addition to consumption of raw materials
and energy, as well as high CO2 emissions,
over 11 billion tons of waste is generated due
to demolition and construction work 1. About
50% of this quantity comes from concrete waste
3. Considerable amount of concrete structures
around the world end their service life due
to demolition, while they still possess some
residual value and could serve much longer.
Very few attempts have been made to reuse
concrete structures of buildings ending their
service life, even though studies have shown
that by doing this, significant environmental
benefits and energy savings could be achieved
2.
Lack of adaptability of connections between
concrete structures is known as one of the
biggest reasons that hinder reuse of precast
concrete elements. In order to improve
the reusability in new concrete buildings,
connections should be designed to allow easy
and cost efficient dismount 4. The ecology
of concrete structures could be significantly
improved by applying the Design for Disassembly
(DfD) in the design of connections. These facts
have been acknowledged by the European
Commission as some of the cornerstones of the
Circular Economy Action Plan 5 that defines a
roadmap for achieving the carbon neutrality of
the construction industry within 2050. Among
other issues, the Action plan implies that new
material recovery targets will be set in EU
legislation for construction and demolition
waste in foreseeable future.
There are many types of concrete buildings
that could already benefit from demountable
connections, which would make it possible
to dismantle and to reuse the structures.
Secondary class buildings, like industry frames,
warehouses, car parks, etc. might only be
needed temporarily at certain locations. After
the required service life, such buildings could
be relocated to serve again wherever needed.
In addition to relocation, removable structures
could be also replaced if they are damaged or
deteriorated.
Bolted connections have great potential to
be the basis for the DfD and to increase the
reusability of precast concrete structures 6. In
principle, untightening of a bolted connection
should be as easy as tightening it.
ARE PEIKKO BOLTED CONNECTIONS
DEMOUNTABLE?
A series of experimental demonstrations have
been organized by Peikko in order to answer
the above question. First, precast columns were
assembled and disassembled from a foundation
on site. Thereafter, identical columns were
supplied to a testing laboratory in order to
investigate how the dismount ability effects
their load bearing behavior.
FIGURE 3 BOLTED PRECAST COLUMN CONNECTION
WITH HIGHLIGHTED RECESS BOXES
PEIKKO CONNECTIONS 1/2021 31
/ScheteligViheralue
