CCP Demidec Floor Brochure - Cornish Concrete Products

Demidec
cornish concrete products
Demidec Flooring and
Permanent Formwork
Demidec
What is Demidec?
Demidec is a thin precast concrete plate, typically 60mm deep, although this can vary
depending on the use. The plate is supplied with a projecting steel lattice girder system
that enables it to provide permanent formwork and integral tension reinforcement for
insitu concrete toppings.
How is Demidec made?
All Demidec floors are manufactured
in a state of the art carousel plant
on precision engineered flat steel
pallets. Shutters are held in place
using magnets thereby ensuring
that the quality of the pallets is not
compromised. Sockets, channels and
electrical boxes can be cast into the
units along with conduits.
Demidec is
made from ecocrete, the
most environmentally friendly
structural precast concrete in the UK
Why choose Demidec Flooring?
Flat Soffit - Demidec floors are flat and
have no camber.
Quality Finish -Demidec floors produce
a soffit ready for direct decoration. Each
plank is cast with a small chamfer along
the horizontal edge. Units are nominally
2400mm wide, although this can be varied
to suit the geometry of the site so that the
joints between units can be expressed.
Thermal Mass Effect - By choosing Demidec
floors, there is no need for a suspended
ceiling and thus the thermal mass effect can
be maximised as the concrete soffit is left
exposed.
Thermal Performance - Part L1A of the
Building Regulations shows a k-value of
138kJ/m2K from above and a k-value of
230kJ/m2K from below. When compared
to a timber floor with a plasterboard ceiling
which has k-values of 24kJ/m2K and 9kJ/
m2K from above and below respectively, the
effect that the thermal mass has on thermal
performance becomes apparent. This
cannot be surpassed by any other form
of construction.
In the drive for low carbon buildings,
designers are consistently selecting
exposed concrete soffits as their material of
choice because of its latent thermal mass.
This can be further enhanced by selecting
heavyweight wall construction such as
CCP’s Crosswall Construction including
Thermowall Insulated Sandwich Panels.
Sound - The density of the product reduces
sound transmission.
Speed of Erection - Due to the increased
nominal width of units and the simple lifting
arrangements, large areas of floor can be
erected in a very short space of time.
Cost - Demidec flooring compares
favourably with the cost of insitu concrete
solutions as well as providing an instant
working platform and a high quality soffit.
For what applications can
Demidec be used?
All Demidec units have an excellent soffit
finish and so are suitable for a variety of
different applications:
Floors for:
/ Residential
/ Commercial
/ Industrial
/ Hotels
/ Accommodation Blocks
Permanent Formwork for:
/ Car Park Decks
/ Bridge Decks
/ Jetties
What is Demidec made from?
Demidec is made from Ecocrete
environmentally friendly concrete which is
responsibly sourced with a minimum of 80%
secondary content in all products.
Are Demidec floors suitable for use with
different types of construction?
Demidec floors are far more versatile
than prestressed concrete floors as they
can be adapted to suit the many different
environments. For example, cover to
reinforcement can be varied to suit different
fire ratings or exposure classes. They can
be also used as permanent formwork for
an insitu concrete floor or as part of a
composite solution where the reinforcement
in the Demidec unit is integral to the overall
design solution.
/ Water Retaining Structures
/ Insitu Concrete & Post Tensioned Floors
Single row of props
Variations
Hollow Core Applications
On Site
By adding polystyrene void formers at the
factory to the Demidec floors, the overall
selfweight of the floors is reduced, thereby
improving performance and reducing the
dead load on the overall structure where
the polystyrene creates a “hollow core”
within the overall floor slab. Void formers
are generally 400mm wide and are fixed
between the lattice girders which are
usually at 600mm centres.
Demidec elements are designed to be lifted
with the hooks of the lifting eye positioned
under the diagonal of the lattice.
Lightweight Concrete
More detailed technical guidance notes
are available on our website, and specific
technical guidance notes will be issued with
each contract.
Demidec can also be made in lightweight
concrete using “Lytag” with a specific
density of 1.8 compared to 2.4 of normal
structural concrete. “Lytag” is also a waste
product and hence its inclusion would
not alter the secondary content of the
concrete. However, if the precast is made
of a lightweight concrete, the insitu topping
will also need to be of a similar density.
Alternatively, the precast elements can
be made in normal density concrete and
the poured insitu topping in lightweight
concrete.
www.cornishconcrete.co.uk
Joints between elements will need to be
sealed prior to the insitu concrete pour to
prevent grout loss. On site reinforcement
will need to be placed and insitu concreting
will be carried out in accordance with the
specification.
Is Demidec a flexible system?
Each Demidec element is designed in the
most efficient way for the particular part
of the structure and its loadings. Sufficient
reinforcement can be added to cope with
localised additional point loads as well
as trimming around openings. Unlike
prestressed floors, the need for additional
supports around openings can
usually be avoided.
Does Demidec always require propping?
Demidec flooring and permanent formwork utilises the lattice girder which gives
the units the stiffness required to take the imposed loads from the insitu concrete.
Generally, the greater the stiffness required, the more lattice girders will be required.
As a rule of thumb, Demidec flooring comes with three propping options:
Propped Units are propped with one single
row of props placed prior to the insitu
concrete pour.
Unpropped use extra lattice girders are used in
the Demidec design giving the units sufficient
rigidity to allow for the insitu concrete.
Multiple Props for longer spans, additional
props are added, typically at 2500mm to
3000mm centres - this would be designed
specifically for each project.
For Health & Safety reasons, units are
generally post propped so that passive fall
systems can be installed prior to the erection
of the floors.
What are Demidec’s capabilities?
Below is an indicative load span table to be used only as a guide. Every Demidec
application will be reviewed by CCP’s in-house design team in order to find
the solution which most meets our customers’ needs.
Indicative Load Span Table
The table shows indicative spans for each depth of slab for various support conditions. This
table is based on dead loading with 0.5kN/m2 allowance for finishes and a superimposed
load of 1.5kN/m2
300
275
250
225
200
175
150
(thick)
9.0 m span
8.0 m span
Key:
7.0 m span
Continuous multiple
+ increased reinforcement
6.0 m span
Simply supported span
+ increased reinforcement
5.0 m span
4.0 m span
Continuous multiple spans
+ minimum reinforcement
Simply supported span
+ minimum reinforcement
3.0 m span
More complex span conditions and
loadings can be easily be accommodated.
For details please contact Cornish
Concrete Products Ltd
As can be seen from the graph the
additional tension reinforcement improves
the performance of the floor. Unlike other
types of floor, Demidec’s performance
can be improved greatly if floors can be
designed as continuous spans. There is
alternate negative and positive bending
along the spans and because of this, the
amount of reinforcement can be reduced,
which will also have its effect on cost.
General Structural Information
Lattice girders are the essential element
in Demidec flooring. They are generally
placed at 600mm centres and ensure
that the panels span the required
distance in the temporary condition. They
also assist the floor in its composite state
with any top reinforcement being tied
into the elements. The top reinforcement
in the slab will be also designed by CCP.
Progressive Collapse -Demidec flooring
deals simply with progressive collapse
as all the elements are tied together in a
monolithic structure.
Environment and Quality
CCP takes its environmental responsibilities
very seriously and is accredited with
the Environmental Management system
ISO14001, are a founder signatory of the
British Precast Sustainability Charter, and
one of the first companies in the UK to be
accredited with BES6001, The Code for
Responsible Sourcing achieving a “Very
Good” status across all of its product ranges.
Concrete is an essential part of the built
environment and with at least 80%
secondary product in every cubic metre of
concrete. CCP’s Ecocrete provides the most
environmentally friendly structural precast
concrete in the UK.
Increasingly, more concrete is being
produced with Ecocrete “Plus” which has an
overall secondary content of at least 85%.
This commitment to environmental matters
assists CCP’s customers in their pursuit of
BREEAM excellence.
CCP is also accredited with the
Quality Management System
ISO9001.
Cornish Concrete Products Ltd
Point Mills, Bissoe, Truro, Cornwall TR4 8QZ
Tel: 01872 864808
Email: info@cornishconcrete.co.uk
www.cornishconcrete.co.uk
www.ecocreteproducts.co.uk
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