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Q) Is it safe?
A)
TASS is essentially a concrete coffer slab system, designed
on the same principles.
The polystyrene TASS blocks act as the void formers
only, playing no structural role and stay in place to
thermally insulate the building.
The method of pouring concrete between the TASS blocks
to create the beams and slab, fully encapsulates the
rebar creating a monolithic structure of reinforced
beams and concrete topping.
During construction, after propping the TASS deck, it
can be worked on and concrete poured with complete safety.
The TASS deck which is made from 350MPa cold rolled
steel ‘ribs’ and high density moulded polystyrene
blocks safely carries workers installing rebar, mesh
and controlling the concrete pour. Unlike concrete rib
and block systems the TASS blocks do not crack or break
leading to possible worker injury.
TASS has been installed since the beginning of 2005
without any cases of structural failure or injury during
construction.
Q)
Am I taking a risk using TASS?
A)
TASS has had over 3 years of successful use
in South Africa in wide ranging projects from residential
to apartment blocks and high rise commercial buildings.
The design and installation of TASS is always controlled
by appointed structural engineers.
The design of the system complies fully with the relevant
structural design codes for concrete suspended floor
slabs.
Q)
Where can I get a TASS slab?
A)
TASS is supplied only through appointed TASS licensees
who are either structural engineers or builders aligned
with structural engineers.
Licensees are fully trained in the system and take responsibility
for the design and installation of TASS.
Details of TASS licensees can be obtained from the ABP
website or by contacting ABP directly.
Q)
Can any builder install TASS?
A)
Yes. The advantages for the builder are many.
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The components are all lightweight and therefore no
heavy lifting equipment is needed.
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As the system components are made to tight tolerances
it fits easily and neatly together.
-
Installation crews of half the size used to install
concrete rib and block systems can place TASS decks
significantly faster.
-
Movement of TASS components around site is easy.
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Service ducts and electrical and plumbing services can
be cut into the TASS blocks with a hand saw as can the
blocks to fit into the wall constraints.
-
The installation process is a similar but simplified,
easier and safer method to laying a concrete rib and
block deck.
-
Compared to installing in situ and coffer slabs TASS
requires much less installation equipment – no
decking, scaffolding and separate edge forming only
support propping.
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If required ABP can supply on site installation training
Q)
Can a TASS slab support heavy loads?
A)
TASS can support heavy loads associated with carrying
machinery and equipment, multi storey building and people
typical of all industrial, commercial and residential
buildings. The load supporting capability is designed
into the system using the variables of; support beams
and columns, slab beam depth, reinforcement configuration
and concrete strength.
Q)
How do I finish the ceiling under a TASS slab?
A)
There are 3 options;
1)
Apply the EPS plaster system Polyplast. The bottom of
the TASS blocks have a 5mm dovetail groove to help hold
the plaster when plastering. Polyplast is applied in
a two stage process with a scratch coat applied on day
1 and the finish coat on day 2. Polyplast has excellent
adhesion to both the steel rib and the polystyrene TASS
blocks, can be smooth finished and does not crack over
time.
2)
Fit a suspended ceiling. The droppers are fixed to the
underside of the steel channel which run at 600mm centres.
3)
Paint the ceiling. For parkades and basements which
do not need a high aesthetic finish the under side of
the TASS slab can be painted with any high quality,
acrylic, water based paint. The advantage of TASS is
that as the components fit closely together and the
underside is therefore flat, a painted finish is perfectly
acceptable.
Q)
What happens if there is a fire?
A)
The
structure of a TASS slab is the same as a concrete coffer
slab with the polystyrene playing no structural role.
The polystyrene used to manufacture the TASS blocks
is a fire retardant grade of material and will self
extinguish if the source of flame is removed. In a fire
the polystyrene will melt leaving the concrete coffer
slab structure in place. The fumes given off from the
melting polystyrene are no more harmful than that from
other organic materials used in buildings.
For behaviour of EPS in fire visit the Expanded Polystyrene
Association website: www.epsasa.co.za.
Q)
Is a TASS slab cheaper?
A)
When evaluating cost you need to look at 4 things: material
cost, design complexity, installation cost and life
cycle cost.
Material cost – in general terms expanded polystyrene
(EPS) is about half the cost of concrete so where EPS
replaces concrete it will be cheaper. EPS replaces the
concrete blocks in rib and block systems and concrete
in in situ slabs.
With
the combination of 350MPa cold rolled pregalvanised
rib and the EPS block, TASS is price comparative with
concrete systems of prestressed concrete ribs and cement
blocks. From a material cost standpoint TASS is less
expensive than concrete in situ slabs.
Design complexity – where complex designs are
required incorporation angles, split levels and curves
TASS offers increased versatility as the blocks and
channels and easily be cut to size/shape and in the
same support design different height TAS blocks can
be used to cope with different levels.
Installation cost – this is the area where the
TASS system offers significant cots advantage over competitive
systems.
vs
Concrete rib and block
The
TASS system components are lightweight and can be installed
without heavy lifting equipment or large labour crews,
quickly.
TASS
decks can be placed with 2 operators positioning the
channels and spacing them correctly with TASS blocks
at the wall ends and then sliding the blocks into position
and cutting them to fit at wall ends. Similarly small
crews can move the TASS blocks and channels around site
and up into multi storey buildings.
Typically
installation crews of half the size of concrete rib
and block crews can install TASS at a faster rate.
The
propping spacing can be extended as the dead load of
a TASS slab is 150kg/m² less than an equivalent
concrete rib and block slab. Typically from 1,2m centres
to 1,6 m centres along the ribs.
Electrical
and plumbing services can easily be cut into the TASS
blocks using a hand saw
vs
Concrete in situ slabs.
TASS
does not require the extensive decking of in situ systems
and the time it takes to place this. TASS edge forming
can be easily done with tack welding channels to the
edges of the ribs removing the need for extensive timber
edge shuttering and support systems.
Overall
the installation of a TASS deck is substantially faster
then in situ formwork saving time, materials and money.
vs
Coffer slab systems
Once
again coffer slabs require extensive decking to position
and hold the coffers in place.
As
stated TASS is in essence a coffer slab system where
the void formers remain in place.
Conventional
coffer void formers have to be removed and transported
away from site whereas TASS remains in place removing
this second operation saving time and money.
Life cycle cost – the key benefit of TASS over
concrete systems is the thermal insulation the system
provides. This will reduce significantly the energy
costs associated with heating and cooling over the life
cycle of the building. In commercial buildings and shopping
centres the size and capital costs of air conditioning
units can be reduced taking into account this insulation
effect.
Q)
What is the spanning capability of a TASS slab?
A)
The TASS system has 4 different block heights with the
largest being the 365mm TASS block, which gives a final
slab thickness of 425mm. This slab can free span (i.e.
unsupported except for the slab perimeter) up to 11metres.
Q)
How much concrete do I need for a TASS slab?
A)
This varies according to the height of the TASS blocks
with the deeper blocks requiring more concrete basically
as the concrete beams between the TASS blocks are deeper.
The concrete requirement per m² of TASS slab for
each different block size detailed on the TASS data
sheet and ranges from 0,11 to 0,17m³ of concrete
per m² of slab.
As
can be seen the amount of concrete used in a TASS slab
does not vary greatly from thinnest to deepest TASS
slab. This is what makes TASS slabs cost competitive
against concrete slabs particularly in situ slabs.
Q)
How quickly can you deliver the TASS components?
A)
The TASS expanded polystyrene blocks are supplied ex
stock and the support channels are also ex stock items.
The only delay on the channel supply is that the channels
have to be cut to length to match the dimensions of
the measured building plan.
This
is opposed to concrete components which have to be moulded
(normally one product per mould per day) and then cured
to gain strength before they can be used.
Q)
Can I use TASS in a multi storey building?
A)
Yes, TASS structurally is a concrete coffer slab system.
The advantages of TASS in multi storey buildings are:
1) the components are lightweight so can be moved up
and into the building easily with limited labour and
no heavy lifting equipment 2) the dead load of a TASS
slab is 150 and 320 kg/m² less than a concrete
rib and block and in situ slab respectively. This has
beneficial implications for the overall structural design
of the building.
Q)
How much does a TASS slab cost?
A)
Cost depends on a number of factors: 1) Size of slab,
2) Span, 3) Location of project 4) Complexity of design.
In order to get a TASS quotation building plans must
be sent to a TASS licensee (available on the website:
www.ABPbuildingproducts.co.za).
The
full cost of a TASS slab will include the TASS design
and supply, installation cost plus cost of the concrete
topping.
Q)
Do I have to prop a TASS slab?
A)
Yes,
to support the weight of the concrete until the concrete
has cured a TASS deck has to be propped. The routine
is to place the support channels and TASS blocks and
then prop. Propping is typically at 1,6 metre centres.
Half the props can be removed after 7 days and the balance
after 14 days. Propping and de propping should always
be done in consultation with you TASS licensee.
Q)
Where can I see a TASS slab?
A)
Once a TASS slab is fully installed it looks like any
traditional slab. If you contact a TASS licensee or
ABP Building Products representative you can be guided
to a TASS project in progress in your area.
January
2008 |
