Is
there an equivalent product available or being developed
anywhere else?
The CSIRO’s original design parameters for HySSIL™
were to develop a cellular, cementitious, monolithic product
to fill the medium density, high strength technology gap
which was identified within the pre-cast concrete industry
worldwide.
To be equivalent to HySSIL™, a competing product
would need to have a similar range of properties, which
include:
- Monolithic structure
- Load bearing (up to approximately 20 MPa) and non
load bearing applications
- Approximately 50% of the density of conventional concrete
- Very low thermal conductivity
- Very high fire resistance
To our knowledge, there is no equivalent product available
or being developed anywhere else in the world. The exhaustive
patent process has also produced strong evidence that
the technology is unique.There is a range of pre-cast
products known as autoclaved aerated concrete (AAC), commonly
seen in Australia under the Hebel brand name. This is
a very lightweight, low strength (non load bearing, less
than 5 MPa) product which cannot be used in external applications
without a protective surface treatment.
There are also a whole range of non autoclaved concrete
products which utilise chemical foams or polystyrene filler.
To date, these products have not been able to achieve
a compressive strength rating of anywhere near that of
HySSIL™.
There is also a lightweight concrete technology which
utilises lightweight aggregates. This is more commonly
seen in higher strength concrete mixes (greater than 40MPa)
and typically poured in-situ. The weight saving against
conventional concrete is typically only around 25%, and
the high strength lightweight aggregate concrete mixes
are relatively expensive. The application of lightweight
aggregate concrete is typically for “in-situ”
pours and not for pre-cast panels.top
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Is
HySSIL™ cost competitive with conventional precast
concrete and other building materials?
Yes, HySSIL™ is very cost competitive with conventional
precast concrete and other building materials.
Compared to conventional pre-cast concrete panels, HySSIL™
is price competitive ex-factory.
However, when an overall design and construction view
is considered, the HySSIL™ cost advantage increases
significantly due to:
- Reduced cartage costs
- Reduced cranage and installation costs
- Reduced structural member costs
The CSIRO is also investigating various component materials
in order to further optimise costs and performance. The
costing studies will be an ongoing CSIRO task which will
review the HySSIL™ formula depending on the availability
and costs of component materials in various locations
around Australia and the world. Consequently, there is
a real potential to reduce costs.
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Why
couldn’t HySSIL™ be mixed on site?
Pre-cast concrete components have gained increasing popularity
with the building industry over the past 20 years due
to superior quality control in the overall building process
and the lower onsite impacts of adverse weather conditions
and the highly unionised on-site labour force. As a result
we would see HySSIL™ remaining as a pre-cast product
in the long term, built under a controlled factory environment
and requiring less onsite time than in-situ concrete.
Technically, at this stage, HySSIL™ needs to be
produced as a flat panel in a controlled factory environment,
such as a conventional precast concrete factory. This
is due to the liquid nature of the mix and the way in
which the cellular structure is formed in the mix by a
chemical reaction.
Whilst this means that HySSIL™ cannot at this stage
be carted to sites in agitator trucks and poured in-situ,
it does not necessarily prevent the development of small
scale transportable production facilities for HySSIL™
to create HySSIL™ panels on site.
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What
is the fire rating of HySSIL™
For the purposes of Building Regulations in Australia,
a fire-resistance level (FRL) of 24/240/240 was achieved
for a 150mm thick panel at 1500 density. CSIRO undertook
testing in accordance with AS1530.
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