HySSIL, building better buildings for a sustainable world

Frequently Asked Questions

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.

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:

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.

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.

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.

CSIRO and the Research and Development Program

The HySSIL research and development projects have brought together a diverse team of scientists, engineers and technologists.

Global Opportunities

HySSIL is looking for partners who have the commercial and marketing skills to capitalise on the HySSIL technology advantages in construction markets around the globe.