Freyssinet Australia Blisters Win Awards

Freyssinet Australia is pleased to announce, that this earlier this month we were awarded with the NSW State Award for Excellence in the Technology and Innovation Category, awarded by the Concrete Institute of Australia.?

We were awarded for the technical development, design and testing of the UHPFRC (Ultra High-Performance Reinforced Concrete) in the form of “ blisters”.

We congratulate everyone involved in the excellent work and close collaboration leading up to this great recognition.?True to our DNA the team have demonstrated that we don’t back away from a technical challenge.?

For the full technical brief of what UHPFRC blisters are, please read the article below:

Freyssinet Australia have designed, developed, and tested an innovative solution for the fixing of additional post-tensioning (PT) tendons to existing bridges. The solution involves precast anchorage blisters comprised of ultra-high-performance fibre-reinforced concrete (UHPFRC) – a first in Australia. The selection of UHPFRC over more common construction materials such as reinforced concrete or steel allows for a significant reduction in the blister size and weight.

The minimalistic nature of the blisters also ensures that they provide a highly sustainable solution to growing infrastructure needs and that works undertaken on infrastructure within urban environments are less likely to affect public perception, both game-changers in the approvals process.

Materials & Concrete Technology

The PT anchorage blisters make innovative use of UHPFRC by combining it with galvanised steel tubes cast in to form the voids required for the clamping bars and PT tendon. The material’s ability to resist large compressive and shear stresses induced by the clamping bars and tendon without traditional reinforcement, has facilitated a significant advancement in the development of the novel PT anchorages.?

Design & Engineering

UHPFRC is still a relatively new material within the Australian construction industry, and there are therefore very few examples of its use, none of which include heavily stressed applications such as a PT anchorage blister. There is also little guidance provided on the design of elements comprised of UHPFRC in Australian Standards. A unique approach to the design was therefore adopted whereby finite element analysis was undertaken to determine stress flow within the blisters but with the basis of the design being formed by full-scale prototype testing carried out in accordance with AS5100.5:2017 Clause 2.6 and Appendix A.

The design was undertaken with asset owners in mind and their desire to minimise the impact on a bridge’s aesthetic, whilst also providing a highly durable and fully replaceable solution to external PT anchorages. The successful testing of the blisters means that these needs can now be met and ensures that asset owners and operators have a highly desirable and sustainable new solution for the addition of PT as part of any required bridge strengthening works. Construction & Construction Practices

The reduced blister size required when using UHPFRC as the anchorage matrix, results in the ability to precast the blisters off site and install them onto the bridge using a lifting system and a group of stress bars. Pre-casting of the UHPFRC blisters off site facilitates significant advantages in quality control when compared with concrete poured on site. Reusable, prefabricated forms can also be utilised to ensure that dimensional tolerances are achieved for all blisters.?

The anchorage blisters utilise large diameter, high tensile (1,080 MPa) stress bars to create a clamping force and friction connection to the existing structure. The innovative use of such high load stress bars significantly reduces the number of holes required to be cored into the existing structure and subsequently, the risk of damaging existing reinforcement and the amount of work required during preparation of the existing structure.

Architectural & Environment

By reducing the amount of material required to be installed onto the bridge, the UHPFRC anchorage blisters reduce the amount of work required to carry out any proposed strengthening works and allow for the finished product to be more easily integrated within a structure’s architecture.

By making the strengthening of bridges more cost effective, aesthetically pleasing, and sustainable, strengthening becomes a far more viable alternative when compared with building new bridges or replacement structures. It also makes strengthening existing bridges an enabler for reduced carbon emissions and reaching long term sustainability targets.

Sustainability & Resilience

Not constructing new structures is the single most effective way to reduce emissions in the construction industry.

Increasing the lifespan of existing structures and their capacity to service current and future loading requirements will be instrumental in helping nations to meet their sustainability targets. The UHPFRC blisters ensure that these structures can be re-imagined as more resilient, futureproof infrastructure.?

The use of UHPFRC anchorage blisters also reduces the volume of material required for any strengthening works specified in order extend the life of an existing bridge. The PT anchorage blisters developed by Freyssinet Australia therefore present a multifaceted approach for asset owners and operators looking to develop more sustainable solutions to their infrastructure needs.?