Bridge Strengthening and Repair: Extending the Service Life of Critical Transport Assets

Slabtec’s specialist capability in structural strengthening, concrete remediation and bridge repair.

Bridges are among the most important assets in any transport network. Whether they support local traffic, heavy vehicles, pedestrians, public transport or essential freight movements, their structural performance has direct implications for safety, access, service continuity and long-term asset management.

Across Australia, many bridges are now required to perform beyond the assumptions of their original design. Increased traffic volumes, heavier vehicle loads, ageing materials, deterioration, changes in compliance requirements, and the need to extend asset service life are all placing greater demands on bridge owners, councils, engineers and contractors.

For many bridge assets, replacement is not the most practical, economical or sustainable option. Strengthening and repair can provide a highly effective pathway to improve capacity, address deterioration, extend service life and minimise disruption to the surrounding network.

Slabtec is a specialist structural remediation contractor with extensive experience in the strengthening, repair and preservation of bridges and civil infrastructure. Our work combines practical construction capability with engineered methodologies, helping project teams deliver durable solutions for complex existing structures.

Strengthening existing bridges for additional load capacity

Bridge strengthening is often required when an existing structure must accommodate increased design loads, changed usage conditions or upgraded compliance requirements.

This work requires more than selecting a strengthening product. It requires a detailed understanding of the existing structure, its constraints, the intended design outcome, and the realities of on-site installation.

Slabtec’s bridge strengthening work may include:

• Carbon fibre reinforced polymer strengthening
• Steel strengthening
• Concrete repair and reinstatement
• Concrete Jacketing
• Installation of strengthening systems in constrained access environments
• Design and construct support
• Collaboration with engineers, councils, contractors and asset owners
• Practical methodologies that reduce disruption and support constructability

In many cases, strengthening works are undertaken beneath bridge decks, around existing beams, within restricted-access zones, or while the asset remains part of an active transport network. These conditions require careful planning, experienced site teams and a strong understanding of both structural intent and construction methodology.

A practical approach to bridge remediation

Bridge strengthening and repair projects are rarely straightforward. Existing structures often present unknowns that only become apparent through investigation, access, preparation or early works.

Slabtec’s value lies in combining specialist strengthening capability with practical remediation experience. Our teams understand that successful bridge works require close coordination between engineers, contractors, asset owners and site personnel.

This includes understanding:

• The structural purpose of the strengthening works
• The condition and variability of the existing substrate
• The impact of access limitations
• The requirements of quality assurance
• The importance of completing works safely and efficiently
• The need to minimise disruption to asset users and surrounding communities

By approaching each project through both technical and practical lenses, Slabtec helps deliver strengthening and repair outcomes that are constructible, durable, and aligned with the asset owner’s objectives.

Supporting councils, engineers and contractors

Small and medium-sized bridges form a critical part of local and regional transport networks. These assets may not always attract the same attention as major bridge infrastructure, but their performance is essential to communities, freight routes, emergency access and local economies.

For councils and asset owners, strengthening and remediation can provide a cost-effective and sustainable alternative to full replacement.

For consulting engineers, Slabtec offers collaborative support in designing structural solutions utilising carbon fibre.

For principal contractors, we bring experienced remediation teams capable of working within complex project environments, often under tight access, staging or programme constraints.

Slabtec supports project teams across:

• Bridge strengthening
• Concrete remediation
• CFRP strengthening
• Steel strengthening
• Structural repair
• Durability upgrades
• Asset life extension
• Design and construct solutions
• Specialist remediation methodologies

Extending bridge service life through engineered strengthening solutions

The preservation and upgrade of existing bridges is becoming increasingly important across Australia. As infrastructure ages and load demands increase, asset owners need practical ways to improve performance while managing cost, disruption and sustainability outcomes.

Strengthening and repair play an important role in this process.

By extending the service life of existing bridge assets, project teams can reduce the need for premature replacement, minimise embodied carbon associated with new construction and keep critical transport links operational.

Slabtec’s experience in CFRP strengthening, steel strengthening and concrete remediation enables us to support bridge projects where the objective is not only to repair what has deteriorated, but to improve the structure’s capacity and long-term performance.

Project Example: Hotham Bridge, West Australia

Client: Advanteering Civil Engineering

Steel strengthening and bridge upgrade works

The Hotham Street Bridge in Victoria required strengthening to support additional load requirements. A number of previous repair options had reportedly been considered, but in the absence of a specific preferred standard method, a new approach was required.

The project team developed a strengthening methodology using steel laminates, with 3 mm laminates selected as part of the structural upgrade approach. Working beneath the existing bridge structure presented additional complexity, particularly where the beams were located under the bridge and access was restricted.

Slabtec’s role included preparing steel beams to ensure the critical bond strength required for the strengthening system was achieved.

Managing practical constraints beneath existing bridge structures

Bridge strengthening often involves working in environments where access, surface condition, substrate preparation and installation tolerances are central to project success.

For the Hotham Street Bridge works, preparation was critical. The performance of the strengthening system depended on the quality of the bond between the existing structural elements and the applied strengthening materials. This required careful surface preparation, quality control and practical site execution.

The project demonstrates Slabtec’s ability to support complex bridge strengthening works where the methodology must respond to both engineering requirements and site constraints.

More about the Hotham Street Bridge Project

Project Example: Delta Bridge, Regional Victoria

Client: Jarvis Norwood

Strengthening concrete planks and beams using CFRP laminates and steel plates

Delta Bridge, located in regional Victoria, required strengthening works to increase load capacity. The addition of new kerbs and a widened footpath exceeded the bridge’s existing capacity, necessitating structural strengthening to support the upgraded configuration.

The strengthening solution employed a combination of carbon fibre-reinforced polymer (CFRP) laminates and steel plates. CFRP flexural strengthening was used for the concrete planks, while steel plate strengthening was required to provide additional capacity to the concrete beams.

For bridge assets of this type, the strengthening method must address both the structural requirements and the practical constraints of working on an existing structure. Access, substrate condition, surface preparation and installation sequencing all influence the successful delivery of the works.

Slabtec completed the strengthening works using specialist CFRP systems and steel strengthening techniques suited to the bridge geometry, load requirements, and the long strengthening runs on the planks.

Structural Strengthening Requirements for Increased Bridge Load Capacity

The bridge planks required significant flexural and shear strengthening to meet the structural requirements associated with the new footpath and kerb.

The works required strengthening to concrete planks and beams beneath the existing bridge structure. This made the selection of a practical, high-capacity strengthening system important, particularly where access and installation conditions required careful management.

CFRP and Steel Plate Strengthening for Concrete Bridge Planks and Beams

Flexural strengthening to the bridge planks was completed using CFRP laminates. On the beams, additional capacity was provided using steel plates.

Sika CarboDur S1214 laminates were used to provide high levels of additional capacity. With a width of 120 mm and a CFRP thickness of 1.4 mm, the laminates were particularly suitable for the long runs required on the bridge planks.

The combination of CFRP and steel strengthening allowed the project team to address the different strengthening requirements across the planks and beams, while retaining a practical installation methodology for the existing bridge structure.

Why CFRP was suited to this project

CFRP strengthening can offer significant advantages in bridge applications, particularly where existing structures require additional capacity but have limited tolerance for added weight, increased member dimensions or intrusive strengthening works.

For the Delta Bridge, the use of CFRP laminates provided:

• High tensile strength
• Low added weight
• Minimal increase to member dimensions
• Suitability for long strengthening runs
• A practical strengthening method for existing bridge planks
• Compatibility with a broader strengthening strategy incorporating steel plates to the beams

This project demonstrates how CFRP laminates and steel strengthening systems can be combined to address increased load requirements on existing bridge assets.

By applying an engineered strengthening solution to the existing structure, Slabtec helped support the bridge upgrade while avoiding a more intrusive replacement pathway

Project Example: Gross Bridge, Horsham

Client: Horsham Council

CFRP strengthening for additional load capacity on a steel bridge

The Gross Bridge at Horsham, Victoria, required strengthening to support additional loads. The project was notable as an Australian first, with carbon fibre reinforced polymer strengthening completed on a steel bridge.

The strengthening requirements were developed through cooperation between the engineers at Horsham Council and the University of Western Sydney, ensuring the required structural performance could be achieved.

Australian-First CFRP Strengthening for a Steel Bridge

A number of strengthening approaches had previously been considered for the bridge. However, in the absence of a specific standard for this type of application, the project had not progressed.

Horsham Council Engineers and the University of Western Sydney worked together to develop the structural requirements using a 3 mm laminate.

The project also presented practical site challenges, with bushfire conditions necessitating the site’s evacuation twice during the works.

Steel Beam Preparation for Critical CFRP Bond Strength

Preparation of the steel beams was critical to the success of the strengthening works.

To achieve the required performance, Slabtec prepared the steel substrate to ensure adequate critical bond strength could be achieved for the CFRP system. This preparation was essential for supporting the long-term performance of the laminate-strengthening solution.

The project demonstrates Slabtec’s ability to deliver specialist strengthening works in technically complex applications, including projects where the strengthening methodology must respond to unusual structural conditions, limited precedent and demanding site constraints.

Specialist Bridge Strengthening Expertise

Gross Bridge highlights the role of specialist strengthening expertise in extending the service life of existing transport infrastructure.

By applying CFRP strengthening to a steel bridge, the project demonstrated how advanced strengthening systems can be adapted beyond conventional concrete applications to meet additional load requirements and extend asset life.

For councils, engineers and asset owners, the project is an example of how collaboration, testing, surface preparation and practical site execution can help unlock a viable strengthening pathway where standard repair approaches may not be available.