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Durability and Service Life Modelling for Cobham Bridge

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BCRC’s Durability and Service Life Modelling

Understanding design life is essential in building sustainable, safe, and cost-effective structures. By carefully planning for and maintaining a structure’s design life, industries can achieve long-term savings, reduce environmental impact, and ensure safety for generations.

In 2022, BCRC Durability Consultants partnered with Fulton Hogan to extend the design life of the super tee beams on the Cobham Bridge, part of the project to build a section of the Hamilton Ring Road in New Zealand. The project aimed to extend the service life of the beams through a specialised protective coating.

This project highlights BCRC’s approach to durability and service life modelling to safeguard long-term resilience in bridge structures.

BCRC’s Design Life Assessment

During the design life assessment, BCRC evaluated the concrete cover across the Cobham Bridge beams. To meet the required design life of 100 years, BCRC recommended a high-performance coating system—Duralkote 700—that ensures protection against carbonation and environmental factors, which is critical for achieving the desired design life.

Solution for Enhanced Durability and Extended Design Life

Testing of the coating was conducted to verify its performance, which surpassed the minimum required specification by far.

This was determined to be sufficient to achieve a minimum design life of 80 years for the super tees after coating application. Together with a period of 20 years plus propagation as proposed in NZS 3101 Part 2 Clause C3.12.1, this provides the intended 100-year design life of the structure.
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Application Process and Quality Assurance in Service Life Modelling

To ensure durability and design life adherence, BCRC developed a rigorous Inspection and Test Plan (ITP) to monitor coating application quality. BCRC specialists went on-site to inspect the initial phase of the coating application and verify its adherence to the ITP.

The whole process was rigorously verified against the NZ standards and industry-accepted best practices.

 Achieving the 100-Year Design Life with Durability and Service Life Modelling

After extensive testing, BCRC’s approach to design life modelling on the Cobham Bridge demonstrated the Duralkote 700 coating’s ability to withstand carbonation. This, combined with the concrete’s protective properties, aligns with New Zealand Standard NZS 3101, ensuring corrosion resistance and supporting the projected 100-year design life.

BCRC’s durability and service life modelling strategies, combined with expert application and quality assurance, have fortified the Cobham Bridge’s super tee beams for long-term resilience. This project underscores the value of advanced design life assessment and maintenance in achieving robust, enduring infrastructures.

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Durability Consulting for $18.5 Million Warehouse Conversion

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A stunning transformation is underway as billionaire philanthropist and renowned art collector Judith Neilson prepares for her latest design statement with an $18.5-million warehouse conversion. Colliers Project Leaders was engaged to upgrade the building at 66 Bay Street, Ultimo, from an existing commercial building to a single 5-storey bespoke luxury residence. BCRC is proud to play a crucial role in this high-profile development, providing expertise and durability consulting for the project.

Set in the heart of Ultimo at 66 Bay Street and designed by Atelier Andy Carson, this adaptive reuse project will transform an early 20th-century warehouse into a luxurious contemporary residence.

With extensive experience ensuring the long-term integrity of heritage buildings, BCRC’s involvement highlights the importance of durability assessment when planning substantial upgrades.

A Vision of Adaptive Reuse

The project aspires to be a prime example of world-class adaptive reuse. Originally constructed in 1911, the warehouse has seen significant changes over the years, including a 1980s renovation that added a fourth floor. The current design is ambitious, calling for the complete removal of internal walls and ceilings, as well as excavation to add a basement level. Inside, the residence will feature a new spiral staircase, lift, fire stairs, and bespoke finishes, while the exterior will receive a modern facelift to blend historic charm with contemporary elegance.

Why Durability Consulting Matters

Given the building’s age and the scale of the renovation, the project called for expert durability consulting to assess the condition of the concrete and avoid costly repairs in the future. BCRC’s role in this project underscores the importance of understanding the structural health of existing materials, especially when repurposing older buildings.

BCRC’s Durability Consulting

BCRC is providing comprehensive consulting services throughout the project, including:

• Concrete Mix Design Review and Assessment: Ensuring that the new concrete used in the project meets the highest standards for strength, longevity, and compatibility with the architectural requirements.

• Advice on Construction Processes and Material Selection: Guiding the selection of materials and construction methods to achieve optimal performance, sustainability, and durability of the concrete elements.

• Top-Class Architectural Finishing of Concrete Elements: Providing expertise to ensure the concrete finishes not only meet structural requirements but also achieve top-quality aesthetic standards that enhance the overall design.

• Construction/Engineering Detail Review: Assessing construction drawings and reviewing subcontractor tenders to ensure the project is executed efficiently and according to specification.

• Thermal Modelling and Crack Control Measures: Addressing potential issues like crack development and temperature control in the concrete to prevent long-term damage and ensure structural integrity.

• Quality Inspection and Supervision: Overseeing the on-site work to ensure all aspects of the renovation comply with durability and quality specifications.

Maximising the Life of Your Asset with BCRC Durability Consulting

The warehouse conversion is on track to be completed later this year. Once finished, it will stand as an exemplar of adaptive reuse, blending historical integrity with cutting-edge design. BCRC’s durability consulting will ensure that this luxury residence will not only be visually stunning but structurally sound for generations to come.

BCRC is a trusted leader in construction materials and durability consulting. We provide expert planning-stage durability consulting, asset service life predictions, and repair/remediation solutions for existing structures. Our unmatched expertise ensures long-lasting, resilient buildings.

This project highlights BCRC’s expertise with heritage structures, and we’re proud to be part of a team that’s creating a unique piece of Sydney’s architecture.

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Durability Consulting for 66 Bay Street Ultimo
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Team Building Event at BCRC: Go-Karting Adventure in Sydney

bcrc team building event

At BCRC, we believe in balancing work with fun and camaraderie! Our recent team-building event brought together our awesome teams from NSW and VIC for an exhilarating day at the go-kart track in Sydney. While we’re experts in durability and materials consulting, we also know how to rev things up off the clock. From zooming around the track to cheering each other on, it was the perfect blend of competition and team building.

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Ensuring Longevity in Timber Structures: Key Design Elements

timber structures durability

Timber structures well detailed and constructed using the correct timber should last at least 25-30 years with minimal maintenance. We were engaged by a southern QLD council to inspect and recommend solutions for a public boardwalk that had deteriorated significantly since installation in 2011.

The elements of good timber design and construction had been overlooked while the developer focused on cost rather than high-performing specification. Consider the avoidance of trapping moisture, fastening horizontally rather than vertically, ensuring slip-resistant surfaces and above all, choosing durable timber.

At BCRC we specialise in supporting Structural Designers, Owners and Contractors to achieve durable timber structures through correct timber species and member selection, ensuring correct detailing and workmanship to achieve the sustainability and beauty of timber structures.

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Protecting Concrete Reinforcement at City Beach SLSC: A GPR Survey

protecting concrete reinforcement at city beach slsc

With most Surf Life Saving Clubs in close proximity to the ocean those responsible for the asset need to consider the risks associated with chlorides-induced corrosion of the concrete’s reinforcement. Of particular importance is knowing what protective measures might be applied to prevent expensive repairs down the track if cover is low. BCRC experts were engaged by Talis Consultants to undertake a cover survey at Perth’s iconic City Beach SLSC.

Using advanced stepped frequency Ground Penetrating Radar (GPR) equipment and a trained technician, BCRC provided a fast and effective survey, with over 50 x 3m long scans covering most panels. The results showed the high quality precast had good cover such that reinforcement corrosion was a low risk.

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Cathodic Protection Solutions for Corrosion Control

cathodic protection solutions for corrosion

Our specialist engineers provide cost-effective remedial solutions to protect important assets from corrosion. For steel and concrete structures, designing and installation of cathodic protection (CP) systems is one of the effective corrosion control techniques, capable of eliminating destructive oxidation of metal assets.

BCRC have designed and assessed the effectiveness of CP systems for several projects, including the recent completion of a deep well impressed current cathodic protection system for steel piles of a 700m bridge over a river in Dubbo, NSW.

Geotechnical survey findings indicated extreme corrosion potential in the surrounding soil, posing a significant risk to the integrity of the bridge pile. After extensive analysis, BCRC’s CP engineers developed a meticulous design for an impressed current cathodic protection system to mitigate the anticipated high corrosion rate of the steel piles, including environmental protection using a cased and sealed anode system.

The system was designed for 7 zones with requirements based on resistivity. The ground-bed resistance and ground potential rise were modelled using SES CDEGS. Step and Touch voltage calculations were performed for all anodes to ensure safe operations.

By ensuring the durability and longevity of the bridge infrastructure, this project contributes to the advancement of sustainable engineering practices in bridge construction and maintenance.

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Cooling Pipe Systems for Concrete in Infrastructure Projects

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Innovative Cooling Pipe Systems for Concrete in Major Infrastructure Projects

BCRC, a leader in construction technology, has pioneered advanced cooling pipe systems to tackle the complex challenges of managing concrete’s heat of hydration and mitigating thermal cracking in key transport infrastructure projects.

Cooling Pipe Systems: An Efficient, Cost-Effective Solution

In Australia’s challenging climate, controlling concrete placement temperatures is a persistent challenge for the construction industry. However, BCRC’s post-cooling techniques offer an efficient and cost-effective solution. By embedding cooling pipes within the concrete structure, circulating water absorbs the heat generated during hydration, effectively regulating temperatures and preventing thermal damage.

Innovation Meets NSW Government B80 Specifications

The cooling system, designed by BCRC’s Technical Director, Dr. Inam Khan, was successfully implemented in the Newell Highway Upgrade – New Dubbo Bridge project. Collaborating with Abergeldie Complex Infrastructure, BCRC developed customized cooling systems for critical bridge elements. These systems met Transport for NSW’s rigorous B80 specifications, achieving a peak temperature cap of 70°C and a temperature differential limit of 20°C. This cooling approach met thermal requirements and significantly reduced formwork removal times, accelerating the construction timeline.

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Dubbo Bridge

A Major Infrastructure Project for the Region

The $263.2 million New Dubbo Bridge is making substantial progress, with a third of its concrete deck—designed to support future traffic—already in place. Jointly funded by the Australian Government, which has contributed $210.6 million, and the NSW Government, which has provided $52.6 million, this project is a vital investment in the region’s infrastructure.

BCRC’s Commitment to Concrete Durability in Harsh Environments

BCRC’s cooling systems underscore the potential for sustainable, effective solutions in modern infrastructure, setting new concrete durability and efficiency standards in Australia’s harsh environments. BCRC’s material engineers ensure that performance and workmanship requirements are rigorously defined for concrete durability. Yet, these standards can only be met if quality control in materials handling, batching, transportation, placement, compaction, finishing, and curing are strictly followed.

With expertise across the entire concrete lifecycle, BCRC offers comprehensive management to achieve fit-for-purpose, high-quality concrete that meets demanding structural needs in challenging climates.

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Case Study: Expert Witness Services for Sydney Safari House

Expert witness services at BCRC

BCRC serves as an expert witness in litigation, insurance and liability matters. Recently, our building consulting and waterproofing expertise was utilised to assess and recommend rectifications for Sydney Safari House, an architecturally-significant property which had been in dispute with its insurer for over two years. The property had sustained significant water damage following a severe incident. The insurer’s initial assessment estimated the damage and repairs at a lower amount than what was ultimately agreed upon after our involvement.

Our remedial and waterproofing team conducted forensic investigation and prepared a detailed report outlining the impact and potential consequences of the water damage on the building and its materials. He also assessed the additional damage that occurred during the extended period of neglect.

BCRC successfully facilitated a resolution to this complex dispute by addressing both the technical and commercial aspects of the damage with the remediating builder. The insurer was satisfied with our clear and comprehensive Scope of Works, which helped mitigate their overall risk. The homeowner was also appreciative of the outcome.

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Design For Crack Control – Expert Opinion

Chart For Crack Control by BCRC durability consultant

Australian Codes include reinforcement stress limits aimed at providing acceptable crack widths, but this simple approach may not achieve the recommended crack widths given in guidance notes (e.g. CIA Z7/06). Required crack widths are not given in the Australian Codes, except the AS 3735 commentary which provides an inaccurate indication of the crack widths that might be achieved using the prescriptive requirements in AS3735, and this can lead to dispute over the acceptability of cracks.

Design for crack width control in Australia has long followed UK methods in BS 8007. In 2007, CIRIA C660 was released as the UK approach to sections in EN 1992 Eurocode 2 for crack control. BCRC introduced C660 to Australia by running a course in Sydney in 2007, with its author and BCRC consultant, Phil Bamforth as the lead speaker.

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In 2018, CIA Z7/06 was released as the Australian method of design for crack control and CIRIA updated its approach in C776 in 2019. Conflicts between these documents, and the extensive experience gained by BCRC’s four experts in design for crack control, led BCRC to have a 3 day workshop in August 2019 with all its staff to review and develop the company approach to all aspects related to crack measurement and control, and heat of hydration. A technical guidance note along with spreadsheets to accurately calculate crack widths is under preparation.

BCRC continues its involvement in developing codes for crack control with Frank Papworth participating in an fib international committee developing a position paper on ‘Cracking and Durability’ with the brief of writing relevant paragraphs for Model Code 2020.

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Investigation and Remediation of Construction Defects

faiz khan investigating construction defects with UPV testing device

A common occurrence on active construction sites is the identification and remediation of defects. Regularly, destructive techniques are undertaken which can lead to costly delays from the testing process and subsequent repair of tested areas. To avoid extensive destructive testing, BCRC employs the use of non-destructive testing (NDT) techniques to understand the extent of defects or to identify their presence in areas of concern. A recent project that BCRC was involved with, examined the extent of cracking and presence of voiding within newly cast concrete walls and columns. A column exhibiting cracking is shown in the image below.

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Ultrasonic pulse velocity (UPV) testing was undertaken to identify the presence of defects; as well as to quantify their extent. UPV testing is a method where transient waves are used to assess the in-situ condition of a material. Factors that affect the wave velocity include:

  • Density
  • Modulus of elasticity
  • Material homogeneity
  • Defects within the material (i.e. voiding, cracking)
Investigation and Remediation of Construction Defects Investigation one

Defects encountered during the wave travel path result in a lower velocity at the test point. By undertaking a comparative analysis between known sound areas and the test area, areas of concern are identified. To allow for the development of a suitable repair methodology, testing needs to identify the areas that required remediation. To ensure that repairs are effective, retesting of the repaired areas is recommended. This approach allows the asset owner to have confidence in knowing the extent of defective concrete has been identified as well as in the soundness of the repaired works that are undertaken.

Investigation and Remediation of Construction Defects last left invest
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Thermal Modelling of Mass Concrete Elements

thermal modeling of mass concrete elements image by BCRC durability consultant

When constructing mass concrete elements, the long term durability of the concrete can be compromised if consideration is not given to limiting peak temperatures and temperature differentials within the concrete. To understand concrete temperature rise, thermal modelling is undertaken considering factors such as the concrete mix design, curing conditions, restraint factors, concrete geometry, tensile strain capacity, coefficient of thermal expansion and reinforcement spacing.

Thermal modelling is used to characterise the behaviour of the concrete during the curing and hardening phases. Limits are placed on concrete temperature rise and distribution to reduce the risk of cracking; as well as to control delayed ettringite formation (DEF). Crack modelling is undertaken to limit crack widths to within allowable code limits.

BCRC recently completed thermal and crack modelling in accordance with standards (such as CIRIA C660, CIRIA 766 and CIA Z7-06) for a transfer wall of a high rise residential complex.

The construction of the transfer wall was proposed to be undertaken in 6 layers with a variable thickness of the wall of 0.6m – 2.3m and a total wall height of 4m. This unique shape and construction sequence created a complex challenge.

FEA analysis was required as the thermal gradient from the lower sections added heat to the newly cast adjacent sections. This analysis could not have been satisfactorily completed using simple spreadsheets due to the complex nature of the project. Field temperatures were measured onsite during a trial pour and were used in the FEA analysis as heat inputs to allow for an accurate determination of the peak temperatures within the concrete.

From our analysis, it was determined that a pour sequence of 6 layers would result in an unacceptable risk to the concrete and therefore the pour sequence was modified to include 8 layers. The modelling process allowed BCRC to provide limits for the concrete placing temperature of the layers to eliminate the risk of DEF formation and to control thermal cracking to within allowable code limits.

The FEA output is provided below.

Output of Thermal Modelling of Mass Concrete Elements