Britain’s First Commercially Manufactured CFRP System Designed Specifically for RAAC Now In Production
There will only ever be one ‘First’.
Structured Carbon is the first organisation in the UK to take a CFRP strengthening system designed specifically for RAAC from engineering concept through to successful manufacture. This is not a trial system or an adapted product. It is a RAAC-specific solution now in production, with final validation testing and full structural verification complete. More detail here
Why This CFRP System Exists
The original CFRP use for RAAC was designed by John Staves FIStructE, CEng, MIoD, who did all the calculations and helped deliver the first engineered CFRP strengthening scheme for RAAC in the UK, installed at Network Rail’s Didcot node. That project was delivered under intense scrutiny, with no tolerance for unproven assumptions. John, the owner of the IP behind that original design, is key to taking this work forward.
Why Generic Carbon Fibre Is Wrong For RAAC
There is a deeply flawed narrative circulating in the market that says if carbon fibre is strong, then more carbon fibre must be better.
That thinking is wrong.
RAAC combines the compressive strength of the concrete with the tensile resistance of steel to form a composite material similar to normal weight reinforced concrete. But the crucial difference is that the concrete has much lower strength than normal weight concrete. Compressive failure is typically hidden below roof finishes. Tensile failure tends to be more visible as soffit cracking. Over strengthening the tension capacity of a RAAC element could lead to hidden compressive failure and sudden collapse. Adding too much tensile strength can make a structure less safe, not more.
Our system avoids that entirely.
Each strengthening scheme is engineered from first principles. Fibre type, weave, orientation and quantity are designed to achieve the required increase in capacity without over stiffening the plank. Adhesives are not chosen by brand reputation but by measured bond performance with RAAC.
We have tested almost every adhesive system that meets the practical constraints of RAAC strengthening, including:
- Direct tensile pull off testing on RAAC substrates
- Lap shear testing of bonded CFRP systems
- Flexural testing of strengthened RAAC planks
- Load deflection testing to serviceability limits
- Creep behaviour under sustained load
- Environmental conditioning including moisture exposure
- Failure mode analysis to confirm substrate governed failure
This is why our system works and why generic systems do not.
The image alongside shows the exact point of failure on a shear test on a section of RAAC cut alongside the reinforcement bars in our lab in Oxford.
What Makes This a 'Designed For RAAC' System
This is not a product. It is an engineered solution.
Every project is bespoke. Each RAAC plank type is assessed, modelled and strengthened to suit its actual condition, geometry and loading. The carbon fibre is woven and specified for that specific plank type. The adhesive is selected and tested for that application. Nothing is assumed.
The system is fire rated, insurable and supported by insurers because it is designed properly. It can be installed with minimal disruption to occupants, making it viable in live schools, hospitals and operational buildings. Because it is bespoke, it can be coloured or finished to suit architectural requirements rather than looking like an afterthought.
Built in monitoring can be incorporated to provide long term assurance. That means building owners do not just get strengthening. They get evidence that the structure remains safe over time with real-time strain, vibration, temperature, humidity and air pressure all with thresholds and all able to trigger contact with specified stakeholders if an unacceptable level is reached.
At a fraction of the cost of full replacement, this system can extend the service life of a RAAC roof by decades when replacement is not immediately viable or necessary.
Individually
Engineered
Each RAAC plank type CFRP is designed using verified survey data
Woven
by Us
Carbon fibre manufactured in house to project specific requirements
Embedded
Monitoring
Integrated sensors provide ongoing structural condition data
Insurance
Approved
Engineered solutions designed to meet insurer and compliance requirements
Where The System Was Designed To Be Used
This system is already suitable for:
Schools and education buildings
Hospitals and NHS estates
Universities and colleges
Commercial and industrial buildings
Public sector assets
Any building containing RAAC internationally
Beyond buildings, the same engineering principles and materials are applicable to civil structures, marine assets and other specialist environments where controlled strengthening is required without adding mass or disruption.
How We Work
Condition Assessment
GPR & Measured dataconfirms actual structural
configuration
Engineered Design
Solutions designedfrom verified structural
parameters
Bespoke Manufacture
Manufactured specificallyto project defined
requirements
Controlled
Installation
Installation & QA
is carried out under
defined procedures
Monitoring
Assurance
Real-Time monitoringprovides trust
and assurance
More Detail
…on the UK’s first end to end CFRP strengthening system designed specifically for Reinforced Autoclaved Aerated Concrete. Not adapted. Not repurposed. Not imported. Designed from first principles for RAAC and nothing else.
“We are not adapting carbon fibre to work with RAAC;
We have designed carbon fibre for RAAC.”
This solution exists because the industry needed something better than generic carbon fibre strips and hopeful assumptions. RAAC does not behave like normal reinforced concrete. Treating it as such is not conservative. It is dangerous.
Our system is British made, engineered plank by plank, bonded with adhesives selected and tested for RAAC specifically, and proven through laboratory testing, modelling and live site validation. It is now in full production and ready to serve schools, hospitals, universities and commercial buildings across the UK and internationally where RAAC was used over the last sixty years.
The Structured Carbon design is grounded in real RAAC behaviour. All calculations are derived from measured site data and validated against physical testing. The system is engineered to perform predictably, not conservatively guessed or over applied. That is what makes it compliant, repeatable and commercially viable.
Our CFRP solution is not fixed or generic. It is tuned to engineer specified requirements using data obtained from GPR and NDT scanning, including plank thickness, reinforcement layout, reinforcement condition and plank type. Each RAAC element is strengthened to its required capacity, not to an assumed worst case.
We can manufacture and supply in batches as small as for a single plank. That means every RAAC element within a building can be remediated using the same engineered system, precisely adjusted to suit its individual condition. Strength is added where it is needed and nowhere else.
This tuning process is fundamental to safe RAAC strengthening and is the reason generic carbon fibre systems fail to address the real risks.
More on why it exists:
We have systematically studied RAAC reinforcement layouts, shear behaviour, modulus variability, failure modes and bond performance. We have tested carbon fibre fabrics, fibre orientations and resin systems specifically against RAAC substrates. We have pulled them off real RAAC, sheared them, loaded them, conditioned them and failed them on purpose so we understand exactly how and why they behave.
The result is not a product you pull off a shelf. It is a system that is painstakingly designed for each project to a defined performance requirement, down to the decimal point.
RAAC CFRP Strengthening FAQs
Answers to Your Most Pressing Queries
Yes. This is the first CFRP system developed and manufactured specifically for RAAC based on extensive testing, modelling and live validation. The design is underpinned by an evidence based approach developed by Neil and John, informed by measured RAAC behaviour, bond performance testing, and structural verification. It is not an adapted or assumed solution. It is purpose designed for RAAC from first principles and taken through to production.
Yes, when it is designed correctly. Unsafe outcomes arise when generic carbon fibre systems are applied without understanding RAAC behaviour. Our system is engineered specifically around RAAC strength, stiffness, shear behaviour and failure modes to avoid those risks.
Its not that simple. Strengthening improves capacity. Monitoring provides assurance. Used together they give building owners confidence that the structure remains safe over time and that performance remains within expected limits.
Yes. This system will not cost more than full roof replacement. In most cases it can be delivered at a fraction of the cost, with far less disruption, while extending the service life of a RAAC roof by decades.
Yes. The system is designed to be retrofitted with minimal disturbance, making it suitable for schools, hospitals and other live environments.
Any more questions?
If you have other questions or need more details, please reach out. We are here to help clarify any concerns and guide you through our services.
Are You Responsible
For A Building
With RAAC?
If you want a solution that is engineered, proven and ready now, we are the carbon fibre specialists you should be talking to.