A structural condition survey is a vital tool for informing and creating an effective concrete repair and corrosion management plan for deteriorating structures, whether it be a building, bridge or multi storey car park. There are many ways to restore and maintain these concrete structures, and choosing the right method is imperative from a financial perspective, but also how long the service life is extended.
What is a Condition Survey?
A structural survey is a comprehensive inspection of a property or piece of infrastructure to provide a detailed evaluation of its current condition and future risk. Condition surveys are often used to unearth hidden structural defects, such as corrosion of reinforcement steel or for a structural steel frame. Being able to understand the nature and extent of deterioration, and overall conditions of a structure is essential before starting a repair project, as it informs engineers and contractors the most suitable protection method to carry out to improve structural resilience.
Experienced chartered engineers often perform condition surveys. At SHL, our specialism is corrosion control and monitoring, so we can therefore enhance surveys performed by engineers who can give the highest level of advice in corrosion science and engineering as expected of Fellow at the Institute of Corrosion.
What Types of Condition Surveys Are There?
- Half-cell contour mapping surveys for corrosion assessment (car park deck example below). This is the best method for detecting the risk severity of corrosion in concrete structures. Itconsists of measuring the potential difference referenced to a standard reference electrode, normally a copper/ copper sulphate (standard portable half-cell) placed on the surface of the concrete with the embedded steel reinforcement.
- Chemical testing for chloride, carbonation, ASR, cement content and petrography. It is important to distinguish between the causes of the corrosion as this will dictate the method to repair the concrete. Carbonation pH testing can be used to evaluate the alkalinity of concrete samples, and testing chlorides work in a comparable way by testing concrete samples.
- Visual Inspections involve an experienced professional looking concrete damage and identifying spalls, cracks and other visible defects.
- Delamination Surveys – Delamination is where the concrete cover debonds from the reinforcement steel. They are not always visible on the concrete surface, but wet stains or nearby spalling concrete may indicate areas of vulnerability. Sounding is a method to identify and locate delamination below the concrete surface by striking the surface of a concrete section with a hammer or steel bar to detect planes of delamination.
There are, of course, many diverse types of structures requiring condition surveys that can be performed dependent on the issue the structure is facing – the above are the main ones we utilise to detect corrosion related problems.
Why Should You Have a Condition Survey?
Concrete and masonry structures often start to show corrosion-related problems well within the service life of the asset. Corrosion of steel is a primary cause of damage to structures, which is being accelerated by the environment and climate change and affecting 70% of infrastructure. It is the simple logic that if these problems are detected well before they can cause considerable damage, asset owners can save on huge repair costs and protect the value of their asset before it declines. Proactive maintenance also prevents safety issues and protects the integrity of the structure, especially if the asset is a historic investment.
Alongside performing the condition surveys, SHL’s services include designing a corrosion management system which will help control structural corrosion issues for the long-term, offering the asset sustainable resilience through low carbon repair methods. We can also offer management of these installed systems partnered an online network management system with service life tracking. Having structural performance data available online means you have access to these archives and data that can be used for due diligence assessments in the future if the asset was to be put up for sale.
Corrosion for concrete structures is inevitable and occurs well within the service life of an asset. Climate challenges we are currently facing is accelerating the rate of corrosion due to more aggressive environments, increased carbonation and chlorides. Structural condition surveys are key for improving the overall resilience of the asset, as hidden issues are detected and controlled before it becomes beyond repair.
The benefits are clear from a financial perspective but being able to provide whole life protection through corrosion management to an asset contributes to the circular economy, meaning buildings are reused or recycled helps contribute to sustainability goals by preserving embodied carbon. Coupled with service life data, online control and archives of data help asset owners keep on top of repairs, being proactive in their maintenance and protecting the structure effectively.