A detailed article exploring how durable and reliable FRP is, based upon 25 years of durability testing
Over the last 25 years especially (3), our industry has seen extensive durability testing of FRP or fibre-reinforced polymer. Particularly, concrete repairs specialists have been eager to discover the long-term effects of using FRP composite on both new and existing concrete structures. This we know – durability testing has proven FRP can last a whopping 50+ years, greatly extending the life of our buildings and structures! This detailed article explores how durable and reliable FRP is, based upon thorough research and cold, hard results. If you would like further information after reading any chunk of our guide, please call our specialist team on 01482 425250 who will be on-hand to help you.
What kind of material is FRP?
FRP is a common acronym for fibre-reinforced polymer, a composite material compromising of a polymer matrix with fibres made of carbon, aramid, or basalt. FRP composite has quickly become a popular choice for concrete repairs specialists looking to reinforce and strengthen a structure; largely due to the multitude of great qualities demonstrated by FRP, including:
The qualities of fibre-reinforced polymer
- High corrosion resistance;
- High durability;
- High flexibility;
- High impact resistance;
- High strength and tensile strength;
- Long-lasting – 50+ years before degradation;
- Low fatigue;
- Low thermal and electrical conductivity;
- Mitigates the need for costly and extensive maintenance;
In addition, FRP is generally quick and easy to install and can be applied using everyday tools found in a concrete specialists’ kit. Many of these qualities cannot be found in previously used strengthening materials such as steel, and hence, this is why we now favour the FRP!
What are the types of FRP composite?
The most common types of fibre-reinforced polymer are:
- Aramid fibre systems;
- Carbon fibre systems (known as CFRP, our chosen FRP at CCUK!);
- Glass fibre systems.
If you would like to learn more about the types of FRP systems, particularly the system we use – carbon fibre-reinforced polymer – please call our highly knowledgeable team on 01482 425250.
What is durable FRP used for?
FRP, or fibre-reinforced polymer, is primarily used to strengthen existing concrete structures or reinforce new ones. The FRP composite material first came about in the 1980s but has grown in popularity over the last two decades, largely because it can easily extend the life of a building or structure by 50+ years (1). Thus, the sought-after quality of FRP is its durability and how easily it can withstand wear & tear, daily pressure, and the common damages endured by concrete buildings and structures.
Common causes of damage in concrete structures
Though one of the strongest materials in the world, concrete is not invisible and can be subjected to various types of damage and deterioration, including:
- Chemical exposure;
- Corrosion and weathering;
- Exposure to extremely high temperatures;
- General wear & tear;
- Poor installation;
- Old age;
- Repeat load-bearing and overloading;
- And more.
For more information on the common causes of concrete damage, please read our recent blog here.
What is the importance of durability in FRP?
First things first – let’s look at the meaning of `durability`, which is described by the English dictionary as `the ability to withstand wear, pressure, or damage`. Now, the majority of commercial concrete buildings and structures need to do exactly this – bridges carrying large lorries, pipelines transporting large volumes of water, and warehouses or factories holding large products and supplies. Although incredibly strong – even concrete needs support in maintaining its durability when its sole purpose is to be exposed to wear, pressure, and damage! This is where our FRP comes in – to increase the load-bearing weight and reinforce any struggling areas of concrete buildings and structures, extending their usage by decades and ensuring they carry on doing their jobs as safely and effectively as they were originally built.
So… how durable and reliable is FRP, exactly?
As an easy-to-follow comparison, FRP is stronger and more durable than steel – a material we’d traditionally have used to strengthen and reinforce concrete structures in applications such as `steel jacketing`. FRP came up trump compared to steel during testing, especially because FRP failed to corrode when exposed to water, however, steel deteriorated.
It is documented by Structure Magazine (4) that UK durability testing has been completed in the following areas:
- Full-scale tests of wall specimens;
- A five-story masonry research building;
- Six-foot diameter columns;
- Column arch rib joints.
These were thought to be the key testing areas that led to the continued and varied use of FRP as an effective retrofit solution for walls, slabs, columns, beams, pipes, and other structural elements of buildings, bridges, and pipelines.
Though exact durability is tough to measure, several multi-million-pound experiments have been completed around the world using FRP on new and existing buildings which have proven the positive effects of FRP years after application. These have been documented in the Slovak Journal of Engineering, and include (2):
- The Canadian Bridge Design Code study: involved drilling and removing concrete cores from five structures 5-8 years of age. The areas which had been treated with FRP were separated and analysed for their physical and chemical composition in a laboratory environment. There was no degradation of the bars and the FRP limited the stress level to 25% of the ultimate tensile strength!
- The Missouri USA Bridge study: involved replacing a deteriorated bridge deck with nine FRP precast concrete panels and studying the behaviour across 4 years via the assistance of load-testing by standard trucks. After the 4 years of testing ceased, NO loss of stiffness was observed and the durability remained the same as its original condition!
The AC 125 Criterion and FRP
As per current building codes, FRP systems are accepted by the AC 125 Criterion. This criterion was created following the 1994 Northridge Earthquake in California (5) and exists to ensure large-scale buildings and structures undergo durability testing – along with environmental testing, physical and mechanical properties testing, and rigorous quality control testing. All of these tests combined aim to assist the building of large-scale buildings that are durable, strong, and safe.
Book your FREE feasibility study for FRP today
If you are looking for an affordable, effective, and low-maintenance strengthening solution for your structure, FRP applications may be for you. For further information or to book your FREE feasibility study, call our highly knowledgeable team on 01482 425250 today. Alternatively, you can book one of our popular Coffee & Catch-ups, where you will get the opportunity to ask as many questions as you need.
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(1)(2) sjce-2020-0015 (sciendo.com)