In May 2023, a team of researchers from Cardiff University, led by Senior Civil Engineering, Associate Professor Dr. Riccardo Maddalena and PhD researcher Ahmad Alhamdan, tested low-carbon concrete samples at META’s Quay 1 site in Pembroke Dock, to see how they performed in harsh marine conditions.
By replacing traditional cement with industrial by-products and using recycled plastics instead of natural aggregates, they created a more eco-friendly concrete.
Over a hundred samples were exposed to salty water, wet-dry cycles, and real-sea conditions, offering the team much better insights than lab tests alone.
The results were promising – while the concrete was slightly weaker, it shrank less and was more watertight. Could this be an option for tidal lagoons, floating wind platforms and port and coastal infrastructure in the future?
We spoke to Dr. Maddalena to find out how the experiment went and what his thoughts are on the all-important results.
Q. What were you researching during your deployment at META and how did you go about it?
We used the META facilities to deploy samples of low-carbon concrete, incorporating by-products and waste plastics. The aim was to compare laboratory data with real environmental conditions.
Concrete is the most used man-made material, made of natural excavated aggregate (sand and gravel) and Portland cement -the latest data suggests it accounts for almost 10% of global CO2 emissions.
When developing a new material, it is paramount to test it for its long-term resilience, and this is not so easy to implement in standard laboratory facilities. As part of the MEECE project (funded by the European Regional Development Fund and led by Cardiff University Prof. Reza Ahmadian), we designed concretes for tidal and sub-tidal structures.
Q. What did you discover during the deployment? Was it what you expected?
We exposed over 100 concrete specimens on an intertidal area, where concrete was subjected to wet and dry cycles of salty water – a very aggressive environment for concrete. Every month we went to the META site to collect specimens for mechanical and physical testing in our laboratories at Cardiff University.
By comparing data from samples exposed to natural environmental conditions, to those aged in laboratory conditions, we discovered that incorporating by-products (i.e. supplementary cementitious materials to partially replace Portland cement), and low-grade plastics (i.e. those types of plastics difficult to recycle and otherwise disposed into landfill, to partially replace natural aggregate), had a beneficial effect – minimising drying shrinkage and increasing the overall water tightness.

However, it is interesting to note that there is a slight reduction in the strength compared to that achieved at laboratory conditions.
Q. How did testing the concrete at META compare with testing in a lab environment?
The META site allowed us to collect results which would otherwise be difficult or impossible to obtain in laboratory conditions. Samples were simultaneously subjected to wet and dry cycles due to tidal actions, as well as chemical attacks due to the sea water compositions.
At Cardiff University we have a new testing facility, the DURALAB – a time capsule for accelerated materials ageing, capable of simulating hundreds of years of ageing of a matter of weeks. However, as with any laboratory facility, there are constraints in how much you can achieve and samples size.
Having a testing area like META it is extremely important in the field of concrete durability, as it allows researchers to expand the scope of the investigation and simultaneously explore multiple environmental effects at once. Coupled with rain and UV exposure, the META site was a unique and complete testing environment for natural exposure of concrete to marine conditions.

Q. there is huge potential for low-carbon concrete to be used in the construction of future tidal lagoons in Wales. how much of an impact would that have environmentally, and where else could it be used?
Using low-carbon concrete in tidal lagoons in Wales could have a significant environmental impact, particularly in creating more sustainable coastal infrastructure. Tidal lagoons are an exciting renewable energy source, but their construction typically requires large volumes of concrete, and that is where low-carbon concrete comes into play.
Low-carbon concrete generally has a much lower pH level, providing more hospitable conditions for the development of biological films and algae. This would provide concrete structures such as sea walls and artificial reefs that are synergistically placed in the sea the ability to support marine life and ecological restoration, without excessive disruptions to marine life.
q. we know concrete production comes at a huge environmental cost. are you hopeful these new methods could be used more widely in the future?
I think there is a real possibility that low-carbon or even carbon-neutral alternatives could replace traditional concrete, especially with the global push for net-zero emissions by mid-century. I am very hopeful that the innovations we’re working on will lead to broader adoption of low-carbon alternatives – the more we successfully demonstrate the viability of low-carbon concrete in real environments, the more we build confidence in such materials.
Regulatory support, industry investment, and consumer demand for sustainable buildings are all helping to drive change. The availability of conventional supplementary cementitious materials such as fly ash and GGBS is decreasing due to drastic changes in the electricity production from coal and the steel making industry respectively. Thus, it is imperative to find alternative solutions to replace the use of Portland cement with sustainable yet durable alternatives.
q. millions of pounds is being invested to decarbonise the concrete industry in the uk, how does it feel to be working on such an important mission?
Working on the mission to decarbonise the concrete industry feels both inspiring and meaningful. Concrete is one of the most widely used materials on the planet, yet its production is also a major contributor to global CO₂ emissions. Knowing that our work could have a substantial impact not only on the industry but on global sustainability efforts is incredibly motivating.
It’s exciting to be part of a community where innovation meets urgent environmental need. We know that what we’re doing today could shape the built environment for generations, potentially setting a global standard for sustainability in construction.

q. do you have any future deployments planned at meta?
We have recently been awarded an EPSRC-funded grant to research the use of lithium mining waste as the next generation of materials to replace Portland cement in concrete production (LITHICRETE). The META testing area will be pivotal to investigate long-term durability of LITHICRETE against marine conditions.
For more information on the project, please contact Dr. Riccardo Maddalena at Cardiff University.