The recent report titled “The efficient use of GGBS in reducing global emissions,” has raised several important points regarding the use of supplementary cementitious materials (SCMs) such as Ground Granulated Blast Furnace Slag (GGBS) and their role in mitigating the environmental impact within the construction industry.
As a pioneering manufacturer of Alkali-Activated Cementitious Materials (AACMs), which acts as a complete replacement for cement, we at Cemfree, welcome this report as an opportunity to engage in a thoughtful and constructive dialogue around these critical sustainability issues with concrete, but believe that the carbon savings benefits of GGBS have not been fully considered or communicated.
Our belief is that GGBS, when used responsibly and efficiently, significantly reduces carbon emissions in construction. Restricting GGBS use would be damaging and counterproductive to protecting the environment and reducing greenhouse gasses.
GGBS providing a solution – now
The cement industry is currently responsible for 8% of the world’s greenhouse gasses and the report rightly emphasises that GGBS is not a silver bullet capable of single-handedly solving this problem. Whilst we agree it should not be seen as the only solution, GGBS remains an indispensable transitional solution. As experts in the use of AACM technology, we have demonstrated that GGBS holds immediate potential for significantly reducing the carbon footprint in construction. We have already demonstrated that carbon savings of up to 85% can be achieved when compared to Portland cement (PC).
AACM technology represents a monumental leap forward in sustainable practice. It currently uses material such as GGBS and Pulverised Fly Ash (PFA) to create ultra-low carbon binders which are used to replace 100% of the PC in concrete. In parallel, Cemfree is developing the next generation of cement replacements utilising a range of widely available waste streams. The AACM industry is rapidly evolving, and GGBS-based AACMs offer a practical and pragmatic solution for reducing carbon emissions now, while we develop solutions for the future.
The urgency of the climate crisis necessitates immediate action. Restricting the use of GGBS, as suggested in the report, would be a counterproductive step backward. Cemfree believe that we must harness the potential of GGBS while continuing to explore alternative materials. This approach allows us to make tangible strides in carbon reduction today, rather than postponing progress until an uncertain future. Companies like Cemfree currently use GGBS and other waste streams, which are already widely used by the industry making it a well-known replacement for 100% of PC in concrete
Inefficient use of GGBS and continuity
The report argues that GGBS is a limited resource, casting doubt on its long-term viability. While the term “limited” may be accurate, it is essential to clarify what this means in the context of GGBS availability.
Recent projections from the Global Granulated Blast Furnace Slag (GBFS) Focus 2023 report indicate a consistent increase in global GGBS production until 2030. These projections provide confidence in the continued availability of GGBS on a global scale. It is also imperative to recognise that GGBS production and supply chains are evolving to meet the growing demand for sustainable construction materials.
As AACM manufacturers, we at Cemfree are committed to maximising the utilisation of GGBS in our products where it has the most impact. Our continued innovation and product development means that GGBS usage in Cemfree products will become more efficient over time. As we continue to develop new versions of Cemfree and work alongside the Low Carbon Concrete Group (LCCG) to bring along standards that allow a broader range of waste streams, we will be able to reduce carbon emissions even further and reduce the reliance on GGBS.
Guidance on using GGBS
The absence of detailed technical data in the report raises valid concerns regarding GGBS usage for specific applications. Questions such as how much GGBS is needed for various scenarios and the optimal proportions for blending with traditional cement require precise answers. Without this information, industry professionals may hesitate to embrace GGBS in their projects.
We agree if restrictions are to be placed on GGBS usage, further in-depth analysis needs to be done to justify this course of action. The UK already imports GGBS for a variety of reasons and without clarity on how much of this is used for technical reasons it is impossible to empower construction practitioners to make informed decisions regarding GGBS usage.
Embracing a holistic approach
In our response to the report, we want to emphasise the importance of adopting a holistic approach to reducing concrete emissions. While GGBS plays a pivotal role, we must also explore other promising avenues for sustainable construction.
In addition to AACMs, we also believe in the potential of carbon capture utilisation and storage, bio-based materials, and circular construction practices. These innovations hold promise for further reducing emissions in the construction sector. As an industry, we should explore and invest in these technologies to diversify our sustainability toolkit.
More importantly, the planet is already benefitting from existing GGBS-based alternatives – they are readily available now – and we see no reason why they shouldn’t be used, given the huge carbon savings that can be delivered immediately.