Charlie Zeynel, advisor to ZAG Group, outlines the landscape for SCM trading in 2025.
Global Cement (GC): What does the global landscape for supplementary cementitious materials (SCMs) look like in 2025?
Charlie Zeynel (CZ): The demand for SCMs of all kinds, slags, fly ash and natural pozzolans, continues unabated. Cement producers are keen to adopt SCMs primarily due to their internal sustainability targets and less to save on raw material costs.
We estimate that the consumption of granulated blast furnace slag (GBFS) and ground granulated blast furnace slag (GGBFS) increased by 20% globally in 2024 compared to 2023. Looking ahead to the rest of 2025, demand for SCMs will increase once again. How much by is up to the global economy overall – something that is entirely out of the control of cement producers, steel producers and those that enable the flow of SCMs between the two.
GC: How are slag supplies changing, in light of trends in the global steel industry?
CZ: There are only around 10 - 12 countries that we could classify as ‘major’ steel producers. The most significant is China, which accounts for 50% of all steel production. Japan and South Korea are also major players, as is the EU, with Brazil, India and some others also supporting significant blast furnaces. This is not new.
What is new, however, is that all major producers are now marketing GBFS as a product, not a ‘byproduct’ and certainly not a ‘waste.’ This has been a creeping trend but now it is established to the point that many steel producers have incorporated GBFS sales directly within their main steel management structure. It is clear that GBFS is a key profit centre, no longer an ‘afterthought.’
Arcelor Mittal has been particularly insistent for many years that, if GBFS can be substituted 1:1 for clinker, it should command the same price as clinker. This is an attitude that is now proliferating through the rest of the steel sector.
GC: How is GBFS being used at present?
CZ: Around 90% of all GBFS that is used is still used in traditional cement and concrete, but this may be decreasing. It’s something to keep an eye on. More and more is being diverted to other kinds of binders, notably geopolymers, and other materials like Ecocem’s ACT product. I’m fairly sure that slag is doing a lot of heavy lifting in these kinds of products. There’s also a lot more slag being directly added at the job site too.
GC: How are GBFS users’ demands changing?
CZ: A common theme across all applications is that slag reactivity is increasingly important. So too is its ability to be mixed easily into the blend. In the ‘good old days’ the attitude was to ‘throw in’ some GBFS to stretch out cement. This relaxed attitude has not survived the increased emphasis on sustainability and on overall performance.
Now we can see that Arcelor Mittal and several Asian players, particularly Japan, are paying increased attention to how their GBFS is used by cement producers. They are refining their slag production processes and other players have taken note. The flow of information is much easier and anyone can ask a large language model ‘how to optimise slag’ and it will bring up a detailed summary of what others are doing. I believe that this side of AI is going to be more transformative than many people realise.
As AI advances, standard ‘laboratory research’ as we know it will be increasingly outdated. It will retain a role, but it will serve to confirm the predictions of AI models. This will speed up research significantly.
GC: How much GBFS was traded in 2024?
CZ: In line with the increased demand for GBFS, traded volumes have risen significantly in recent years. In 2020-2022, around 20Mt of GBFS was traded trans-continentally. For 2024, I would say that the figure was more like 40Mt. My estimate is that 10Mt is exported from China, another 10Mt from Japan and the remaining 20Mt from all other producers. Much of the increase is due to decreased demand for cement in China, which has impacted the country’s ability to consume its GBFS domestically. 2 - 3 years ago, there was virtually zero GBFS exported from China.
The issue with these numbers is that nobody has complete access to all of the information regarding GBFS trade volumes, so we rely on compiling information through both official and unofficial channels and methodologies.
GC: What has the increased global availability done for prices?
CZ: Increased GBFS use and increased quality demands point towards higher prices. The appearance of large volumes of Chinese GBFS did impact the average price for a while, but they are now on the rise again. On top of this, there is increased variation in different markets. It may be an over-simplification in some cases but, due to historical concerns about the quality and/or reliability of Chinese slag, a lot of it is heading towards markets that are relatively new to SCMs, for example in parts of Asia and Africa. These markets can currently handle more variable quality in exchange for a lower price point, up to half the price of more well-established GBFS exporters in some instances. In markets that are more experienced with SCMs – particularly Australia, Europe and North America – we see demand for higher-quality GBFS, primarily from Europe and Japan. These markets are willing to pay a premium for consistent high quality. Traders must be increasingly discerning and selective to operate successfully in this changing environment.
GC: How have the Trump Administration’s tariffs on Chinese imports affected the market?
CZ: The Administration’s 145% tariff on all Chinese imports includes SCMs, which means that much Chinese GBFS is unlikely to enter the US for a while. In the short- to medium-term Chinese GBFS will serve other markets, which will further play into the price stratification that I just mentioned.
Even more importantly than the tariff, however, is US TR Section 301. This will impose a US$18/t cost on imports arriving on all Chinese-built vessels – regardless of where it is flagged or who it is owned by – from 14 October 2025 until 16 April 2026. The current proposal calls for the equivalent cost for Chinese-owned and operated vessels to be US$50/t. From 17 April 2026 to 16 April 2027 the rates will increase to US$23/t and US$80/t, respectively. For the following 12 months they will increase to US$28/t and US$110/t and then to US$33/t and US$140/t.
If fully enacted, this may effectively divide the global freight market into vessels that can commercially supply to the US and those that can’t. This is already affecting the market, such that many ship owners are reluctant to quote rates beyond the short term. This has increased prices and they could rise further. It has complicated supply chains significantly. It is also unclear exactly how the tax or tariff will be imposed.
Everyone and everything remains somewhat confused with questions abounding. What exactly is the tax? Who should pay? What about ships already in transit? However, I think the best course of action is just to keep calm and carry on. The new rules affect all operators to some degree. It makes no sense to overreact and make long-term decisions based on what could yet be short-term measures.
In parallel, there is an ongoing re-evaluation of the contractual world to accommodate the new eventualities caused by the potential for tariffs. The boundaries of who is responsible for which costs are shifting. It represents a lot of additional leg-work for all participants in the trading business and the solution is not yet fully crystalised. I believe everyone involved should take care to play by the new rules to the best of their knowledge, and not try to second guess future changes or look for loop holes and short cuts. Eventually it will work itself out.
GC: We’ve discussed GBFS quite extensively. What about other SCMs?
CZ: Fly-ash remains a key SCM, but nowhere on the scale of GBFS. The changes described above affect it too, of course. Supplies of fly ash are also diminishing in many markets as the world gradually switches away from coal-fired power stations. This has meant that many operators have investigated ash ponds, which – in theory – have plentiful supplies. However, this trend has not come as fast as expected. It may be that it is more difficult and more expensive to extract and clean the ash than had been predicted. There’s certainly enough material sitting in ponds all over North America, Europe, Asia, Australia and elsewhere. Maybe the pressures described above will make it more attractive by comparison. However, I think that GBFS will continue to be produced in appreciable quantities over the next 20 - 30 years. Maybe I’m wrong... the whole SCM picture is becoming more nuanced and difficult to read. Players who are level-headed will likely prevail.
GC: Thank you very much Charlie.
CZ: You are very welcome!
