The use of limestone calcined clay cement (LC³) is gaining momentum as a path to decarbonisation for the cement sector and Chryso Southern Africa is i
The use of limestone calcined clay cement (LC³) is gaining momentum as a path to decarbonisation for the cement sector and Chryso Southern Africa is investing its depth of expertise and research capability to support this exciting opportunity.
Clinker reduction has emerged as one of the most effective levers for lowering CO₂ emissions and LC³ is one of the supplementary cementitious materials (SCMs) to achieve this, according to Mpume Mabaso-Mlalazi, research and development manager at Chryso Southern Africa. However, while LC³ offers clear environmental benefits, its successful implementation is far from straightforward, she warns.
Unlike traditional SCMs such as fly ash or slag which are industrial by-products calcined clay is derived from natural deposits which introduce a high degree of variability. “Clays vary considerably in terms of their mineralogy, chemical composition and granular properties. These factors depend on where the clay is sourced and their variability becomes a challenge for cement producers trying to maintain consistency.”
Having presented at the 5th International Conference on Calcined Clays for Sustainable Concrete (ICCCSC 2026) in Cape Town earlier in the year, she says speakers at the event once again emphasised that LC³ was sensitive to raw material variability and early-stage hydration behaviour.
“The primary technical challenge in LC³ adoption lies in managing the inherent variability of calcined clay while maintaining predictable performance in cement and concrete,” she says. “Rheology and water demand are particularly problematic issues as clays are thirsty. Their high demand for water directly affects how the material behaves in both cement and concrete.”
The tension is that, while increased water content may improve workability, it compromises strength and durability. A delicate balance is required which demands precise understanding and control. Compounding this issue is a phenomenon known as polymer intercalation, where clay particles absorb and immobilise admixture molecules particularly superplasticisers thereby reducing their effectiveness.
“Where the clay essentially ‘captures’ the admixture a much higher dosage is required to achieve the same effect. This can increase cost and reduce efficiency.” To address these challenges, Chryso has invested heavily in R&D, building a deep understanding of calcined clay behaviour through global research initiatives dating back to 2019. The company can now characterise clays with precision, enabling targeted solution design.
“While standard techniques such as X-ray diffraction and particle size analysis are widely used, we have developed a proprietary clay test method to assess intercalation risk. This patented method allows us to quantify how strongly a given clay will interact with admixtures; this information is critical for optimising formulation strategies.”
The test evaluates the risk of polymer intercalation, from which can be determined the most suitable chemistry and dosage of superplasticiser – an important aspect of customisation. This capability allows Chryso to move beyond generic solutions toward configuration-specific admixture design.
“We can help customers optimise their mix designs through advanced admixtures,” she says. “Successful LC³ implementation needs more than binder innovation; it depends on mix design flexibility and system-level optimisation.”
This aligns strongly with Chryso’s strengths in hydration control, rheology management and strength development optimisation, as well as adjusting for durability and transport properties. The company can now collaborate with customers on tailored admixture packages that bridge laboratory design and real-world performance, she argues. Given the high water-affinity of clays, controlling water demand is essential. Chryso leverages its expertise in polymer chemistry to design superplasticisers that remain effective even in the presence of reactive clays.
“Our key expertise is understanding how to deal with water in these systems,” Mabaso-Mlalazi notes. “That’s why we say polymer chemistry is central to solving LC³ challenges.”
Optimising rheology is also critical to maintain flowability without compromising strength. Chryso’s tailored admixtures enable improved dispersion and workability even in systems with high clay content. In terms of strength development, Chryso solutions optimise hydration kinetics and particle interactions to support early and long-term strength development. These capabilities include product ranges such as EnviroAdd® for cement and EnviroMix® for concrete, which are specifically designed to address the unique challenges of low-clinker systems.
“We have created entirely new product ranges based on what we’ve learned about clay behaviour. These are not traditional admixtures; they are designed specifically for LC³ configurations.” She points out that durability and long-term performance also remain key concerns in LC³ adoption, with the recent conference highlighting factors such as transport properties, carbonation resistance, chloride ingress and microstructural development.
As clinker content decreases, these properties become more sensitive to mix design and material interactions. Our approach is to integrate durability considerations into the overall optimisation strategy ensuring that performance is not compromised in pursuit of lower carbon. Importantly, Chryso also treats cement and concrete as a connected system rather than isolated components by operating across the full value chain. With its respective solutions for cement and concrete, the company acts as a bridge to ensure that what is produced at the cement plant will perform correctly in the final concrete. This integrated approach is particularly important for LC³ where changes at the binder level can have cascading effects on concrete performance.
Mabaso-Mlalazi concludes that industry is now shifting from research to full-scale deployment of LC³, which demands more support for industrial rollout and application readiness. Chryso is well equipped to provide such support, adding considerable value through its technical assistance during raw material qualification, plant-level optimisation strategies and field support for concrete producers adapting to LC³ mixes.
“As more markets in Africa and beyond push toward decarbonisation, Chryso can play a central role in ensuring LC³ concretes are consistent, durable and application-ready.”
