Ready access to deposits of clay gives local communities across Africa the opportunity to produce limestone calcined clay cement (LC³), notes construction chemicals solutions company Chryso Southern Africa. The company says it is supporting this drive with both research and technical support, helping to find innovative solutions to the challenges posed by clay variability.

While South Africa has access to traditional supplementary cementitious materials (SCMs) like fly ash and slag, most African countries need to rely on natural clay deposits to reduce the clinker in cement, says Chryso Southern Africa research and development manager Mpume Mabaso-Mlalazi.

“LC³ has the potential to transform cement production across Africa. However, this requires that we manage the variability and performance of clay holistically - from raw material selection through to final concrete,” notes Mabaso-Mlalazi.

Chryso has analysed over 30 calcined clays to characterise variability in mineralogy, fineness, reactivity and water demand. The company has developed advanced testing methodologies, including a proprietary clay test to assess polymer intercalation and its impact on admixture efficiency.

“Clays have a high affinity for water but we don’t want excess water in concrete because it compromises strength,” she explains. “Managing that balance therefore becomes critical to the application and scalability of LC³.”

Mabaso-Mlalazi explains that this challenge is closely linked to rheology, or how the material flows, and ultimately impacts both workability and strength development. In addition, interactions between clay particles and chemical admixtures–particularly superplasticisers, can reduce admixture efficiency.

The company designs tailored polymer chemistries and specialised product ranges engineered to stabilise performance, control rheology and optimise strength development. It aims to link laboratory research to industrial application, enabling customised, cost-effective solutions that support consistent, scalable adoption of LC³ across diverse raw material conditions. The increased use of lower-carbon LC³ supports the cement industry’s move towards decarbonising production by reducing the proportion of carbon-intensive clinker in cement.

By addressing the technical complexities of LC³ – particularly its variability, rheology and admixture interaction – the company says it is enabling producers to adopt low clinker systems.

“By doing this, Chryso is not only supporting decarbonisation targets, but also helping to build a more resilient and sustainable construction ecosystem for Africa,” Mabaso-Mlalazi says. “We make the technology easier to use, more reliable and more affordable, which will ultimately enable the scaling up of LC³.”