Illite fantastic: research points the way for cheap, low-emission cement substitute 

Researchers at RMIT University say that a new method to process a clay type into a low-carbon substitute for cement in concrete could prove “economically and environmentally scalable”.

According to a statement from the university on Thursday, the team has demonstrated a way to turn cheap and abundant illite clay with low-grade kaolinite clay into a material able to replace a portion of cement.

Cement is a high contributor to industrial greenhouse gases, though previous partial substitutes have been based on high-grade kaolin clay, which is also in industrial demand for products including ceramics and paints.

The new research – published in Construction and Building Materials (linked) – articulates a new way of combining equal parts illite and kaolin, with the mixture heated to 600 Celsius. It was able to replace 20 per cent of cement in the mix and provide strength and durability benefits, as well as holding “more water in a chemically stable form,” according to RMIT.

Project lead Dr Chamila Gunasekara explained: “Porosity is reduced significantly by 41 [per cent], with its compressive strength increased by 15  [per cent], where changes in the way iron compounds formed help create a tighter and more compact internal structure.”

Lead author on the paper, Dr Roshan Jayathilakage, added that there were energy efficiency benefits as well.

“Since raw materials are processed together, it streamlines industrial operations and lowers fuel use compared to multiple calcination steps,” Jayathilakage said. 

“This makes the method not only technically sound but also economically and environmentally scalable.”  

The research also made use of a new computational tool for concrete analysis, developed in partnership with Hokkaido University, Japan, and was supported by the ARC Industrial Transformation Research Hub for Transformation of Reclaimed Waste Resources to Engineered Materials and Solutions for a Circular Economy (TREMS). 

Picture: supplied

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