State-owned power utility Eskom has showcased how it incorporates recycled legacy coal ash into road construction at its Kusile power station, in Mpumalanga.

This first-in-country initiative was launched by Eskom Rotek Industries, which aims to enhance the group’s operational efficiency and sustainability practices.

The utility has built a new access road stretching 759 m across two sections. The road accommodates the daily passage of between 1 200 and 1 600 trucks, each weighing 34 t, as Eskom works to build a new coal conveyor belt.

As part of its research, testing and development work, Eskom is using about 2 900 t of legacy coal ash per kilometre of road, adhering to conventional road-building standards.

By replacing traditional cement with recycled ash, the project contributes to a reduction in CO₂ emissions, since every tonne of cement saved reduces emissions.

The road construction involves geopolymerisation, which is a chemical process that transforms aluminosilicate ash into geopolymer concrete. This innovative material serves as a sustainable and durable alternative to traditional cement.

By applying this technology to the Kusile West Access Road, Eskom is advancing sustainable infrastructure development in South Africa.

Legacy ash, a by-product of coal-fired power generation, comprises weathered fly and bottom ash. Its application in road construction not only decreases reliance on conventional cement but also mitigates carbon emissions, marking a significant milestone in Eskom’s sustainability journey.

This approach opens new revenue streams for Eskom, while alleviating the costs associated with legacy ash management.

Eskom’s ash beneficiation activity is helping the provincial government to foster job creation and stimulate regional growth.

From a legal point of view, Eskom is authorised to use coal ash in various applications, including road construction and brick manufacturing, which is yielding significant economic and environmental advantages.

Currently, Eskom produces about 34-million tonnes of coal ash every year, of which only 7% to 10% is beneficiated, with the remainder stored in ash disposal facilities. Classified as Type 3 hazardous waste, coal ash management incurs significant environmental and financial liabilities.

The innovative use of legacy ash minimises ash volumes in dumps, thereby reducing both environmental impact and cost.

Eskom is also actively working to expand the commercial use of coal ash generated during electricity production.

About 10% of the ash from Eskom's coal-fired power stations is now being repurposed by various industries.

Finding additional applications for coal ash not only reduces the environmental footprint of ash disposal facilities but also minimises fugitive dust. As Eskom seeks new uses for fine fly ash from its newer power stations, the potential environmental and socioeconomic benefits continue to grow.

“This builds on the legacy of earlier power station closures that repurposed clinker ash for bricks to construct many homes; these dumps are now almost depleted.

“This project represents a significant leap forward in Eskom as it transitions to a sustainable organisation,” Eskom concludes.