Eskom’s plan for South Africa’s broken roads

South Africa, already facing steep expenses to enhance its port, rail, and electricity infrastructure, now faces an extra R307 billion cost to repair and upgrade its vast network of national roads.

On 10 September, Transport Minister Barbara Creecy outlined that the South African National Roads Agency (Sanral) requires this amount for the design and construction work on 1,437 projects.

However, state-owned power utility Eskom believes that it has a solution that could significantly slash this price: legacy ash.

Legacy ash, a by-product of coal-fired power generation, comprises weathered fly and bottom ash.

In a first for South Africa, Eskom launched a pilot project using recycled legacy coal ash in road construction at its Kusile Power Station in Mpumalanga.

Using this ash, Eskom has thus far built a new access road, stretching 759 meters across two sections.

This heavy-duty road is designed to support the daily passage of 1,200 to 1,600 trucks, each weighing ~34 tonnes, during the construction of a new coal conveyor belt.

Currently, Eskom produces around 34 million tonnes of coal ash annually, of which only 7% to 10% is beneficiated, with the remainder stored in ash disposal facilities.

As a result, Eskom’s Research Division explored geopolymerization, a chemical process that transforms aluminosilicate ash into geopolymer concrete, which serves as “a sustainable and durable alternative” to traditional cement.

“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,” said the power utility.

Classified as Type 3 hazardous waste, coal ash management incurs significant environmental and financial liabilities.

The effort to find additional uses for coal ash aims to decrease the environmental impact of disposal facilities and reduce fugitive dust.

As part of its Research, Testing and Development initiative, Eskom is utilising around 2 904 tonnes of legacy coal ash per kilometre of road.

“The innovative use of legacy ash minimises ash volumes in dumps, thereby reducing both environmental impacts and costs,” said Eskom.

By replacing traditional cement with recycled ash, the project contributes to a reduction in carbon dioxide emissions—every tonne of cement avoided equates to less carbon dioxide (CO2) produced.

“This approach opens new revenue streams for Eskom while alleviating the costs associated with legacy ash management,” as replacing cement with ash allows Eskom to earn carbon credits, added the utility.

Eskom, in collaboration with the Mpumalanga government, is currently implementing ash beneficiation initiatives aimed at job creation and regional economic growth.

The initiative utilizes coal ash under Waste Exclusion Regulations for applications such as road construction and brick manufacturing, offering both economic and environmental benefits locally.

Currently, around 10% of ash from Eskom’s coal-fired power stations is being repurposed by various industries.

Eskom said that it is now focusing on expanding the commercial utilisation of fine fly ash from its newer power stations, enhancing both environmental and socio-economic outcomes, building on previous initiatives that repurposed clinker ash for housing, with those dumps now nearly depleted.

The legacy ash road is not the first experiment that has been conducted in South Africa with alternative road materials.

It’s been five years since the first plastic road was laid down in Jeffreys Bay, and the latest update of the road indicates it lasts longer than traditional tar—showing massive potential for the future of road construction in South Africa.

In 2019, the Kouga Municipality, in partnership with Scottish firm MacRebur and local civil engineering experts, embarked on this innovative pilot project, which has since shown significant promise.

Five years after its completion, the plastic-infused road has demonstrated remarkable durability compared to traditional tar roads.

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