Eskom is getting into road construction and maintenance in South Africa, using coal ash from its powerplants to assist with the country’s infrastructure development.
The utility recently completed a new road near one of its stations in Mpumalanga, demonstrating how coal ash can be used as a cost-effective alternative to traditional materials like concrete.
Paving the way
Eskom’s Research, Testing, and Development initiative is currently investigating ways in which it can recycle and re-purpose its growing supply of “legacy ash” – a term used to describe the fly and bottom ash that is produced and dumped by the utility’s coal-fired power stations.
The research division has explored geopolymerization, which is a chemical process that transforms aluminosilicate ash into geopolymer concrete, making it a viable alternative to conventional cement-based concrete for the creation of new road surfaces.
In a recent interview with Newzroom Afrika, an Eskom representative explained that the process involves combining legacy ash with other waste materials from the metal industry, such as aluminium and silicon, to provide strength, creating what is referred to as “Activated Ash.”
This theory was recently put to the test, as Eskom built a new access road near the Kusile Power Station in Mpumalanga using the so-called legacy ash material.
The Kusile West Access Road was created to support the daily passage of 1,200 to 1,600 heavy trucks transporting coal while the plant awaits the completion of a new coal conveyor belt.
Each truck weighs approximately 34 tonnes, illustrating that the ash road is durable enough to support the weight of heavy goods vehicles, and teams will be conducting monthly tests of the surface to examine its longevity.
The new path stretches 759 metres across two sections, and Eskom estimates that it will utilize roughly 2,904 tonnes of ash per kilometre of road going forward.
To put this in perspective, the power company generates 34 million tonnes of coal ash annually, of which only 7% to 10% is repurposed while the remainder is stored in ash disposal facilities.
Coal ash is classified as a Type 3 hazardous material and creates significant environmental and financial liabilities, so the new road initiative can help to drastically reduce the amount of waste that gets dumped.
Additionally, using Activated Ash produces far less carbon dioxide than an equivalent amount of concrete, making it a more sustainable resource for infrastructure development.
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