Modern Quarrying

High quality dolerite aggregate from B&E International’s Howards Quarry at eMalahleni is keeping Much Asphalt’s nearby static plant well stocked to produce asphalt for the N4 highway project and developments as far as Nelspruit over 200 km east.

Dolerite Howards QuarryAs one of Southern Africa’s largest commercial suppliers of hot and cold asphalt products, Much Asphalt keeps a close eye on standards and specifications of both its ingredients and its final product, according to its eMalahleni branch manager Gavin Roos.

“The quality of stone we use is an important aspect of asphalt production, as it gives the road its strength. Dolerite is particularly good for asphalt because it’s a strong stone and it doesn’t crush under weight, so it is able to withstand the heavy truck traffic that our highways must endure without deteriorating,” he says.

Before making its choice of aggregate supply, Much Asphalt takes samples from source quarries and sends them for specialised laboratory testing.

“This allows us to establish that the key aspects like fraction sizes, aggregate crushing value (ACV) and moisture content are suitable for our use and is in line with Committee of Land Transport Officials (Colto) standards,” Roos explains. “Permeability and adhesion properties are also important, as we must ensure that the bitumen is going to adhere fully to the stone, or this leads to stripping on the road where stones begin to come loose.”

At plant level, the focus is then on maintaining a consistent grading of the stone ensuring that every load that is delivered is up to standard. Howards Quarry trucks in supplies daily so that Much Asphalt always has substantial stockpiles; this helps in retaining a consistency of aggregate, which is blended on-site by means of a pay-loader.

Good dolerite sources are being systematically depleted and quality aggregates produced from this igneous rock have become scarce, according to Howards Quarry manager Andre Kamfer. “The result is often that quality materials have to be hauled over ever-increasing distances, adding to the overall cost of a project.

Fortunately in this case, the Much Asphalt facility at eMalahleni – one of 15 static plants that the company operates around South Africa – is just a few kilometres down the N4 highway from the quarry.

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