SINCE the Carbon Tax Act came into effect in 2019, there has been a drive towards reducing emissions in almost every sector, including the road construction industry.
That’s according to Wynand Nortjè, Technical Manager at Shisalanga Construction, who said the KwaZulu-Natal-based company had gained a reputation for developing environmentally sustainable asphalt alternatives.
One such product is Warm Mix Asphalt (WMA). This technology allows for standard Hot Mix Asphalt (HMA) to be paved at much lower temperatures. For asphalt to be classified as WMA, the product must be functional at temperatures between 20-30 degrees lower than standard varieties.
Nortjè said the company’s Cliffdale site had been at the centre of several innovations, including all the first development in South Africa for WMA, EME and Recycled Asphalt.
“When we started producing WMA in the late 2000s, we always said it should give equal or better properties than regular asphalt mixes. Since then, standards have not been amended. We still adhere to these strict specifications to ensure a quality product.”
Nortjè said the main advantage of WMA is its ability to be paved at lower temperatures. Given that WMA can be compacted at temperatures between 80-100 degrees, this technology significantly extends the paving window.
The knock-on effects of a slower cooling rate give rise to a number of additional benefits. Less energy is required to heat the mix which reduces overall carbon emissions and in turn decreases the cost of production. It allows for the reduction of compactive effort which reduces carbon emissions from rollers.
“With the new Carbon Tax Act coming into effect, there’ll be a big drive towards WMA. The product is also beneficial for our workers. It’s not as hot so emissions are reduced. It’s safer to work alongside when paving.”
WMA can also be hauled longer distances than regular asphalt. Nortjè said the company had successfully transported WMA over a five-hour drive to Sani Pass in the middle of winter where it was used to pave the road with no issues.
“We haven’t had any failures so we know it can handle extreme traffic conditions. It’s performing exceptionally well for the work we’ve done up to date.”