Meeting demand for high grade bitumen

AECI SprayPave is now able to offer the asphalt industry scarce 10/20 penetration-grade bitumen using unique technology that enables the production of specialist bitumen products. It is a major breakthrough that supports growth in the local roads sector going into 2021.

Responding to the ongoing bitumen shortage in South Africa, the company acquired a multistage bitumen converter from Technix Industries in New Zealand in 2015 – only the second to be commissioned worldwide. The technology enables AECI SprayPave to achieve predictable and repeatable conversion of penetration-grade bitumen available from South African refineries to grades that are both lower in penetration and higher in softening point than the feedstock bitumen.

“We are very excited to be able to add 10/20 bitumen, which is currently in short supply, to our offering,” says Eddie Jansen van Vuuren, director, AECI SprayPave. “The 10/20 bitumen product conforms to the penetration-grade bitumen specification.”

This 10/20 bitumen is commonly used in the production of high modulus asphalt (EME), which is well suited to highly trafficked roads likely to suffer significant fatigue and stress. Currently, this grade of bitumen is only supplied by one South African refinery.

Other local refineries have not been able to produce 10/20 bitumen due to higher demand for other ‘normal’ grades and difficulty in meeting the required specifications. Unforeseen breakdowns and scheduled shutdowns at refineries add to the problem, points out Jonathan Bell, technical manager: Cape Town, AECI SprayPave.

The multistage bitumen converter uses pressure, heat and air to precisely convert bituminous refinery feedstocks into high grade bitumen. The softness, penetration index and physical properties of the bitumen can be changed to meet exact design specifications.

The controlled processes in a bitumen converter make it possible to rearrange chemical structures to create asphaltenes. The gentle process and highly efficient addition of air, and therefore oxygen (air rectification), preserve the highly polar aromatic/resin fraction and minimise coke build-up.

In addition to the 10/20 product, the current bitumen line-up offered by AECI SprayPave includes 70/100, 50/70 and 35/50. “The converter has enabled us to deliver SABScertified 50/70 bitumen to the Western Cape since it became fully operational three years ago, with steady expansion of the product range since,” explains Bell.

The value of this technology to the local asphalt sector was highlighted when only soft-grade bitumen was available locally and the converter was able to overcome this shortfall through the successful production of 50/70.

“Our technical relationship with the plant manufacturer, Technix Industries, remains strong with a high level of collaboration to deliver value to Southern African customers,” Bell continues, adding that throughputs of 30 to 60 tonnes per day can be achieved when converting from conventional 70/100 to 10/20.

Herman Marais, technical director, AECI Much Asphalt (AECI SprayPave’s parent company), says the demand for EME incorporating 10/20 penetration-grade bitumen is growing in South Africa, where the technology is proving valuable for hightraffic-load routes.

Marais adds: “Demand is anticipated to increase exponentially when the major N3 freeway contracts are awarded, as several of these projects will use EME.”