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.
In response to an 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 AECI SprayPave director Eddie Jansen van Vuuren. “The 10/20 bitumen product conforms to the penetration grade bitumen specification.”
10/20 bitumen is commonly used in the production of high modulus asphalt (EME), which is well suited to high 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, Jonathan Bell, AECI SprayPave’s Cape Town technical manager, points out.
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 SABS certified 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 successful production of 50/70,” he says.
“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 says throughputs of 30 to 60 tons per day can be achieved when converting from conventional 70/100 to 10/20.
Herman Marais, technical director at AECI Much Asphalt, AECI SprayPave’s parent company, adds that demand for high modulus asphalt incorporating 10/20 penetration grade bitumen is growing in South Africa. “The technology is proving valuable for high traffic load routes. Demand is anticipated to increase exponentially when the major N3 freeway contracts are awarded, as several of these projects will use high modulus asphalt.”