SASOBIT An asphalt additive that reduces the viscosity and penetration, while increasing the softening point, of bitumen
With local road infrastructure gradually deteriorating, most bitumen and asphalt customers are likely to consider products, additives and mixes that could significantly extend the life of roads, says petrochemicals major Sasol.
“Road-deterioration challenges could be overcome . . . [using] Sasol’s asphalt additives, such as Sasobit, which offers high resistance to asphalt deformation and, thereby, increases the service life of roads,” says Sasol asphalt additives for sub-Saharan Africa and Latin America performance chemicals sales manager Abraham Aphane.
Sasol’s performance chemicals division aims to showcase the benefits of several of the company’s flagship performance chemi-cals, particularly to new industry players, at this year’s Conference on Asphalt Pavements for Southern Africa, which will take place from August 16 to 19 at Sun City, in the North West.
These chemicals include Sasobit and Sasolwax Flex, which are used as asphalt additives in the road construction industry.
Sasobit is a high molecular-mass synthetic aliphatic hydrocarbon, with a molecular chain length of between C40 and C120. It is produced from natural gas through the Fischer-Tropsch process and, as an asphalt additive, it reduces the viscosity and the penetration and increases the softening point of the bitumen.
By reducing the viscosity of the bitumen at working temperatures, the mixing and construction temperatures of the asphalt can be reduced by between 20 °C and 40 °C, depending on the dosage levels, stresses Aphane.
“Moreover, Sasobit ensures a significant energy cost saving of between 10% and 15% at the premixing plants – an added benefit to industry when considering the cost of energy.”
Aphane adds that Sasobit also enables the significant reduction of fumes emissions, “also making it more pleasant for workers”.
Additional advantages of Sasobit include ease of handling, extended asphalt life through reduced bitumen ageing, reduced compaction effort to reach the required asphalt density, and increased asphalt deformation resistance.
Meanwhile, Sasolwax Flex is a dry blend of Sasobit – styrene-butadiene-styrene (SBS) – and Sasolwax Link TX in an optimised ratio. Aphane notes that this asphalt additive combines the typical benefits offered by Sasobit with balanced viscoelastic binder properties.
Aphane notes that using Sasobit and Sasolwax Flex further provides the opportunity for warm-mix-asphalt technology, thereby increasing the asphalt paving window, particularly in winter, and reducing the energy demand associated with road construction and paving.
He further explains that warm-mix asphalt enables asphalt pavement material producers to reduce the temperatures at which the material is mixed and placed on the road, which, in turn, can result in reduced fuel consumption and greenhouse gases.
Other products that comprise Sasol’s performance chemicals (Sasolwax) offering in the road construction industry include Sasolwax Link TX, a crosslinking agent used to crosslink SBS in bitumen modification; Sasolwax BituGlide, a hydrocarbon oil emulsion used as an asphalt releasing agent and Sasolwax 1655, an enabler for the use of high reclaimed asphalt content in asphalt mixes.
Aphane further notes that the “excellent” global successes achieved with Sasol’s products over the last two decades are appreciated by the industry. Some of the more recent findings will be presented in technical papers by independent research institutes, road construction companies, asphalt manufacturers and bitumen suppliers alike.
“Sasol aims to highlight the results achieved by these products and to harness the message of the derived energy savings,” he says.
Meanwhile, Aphane acknowledges that the recent slowdown in the country’s infrastructure development, including new road construction, has a rippling effect on road construction. Nevertheless, he believes that the whole road construction value chain is improving.
“In the past two months, we have seen several major road construction and rehabilitation projects coming on line, such as the resurfacing of the N1 from Kroonstad to Bloemfontein, both in the Free State, and associated projects, such as the bus rapid transit systems, which are being implemented in Pretoria, in Gauteng, and Rustenburg, in the North West,” says Aphane.
Moreover, the Gauteng provincial government last month launched a project, valued at R295-million, to upgrade the N14 freeway from Krugersdorp to Pretoria.
Engineering News reported last month that the project would aim to not only repair the freeway but also provide the road with a new design life that would enable it to function for an additional 20 years.