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SAMISEAL M500 CONVENTIONAL BITUMEN TENDS TO BECOME BRITTLE AT LOW AMBIENT TEMPERATURES AND SOFT AT HIGH ROAD SURFACE TEMPERATURES. SAMI BITUMEN’S SAMISEAL M500 BINDER SOLVES THIS ISSUE IN SPRAYED SEALING APPLICATIONS, HELPING RETAIN THE AGGREGATE BETTER. BITUMEN TECHNICAL MANAGER GERARD GNANASEELAN EXPLAINS.
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emperatures tend to vary greatly in parts of Australia, particularly in the sub-tropical regions of north Queensland and the Northern Territory and across the Australian Outback. As such, conventional, non-modified bitumen is not always the best option for sprayed sealing in these regions. Bleeding or flushing seen with sprayed seals is a common symptom that shows the bitumen has become soft under the high temperature and is ‘pumped’ above the cover aggregate under the traffic load. The consequence is the formation of a slick membrane of bitumen on the road that can be picked up by tyres and constitutes a traffic hazard due to reduced skid resistance. Sprayed seals becoming brittle and cracks in cold temperature is another hazardous outcome if the binder lacks flexibility. Here too, loss of aggregate may lead to the road becoming slippery and resulting in accidents. The SAMIseal Multigrade M500 bitumen was developed by SAMI Bitumen Technologies specifically for such applications. SAMIseal M500 is a grade of bitumen used for sprayed sealing applications and available on request for contractors looking for improved temperature susceptibility and superior performance compared to standard grade bitumen. “This is a niche product in our portfolio,” says Gnanaseelan. “The SAMIseal M500 is characterised by low temperature susceptibility. It remains stable over a wide range of ambient temperatures, which means it’s flexible at low temperatures and stiffer at high temperatures. According to Phil Stevens, SAMI Bitumen’s State Manager for Queensland, the SAMIseal M500 bitumen is manufactured from the same sources as conventional bitumen, but
The SAMIseal M500 is a bitumen used for sprayed sealing applications.
requires further processing to reduce its temperature susceptibility. “We manufacture the SAMIseal M500 bitumen by compositionally adjusting the bitumen feed stock and processing it in an oxidiser. This allows the product to impart lower temperature susceptibility and superior adhesion characteristics compared to conventional sealing grade binders,” says Stevens. Both hot and arid climates and cold and moist climates can benefit from the use of the SAMIseal M500 binder, he adds. “A bitumen like the SAMIseal M500 has the ability to remain stable under high road surface temperatures, where bitumen has a
tendency to get soft, and also at night time and in cooler climates, it has the ability to remain resilient and not crack,” he says. “That’s the beauty of this product: it is tough in hot temperature and flexible in cold temperature.” SAMISEAL M500 DELIVERS Being a premium product in SAMI’s portfolio, the SAMIseal M500 has already received interest from major contarctors, according to Stevens. “SAMIseal M500 is a premium product, so naturally it comes with a premium value compared to conventional bitumen. But the fact that major contractors still have a high roadsonline.com.au
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