EMBRACING THE BENEFITS OF
HIGH FLOAT EMULSIONS
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SAMI BITUMEN TECHNOLOGIES HAS RECENTLY DEVELOPED SAMIFLOAT, A CATIONIC HIGH-FLOAT THIXOTROPIC SPRAYED SEALING EMULSION. SAMI’S NATIONAL R&D AND INTRO LABORATORY MANAGER KANJANA YINDEE TALKS ABOUT THE PRODUCT’S BENEFITS AND POTENTIAL APPLICATIONS FOR AUSTRALIAN PAVEMENTS.
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espite xx their many environmental and safety Xxx benefits, bitumen emulsions have traditionally not been the preferred method of sprayed sealing for Australian contractors, with hot modified binders currently dominating the field. But SAMI Bitumen Technology’s National R&D and Laboratory Manager Kanjana Yindee believes that could be changing soon. One of the reasons bitumen emulsions have not achieved a significant penetration rate in Australia so far, she observes, is due to lack of confidence among contractors that they can provide the performance requirements. “Unlike other countries, limited amount of emulsion has historically been used in sprayed seals in Australia. As the local industry migrates towards using more emulsion binders, the manufacturers should aim to provide high performing, user-friendly products, and we will need to retrain the crews in the construction practices to deliver high performing sprayed seals. Details such as whether we need to precoat the aggregates or whether we can just wash
them with water are some of the issues to be addressed,” says Yindee. “Using emulsion for sprayed sealing is more environmentally-friendly than using hot unmodified or hot polymer modified binders. The latter options require using a high percentage of cutters, sometimes up to six per cent or more, which is associated with emission of volatile fumes. So, using emulsion fits very well with the industry’s overall direction towards more sustainable sealing,” she adds. To address these and other challenges associated with using conventional emulsions for sprayed sealing, the team at SAMI Bitumen Technologies have come up with an innovative product: a cationic high float rapid-setting emulsion modified with latex, known as SAMIfloat. What makes the high float SAMIfloat binder different, Yindee explains, is its gellike structure of the binder, which offers better aggregate adhesion and prevents emulsion run-off, or bleeding. “Unlike conventional sprayed seal emulsions, after the water evaporates,
SAMIfloat leaves more than just the sprayed seal binder behind,” she says. “The gel structure allows a thicker binder coating on the aggregate particles. This thicker film prevents aggregate stripping and is more resistant to oxidation from exposure to the atmosphere.” The result, Yindee explains, is more durable, better-performing sprayed seals. “The SAMIfloat residue is resistant to flow at high road surface temperatures allowing for a softer bitumen to be used that will resist bleeding at high temperatures. The softer binder also does not become as brittle at low temperatures and resists stone loss. The thixotropic gel structure doesn’t flow at pavement surface temperatures, that’s why they tend to bleed less than other unmodified emulsions or cutbacks,” she says. SAMIFLOAT AND GRADED SEALS The concept of developing a cationic high float emulsion product, Yindee says, initially emerged when Trevor Distin, Colas Australia’s Technical and Marketing Manager, contacted Yindee looking for a cutback-free
The SAMIfloat emulsion is ideal for sprayed sealing applications, as it resists bleeding at high temperatures.
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ROADS DECEMBER APRIL 2021 2021
