Spraying Bitumen Emulsion

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• published: 21 Oct 2015
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Road Science Technical Team Manager John Vercoe explains Bitumen Emulsion and the benefits of using this product over conventional Bitumen. By finding a way to adjust the particle sizes of the bitumen emulsion droplets, Road Science has created an emulsion that can be sprayed at 80°C (a significant reduction from the normal operational temperature for hot or cutback bitumen of 180oC). It also cures faster, is more weather-resistant and stores for longer. Health and Safety Emulsions allow the temperature of transported and sprayed bitumen to be below 100°C (typically around 80°C). This keeps people safe throughout every stage of handling the product. New generation emulsions eliminate the risk of explosion as the need for adhesion and ‘cutback’ agents such as kerosene are no longer required. Roading teams are more comfortable using emulsions as they know they can return home without having to deal with fumes and kerosene clouds that hot cutback bitumen creates. The benefits of using a Road Science Emulsion over cutback are not only technical, but social and environmental. An independent study by CarboNZero has revealed new generation emulsions have almost half the carbon footprint of hot or cutback bitumen. The use of emulsion complies with new Health and Safety legislation. This legislation shifts responsibility to the person purchasing products and services making them more liable than ever before. Technical benefits of using Road Science Bitumen Emulsions Road Science bitumen emulsion has a superior thickness to hot or cutback bitumen, giving it a high resistance to flow with less chance of run off and the ability to seal on steep slopes with greater confidence. The ability to spray emulsions in cooler temperatures allows sealing work to start earlier in the season. In damp conditions emulsions adhere to sealing materials better than hot or cutback bitumen. Emulsions can be stored for in excess of three weeks which means weather and operational delays are more easily managed. It is widely understood, accepted and can be demonstrated that emulsion binders provide better adhesion to chip than cutback binders do. This leads to some designers using less binder for emulsion than for the equivalent cutback seal. An emulsion can be defined as a dispersion of small droplets of one liquid in another, it is the process of combining two liquids that cannot be mixed. It is, in essence, the same process by which many foods, including tomato sauce, remain suspended and pourable without the elements separating or settling. Comparing hot or cutback bitumen to bitumen emulsions is like comparing oil based to water based acrylic paints. One is an oil based system and the other a water based system (emulsion). The delivery method to the pavement surface for both products remain the same and over time the final binder on the road returns back to bitumen.