This paper provides an overview of current sealing practice in Australia, including priming and primersealing, types of sprayed seals and their selection, the current national seal design procedure, and plant and field procedures commonly used. Asphalt is the preferred treatment in urban areas, on heavily trafficked urban freeways and arterial roads, and areas of high traffic stresses. Sprayed sealing is the surfacing treatment commonly used in rural areas, and is the most economic type of surfacing for the rural road network. It is also used for specific applications, such as strain alleviating membranes to minimise crack reflection, on all classes of roads. The main type of sprayed seal is a single layer of binder covered with a single layer of aggregate (single/single seal) used on both new and resurfacing work. On new work the pavement material is usually locally available gravel, often of marginal quality, with better quality crushed rock material used on the more heavily trafficked roads. Sprayed seal design as referred to in this paper is the design of rates of application of binder and aggregate spread rates. The continued success of sprayed seals as a surfacing requires care in choosing an appropriate treatment for the conditions, a high standard of preparation of pavements and attention to detail. To successfully select and design a sprayed seal requires a mix of engineering and practical know how. (a).
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