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Typical asphalt rubber blending plant site
Are all asphalt rubber binders created alike? The correct answer is definitely no!
In many asphaltic compositions it is particularly desirable to have a high degree of flexibility combined with toughness and durability. High ductility is especially desirable for meeting the specifications demanded in industrial asphalts used in materials such as roofing shingles, built-up roofs, canal linings, pipe coatings, etc. Additionally, because of the temperature stress to which these asphalts may be subjected, it is desirable to have an asphalt which can withstand low temperatures over time without developing significant brittleness and not flow at high temperatures. The parameters of these conditions may also be expressed as the well known physical properties of asphalt: viscosity, penetration and softening point.
Ethylene polymers are characterized by a low polarity and low reactivity plastomers. They are like waxes in this respect, having a low dielectric constant and being soluble in hot oils, hot wax and hot hydrocarbons. They also are well known to be inert. For some uses it is desirable to modify the ethylene polymers to make them flexible, to impart more polarity to the polymers, and to be able to use them in reaction with other resins. The basic process used to modify asphalt cement with polymers (primarily SBS polymer) is to introduce both liquid asphalt cement and polymer pellets into a heated mixing (or wetting) tank, where they are mixed and the polymer is softened.
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Conventional versus Modified Asphalts