Question

Use a ven-diagram to compare and contrast asphalt cutbacks and emulsions. Be sure to address what they’re made of, how they work, the types of applications they’re used for, safety, environmental concerns, and cost. Section 9.1, 9.72 and 9.73 in your book may be helpful for this question.

Cutbacks and Emulsions

Answer 1

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• Asphalt :

Generally, asphalt is less expensive up front to install. Although asphalt is better suited for colder temperatures, it can handle weather extremes because it is made with tar, which is flexible in nature. This makes it possible for asphalt to expand and contract with the heat and cold. In very extreme heat, however, the oily finish on asphalt may be tracked into your home or business. Asphalt has a lifetime of around 20 years when properly maintained. If cracks or holes do appear over time, they can be repaired without too much trouble and the patching will blend more easily with the existing asphalt. As far as the look of asphalt goes, it will likely have rough edges and there are limited options for color and texture.

Vs

• Cutbacks :

Cutback is Low Viscosity Bitumen.

• A cutback asphalt is simply a combination of asphalt cement and petroleum solvent. Like emulsions, cutbacks are used because they reduce asphalt viscosity for lower temperature uses (tack coats, fog seals, slurry seals, stabilization material). Similar to emulsified asphalts, after a cutback asphalt is applied the petroleum solvent evaporates leaving behind asphalt cement residue on the surface to which it was applied. A cutback asphalt is said to “cure” as the petroleum solvent evaporates away. The use of cutback asphalts is decreasing because of (Roberts et al., 1996[1]):

• Environmental regulations. Cutback asphalts contain volatile chemicals that evaporate into the atmosphere. Emulsified asphalts evaporate water into the atmosphere.
• Loss of high energy products. The petroleum solvents used require higher amounts of energy to manufacture and are expensive compared to the water and emulsifying agents used in emulsified asphalts.

• In many places, cutback asphalt use is restricted to patching materials for use in cold weather.

Vs

• Emulsions :

Bitumen emulsion is a mixture of fine droplets of bitumen and water. But as the bitumen is a petroleum product it doesn’t mix with water and as it is sticky in nature, it doesn’t easily gets disintegrated into fine droplets. To overcome this problem an emulsifier is used.

Emulsifier can be defined as a surface-active agent. Emulsifier keeps the bitumen in its fine droplet state by disallowing it to mix with other droplets. As the droplets are very fine they suspend in water.

Advantages and Uses of Bitumen Emulsions are:

• Bitumen emulsion are used extensively in bituminous road construction. Other than this they are used for maintenance and repair work.
• Emulsions can be used in wet weather even if it is raining.
• Is ecofriendly as it is water based.
• Bitumen emulation is also used in soil stabilization in desert areas.
• It doesn’t need extra heat while placing.
• There is no wastage in placing and laying of bitumen.
• They possess anti-stripping properties.

Limitations of Bitumen Emulsion :

• Storage time of bitumen emulsion ranges from few days to 6 months depending upon the percentage of Bitumen added while production.
• Setting time may vary due to temperature, wind and type of emulsion.
• Not a single type of bitumen emulsion can be used for all works it depends upon the aggregate type setting time nature of work etc.

Venn Diagram :-----

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