Using Polymer Modified Asphalt Emulsions in Surface Treatments A ...

molecular weights ranging up to 100,000. The adhesion of asphalt to mineral aggregate
particles is also thought to depend on the polar attraction between asphalt particles and
the negatively charged surfaces of most aggregates. Although asphalt is not a polymer
in the strict sense of the word, it is regarded as a thermoplastic material because it
becomes soft when heated and hardens upon cooling. Within a certain temperature
range, asphalts also exhibit modest viscoelastic properties which can be improved upon
via the addition of polymer modifiers.
2.1.4 Polymer Modified Asphalt (PMA)
In general terms, the addition of polymers to asphalt binders results in the modification
of certain key physical properties including the:
• Elasticity;
• Tensile Strength;
• High and Low Temperature Susceptibilities;
• Viscosity; and,
• Adhesion and Cohesion.
Depending upon the form of modification desired, improvements in pavement longevity
can be achieved through the reduction of fatigue and thermal cracking, decreased high
temperature susceptibility (e.g., rutting and shoving), and enhanced aggregate retention
in applications such as chip seals. Polymer modifiers are utilized to extend the lower
and/or upper effective temperature operating ranges of pavements, and to add elastic
components that allow it to recover from loading stress.
A variety of testing techniques and equipment are available which may be used to
evaluate and quantify the performance characteristics of polymer modified binders and
emulsion residues. A few of the most common of these include:
• Dynamic Shear Rheometer (DSR) – Used to measure the shear modulus
(resistance and phase angle) of asphalt within intermediate to high operational
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