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

In this regard, the test result data provided in Table 10 reveal the following:
1. Noting that the Ring & Ball test results for the unmodified binders are equivalent
to, or better than the modified binder, and considering the deformation rate
results, it appears that softening point is not a good indicator of high temperature
deformation potential in polymer modified binders;
2. The ZSV results correlate well with the deformation rate test results, suggesting
this may be a preferable method for assessing rutting resistance; and,
3. The improved high temperature susceptibility imparted by polymer modifiers
extends to higher temperatures.
In high temperature applications, Vonk recommends SBS concentrations of at least 5%
to insure that the polymer phase forms a resilient and continuous network throughout
the mixture (76). As has been suggested previously, it is this network that ultimately
imparts the elastic response desired to resist permanent forms of deformation (4, 12,
and 14). Vonk’s work focuses primarily on the modification of asphalt binder cements,
and as such, the implications for desirable polymer concentrations in soap pre-batched
or co-milled emulsions are uncertain. However, this research undoubtedly has valid
implications in emulsion applications where the bitumen is subjected to direct forms of
modification (i.e., pre-blending) prior to emulsification (one example would be the use of
SBS). Moreover, the interplay between polymer concentration, ZSV, and the
measurement of high temperature deformation potential, have significance in emulsion
treatments such as microsurfacing which are commonly used to fill wheel rut paths.
Vonk (2004) and Demazes et al (2000) note that the measurement of ZSV in modified
binders containing a substantial polymer network is inaccurate because one
requirement of this test is the development of steady-state viscosity under constant
stress – a state which the elastic components of such a mix cannot attain (i.e., viscosity
appears to grow infinitely) (62, 76). Although Desmazes offers an extended ZSV testing
protocol that may yield improved accuracy and reliability, Vonk suggests that this
phenomenon could be utilized to evaluate proper polymer dosing. More specifically, as
ZSV begins to trend toward infinity, this provides a solid indication that a pervasive, 3-
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