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

Gerard et al (2001) have compared the performance of plastomer-modified, elastomermodified,
and unmodified asphalt binders with respect to fracture toughness and crack
propagation characteristics at low (i.e., -20º C.) temperatures (33). It has been
demonstrated that generally, the use of polymer modifiers increases the facture
toughness of asphalt binders. However, SB- and SBS-based modifiers exhibited
substantially better fracture toughness than did comparable EVA and EMA modified
mixtures owing to respective differences in crack propagation behavior as shown in
Figure 8. More specifically, Gerard et al report that EVA and EMA modified mixes
propagate cracks at the interface between the polymer and asphalt phases, leading to
brittle behavior and stone pull-out. In contrast, the continuous polymer network formed
in binders modified with elastomeric additives tends to stretch as the energy from the
crack propagates through the polymer domains – impeding crack development in a
phenomenon referred to as “crack-bridging” (33). In summation, the results suggest
that SB and SBS modifiers provide for diminished low temperature susceptibilities as
compared to similar EVA and EMA mixtures.
Neat Asphalt
EVA 18 (6%)
SBS (4%, 18% PS)
EMA 28 (6%)
EVA 28 (6%)
SBS (4%, 28% PS)
SBS (4%, 28% PS)
SB (4%, 12% PS)
Styrelf (4%)
0 20 40 60 80 100 120
KI c
Figure 8: Fracture Toughness at -20º C. (33)
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