Phase behaviour study of epoxy asphalt binders with differential scanning calorimetry

The glass transition parameters are used to study the miscibility, or lack of it, in polymer modified asphalt binders. In this study, a
quantitative assessment of the contribution of thermodynamics of mixing to glass transition was conducted in a differential scanning
calorimetry for four asphalt binders modified with an elastomeric epoxy system. Especially, the values of heat capacity (Cp)
and subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the
entropic changes. Emphasis was also given on examining the enthalpy of mixing as a function of the composition of epoxy asphalt
binders during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations
of Tg,mix obtained from the ideal mixing rule, or ΔT_(g,mix), led to negative values of the entropy of mixing (ΔS_mix^c),
dictating the presence of internal repulsive forces between the asphalt and epoxy components. The soft in properties and sol type
base binders are also associated with epoxy asphalt binders of low ΔT_(g,mix) values. Overall, the incorporation of the epoxy system
in asphalt binders increases the Tg and decreases the amount of ΔS_mix^c, and such performance imposes the formation of
phase‐separated binders.