Characteristic properties of modified bitumen and asphalts with thermoplastic polymers

1 Characteristic properties of modified bitumen and asphalts with thermoplastic polymers 

Some of the characteristic properties of thermoplastic polymers are modified when they are added to bitumen. Penetration decreases and softening point increases in particular. These changes indicate that the bitumen becomes harder and less susceptible to temperature variations. Additionally, bitumen s binding ability increases. However, the Fraass breaking point and bitumen elasticity did not significantly improve (Brule and Lebourlot 1993). 

The use of modified bitumen thermoplastic polymers in asphalts significantly increases asphalts dynamic and static stiffness modulus. 

Early investigation on the effect of polymers on rolled asphalt surfacing found that the most effective and simplest polymer to use was the EVA copolymer (Denning and Carswell 1981a). 

However, it does not improve the elastic behaviour of the asphalt (bituminous mixture). Thus, asphalts with thermoplastic polymer-modified bitumen present good resistance to deformation at high ambient temperatures, but generally their fatigue cracking resistance is similar to or even less than that of asphalts with unmodified bitumen. 

---