Polymer modified bitumen (PMB) is bitumen combined with one or more polymer materials. This modification is done with the aim of enhancing the mechanical properties of the bitumen material. Polymer modified bitumen is typically used on road pavements, particularly those that are intended to withstand heavy-duty traffic and extreme weather conditions. This material is also used as a sealant in residential roofing applications. PMB is typically made by combining bitumen with a styrene-butadiene-styrene (SBS) copolymer. The addition of the polymer makes the bitumen more elastomeric in nature. Some of the desirable properties of polymer modified bitumen include improved strength, cohesiveness and resistance to fatigue and deformation. PMB also possesses less temperature sensitivity than plain bitumen. This is particularly crucial for pavement applications because the material will not flow or become soft in high temperatures while it maintains its workability and flexibility in colder temperatures. Styrene-butadiene styrene (SBS), which acts as a binder modification agent, is known to increase the longevity of pavements that are subjected to a range of onerous loading on a daily basis including high traffic loading and high thermal stresses. Other benefits of PMB when used in pavement applications include:
Stronger road with increased stability and greater rigidity.
Better resistant towards rainwater and water stagnation.
Better resistance to permanent deformation
Reduction in pores in aggregate and hence less rutting and ravelling.
Much higher durability
|Characteristics||Grade & Requirements|
|Penetration at 25℃, 0.1 mm, 100 g, 5 s.||90 to 150||50 to 90||30 to 50|
|Softening point (R&B), ℃, Min||50||55||60|
|FRAASS breaking point1), ℃, Max||-20||-16||-12|
|Flash point, COC, ℃, Min||220||220||220|
|Elastic recovery of half thread in ductilimeter at 15 ℃, percent, Min||70||70||70|
|Complex modulus as (G*/ sin δ as Min 1.0 kPa at 10 rad/s, at temperature ℃)||52||58||70|
|Separation, difference in softening point (R&B), ℃, Max||3||3||3|
|Viscosity at 150℃, Poise||1-3||2-6||3-9|
|Thin film oven test and tests on residue:|
|a) Loss in mass, percent, Max||1.0||1.0||1.0|
|b) Increase in softening point, ℃, Max||7||6||5>|
|c) Reduction in penetration of residue, at 25℃, percent, Max||35||35||35|
|d) Elastic recovery of half thread in ductilimeter at 25 ℃, percent, Min||50||50||50|
|OR Complex modulus as (G*/ sin δ as Min 2.2 kPa at 10 rad/s, at temperature ℃)||52||58||70|