What is the key advantage of PMB over conventional bitumen?

PMB has superior elasticity and a wider useful temperature range, providing better resistance to permanent deformation (rutting) at high temperatures and thermal cracking at low temperatures.

What does PMB 70 mean?

It is a grade of PMB with a penetration value in the range of 60-80 at 25°C. The number '70' is the approximate mid-point of this penetration range (Clause 4 & Table 1).

What is the minimum elastic recovery for PMB 40?

The minimum elastic recovery at 15°C for PMB 40 grade is 70% (Table 1).

How do I check for storage stability of PMB?

Perform the separation test as per Annex A. The difference in softening point between the top and bottom samples after conditioning should not exceed 3°C (Table 1).

IS 15462

: 2019

Polymer Modified Bitumen (PMB) - Specification

CurrentFrequently UsedSpecificationTransportation · Roads and Pavement

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This standard provides the specifications for Polymer Modified Bitumen (PMB), a special binder used for constructing durable and high-performance pavements. It classifies PMB into different grades based on performance parameters and defines the required physical and rheological properties like elasticity, viscosity, and temperature stability to resist pavement distresses like rutting and cracking.

Specifies requirements for various grades of polymer modified bitumen (PMB) used for flexible pavement construction to enhance performance.

Quick Reference Values

Min Softening Point for PMB 4060 °C

Min Elastic Recovery at 15°C for PMB 4070 %

Penetration Value at 25°C for PMB 7060-80 (0.1 mm)

Max Separation Difference in Softening Point3 °C

Min Flash Point (Cleveland Open Cup)220 °C

Complex Modulus (G*/sin δ) at 76°C for Grade PMB 76-10min 1.0 kPa

Practical Notes

The 'Separation Difference' test (Annex A) is critical to ensure the polymer and bitumen have blended homogenously and will not separate during hot storage, which is a common site issue.

Grade selection (e.g., PMB 40, PMB 70, or performance grades like PMB 76-10) is crucial and should be based on the project's climate and traffic loads as guided by Annex D.

PMB requires higher mixing and compaction temperatures than conventional bitumen; always follow the manufacturer's specific recommendations to ensure proper workability and performance.