Production of hot asphalt mixes with Polymer modified Bitumen (PMB) is mandatory for enhancing the performance of bitumen used in road, runway and racetrack applications both by improving life expectancy and reducing maintenance levels.
There are 4 important issues for good quality PMB:
Bitumen quality, polymer compatibility (the most used polymer is SBS), mill performance (a high quality mill with high power is fundamental to grant the perfect blending of polymer and bitumen) and good agitation of the final product (which is guaranteed by two agitators in each tank).
The plant is specially designed for polymer modification of bitumen with a capacity up to 40ton/h (theoretical capacity, with 5% SBS granular polymer and bitumen temperature at 180°C) and is fitted into a containerized body for stronger structure and easy transportation.
It is very flexible and can be adapted to any jobsite thanks to its special lay-out. The batch production can vary from 1 to 6 tons, and the number of passes through the mill can vary, depending on the percentage of polymer required to modify the bitumen.
The method for establishing whether or not the polymer has been completely dissolved is the ‘stretched film’ test: un-dissolved/swollen particles appear as dark spots when a thin film of the blend is viewed with transmitting light.
The polymer has dissolved completely when there are no more physical particles of polymer present in the blend. The time required depends on the efficiency of the previous stages, the chosen bitumen and the chosen polymer grade, but is usually independent of the batch size.
The above method gives a certain indication of the results, but to be able to determine the exact mixing time, and the number of passages required through the mill, further lab testing is required, such as dynamic viscosity.