engleski

Evaluation of ageing properties of polymer mdified bitumen

Polymers are the most common modifiers currently being used to improve bitumen, BIT, viscoelastic properties. The polymers increase the temperature range over which a binder resists both rutting and thermal cracking as well as lengthening the time before fatigue failure. In this paper SBS block copolymer is used as polymer modifier. The ageing properties of polymer modified bitumen, PMB, have the main role in quality of PMB dispersions and solid PMB. In road application BIT and PMB dispersions are exposed to thermooxidative ageing in production of PMB dispersions, during their storage, mixing and transporting. The thermooxidative processes in PMB dispersions affect the quality and ageing processes of solid PMB in their service life. From this reason it is very important to determine the intensity of thermooxidative degradation of pure component as well as PMB dispersions. In the paper the bitumen and BIT/SBS blends are aged by means of Rolling Thin Film Oven Test, RTFOT, at temperature 163 oC in the presence of oxygen. The chemical and rheological evaluation of ageing properties of PMB is investigated. The oxidative degradations of BIT, SBS and BIT/SBS blends are followed by IR spectras. Thermooxidative stability of PMB is evaluated on the base of viscosity changes of PMB dispersions by rotational viscosimeter. The ageing of solid PMB is evaluated through the changes of viscoelastic behaviour by Dynamic Mechanical Analyzer, DMA. The changes in rheological properties, chemical and physical structures of aged PMB dependent on a combine effect of SBS and bitumen oxidation and degradation processes, which varied with the content of polymer. The relationships between rheograms, viscoelastic measurements, chemical and morphological structure of aged PMB is obtained. The intensity of ageing processes is established.

Polymer modified bitumen (PMB), Ageing, Thermooxidative degradation, PMB disperssion, Rheograms, PMB solid, Viscoelastic behaviour, Morphological Structure

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