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Bitumen for paving applications

Excellent aging resistance

The 6th conference of European Asphalt Technology Association (EATA) took place in Stockholm on 15-17 June. Xiahou Lu from Nynas presented how the modified binders with SBS polymers display excellent aging resistance.

At the industry session of the conference, Xiaohu Lu, Senior Researcher at Nynas, made a presentation on Bitumen-Related Research in Nynas with special focus on bitumen chemistry and polymer modified bitumen (PMB).

Bitumen research in Nynas covers a quite wide range of areas, including basic bitumen chemistry, bitumen modification, asphalt paving at reduced temperatures, material characterization and performance testing, and various international collaborations such as participating in European projects and RILEM activities, and supporting fundamental research in universities and institutes.

 

The durability of PMB

As for polymer modified bitumen (PMB), basic aspects on morphology, storage stability and rheology were presented. It is evident that PMB morphology is dependent on the base bitumen and is largely affected by the temperature. The morphology of PMB has a strong effect on the mechanical properties of the binder, suggesting sample preparation is very important in binder tests, and also proper morphology is needed in order to improve asphalt mix performance.

The durability of PMB has been demonstrated by a number of applications/projects in Sweden, including porous asphalts in silent pavements, bridge deck application on the High Coast Bridge, as well as test road on E6 which is still on-going with VTI. In general, the modified binders with SBS polymers display excellent aging resistance and good rheological properties even after many years in the field. Enhanced asphalt performance in terms of fatigue, low temperature cracking and rutting was also observed.

In the area of bitumen chemistry, Nynas has developed a thermodynamic model, in which different molecules are kept in solution as a single-phase. By using solubility parameters, we can quantify chemical interactions in the bitumen. We also found a strong relationship between bitumen elasticity and certain molecular structures. Another topic under bitumen chemistry is natural wax. After a systematic study, we have now a better understanding of bitumen wax, especially in terms of chemical compositions and microstructures, as well as the impact on binder properties and asphalt mix performance.

22 countries participated

The conference was attended by over 100 people from 22 countries. About 30 presentations were made in nine sessions including one for industry. The addressed topics included additives and bitumen modification, asphalt mixture design and durability, testing techniques, materials modeling, pavement performance, and environmental aspects (warm mix asphalt, reclaimed asphalt pavement, etc.).