B2Last®

Improving Bitumen Performance through Chemical Modification

Aging Behavior and Reusability of B2Last®-Modified Asphalt

Since 2015, RWTH Aachen University Chair and Institute of Highway Engineering and BASF SE are working together on the development of a new chemical bitumen additive. This additive called B2Last®, is a low-viscosity liquid that cross-links bitumen constituents. This network works as reinforcement between certain functional groups in the bitumen and influences its mechanical properties. More functional groups are created by bitumen aging due to oxidative aging. Therefore B2Last® works particularly well in asphalt mixtures with high proportions of asphalt granules. The asphalt granules’ bitumen has got more functional groups that function as docking sites for B2Last®. Presumably this improves the workability of asphalt mixtures with high proportions of asphalt granules. In 2019 and 2020 several routes have been asphalted with B2Last® in Germany and in the US. Laboratory results have shown that the additive can improve deformation stability and fatigue resistance of bitumen without affecting its low-temperature behavior.

In addition to that, after the initial paving of this modified asphalt with 50% asphalt granules, the construction crew considered it very well to work with. Following this first positive impression, further investigations have been carried out to determine whether it is possible to reduce the temperature during production and paving of asphalt. Results gained by laboratory research have shown that it is indeed possible to carry out the route’s construction at a temperature drop of 30°C.

This project focuses on aging processes and reusability of B2Last®-modified asphalt. For this purpose, extensive investigations are planned, both at bitumen and asphalt level.