Sustainable road construction with B2Last®

Are you looking for a sustainable yet high-performance bitumen additive? BASF developed an intelligent and innovative bitumen modification that helps you in significantly reducing CO2 and bitumen emissions and making roads more durable.


Be it an increasing heavy load traffic or more extreme weather conditions because of climate change – today, road surfaces are subjected to ever-higher stresses. Additives for bitumen play a decisive role in the durability of asphalt. At the same time, occupational health and safety, environmental protection and the reduction of CO2 emissions are of high importance for road construction. 

With B2Last®, BASF has developed an innovative bitumen additive that combines both asphalt performance and sustainability: Temperature-reduced paving with a high recycled asphalt content is made possible through the use of B2Last®, while guaranteeing consistent workability. This creates significantly lower bitumen and CO2 emissions, while the asphalt resistance is also increased, thereby extending the life span of the road.

B2Last® is therefore the bitumen additive for sustainable road construction.


Your benefits at a glance

  • Increased asphalt performance – Using B2Last increases the hardness and elasticity of the asphalt. This increases the life span of the road.
  • Saving primary resources – Using large amounts of asphalt granulate (AG) is also possible at reduced laydown temperatures, while retaining unchanged workability of the asphalt mix.
  • Reduced CO2 emissions – 30-40 °C lower asphalt mix production and laydown temperatures (warm mix asphalt) This saves energy and resources.


Reactive modification of bitumen

B2Last crosslinks bitumen components to form a polymeric network with strong elastic properties and excellent durability and crack resistance across a wide range of temperatures. B2Last is integrated into the polymeric network and is fully consumed during the reactive modification. 

The dosage amount for B2Last increases the elasticity and softening point, while the low-temperature behavior remains unchanged. The selection of the virgin bitumen enables the temperature properties to be adapted. This makes it possible to flexibly vary the performance of the binding agent across a wide range. 

Asphalt specimens (reactive-modified and non-modified) after the pressure swell test

Temperature-reduced installation through reactive modification  

B2Last is homogenized with bitumen during the manufacturing process of asphalt. The flow capability of the binding agent is initially increased through B2Last as a low-viscosity liquid. This enables the manufacturing and processing temperatures of the mixed product to be reduced without negatively affecting the compactability.

Throughout the transport and installation processes, reactive modification causes B2Last and bitumen to form a polymer network. Here, reactive groups in the bitumen components act as anchors for B2Last. In particular bitumen from asphalt granulate (AG) displays a high content of reactive groups, enabling high connectivity of virgin bitumen to recycled bitumen. This guarantees excellent workability of the mixed product, as well as enabling the use of high AG content. Following the complete compacting process and cooling of the asphalt, the reactive modification is complete and the asphalt displays its maximum stability.



The chemistry behind reactive modification

The components in bitumen form an interconnected network following reactive modification. This chemical networking primarily takes place between the contained resin and asphalt components. This is due to the fact that they possess a particularly high content of what are known as functional groups. It is on these groups that B2Last docks during the production and processing of the asphalt. 

Interaction with aged bitumen from asphalt granulate (AG)

The bitumen from recycled asphalt granulate displays a high content of asphalts and increased functionality. This aspect also has a positive effect on the reactive modification. B2Last can use this bitumen to establish an especially dense network and also establish good crosslinking of the different bitumen types. The binding agent becomes more homogeneous and allows excellent workability of the produced asphalt mix, even when it contains a high content of recycled asphalt.

Bitumen aerosols and vapors

B2Last enables asphalt mix production and laydown temperatures below 140 °C (warm mix asphalt) and thereby reduces bitumen aerosols and vapors. For asphalt applications, a reduction in emissions on the site of up to 65% can be achieved compared to a reference project performed at around 170 °C (hot mix asphalt). B2Last can therefore make an important contribution to complying with the limit value of 1.5 mg/m³ which will apply in Germany from 2025. 

Product safety

We value the health and safety of people above all else – in all plant trials, we instruct our customers on safe processing and handling the product. The product emissions are also recorded during the manufacturing and processing steps of B2Last modified mixtures. Here, the numerous measurements in practice confirm that the emissions produced during the manufacturing of modified mixtures with B2Last are significantly below those of the maximum permitted workplace concentrations.

Measurement of bitumen emissions
B2Last - Asphaltierung der PWC-Anlage A96 Kreuzlinger Forst am 19.06.2019
Measurement of product emissions

Our solution for sustainable road construction

  • Reduced asphalt mix production and laydown temperatures at still high reclaimed asphalt ratios while maintaining asphalt performance and its excellent workability
  • Less energy needed for heating bitumen, aggregates and reclaimed asphalt
  • Occupational health & safety – less bitumen emissions, B2Last® makes work safer
  • Enables high reclaimed asphalt ratios – saving primary resources
  • Increased road life time – excellent rutting behavior and fatigue resistance across broad temperature range
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The new additive has already successfully been tested in real-life conditions

Alongside several stretches of road in the USA, several kilometers of public roads in Bavaria, North Rhine-Westphalia and in Rhineland-Palatinate have been paved using the product. The modified asphalt impressed everywhere, not just in regard to manufacturing and installation, but also during performance testing thanks to its excellent properties.