B2Last^® - Questions and Answers

B2Last is an innovative liquid asphalt modifier developed by BASF. Unlike other modification systems which are blended and can separate, B2Last reacts with the liquid asphalt at a molecular level to improve the functional characteristics of the asphalt base.

At room temperature, B2Last is a low viscosity, black liquid. The additive neither contains water nor solvents. 

B2Last is a reactive liquid modifier rather than a solid polymer modifier allowing for a faster modification time. Rather than taking the time to develop and let down a concentrate, there is a requirement to allow B2Last to fully react with the liquid asphalt. Once reacted the result is a stable asphalt base with improved functionality.

The dosage of B2Last can be selected depending on the desired properties and the bitumen used. Previously, a B2Last content of 1% to 3% with regard to the total binding agent has proven to be practical (equal to approx. 0.8 to 1.5kg per metric ton of mixture).

B2Last significantly increases the useful temperature interval (UTI) of the liquid asphalt while maintaining workable levels of viscosity. B2Last also reduces stripping of the aggregates from the binder and leads to a more sustainable, flexible pavement.

B2Last is compatible with the majority of liquid asphalts. However, based upon the reactive groups within a given liquid asphalt, functional performance improvement levels are variable depending on formulation. Liquid asphalts can also be blended to increase compatibility with B2Last.

At storage temperatures of between 20°C and 25°C (68°F and 77°F) and excluding moisture, the shelf life of B2Last is at least 12 months. Storage is possible at temperatures of 0°C to 70°C (32°F and 77°F), but this may reduce the storage period. Collecting troughs can also be used to protect against leakages.

B2Last can be implemented in a liquid asphalt tank or terminal environment with minimum to no modifications to existing terminal operations. BASF technical support is available to discuss specific options for your terminal or tank environment.

B2Last, a liquid adhesive modifier can significantly increase and expand the Useful Terminal Interval (UTI); stiffen the asphalt while maintaining flexibility (does not become brittle), and crosslink with the asphaltenes in the asphalt matrix eliminating phase separation within the liquid asphalt.

Facilities implementing B2Last achieve are able to achieve operational savings due to reductions in time, labor and energy required to make and use traditional polymers. Since B2Last is a liquid that can be injected into liquid asphalt, so there is nothing to grind requiring less energy to produce. While time is required for B2Last to react with the liquid asphalt, batches of B2Last modified asphalts can be made on “On-demand” requiring significantly less time and personnel to produce.

In Hamburg Wheel Tracking tests for both laboratory and field mixes, B2Last has shown the ability to significantly reduce both rutting and stripping. Additional tests utilizing the Ideal-CT tests have shown Improved crack resistance over control mixes.

B2Last, a reactive liquid modifier, works differently than common asphalt modifiers that are blended into liquid asphalt. There is no need to create a B2Last concentrate as the modification reaction allows for on-demand modification

B2Last is compatible with other standard liquid asphalt modifiers, users of B2Last are encouraged to introduce B2Last first and complete the reaction before adding other modifiers such as styrenic block co-polymers and polyphosphoric acid. Additionally, certain asphalts have shown a highly complementary relationship between B2Last and SBS resulting in extremely modified asphalts with very workable viscosities.

The dosage of B2Last can be selected depending on the desired properties and the bitumen used. Previously, a B2Last content of 1% to 3% with regard to the total binding agent has proven to be practical.

While specific states vary in their authorized materials, B2Last is able to support both AASHTO M320 and M332 Performance Grade (PG) specifications. In many cases modified asphalt producers have noted that they are able to use less B2Last and simplify their formulations.

B2Last supports both AASHTO M320 and M332 DOT specifications. BASF technical services is available to work with you to evaluate your liquid asphalt to determine initial compatibility with B2Last.

Response from construction companies and their paving crews has been overwhelmingly positive. In paving operations in both the United States and Europe, paving crews have commented that there is significantly less “asphalt” smell as B2Last has the ability to lower Volatile Organic Compounds (VOC’s).

Paving crews have also commented that B2Last mixes have significantly less build up and need for release agent than traditional polymers. Finally, pavements modified with B2Last have improved compaction over traditional polymer modified asphalts.

Multiple field trials using B2Last have been completed in both the United States and Germany with its trial partners. Additional DOT and commercial trials are ongoing and being planned.

B2Last can be used in all asphalt layers (load-bearing, binder and top layers). The most experience gained with B2Last is based on stone mastic asphalt (SMA) and asphalt concrete (AC), however, use in other systems is conceivable. For example, use in mastic asphalt is currently being developed.

B2Last stiffens the liquid asphalt while maintaining a degree of flexibility to reduce cracking. This effect boosts both the rutting and fatigue behavior at high service temperatures while, providing enough elasticity to deliver excellent crack resistance at low service temperatures.

Common polymers used in liquid asphalts, tend to be solids. B2Last a liquid is different. Although B2Last has some polymeric properties it is actually based on a monomeric chemistry.

B2Last chemically crosslinks bitumen components to become a part of the asphalt matrix. Once the reaction is completed, B2Last enhances the functional characteristics of the liquid asphalt and cannot separate from the asphalt matrix. Most asphalt modifiers are “blends” that can separate from the liquid asphalt over time.