Modifications of asphalt materials and applications through processing and usage of additives has been under development for more than 100 years. Factors such as the requirement of performance graded asphalt specifications, rise in heavy traffic patterns, efforts to recycle waste, new technologies for refining materials and developments in the field of copolymer chemistry have resulted in the growth of novel asphalt binders in the recent past.

It is important to note that all such changes in terms of modified asphalt binders have a cost associated to it, which makes it important for manufacturers and end users to track relevant performance parameters, which can be supported by changes in production processes and additive improvements.

Engineering efforts have been pushing for the development of specific mix and binder properties, for unique applications. The end results of modifying asphalt surfaces are largely dependent on factors such as the grade of the base asphalt, concentration, refining process, molecular weight, the crude sources, chemical composition, the additive’s molecular characteristics, and particle size.

Polyphosphoric Acid Use Driven by Rheology Changes in Asphalt Binders

Polyphosphoric acid has been a mainstream ingredient in asphalt binder formulations in the recent past, and is often used either in combination with synthetic polymers, or as a solo modifier in asphalt binders, and is rapidly finding traction in novel, advanced asphalt and bitumen paving applications. The trend can be attributed to its resistance to varied weather and traffic conditions.

Polyphosphoric acid is largely used in an air-blowing oxidation procedure, in the form of reactive polymer additives used in bitumen, which reacts to certain components in asphalt involving the use of specific elastomeric types of polymers. In such applications, polyphosphoric acid boosts the performance grade of asphalt binders in terms of high temperature applications, without compromising on low temperature characteristics.

Asphalt is a colloidal substance comprising asphaltenes, which is covered with polar resins and saturate and aromatic oils. The addition of polyphosphoric acid increases the asphaltene concentration, while cutting down the concentration of resins, which can have a substantial impact on the reorganization of asphaltene structures in the asphalt mixes. This affects the rheological properties of the asphalt binders, which enables greater resistance against stress and temperature changes in comparison to neat asphalt formulations.

The key benefit of such combinations is that the polymers in asphalt and polyphosphoric acid in combination, achieve optimum performance in the binder material. Such combinations reduce the need for including antistripping agents for asphalt formulations, by bolstering the properties of adhesion.

Further, the application of polyphosphoric acid with either ethylene and propylene terpolymers or SBS has proven to result in superior end products, than by the individual polymer modified bitumen materials. Alternatively, polyphosphoric acid in combination with crumb rubber modified bitumen enables desired modifications, without the drawbacks that are associated with higher dosage formulations.

This not only improves elastic recovery, but also aids in better PG ratings, and stability in storage. Consequently, paving processes require lower amounts of binders in asphalt formulations in comparison to a pure crumb rubber modification process.

Finally, the addition of polyphosphoric acid has been found to not increase the speed of aging in asphalt surfaces, but in fact has been found to slow down aging in select conditions. The application has been proven through studies of a range of crudes, which demonstrated the reduction of asphalt oxidation, while boosting aging performance in low and high temperature environments.

UPM Asphalt Binding Materials Gain Traction in Repair Applications

In terms of troubleshooting problems in concrete or asphalt surfaces, including large cracks, disintegration, or pot holes, operators in the transport infrastructure industry have been pushing for the adoption of UPM.

UPM is rapidly gaining popularity as a cold mix asphalt patch of high quality standards, which has found specialized use in repair applications in asphalt paving surfaces. The material is not only convenient in terms of usage, but also does not require any specialized machinery for application. It has gained a reputation for high durability, and has consequently become a material of choice in numerous countries around the world, providing similar performance standards to hot and warm mix asphalt additives, without the temperature constraints.

UPM is suitable for applications in wet and dry weather conditions, with various formulations available, which is designed to take external temperatures into account, assuring superior results after application. Further, UPM works by a very fast rate of curing at a surface level, which means there is minimal down time before a repaired piece of road is accessible to traffic. On the other hand, the lower levels of UPM cure at slower rates, which allow for contraction and expansion of the material into the surrounding asphalt bolstering surface bonding properties.

Applications in Asphalt Types Drive Demand for Unique Binders

Asphalt formulations can be largely classified into type 1, type 2 and type 3 variants. Of these, type 1 asphalt is a type of oxidized bitumen formulation usually available in bulk liquid forms. This type of asphalt binder is commonly used for applications with cover boards, organic felt, and insulation. Type 2 variants can also be used with glass felt, and modified membranes, in addition to higher slope cover boards. Finally type 3 alternatives allow applications of latex modified bitumen rolls, flashing systems, vertical slope applications, and a number of damp proofing applications.

With the requirements of modern transport infrastructure, binders are supplemented with the use of asphalt rejuvenator materials to extend the life of asphalt surfaces, while keeping the costs of construction activities to a minimum.

Asphalt pavement rejuvenators are bituminous emulsifier treatments for asphalt surfaces, which have been developed to protect and preserve road surfaces, and have rapidly gained popularity for applications in cities, and municipalities. These products supplement and replenish asphalt binder materials, which has aged with weathering and oxidation, with the objective of bolstering the service life of the roads. Such materials provide an eco-friendly and economical alternative to the conventional asphalt overlay operations, bolstering the adoption of polymer modified binders as a feasible option.