Bitumen is ‘cutback’ by adding controlled amounts of petroleum distillates such as kerosene. This is done to reduce the viscosity of the bitumen temporarily so it can penetrate pavements more effectively or to allow spraying at temperatures that are too cold for successful sprayed sealing with neat bitumen. The materials used to cutback bitumen will evaporate after application to leave the remaining material similar in hardness to the original bitumen.
Applications of Cutback Bitumen in Bituminous (asphalt) Pavement Construction and Maintenance:
· Prime and Tack Coating
The process of priming involves applying a low viscosity binder to a prepared but usually unbound aggregate base. It is intended to be absorbed by the top layers of the base and provide a surface more easily ‘wetted’ by a subsequent bituminous covering. The primer will be able to carry traffic for a short time (although this practice is uncommon) and help control dust. Generally, primers are applied at rates between 0.5 and 1.4 L/m2. Cutback bitumens suitable for priming are also used for tack coats, which are applied to an underlying surface to help with the adhesion of subsequent asphalt layer. A typical application rate is between 0.2 and 0.4 L/m2.
· Prime Sealing
Where temperatures are too cool for an effective priming operation, or where traffic is likely to upset a primed surface before the final seal can be sprayed, a primer seal can be used to give adequate protection of the pavement for periods of up to 6 to 12 months. Cutback bitumens suitable for primer sealing can also be used in the manufacture of pre-mix asphalt, which is used in patch repairs.
· Spray Sealing
Cutback bitumens are used extensively in sprayed sealing applications, particularly in cooler weather where they provide improved initial stone retention due to their lower viscosity. Typically, a single application of the appropriate cutback bitumen is sprayed onto the primed pavement onto which aggregate is laid.
Eagle Petrochem supplies and provides transfer of technology for production of all cutback Bitumens in correspondence to ASTM D2026, D2027, D2028, AASHTO M82-75 (2008), AASHTO M92-92 (2008).
Rapid Curing Cutback Bitumen is made by reducing the viscosity of and ordinary bitumen by adding mostly petroleum type solvent. Cutback Bitumen are used because their viscosity is lower than that of neat asphalt and can thus be used in low temperature applications.
In many places, cutback asphalt use is restricted to patching materials for use in cold weather cutback MC-30 is medium curing (MC) cutback asphalt consisting of penetration grade asphalt cement and diluent or cutter of medium volatility.
The invention relates to bitumen cutback, in particular to the use of fatty acid esters as bitumen cutback agents. These bitumen cutback agents may also be described as cutters, cutback additives, bitumen solvents, or bitumen thinners.