Cutback bitumen is produced by adding a suitable solvent (e.g. kerosene or gasoline) to bitumen. The more solvent in Cutback bitumen, leads to the more viscosity in bitumen.
Cutback bitumen is used when there is limited access to heating equipment. The adhesive materials help the lower bitumen heating requirement before using and will evaporate as the bitumen is applied. Cutback bitumen is liquid at room temperature or liquefied with a little heat. This bitumen is used in road construction for surfacing and pavement, infiltration and on-site mixes, and it’s is more appropriate for cold regions.
The rapid-curing (RC) cutbacks are prepared by solving bitumen in gasoline. Due to the high rate of evaporation of gasoline, the bitumen dissolved in gasoline hardens faster.
RC cutbacks are divided into RC250, RC70, RC800 and RC3000 categories. The numbers indicate the viscosity of bitumen.
MC cutbacks are achieved by solving pure bitumen into kerosene which evaporates more slowly than gasoline. MC cutbacks are divided into five groups with their viscosity varying from 3-4 to 6,000 at 60 degrees Centigrade.
Slow-curing cutback are manufactured by solving bitumen in gasoil or fuel oil or directly from distillation of crude oil. SC cutbacks do not evaporate under normal weather conditions, but they gradually experience changes in their molecular form. SC cutbacks are divided into SC 70, SC 250, SC800 and SC 3000.
| Test | Mc30 | Mc 70 | Mc 250 | Mc 3000 | Method |
|---|---|---|---|---|---|
| Kinematic Viscosity @60o C (cst) | 30-60 | 70-140 | 25-500 | 3000-6000 | ASTM D-2170 |
| Flash point oc (tag) | Min 38 | Min 38 | Min 66 | Min 66 | ASTM D-3143 |
| Water Content% | Max 0,2 | Max 0,2 | Max 0,2 | Max 0,2 | ASTM D-95 |
| Distillation @190oC% | - | - | - | - | ASTM D-402 |
| Distillation @225oC% | 25Max | 20Max | 10Max | - | ASTM D-402 |
| Distillation @260oC% | 40-70 | 20-60 | 15-55 | 15Max | ASTM D-402 |
| Distillation @316o C % | 75-93 | 65-90 | 60-87 | 15-75 | ASTM D-402 |
| Residue of Distillation @360% | 50Min | 55Min | 67Min | 80Min | ASTM D-402 |
| Penetration @25oC. 10/mm | 120-250 | 120-250 | 120-250 | 120-250 | ASTM D-5 |
| Solubility in TCE | 99.0Min | 99.0Min | 99.0Min | 99.0Min | ASTM D-2042 |
| Ductility @25 o C 5cm/mm | 100Max | 100Max | 100Max | 100Max | ASTM D-113 |