Did you know that various types of cutback bitumen have different applications? Depending on the climate and the condition of the soil, various grades of cutback bitumen should be used.
Although MC-30 and MC-70 both perform well in the process of road construction, they are not the same in terms of specifications and applications. Thus, they cannot be applied to a base interchangeably. That’s why in this article, we are going to take a broader look at MC-70 cutback bitumen as well as its applications and advantages.
What is MC-70 Cutback Bitumen?
MC-70 cutback bitumen is one of the most widely used grades of bitumen across the world. This grade of bitumen is in the category of medium curing cutback bitumen and its viscosity is 70min and 140max.
Bitumen MC-70 is produced by adding medium volatility solvents (generally kerosene) to ordinary bitumen. This grade of cutback bitumen is widely used for prime coating in a moderate climate. With the help of MC-70 bitumen, we bind and waterproof the aggregates in the road base, before placing the final layer of asphalt on the surface.
Since MC-70 bitumen is in the category of medium curing cutback bitumen, it penetrates the base at a moderate speed and needs 48 hours to evaporate.
MC-70 Bitumen
What are the Applications of MC-70 Bitumen?
MC-70 bitumen (also called MC-70 asphalt) is designed to be used as a primer in coating roads. This grade of bitumen is usually heated and sprayed on the road base, before the final layer of asphalt is laid.
Since the kinematic viscosity of MC-70 ranges from 70 to 140, it will properly coat and bond loosely bonded and fine grained soils such as well graded sand. It is, thus, not suitable for densely graded base courses. For these types of bases, MC-30 cutback bitumen performs better. Find out more in our article about the differences between cutback bitumen MC-70 and MC-30.
Another use of MC-70 bitumen is for dust control on unpaved roads. Since cutback bitumen contains hazardous solvents, its application for controlling dust is prohibited in some countries.
How to Use MC-70 Bitumen?
There are a few points that need to be considered before the application of MC-70 cutback bitumen. The recommended application temperature for MC-70 is 50 °C. Before the application of MC-70 in prime coat, the course should be clean and the primer needs to be heated for spraying.
When applying MC-70 bitumen on a road base, the surface must be clean and its temperature needs to be 10 °C.
Specifications of MC-70 Bitumen
| Cutback Bitumen Medium-Curing-70 Specifications | |||
| Properties | Specification Limit | Test Method | |
| Min | Max | ||
| Kinematic viscosity at 60°c ,cST | 70 | 140 | ASTM D2170 |
| Flash point(tag open cup), °C | 38 | — | ASTM D3143 |
| Distillation test Distillate, volume per cent of total Distillate to 680°F (360°C) |
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Residue from distillation to 437°F (225°C) to 500°F (260°C) to 600°F (316°C) to 680°F (360°C), per cent volume by difference |
— | 20 | ASTM D402 |
| 10 | 70 | ||
| 65 | 93 | ||
| 55 | — | ||
| Test on residue from distillation test | |||
| Viscosity at 140°F (60°C) | 30 | 120 | ASTM D2170 |
| Penetration 77°F (25°C) 100g, 5s mm | 120 | 300 | ASTM D5 |
| Ductility 77°F (25°C) 5cm/min cm | 100 | — | ASTM D113 |
| Solubility in trichloroethylene % | 99 | — | ASTM D2042 |
| Water, percent volume | — | 0.2 | ASTM D95 |