Bitumen 60/70 and 80/100 are two widely used grades in road construction and asphalt industries. Each of these bitumens has unique characteristics that are more suitable for certain climatic conditions and projects. In this article, we will examine the differences, similarities and applications of each of these grades.
Definition
Bitumen 60/70
This grade is placed in the category of medium penetrating bitumen and due to its relative hardness and suitable flexibility, it is considered one of the most used grades in asphalt construction. The number “60/70” indicates the penetration range of bitumen at 25°C (between 60 and 70 tenths of mm).
Bitumen 80/100
This grade is softer than 60/70 bitumen and is usually used for areas that require more flexibility. The permeability of this bitumen at 25 degrees Celsius is between 80 and 100 tenths of mm.
Important differences
Hardness and flexibility
Bitumen 60/70 is harder than bitumen 80/100 and is more resistant to deformation at high temperatures. 80/100 bitumen is more flexible due to being softer and causes less cracking at low temperatures.
Resistance to temperature
Bitumen 60/70 is more stable at high temperatures and is more suitable for areas with hot summers. Bitumen 80/100 performs better at low temperatures and is more useful in cold regions where there is a possibility of freezing and thermal expansion.
Uses
Bitumen 60/70
Bitumen 60/70 is suited for highways, busy roads, and areas where the asphalt is going to face heavy pressure and wear. 60/70 bitumen is harder and, as such, can withstand heavy loads and hot temperatures without deforming or rutting. It is often used in urban centers, main roads, and highways with high traffic volumes, and zones with higher ambient temperatures. Here, in those areas where road surfaces are subjected to high stress from traffic as well as atmospheric conditions, 60/70 bitumen provides a more durable and stable road surface.
Bitumen 80/100
On the other hand, Bitumen 80/100 is more elastic and softer than 60/70 and is therefore utilized in low-traffic roads, rural roads, and uses requiring a higher degree of elasticity, especially under cold conditions. Higher elasticity avoids crack or surface damage when the asphalt expands or contracts with the temperature change. Bitumen 80/100 is generally used in less busy roads where the need for high-performance heavy duty is less, and where the weather is more susceptible to temperature fluctuations. This type of bitumen is ideal for country roads, small streets, and areas where roads are exposed to freezing temperatures or fluctuating temperatures due to the flexibility which will not easily crack under such weather conditions.
Climatic Conditions
Bitumen 60/70 in Tropical and Temperate Climates
Bitumen 60/70 is stiffer than bitumen 80/100, having improved stability at high temperatures. In tropical climates with steep temperature rise, softer bitumen can become loose and lead to permanent surface deformation, i.e., rutting. Bitumen 60/70 is less prone to this issue due to its higher hardness.
For urban areas or highways with heavy traffic under high-temperature conditions, high resistance bitumen is required, and bitumen 60/70 is best for such conditions.
In tropical countries where there is little or no difference in temperature between day and night, there is less risk of thermal cracking, a situation where 60/70 bitumen is effective.
Bitumen 80/100 in Cold and Moderately Cold Conditions
Bitumen 80/100 is softer than 60/70, being more flexible at low temperatures. The harder bitumen may be brittle in cold weather, leading to cracks, but 80/100 bitumen’s flexibility negates this effect.
The temperature fluctuations that occur daily, as well as during seasonal changes, in cold weather can cause the asphalt to expand and contract. Bitumen 80/100 is better able to handle the fluctuations, meaning that there will be less chance of cracking.
In areas where snowfall or freezing temperatures are prevalent, 80/100 bitumen’s elasticity reduces the harmful effects caused by the freeze-thaw cycle and deicing operations.
Conclusion
The difference between 60/70 and 80/100 bitumen is their penetration rating, which indicates the hardness and acceptability of the bitumen. 60/70 bitumen is harder and less permeable, so it is more suitable for areas with high temperatures or under heavy traffic, as it provides greater thermal resistance and strength. In contrast, 80/100 bitumen is softer and more consumable and is suitable for cooler areas, as it does not crack at lower temperatures.
to make the right choice between 60/70 and 80/100 bitumen, one must consider the type of project, weather conditions, and costs.
Both grades may be suitable when the project is in a temperate climate. But factors such as the type of traffic load, costs and project priorities can play a role in the final decision.
