ج. آوریل 19th, 2024

The relationship between the lifetime of street asphalt and air humidity

The relationship between the lifetime of street asphalt and air humidity

Street asphalt is a common material used for paving roads, driveways, and parking lots. It is composed of aggregates such as gravel, sand, and stone, and asphalt cement, which acts as a binder. Asphalt is durable, flexible, and economical, but it also has a limited lifespan that depends on various factors.

One of these factors is air humidity, which is the amount of water vapor in the air. Air humidity can affect the performance and durability of asphalt in several ways. In this article, we will explore how air humidity influences the lifetime of street asphalt and what can be done to extend it.

How air humidity affects asphalt

Air humidity can affect asphalt in two main ways: by causing moisture damage and by affecting the temperature.

Moisture damage occurs when water penetrates into the asphalt layer and weakens the bond between the aggregates and the asphalt cement. This can lead to cracking, raveling, potholing, and other forms of deterioration. Moisture damage can be exacerbated by freeze-thaw cycles, which cause expansion and contraction of the water in the pores of the asphalt.

The temperature of the asphalt is also influenced by air humidity. High humidity can lower the evaporation rate of water from the asphalt surface, which can result in higher temperatures and increased oxidation of the asphalt cement. Oxidation makes the asphalt more brittle and prone to cracking. Low humidity can increase the evaporation rate of water from the asphalt surface, which can result in lower temperatures and increased contraction of the asphalt. Contraction can also cause cracking and shrinkage of the asphalt.

The optimal range of air humidity for asphalt performance is between 40% and 60%, according to some studies. However, this may vary depending on other factors such as traffic load, pavement thickness, drainage conditions, and climate.

How to extend the lifetime of street asphalt

The lifetime of street asphalt can be extended by applying proper maintenance and rehabilitation techniques that prevent or mitigate moisture damage and temperature fluctuations. Some of these techniques include:

  • Seal coating: This involves applying a thin layer of liquid asphalt or emulsion over the existing asphalt surface to seal the cracks and pores and protect it from water infiltration and oxidation. Seal coating should be done every 3 to 5 years, depending on the condition of the pavement.
  • Crack sealing: This involves filling the cracks in the asphalt with a hot or cold applied rubberized material that prevents water from entering and expanding the cracks. Crack sealing should be done annually or as needed, depending on the severity of the cracking.
  • Patching: This involves removing and replacing damaged or deteriorated sections of asphalt with new material that matches the existing pavement. Patching should be done as soon as possible after detecting a problem, to prevent further deterioration and safety hazards.
  • Overlay: This involves placing a new layer of asphalt over the existing pavement to restore its smoothness, strength, and appearance. Overlay should be done every 15 to 20 years, depending on the condition of the pavement.
  • Recycling: This involves reusing the existing asphalt material by milling it off, heating it up, adding new binder and additives, and placing it back on the pavement. Recycling can reduce costs and environmental impacts by saving natural resources and reducing waste.

Conclusion

Street asphalt is a widely used paving material that has a finite lifespan that depends on various factors, including air humidity. Air humidity can affect asphalt by causing moisture damage and temperature fluctuations that can lead to cracking and deterioration. The lifetime of street asphalt can be extended by applying proper maintenance and rehabilitation techniques that prevent or mitigate these effects. By

doing so, we can ensure that our streets are safe, functional, and aesthetically pleasing for years to come.

Author : Hamidreza Aghdasi Minabi

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