Anyone who has ever driven over a pothole or had to navigate around a large crack understands that asphalt deteriorates and loses its structural integrity as it ages. Much damage to asphalt over time is caused by external factors, such as temperature fluctuations, harsh weather conditions, exposure to ultraviolet radiation from sunlight, and pressure from vehicles and other heavy loads.
Another critical factor in the long-term decay of asphalt surfaces is the chemical changes in the binding agents that hold the gravel together. While this is a complex topic that requires advanced knowledge to fully understand, here is a brief overview of what you need to know about the science of asphalt aging and its primary chemical causes.
Asphalt’s exposure to prolonged heat can lead to significant chemical changes that affect its lifespan and performance. Two key processes – volatilization and polymerization – occur when the binding agents sustain high temperatures and ultraviolet radiation.
Just as water can evaporate into vapor at high temperatures, the chemicals in asphalt binding agents can also vaporize when exposed to substantial heat over time, such as under direct sunlight. This process is known as volatilization.
A common issue in areas that experience hot climates is the “polymerization” of asphalt binding agents. This occurs when the molecules in these agents reform into polymers with different chemical structures, causing them to bond in various ways. For asphalt, polymerization often occurs after long-term exposure to heat and UV rays from direct sunlight.
Understanding these changes is crucial for maintaining asphalt’s structural integrity, especially in regions with intense sunlight.
The number of electrons revolving around a molecule or atom affects its chemical makeup and structure. When different particles interact, one may transfer electrons to the other. This transfer of electrons, which alters the chemical structure of the particles involved, is called oxidation. Despite the name, oxidation does not always involve oxygen. Long-term exposure to air is a common cause of oxidation in asphalt binding agents.
Thixotropy, also known as “steric hardening,” describes a chemical change in asphalt that occurs when it is exposed to cold temperatures for extended periods, causing the binding agents to become brittle. However, this change can be reversed with heat and happens only in temperatures below freezing.
Understanding what you need to know about the science of asphalt aging is essential. Chemical breakdowns can diminish your asphalt’s functionality and overall lifespan, leading to costly repairs. Fortunately, Integrity Paving & Coatings can help reseal, patch, repair, or replace your damaged asphalt and concrete. Reach out to us today for comprehensive paving services.
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