What component is fundamental to the structure of asphalt shingles?

The fundamental component of asphalt shingles is bitumen. Bitumen is a viscous, waterproof material derived from crude oil, which acts as a binding agent in asphalt shingles. It provides the essential qualities of durability, flexibility, and weather resistance that are crucial for protecting roofs. In asphalt shingles, bitumen forms the core foundation, ensuring that the shingles can withstand various environmental conditions, including rain, wind, and temperature fluctuations.

Cellulose, while it may be used in certain types of asphalt shingles as a reinforcement material, is not the primary or fundamental component. Instead, it plays a role in enhancing the structural integrity and improving the overall performance of the shingles, but it does not serve as the main component.

The other components, such as sand and granules, serve specific purposes in the functionality of asphalt shingles; sand helps in creating a textured finish and may aid in asphalt's solar reflectance, while granules are commonly added to the surface for UV protection and aesthetic appeal. However, neither sand nor granules fundamentally constitute the structure of asphalt shingles in the same way that bitumen does.