What are the chemical compounds added to asphalt mix that help keep shingles waterproof and flexible?

The correct answer relates specifically to the role of volatiles in the formulation of asphalt shingles. Volatiles are chemical compounds that, when added to asphalt mixtures, play a crucial role in altering the physical properties of the asphalt. They help maintain the waterproof characteristics of the shingles while also contributing to their flexibility. This is especially important since shingles are exposed to various weather conditions, and the ability to maintain flexibility prevents cracking and ensures long-lasting performance.

While additives can generally enhance the properties of materials, they are a broader category that might not specifically convey the unique role of volatiles in this context. Filler materials usually refer to substances that provide bulk or alter the density of the mixture but do not primarily contribute to waterproofing or flexibility. Sealants, on the other hand, are used more in applications where joints or seams need to be made watertight, rather than in the fundamental mix of asphalt itself. In summary, volatiles are specifically responsible for enhancing the waterproof and flexible properties of asphalt shingles, which is why they are the correct choice.