What happens to asphalt binder at room temperature?

At room temperature, asphalt binder exhibits characteristics that lean towards becoming a solid. This is primarily due to its complex composition of heavy molecules that do not remain fluid at typical ambient temperatures. Although asphalt can flow at higher temperatures when heated, as the temperature decreases, the viscosity increases, causing it to thicken and eventually harden.

The texture and consistency of asphalt binder are affected by factors such as its molecular weight, the presence of additives, and environmental conditions. At room temperature, this leads to a state more akin to a solid, which is important for its performance in construction applications, as it provides structural stability for paving and roofing materials.

Other options describe states that do not accurately represent asphalt binder at room temperature. While it can exhibit some fluid behavior at elevated temperatures, it is not considered a fluid at room temperature. Evaporation is not a concern under normal conditions either, as asphalt binder consists of heavy hydrocarbons that do not readily evaporate. The semi-liquid state is also an overstatement since it does not retain sufficient mobility at room temperature to be considered semi-liquid; instead, it tends more towards a solid state.