When can the prime coat be applied?

Answer: C — When the atmospheric temperature is above 40 degrees Fahrenheit

The prime coat can be applied when the atmospheric temperature is above 40 degrees Fahrenheit because this temperature ensures that the materials used in the prime coat can adequately adhere to the surface and properly react with the subsurface layers. Applying a prime coat in warmer conditions allows for better curing and adhesion properties, leading to a more effective bond between the pavement layers. Applying the prime coat at temperatures below 40 degrees Fahrenheit may result in poor adhesion and incomplete curing, which can compromise the integrity of the roadway. Similarly, applying the prime coat on a wet surface can lead to inadequate bonding, as moisture can interfere with the chemical reactions necessary for proper adhesion. High moisture content in the substrate can create similar issues, potentially leading to failure in the application. Therefore, the requirement for a minimum temperature ensures optimal conditions for the successful application of the prime coat.