Final answer:
The current method to grade asphalt cement is through the Performance Grade (PG) system, which considers the expected temperature conditions and uses standardized tests to ensure the asphalt's suitability for different environments.
Step-by-step explanation:
The current way to grade asphalt cement is based on the Performance Grade (PG) system which accounts for the climatic conditions and expected temperatures (both high and low) the asphalt cement must endure. The grading system was developed through the Strategic Highway Research Program (SHRP) and is widely adopted in the PG grading system.
Specifically, the grade is designated by two numbers representing the average seven-day high temperature (in °C) and the minimum pavement temperature (in °C) designed to resist, such as PG 64-22. Further tests, such as the Dynamic Shear Rheometer (DSR) and the Bending Beam Rheometer (BBR), are used to determine the high-temperature and low-temperature performance of the asphalt binder, respectively. The performance-based approach allows engineers to select an appropriate asphalt cement grade for specific environmental conditions and expected loads.